CROWN AND TILLER FORMATION IN WHEAT AND BARLEY Thesis for the Degree of Ph. D. MICHIGAN STATE UNIVERSITY WILLIAM ELLIOTT HALL. 1969 LIB R A F Y Michigan '3 .153 University This is to certify that the thesis entitled ‘ CROWN AND TILLER FORMATION IN WHEAT AND BARLEY presented by William Elliott Hall has been accepted towards fulfillment of the requirements for __P_@___ degree in M11 Sci ences flajhr professor Date @307 415: /?éi 0-169 " BINDING av ; A" INIAB & SflIS' 500K BINDERY INC. L I " unmnv BINDERS I A; 4. L. ,-_h#!" EXpe :ion and ti: 0f the cram 569th. Lig‘. location of Ever 11:15 ¢ ccleOptiles light. Em; +. .10?“ bet-wee: seedlings t: ”Odes. Bar' COGES than ‘ depthS. whee wove the 01 ually Cove] ABSTRACT CROWN AND TILLER FORMATION IN WHEAT AND BARLEY BY William Elliott Hall EXperiments were conducted to study the crown loca- tion and tiller formation in wheat and barley. The location of the crown was manipulated by altering light and seeding depth. Light played an important role in determining the location of the crown. Seedlings grown in pots under tar paper lids deve10ped crowns above the soil surface after the coleOptiles were threaded through holes in the lids into the light. Environmental conditions promoting extreme elonga- tion between the seed and crown caused wheat and barley seedlings to produce one or more subcrown nodes and inter— nodes. Barley had shorter and more numerous subcrown inter- nodes than wheat, but failed to emerge from excessive seeding depths. Wheat and barley seedlings deve10ped second crowns above the original crown when emerged seedlings were par— tially covered during the tillering stage. The second mm develc shallot seed Var) through col< location. William Elliott Hall crown develOped closer to the soil surface than crowns from shallow seeding. Varying the light intensity by growing seedlings through colored beads disclosed the role of light in crown location. in CROWN AND TILLER FORMATION IN WHEAT AND BARLEY BY William Elliott Hall A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Crop and Soil Sciences 1969 Clo/m" Lg ..» 2. .3 ”" / 0 ACKNOWLEDGMENTS The author wishes to eXpress his sincere apprecia— tion to Dr. C. M. Harrison for his encouragement during the course of this investigation and for his helpful suggestions and criticism while preparing the manuscript. Many thanks are also due to Drs. J. E. Grafius, E. H. Everson, A. E. Erickson and L. W. Mericle who served as guidance committee members and gave helpful suggestions for manuscript preparation. Grateful appreciation is eXpressed to the Michigan CrOp Improvement Association whose financial assistance made this study possible. The moral support and sacrifice of the author's family during the course of this investigation is also recognized and deeply appreciated. ii TABLE OF CONTENTS LIST OF TABLES O O O O O O O O O O O O O O O O O O 0 LIST OF FIGWES O O O O O O O O O O O O O O O O O 0 INTRODUCTION 0 O O O O O O O O O O O O O O O O O O 0 REVIEW OF LITERATURE . . . . . . . . . . . . . . . . PROCEDWES . O O O O O O O O O I O O O O O O O O O O EXPERIMENT I. SEEDBED PREPARATION AND DEPTH OF SEEDING . . II. THE EFFECT OF DAYLIGHT, DEPTH OF SEEDING, SOIL PRESSURE AND VERNALIZATION ON CROWN FORMATION AND TILLER PRODUCTION . . . . . III. THE EFFECT OF DEEP FURROW SEEDING AND CROWN COVERING ON PLANT SURVIVAL, LOCATION OF THE CROWN AND TILLER FORMATION . . . . . . IV. THE EFFECT OF SEEDING RATE AND FURROW TREATMENT ON TILLER FORMATION AND CROWN IOCATION . O O O O O O O O C O O O O O O O V. DETERMINATION OF WAVE LENGTH OF LIGHT AFFECTING CROWN LOCATION . . . . . . . . . VI. TO DETERMINE IF LIGHT QUALITY ON THE SOIL SURFACE INFLUENCES CROWN LOCATION . . . . DISCUSSION 0 O O O O O O O O O O O O O O O O O O O O CONQ‘US IONS O O O O O O O 0 O O O O O O O O O C . 0 B IBLIWRAPHY O O O O O O O O O O O O O O O O O 0 ° . iii Page iv vi 10 ll 18 34 46 55 64 79 82 84 Table Ave: of 1 fir: The of I dif Per loc Fre bea Jun on The in Olc‘ The cer Cu: AVE (211‘ LIST OF TABLES Table Page 1. Average depth of seeding and crown location of two barley varieties seeded in soft and firm seedbeds, September 1965 . . . . . . . . . 12 2. The average number of tillers per plant as of April 1965 on‘Wong barley seeded at different depths . . . . . . . . . . . . . . . l4 3. Percent of plants forming tillers at various locations when seeded at two depths . . . . . . 15 4. Frequency table showing plants and head- bearing tillers per three foot row on June 23, 1965 in barley nurseries seeded on differently prepared seedbeds . . . . . . . 17 5. The average number of tillers on five plants in cultures on January 27, 1965 (12 weeks Old) 0 O O O O O O O O O O O O O O O O O O O O 22 6. The average number of tillers over 2.54 centimeters in length of five plants in cultures on May 12, 1965 . . . . . . . . . . . 23 7. Average tillers per plant in cultures receiving early cold treatment and comparable cultures receiving later cold treatment . . . . 25 8. Average tillers per plant on May 12, 1965 in cultures seeded at the 2.5 centimeters depth and having 5.1 centimeters of soil added after emergence compared to cultures seeded at 2.5 and 7.6 centimeters . . . . . . . . . . 28 9. Average length of subcrown internode of five wheat and barley plants in covered and uncovered pots at various seeding depths as measured May 12, 1965 . . . . . . . . . . . . . 31 iv Table 10. ll. 12. l3. 14. 15. l6. l7. l8. 19, 20, 21. Lengt treat 7.6 c Avere plot Avera on te methc Aver; BRO l methc Aver; from treat Avere row! furr< Aver; Varit and ; AVerl seed AVeII Crow, IEaf LGad Phot file and Perc and I Cand meas filt AVQr Chlo IEaf Unde Table 10. ll. 12. l3. 14. 15. l6. 17. 18. 19. 20. 21. Length of subcrown internode of early cold treated plants and other plants seeded at 7.6 centimeters as measured May 12, 1965 . . Average plant survival of varieties in plot treatment on March 1, 1966 . . . . . . . Average number of tillers and their location on ten plants produced with different seeding methods, counted April 21, 1966 . . . . . . . Average depth of crown formation of wheat and barley grown with different seeding methods as measured April 21, 1966 . . . . . Average number of plants per three foot row from different seeding rates and furrow treatments, July 21, 1966 . . . . . . . . . . Average number of tillers per three foot row produced by different seeding rates and furrow treatments, July 21, 1966 . . . . . . Average tillers per plant produced by varieties in different rate of seeding and furrow treatments, July 21, 1966 . . . . Average yield of grain produced by different seeding rates and furrow treatments . . . . . Average measurements of subcrown internode, crown to chloroPhyll, and length of tallest leaf of wheat plants grown through colored beads, May, 1969 . . . . . . . . . . . . . . Photometric data for colors of cellophane filters as determined by SpectrOphotometer and calculated at peak light transmission . . Percent of light transmitted, foot-candles and energy values received from 2500 foot- candle light source as determined by measured Optical density of each cellOphane filter . . . . . . . . . . . . . . . . . . . Average distance from seed to crown, area of chlor0phyll development, and tip of tallest leaf of wheat and barley seedlings grown under cellOphane filters, May 1969 . . . . . Page 32 37 40 42 50 51 53 54 62 68 71 75 Figure Corr for Cul of on Con ple vex Ple aft the see Figure 1. LIST OF FIGURES Comparison of seeding depth and crown formation in soft and firm seedbeds . . . . . Cultures to study effect of daylight, depth of seeding, soil pressure, and vernalization on crown formation and tiller production . . Comparison of plant growth made prior to placing cultures in the cold room for vernalization . . . . . . . . . . . . . . . . Plants of Gaines wheat both seeded at the 7.6 centimeter depth and dug six months after seeding. Plant No. 7 was placed in the cold room early, three weeks after seeding, where it remained for 120 days. Plant No. 6 was placed in the cold room at 60 days after seeding where it remained for 60 days . . . . . . . . . . . . . . . . . Seedlings growing in pots covered by tar paper lids often produced the crown above the soil surface . . . . . . . . . . . . . . Plant of Gaines wheat seeded at depth of 10.2 centimeters produced a node at 2.2 centimeters and a crown at 7 centimeters above seeding depth . . . . . . . . . . . . . Two crowns were formed by Hudson (33) and Gaines (5) when 5.1 centimeters of soil was added to pots after plants emerged from a 2.5 centimeter seeding depth . . . . . . . . Size and tillering of seedlings of Hudson (H), Wong (W) and Avon (A) at time of closing half the deep furrow plots. Seeding treat- ments are (S) shallow seeded, (F) deep furrow and (D) deep seeded . . . . . . . . . . . . . vi Page 13 20 24 27 29 30 33 36 F igure 10. ll. 12. l3. 14, 15, 18, 19. P101 fur] are $86! sha dee Air eXp Air eXp Whe on Huc‘ wer dee ric the We] Figure 9. 10. ll. 12. l3. 14. 15. l6. l7. l8. 19. Page Plot treatments after closing the deep furrows lower left. The Open deep furrows are shown directly above them. The deep seeded plot is at the lower right and the shallow seeded plot is adjacent to the Open deep furrow plot . . . . . . . . . . . . . . . 39 Air and soil temperatures of furrow plot eXperiment, January 25 to February 2, 1966 . . 43 Air and soil temperatures Of furrow plot eXperiment, February 8 to 16, 1966 . . . . . . 44 Two furrow treatments applied to winter wheat and barley to determine the effect on crown location . . . . . . . . . . . . . . . 47 Hudson barley in the foreground where ridges were leveled and crowns covered. The Open deep furrow plots are in the rear. The ridges have sloughed down somewhat during the winter season. Stands in both plots were considered the same . . . . . . . . . . . 49 Wheat seedlings emerging through colored beads from seeding depths of eight centimeters . . . . . . . . . . . . . . . . . . 56 Percent of light transmission at different wave lengths through glass beads . . . . . . . 58 Average height, location of chlorOphyll and crown development on wheat plants grown through colored beads . . . . . . . . . . 59 Location of crown develOpment on wheat plants grown through red beads on the left and black beads on the right . . . . . . . 60 Comparison of location of crown develOpment of Avon wheat plants in relation to layer Of beads C O O O O O O O O O O O O O O O O O O 61 Colored cellophane paper used as filters to restrict wave length reaching soil surface in pots . . . . . . . . . . . . . . . . 65 vii Figure 20. 21. 22. 23. Perce lengt Grow: under ble 9 same to m: the r Perce barle filte Whea cold dept' Figure 20. 21. 22. 23. Percent transmission of different wave lengths through cellOphane filters . . . . Growth of wheat and barley seedlings made under colored cellOphane filters. Compara- ble growth was made between filters of the same color, but different energy values due to multiple layers Of cellOphane except for the red filters . . . . . . . . . . . . . . Percent of seedling emergence of wheat and barley sown under colored cellOphane filters 0 O O O O O O O O O O O O O O O O 0 Wheat and barley seedlings grown under colored cellOphane filters from seeding depth of eight centimeters . . . . . . . . viii Page 67 69 72 74 Ear tillering 5‘: production use excessi per unit a1“ detrimental competition A h environmer‘xt contains t1“ barley vari in the Spri system and deve 10pme n1 tile lengt] 1964) has restr ictim INTRODUCTION Early agriculturalists recognized the value of tillering and crown formation in small grain plants. Tiller production is variable, however, and a common practice is to use excessive seed to insure a sufficient number of heads per unit area for high yields. Such excess seeding may be detrimental to yields when limited rainfall results in plant competition for available moisture. A better understanding is needed of the influence of environmental factors affecting the crown region. The crown contains the meristematic tissues of overwintering wheat and barley varieties from which comes the resumption of growth in the Spring. It is also the origin of the secondary root system and the site of tiller bud formation. The recent develOpment of the semi-dwarf wheat varieties whose coleOp— tile length is also reduced (Allen _E._l., and Sunderman, 1964) has added to the problem of establishing a stand by restricting seeding depth. With the advent of hybrid wheat production and the anticipated high cost of seed, the effect of seeding rates will be carefully analyzed and reduced to a minimum making tillering increasingly important. The affecting t' tillering. of the crow production the greates night allev dwarf wheat The purpose of this research is the study of factors affecting the location of the crown and its relationship to tillering. If it were possible to manipulate the location of the crown, better winter survival and more uniform tiller production might be achieved. Cultural practices to promote the greatest possible elongation of the subcrown internode might alleviate the depth Of seeding problem Of the semi— dwarf wheat varieties. Sev develOpment (1921) has ' production. studies com of corn, wh detailed de the oat pla Som interpretat ”“311 (193 homolOgies m In node and th bEtWeen the during germ PIESentS tit ShOot and a srwth pro; cereals t0 REVIEW OF LITERATURE Several references are available eXplaining the develOpmental anatomy and morphology of grasses. Percival (1921) has written a complete treatise on wheat and wheat production. Avery (1930) and McCall (1934) made anatomical studies comparing the develOpment of embryos and seedlings of corn, wheat and oats. Bonnett (1961) has given a detailed description of the histology and develOpment of the oat plant. Some confusion has existed in the terminology and interpretation of the grass embryo and its develOpment° McCall (1934) did much to clarify the terms and eXplain the homolOgies existing between three genera Zea, Triticum, and Azggg. In all three, the scutellum diverges from the second node and the coleOptile from the third node. The difference between the three lies in the location of intercalary growth during germination and seedling develOpment. Esau (1953) presents the modern View of anatomical differentiation in shoot and axes and cites 73 references on this complex growth process. Robbins (1931) compared the tillering Of cereals to the branching of other herbaceous plants except that it occurred at the lower nodes. He stated that the average depth Of the tillering node in cereals was about one to two been plant normal pro grasses. internodes node of th Weaver (19 roots) of surface. tion to t} described two sets c PIOd'oced ; second Se' 530m usu. reported! failed to crop. M Of Var-10t (Bufom’ usually 1 and discl 3" 1935 1961; Fan one to two centimeters, regardless of the depth the seed had been planted. Bonnett (1964) described tillering as "the normal process of branching in barley, other cereals, and grasses. It is the production of shoots with uneXpanded internodes in the axils of the leaves which originate at the node of the stem just beneath the surface of the soil." Weaver (1926) stated that the secondary root system (crown roots) Of wheat develOped within an inch or two of the soil surface. The number Of roots increased somewhat in prOpor- tion to the number of tillers. Locke and Clark (1924) described the normal situation of the wheat plant develOping two sets of roots. The seminal, or seedling roots, were produced at the time of germination of the embryo. The second set, the coronal or permanent roots arose from the crown usually just below the surface of the ground. They reported, however, on two examples where the crown roots failed to develOp and the seminal roots sustained the wheat crOp. Many early workers sought to determine the effects of various cultural practices on the number of tillers (Buffum, 1898 and Grantham, 1917). Researchers today usually include tiller counts as influenced by treatments and discuss its importance in relation to yield (Aamodt g3_ .11., 1935; Rohde, 1963 and Woodward, 1966; Brown t 1., 1961; Kmoch t 1., 1957; McNeal and Davis, 1954). _--— A f tillering. stage began , , . When were no lon duced more Aspinall (l restricted to heading pointed out production tillers, 1 ever system barley plar vitallY irn Let In tiller ( barley, am his text, apical bud YOUng eXpa We genesis of applied tc and shOOt .A few studies have been aimed at the control of tillering. Bonnett (1933) found that "when the reproductive stage began, the vegetative stage (tillering) was retarded. . . . When internode elongation began, axillary tiller buds were no longer formed." He concluded late varieties pro- duced more tillers because of the extended vegetative period. ASpinall (1961) working with barley did not find tillering restricted to early phasic develOpment but continuous even to heading when sufficient nutrients were supplied. He pointed out that perennation of grasses is attributed to the production of vegetative tillers after flowering of early tillers. In a later paper (1963) he concluded "that what- ever system Of apical dominance was Operative within the barley plant, the distribution of mineral nutrients was vitally involved." LeOpold (1949) demonstrated the influence of auxin in tiller production of two grass Species, one of which was barley, and that apical bud dominance reduced tillering. In his text, LeOpold (1955) pointed out that in addition to the apical bud exerting inhibitory effects on lateral buds, young eXpanding leaves were also rich sources of auxin and known to inhibit the develOpment of axillary buds. Wardlaw (1952) reviews the biochemistry and morpho- genesis Of plant organs and states that indoleacetic acid applied to cut surfaces of roots and shoots stimulates root and shoot growth. Inge and Loomis (1937) studied the elongation c possibility Erie per plant 01 to 2500 foot the rate of in the rate to a greatei apical domi: An increase the total n‘ emergence w dominance a Ric w0ft relati morphfloqy. tures, as t elongatiOn observed th Point of th ing from th tile elonga emergenCe f temPEI‘ature ”memes. Marquis Spr elongation Of the first internode in maize and discuss the possibility of auxin control of elongation. Friend (1965) found that the total number of leaves per plant obtained by increasing light intensities from 200 to 2500 footcandles was brought about by an increase in both the rate of leaf emergence on individual axes and an increase in the rate of tillering. As the rate of tillering increased to a greater extent than rate of leaf emergence, he concluded apical dominance was reduced by increasing light intensity. An increase in temperature from 10 to 25 C also increased the total number of leaves and tillers, but the rate of leaf emergence was stimulated more than tillering so that apical dominance appeared to be increased by higher temperatures. Richards, Hagen, and McCalla (1952) have summarized work relating to influence of soil temperature on seedling morphology. There was general agreement that high tempera- tures, as they stimulated plant growth, produced greater elongation of the subcrown internode. Dickson (1923) Observed that with temperatures above 20 C, the growing point of the culm broke through the coleOptile before emerg- ing from the soil. At temperatures below 16 C, the coleOp- tile elongated faster than the growing culm until after emergence from the soil. He also studied the effect Of temperature on tiller production in Spring and winter wheat varieties. Optimum temperature for tiller production in Marquis Spring wheat was found to be 20 to 24 C. Below 8 and above 2 temperature were in ger Taylor and a tendency perature he 12 C more t tillers; at Optile node tillering 5 FederatiOn, Perature, Lic Seliger anc‘ of light ir iStics and measuremem at the Soil work and p} in rate 0f varieties. the actiOn periodism a initiatiOn Photoperiod L p‘iotoper iod and above 32 C few tillers were formed. The cardinal temperatures for shoot develOpment in Turkey winter wheat were in general about 4 C below those of Spring wheat. Taylor and McCall (1936) noted that Turkey winter wheat had a tendency to produce tillers at the coleOptile node. Tem- perature had a definite effect on this characteristic. At 12 C more than 80 percent of the plants produced coleOptile tillers; at 16 C about 50 percent had tillers at the cole- Optile node, and with temperatures above 20 C, coleOptile tillering seldom occurred. The Spring wheat variety, Hard Federation, did not produce coleOptile tillers at any tem- perature. Light plays a most important role in growth. Seliger and McElroy (1965) reviewed the biological effects of light in addition to eXplaining its physical character— istics and measurements. Gieger (1965) described light measurements as well as other environmental determinations at the soil surface. Hurd-Karrer (1933) reviewed the early work and presents the differences of photOperiodic response in rate of develOpment and yields of winter and Spring wheat varieties. The classical review of McKinney (1940) eXplained the action and interpretation of relationships between photo- periodism and vernalization. Hendricks (1958) discussed the initiation of the flowering stage of growth as a result of photOperiodism. Guitard (1960) Observed that various photOperiods during different stages of growth resulted in differer light pr tire) 51 to the c duratior produce: elongat tillers relatio (Downs and W11 a resu] and Bax (1963), Shggest PIOlonc after . different photOperiodic responses. Increased length Of light period during the internode elongation (early vegeta- tive) stage caused earlier initiation of tillering relative to the develOpment of the first culm. The longer the duration of tillering, the greater the number of tillers produced. Increases in length of photOperiod following elongation of the first culm did not influence the number of tillers. Varietal differences in photoperiod response in relation to tillering has been reported by several workers (Downs _£._1., 1959; Aspinall, 1966; Wiggans and Frey, 1957: and Williams and Williams, 1968). The list of workers showing increased tillering as a result of fertilizer is extensive. Included are: McNeal and Davis (1954), McNeal (1960), Brown _£I_l, (1961), Rohde (1963), and Woodward (1966). Only Aspinall (1961, 1963) suggested that nutritional availability was responsible for prolonged tiller production or resumption of tiller growth after the floral stage had been initiated. The other major cultural practice influencing tiller formation is rate of seeding. From the work Of Buffum (1898) to the present, there are papers reporting the effect of seeding rate, or row spacing on tiller production, as it pertains to a component of yield (Sprague and Farris, 1931; Wilson and Swanson, 1962; Kindra gt a1., 1963; and Middleton .35 1.. 1964). Bonnett (1933) defines tillering as "the normal p1 utilizin< formatio: cated th. factors . (1923) f- factors perature varietie hardy va location to produ istic, a advantag damaged lmpOrtan all new Plant at 1935: Pa importer she“ (19 PractiCe sudangrE i“Crease Plant, IQOt SYS normal process of adjustments of growth and is a method of utilizing the environment to a fuller extent." There have been few studies on the depth of crown formation or location of crown roots. Pinthus (1969) indi- cated that coronal roots were affected by environmental factors only as tiller production was affected. McKinney (1923) found depth of tillering varied with environmental factors such as depth of seeding, amount of light and tem- perature. Webb and Stevens (1936) observed that hardy varieties of winter wheat have deeper crowns than do non- hardy varieties. This emphasizes the importance of the location of the crown. Friedberg (1932) found the tendency to produce tillers from the coleOptile a varietal character- istic, as did McCall and Taylor (1936). He pointed out the advantage such varieties had for recovery when the crown was damaged by frost. Janssen (1929) further emphasized the importance of the crown when he stated that in winter wheat all new roots in the Spring develOped from the crown of the plant and not from old roots. Other workers (Aamodt _El_l., 1935; Pauli, 1960; and Stickler and Pauli, 1964) related the importance of tiller survival and tiller density to yield. Shen (1964) in his studies with sudangrass reported the practice of ridging sugar cane in Taiwan. He found ridging sudangrass resulted in suppressed tillering but generally increased plant height, dry weight and yield of a single plant. He attributed this to the better develOped crown and root system of ridged plants. experimer. These ex; of seedir soil pres tiller p1 and crow: tiller f. treatmen' minatiOn determm 3er lo PROCEDURES This research was conducted in six separate experiments each designed to give Specific information. These eXperiments were: (1) Seedbed preparation and depth of seeding; (2) The effect of daylight, depth of seeding, soil pressure and vernalization on crown formation and tiller production; (3) The effect of deep furrow seeding and crown covering on plant survival, crown location and tiller formation; (4) The effect of seeding rate and furrow treatment on tiller formation and crown location; (5) Deter— mination of wave length affecting crown location, and (6) To determine if light quality at the soil surface influences crown location. 10 ing wi: winter was prc the no: cultip. tillag The no: minim-m RAH 4 EXPERIMENT I SEEDBED PREPARATION AND DEPTH OF SEEDING Methods This eXperiment consisted of collecting and measur— ing winter barley plants of two varieties seeded in a 1965 winter barley varietal nursery. The seedbed for the nursery was prepared in two ways. Two replications were planted in the normal manner of plowing, two harrowing Operations and cultipacking. The other two replications were planted where tillage consisted of only plowing and a single harrowing. The normally prepared seedbed was quite firm while the minimum tilled seedbed was very soft and permitted deeper sowing. Plants were dug on October 27, 1964 in a 12—inch row section from each replication, and the distances from soil surface to crown node and from crown to seed remnant were determined. On June 23, 1965 additional plants were dug and the number of head-bearing tillers per plant were counted. Notations were made as to whether the tiller was formed at the crown node or arose from the coleOptile node. 11 0- nc 0&3 a“ centlme ing den the crc seeded above t plants Table Seedls Buds WC-ng Axle:- Crown Huds wont AVeI A" v Lac SQec *ffe: 12 Data and Results The minimum tilled seedbed, being soft, had the seed placed at the average depth of 6.3 centimeters while the normal tilled seedbed, being firm, had seed placed 1.9 centimeters. Figure 1 illustrates the differences of seed- ing depth. Table 1 shows the seeding depth and location of the crown node of the two winter barley varieties. When seeded at the lower depth, the crown formed 3.1 centimeters above the seed. At the shallow depth, only a few Hudson plants formed an internode raising the crown above the seed. Table 1. Average depth of seeding and crown location of two barley varieties seeded in soft and firm seedbeds, September 1965 Seedbed Preparation Minimum (soft) Normal (firm) centimeters Seeding depth Hudson 6.3 2.1 Wong 6.3 1.6 Average* 6.3a 1.9b Crown depth Hudson 3.3 2.0 Wong 3.0 1.6 Average* 3.2a 1.8b Average distance from seed to crown* 3.1a 0.lb *Averages with different letters are significantly different at the 5%.level. .mpmncwom EHHM @Cm qum CH GoflumEHOM czouo tam cummp mcflpmwm MO COmHHmmEOU .H muomam .ovosuouzfl C3ouon3m boom320Ho :m cm: muzmam :Omosm 3ow m waco .chOC m:apoom .men 02o o>onm one 0u mmOHU tomcao>o© m:3OHU oza .2omoo A20:U:H N.HV nuoooEHucoo H.m moiqow mz3oao SA muouofiubcoo o.a oowmuo>m Afiqfluv Con .zomoc CH muoooianzoo m.o Comoqo>o Auwomv Iwomm twaaao H6204uzo>COo :H vowoon moqumm UoQUmmm coaauu :314449 :a Common MOAAGQ 14 The remaining Hudson plants and all Wong plants formed the crown at the seeding depth. Examination of seedlings showed tillers produced in groups progressively in the crown as described by Sarvella, Nilan and Konzak (1962). Tillers were formed successively from nodes of the germinating seedling. The first node of barley capable of producing a tiller is the coleOptile node. This and other tillers attached to the coleOptile tiller are described in Table 2 as group 1. Tiller groups 2, 3, and 4 are tillers arising from each successive node. The number of tillers produced per plant was less from the shallow seeding because fewer tillers formed in the fourth group. Table 2. The average number of tillers per plant as of April 1965 on Hudson and Wong barley seeded at different depths Seedbed Preparation Minimum (soft) Normal (firm) Tiller Location* Tiller Location* 1 2 3 4 Total 1 2 3 4 Total Tillers per plant Hudson 0.7 2.4 2.2 1.9 7.5 0.3 2.5 2.1 1.5 6.4 Wong 1.1 2.5 2.4 1.7 7.6 1.0 2.5 2.3 1.5 7.3 Average 0.9 2.5 2.3 1.8 7.5 0.7 2.5 2.2 1.5 6.9 *Tiller location: 1 = tillers formed at coleOptile node, 2-3—4 = tiller groups formed at crown. Avarietal tillers at mme tille and 3 shm tiller-grc ofplants WT um coleo; plant at t produced a with shalj formed ti: and 51 pez at the (:01 IEible 3. \\ H‘JdSOn w0nd node, 2‘3 15 .A varietal difference in the number of plants producing tillers at the coleOptile node was observed. 'Wong produced more tillers at the coleOptile node than Hudson. Tables 2 and 3 show the average number of tillers per plant formed as tiller-groups at the different seeding depths and the percent of plants forming tillers in the different groups. Wong produced an average of 1.1 tillers per plant at the coleOptile node with deep seeding and 1.0 tillers per plant at the coleoptile node with shallow seeding. Hudson produced an average of 0.7 with deep seeding and 0.3 tillers with shallow seeding. Only 31 percent of the Hudson plants formed tillers at the coleOptile node in the shallow seeding and 51 percent in the deeper seeding. WOng produced tillers at the coleOptile node on 92 and 85 percent of the plants in the deep and shallow seeding, reSpectively. Table 3. Percent of plants forming tillers at various locations when seeded at two depths Seedbed Preparation Minimum (soft) Normal (firm) Tiller Location* Tiller Location* 1 2 3 4 l 2 3 4 Hudson 54 100 100 85 31 100 100 85 Wong 92 100 100 92 85 100 100 100 *Tiller location: 1 = tillers formed at coleOptile node, 2—3-4 = tiller groups formed at crown. 16 On June 23, 1965, after full-heading of the barley plants, the number of plants and head—bearing tillers were counted in three foot rows (Table 4). The deeper seeding had slightly more head-bearing tillers per plant. Although the nursery was supposedly seeded at a uniform rate for all varieties, Wong had a greater plant density in the samples than did Hudson. The tiller density per plant however was not significantly different. Thirty-four plants of Hudson in the soft, minimum tilled seedbed produced 99 tillers, or an average of 2.9 heads per plant while the plants in the firm seedbed aver- aged 2.6 heads per plant. ‘Wong plants produced 3.2 heads per plant in the soft seedbed, and 2.3 in the firm seedbed. .With the shallow seeding, more plants produced only one tiller per plant. More Wong plants produced three heads per plant with the deeper seeding. 17 Table 4. Frequency table showing plants and head-bearing tillers per three foot row on June 23, 1965 in barley nurseries seeded on differently prepared seedbeds Seeding Depth 6.28 centimeters 1.86 centimeters Tillers per Plant Plants Tillers Plants Tillers Hudson 1 9 9 10 10 2 6 12 9 18 3 6 18 4 12 4 8 32 3 12 5 4 20 5 25 6 I. O. l 6 7 .0 O. I. O. 8 1 8 .. .. Total per 3-foot row 34 99 32 83 Average tillers/plant* 2.9 2.6 Wong 1 7 7 20 20 2 11 22 10 20 3 12 36 12 36 4 2 8 4 16 5 5 25 l 5 6 5 30 2 12 7 2 14 o. oo 8 .. .. 1 8 Total per 3-fOot row 44 142 50 117 Average tillers/plant* 3.2 2.3 Total for depth 78 241 82 202 Average* 3.1 2.5 *Statistical analysis failed to show significant differences between average at the 5% level. EXPERIMENT II THE EFFECT OF DAYLIGHT, DEPTH OF SEEDING,-SOIL PRESSURE AND VERNALIZATION ON CROWN FORMATION AND TILLER PRODUCTION The purpose of this eXperiment was to study the influence of certain environmental effects on the location of the crown, i.e., light, soil compaction, ridging (or addition of soil over emerged seedling), and length of pre- vernalization period. It was conducted in the greenhouse to facilitate precise seeding depths and controlled prevernali- zation period. Methods Fourteen treatments were designed for the following comparisons: 1. Dark versus light on the soil surface 2. Seeding depths of 2.5, 7.6 and 10.2 centimeters 3. Seeding depth of 7.6 centimeters versus seeding at 2.5 centimeters and later covering crowns to a depth of 7.6 centimeters 4. Loose versus packed soil over seed 5. Long versus short prevernalization period. 18 19 Two varieties of winter wheat, Gaines and.Avon, and one variety of winter barley, Hudson, were used. Gaines is known for its prolific tillering when seeded early. Avon and Hudson are varieties commonly grown in Michigan. Forty-two, six-inch clay plots were used. Accurate seeding depths were obtained by placing a rule along the inside of the pot and after placing the seed on one inch of soil, filling the pot to the required depth. Eight kernels were seeded and were thinned to five plants per pot. How- ever, in some cultures less than five seedlings emerged. Eighteen pots were covered individually with rigid tar paper to prevent light from reaching the soil surface and the remaining 24 pots received normal daylight (Figure 2). As seedlings in the covered pots reached the tar paper lid, small holes were punched in the lid and the coleOptile or first foliage leaf threaded through it. Thus the plants in covered pots received daylight after they reached the top of the six-inch pot. Watering was done by filling the saucers in which the pots were sitting to eliminate the necessity of removing the tar paper lids. Eighteen pots, nine covered and nine uncovered, had extra pressure exerted on the soil above the seed resulting in a packed seedbed condition. The remaining 24 cultures had a loose soil covering. To determine the effect on the number of tillers from seedlings having a short growing period from planting until winter dormancy, three cultures (one of each variety) .soauospoum HoHHHu 0cm coHumEHOM czouo co soHumNflHmcuw> can .oudmmmum HHOm .mcflooow mo numop .unmflahmo mo uoowww hosum ou mouduaso .N mudmam .usmwu orb so A50 N.oav mcflpomm meow tam oaoofle onu CH AEU o.hv .oocomHmEm ufiauom cameo Edflpme .uuoa osu do AEU m.mv ms“ Cu pervade mm3 mac: HamEm m pHH nomad looow 30aamnm .HAOm mo nuanced msoflum> Hmu onu monommu mw>moa mdaacoom mfi cua3 muom mcflaaaw an ooaamuno mcumoo .oomwudm HHOm mascomwu Eouu unmaaxmc mcuooom ucmumwwac ouoz .muOd touo>oosD usm>ouo ou Momma Hmu :DHS oono>oo muom 21 were placed in the cold room at 2 C three weeks after seed- ing. The remaining 39 cultures were placed in the cold room 60 days later where they and the original three remained for 60 days. The three cultures with a short vegetative period thus were subjected to the 2 C temperature a total of 120 days. Data and Results Too much pressure was used to compact the soil over the seed and only 18 of 90 seeds emerged. Most emergence was from the shallow (2.5 centimeters) seeding. Compaction reduced soil pore numbers and size creating a poor environ- ment for germination and growth develOpment. The coleOptiles of germinating seedlings were crinkled from growth elongation against the soil pressure. For this reason, comparisons do not include packed soil. Tiller Production Tiller counts were made on January 7, 1965 at the time the cultures were placed in the cold room and again on May 12 at harvest after having been out of the cold room for six weeks. At the time of the January 27 reading, the plants were 12 weeks old. Only a small amount of tillering had occurred as shown in Table 5. In covered pots the deep seeded cultures had slightly more tillers than the shallow seeded. 22 Table 5. The average number of tillers on five plants in cultures on January 27, 1965 (12 weeks old) Tillers per Plant Seeding Treatment Depth Gaines Avon Hudson Average (cm) Covered 2.5 1.3 1.0 1.0 1.1 7.6 1.0 1.0 1.0 1.0 10.2 1.1 1.2 1.5 1.3 Average 1.1 1.1 1.2 1.1 Uncovered 2.5 1.0 1.0 1.0 1.0 7.6 1.3 1.0 1.0 1.1 10.2 1.0 1.0 1.0 1.0 Average 1.1 1.0 1.0 1.0 Average for Variety 1.1 1.0 1.1 The second tiller count was made when the plants were six months old, prior to heading. Only tillers exceed- ing 2.54 centimeters in length were counted. Much tillering had occurred since the previous count as shown in Table 6. Gaines produced more tillers per plant than the other varieties. The deeper seeding of all varieties pro- duced the most tillers. There was little if any difference in number of tillers due to light treatments. Figure 3A shows the comparable growth of plants grown in covered pots with those uncovered prior to being ‘ placed in the cold room for vernalization at 12 weeks of age. 23 Table 6. The average number of tillers over 2.54 centimeters in length on five plants in cultures on May 12, 1965 Tillers per Plant Pot Seeding ' Treatment Depth Gaines Avon Hudson Average* (cm) Covered 2.5 3.7 1.3 1.8 2.3a 7.6 4.3 4.0 5.3 4.5b 10.2 11.9 5.5 6.4 7.9c Average* 6.6a 3.6b 4.5b 4.9 Uncovered 2.5 3.8 1.0 1.7 2.2a 7.6 7.8 5.0 4.0 5.6b 10.2 7.9 7.0 5.0 6.6b Average* 6.5a 4.3b 3.6b 4.8 Average for Variety* 6.6a 4.0b 4.0b *L.S.D. (5%.level) between: seeding depths . . . . . . . 1.9 tillers/plant varieties . . . . . . . . . . 1.9 tillers/plant seeding depths within variety 1.2 tillers/plant Averages with different letters are significantly different at the 5% level. .coHumNflamsuo> Mom Eoou taco may CH mmuduasu manomam Cu Hoflum dome nusoum unmam mo GOmAHmmEOO .m ousmam .Aummuv somosm paw .AoHUpHEV co>< .Amuom N uconwv mocamo oum .Hmou Aw tam m muomv EU N.oa mmHumHHm> .mousumuomfiou HoEHoz Um: o>mn tam “waooflfi Aw tam N muomv 9.5 uwoa onu c0 muom m onu OHM:3 whom 00 uuGOHw Am tam H muomv m.m mo mnummw How Eoou paoo CH msflon an pooumuou coon mammomm £943 muom Auzmfluv pono>oocs USN Auwwav ©0H0>oo :4 umm£3 mocwoo .d mo: unmau so moon m CH mquHd mo zuSOHO 25 Plants in the covered pots (l, 2 and 3) were slightly taller than those in the uncovered pots (5, 6 and 8). Depth of seeding does not appear to have influenced the growth. The plants given the early cold treatment were suppressed in growth and tiller develOpment at the time the other cultures were placed in the cold room. Figure 3B compares the growth of plants prior to being placed in the cold room (6, 20 and ‘1‘. A. 34) with plants having been in the cold room for 60 days (7, 21 and 35). No tillering had occurred in the latter cu1-‘ ‘V tures at this time. When tiller counts were made on May 12, six weeks after being removed from the cold room, plants in pots 7, 21 and 35 still had not formed tillers. Table 7 compares the tillers per plant in cultures receiving the early cold treat- ment and others seeded at the same depth. Plants receiving Table 7. Average tillers per plant in cultures receiving early cold treatment and comparable cultures receiving later cold treatment Length of Variety Cold Seeding Treatment Depth Gaines Avon Hudson Average (cm) number of tillers per plant 60 days 7.6 7.8 5.0 4.0 5.6 120 days 7.6 1.0 1.0 1.0 1.0 26 60 days of cold treatment had an average of 5.6 tillers per plant while plants receiving 120 days of cold treatment pro- duced only the main culm. Figure 4 shows the crown and subcrown develOpment of a plant of Gaines wheat receiving the early cold treat— ment and one having the later cold period. ‘When plant No. 6 was placed in the cold chamber for vernalization it had only ‘.-‘12" 1 four tillers (Figure 38). There was no apparent growth dur- ing the 60 day period when temperatures were held at 2 C. ’Ir At the second tiller count six weeks after having been e removed from the cold room and as shown in the photograph it had 18 tillers. Plants which were seeded at the 2.5 centimeter depth and after emergence covered with soil to 7.6 centimeters had not produced tillers prior to placing the pots in the cold room. On May 12, plants had tillered and tillers per plant are shown in Table 8. The tillering of covered plants was comparable to the shallow seeded cul- tures and less than the deep seeded ones. Crown Formation In cultures not given the early cold treatment, crown formation occurred prior to placing the pots in the cold room for vernalization. Figure 5A shows Hudson seeded at 2.5 centimeters in a covered pot prior to being placed in the cold chamber. The crown had formed above the soil sur- face. This phenomenon occurred in many of the covered pots. 27 Figure 4. Plants of Gaines wheat both seeded at the 7.6 centimeter depth and dug six months after seeding. Plant no. 7 was placed in the cold room early, three weeks after seeding, wnere it remained for 120 days. Plant No. 6 was placed in the cold room at 60 days after seeding where it remained for 60 days. 28 Table 8. Average tillers per plant on May 12, 1965 in cultures seeded at the 2.5 centimeters depth and having 5.1 centimeters of soil added after emer- gence compared to cultures seeded at 2.5 and 7.6 centimeters Variety Seeding Depth (centimeters) Gaines Avon Hudson , Average* number of tillers per plant i 2.5 + 5.1 3.67 2.75 1.00 2.36b ' 2.5 3.75 1.00 1.67 2.70b 7.6 5.60 5.00 4.00 5.60 ‘1‘"- *L.S.D. (5% level) between treatments--1.54 tillers/ plant. Table 9 shows the length of the subcrown internode as mea- sured on May 27, 1965 when plants were harvested. The increased length of this subcrown internode is most evident from the deep seeding. While not many deep seeded plants in covered pots produced crowns above the soil surface, Gaines had one such plant as shown in Figure SE. -The more common crown formation of deep seeded (10.2 centi- meters) plants is shown in Figure 6, where Gaines formed the crown at seven centimeters above the seeding depth. Note that this is not a single subcrown internode as a node was also formed at 2.2 centimeters above the seeding depth. No roots or extension of the axillary bud occurred at this node, so there was no crown formation. 29 .momeSm HHOm ecu w>onm szouo wnu woodpoum Goumo mega momma Hmu an ©wno>oo muom GA mcazoum mmcaapomm .m ousmflm .oomuHSm .nudmo mcflpoom o>onm EU m.v C3OHU HHOm ocu o>onm cacao m coospoHQ mud poustoud oomeSm HMOm on» zoaon Ludo: E0 N.OH um tmpmmm umocz meadow .m EU m.N powwow unmam moaumn compsm .4 3O Figure 6. Plant of Gaines wheat seeded at depth of 10.2 centimeters produced a node at 2.2 centimeters and a crown at 7 centimeters above seeding depth. 31 Table 9. Average length of subcrown internode of five wheat and barley plants in covered and uncovered pots at various seeding depths as measured May 12, 1965 Length of Subcrown F " Internodes Light Seeding Treatment Depth Gaines ~Avon Hudson Average* (cm) Covered 2.5 4.5** 5.2** 4.8** 4.2**a ; pots 7.6 6.9 7.9** 7.1 7.3b * 10.2 7.1 9.0 6.0 7.4b JT"” Average 5.5 7.4 6.0 6.3 Uncovered 2.5 2.1 1.5 1.2 1.6a pots 7.6 5.6 4.6 5.2 5.1b 10.2 8.8 9.4 8.2 8.8c Average 5.5 5.2 4.7 5.2 Average for Variety 5.5 6.3 4.4 *L.S.D. (5%.level) between seeding depth 3.1 centi- meters seeding depth within light treatment. **Distance is greater than seeding depth, indicating that crown formed above soil surface. 32 The plants with an early cold treatment produced a slightly longer subcrown internode than did comparable seeded plants later vernalized. Table 10 compares the dis- tance from the seeding depth to crown of plants treated to early cold with other untreated plants seeded at 7.6 centi- meters. The addition of 5.1 centimeters of soil after emergence to plants in pots seeded 2.5 centimeters deep, resulted in two crowns being formed. Figure 7 shows the two nodes formed by Gaines and Hudson. The original node was r‘ww _-.-. Tu slightly below the soil surface of 2.5 centimeters and the second crown formed well above this level, but below the final soil surface of 7.6 centimeters. The barley plant formed only roots at the lower crown, but the wheat plant formed both roots and one tiller. Table 10. Length of subcrown internode of early cold treated plants and other plants seeded at 7.6 centimeters as measured May 12, 1965 Length of Subcrown Internodes ‘Pot Seeding Treatment Depth Gaines Avon Hudson Average centimeters Light, -Early cold 7.6 6.5 5.1 5.6 5.7 Light 7.6 5.6 4.6 5.2 5.1 33 Figure 7. Two crowns were formed by Hudson (33) and Gaines (5) when 5.1 centimeters of soil was added to pots after plants emerged from a 2.5 centimeter seeding depth. EXPERIMENT III THE EFFECT OF DEEP FURROW SEEDING AND CROWN COVERING ON PLANT SURVIVAL, LOCATION OF THE CROWN AND TILLER FORMATION As a result of the observed manipulation of the crown location in EXperiment II, attempts were made to do the same in the field. The eXperiment would also permit a study of winter survival in relation to location of the sn~ crown and protection by snow cover in the bottom of deep furrow seedings. Methods Hudson and‘Wong were selected to represent two levels of winter-hardiness in barley and Avon as a common winter wheat variety. Plot treatments were as follows: 1. (S) shallow seeding made in the normal manner, i.e., without cultivator shovels. 2. (D) deep seeding done by increasing the pressure tension on the seeding shoes. 3. (F) deep furrow seeding done by attaching six- inch cultivator shovels in front of the seeding 34 35 shoes and placing the seed in the bottom of the furrows. 4. (C1) closed deep furrows which were seeded as in treatment 3 but the ridges leveled after emergence. The cultivator shoes made a furrow eight centimeters F"‘ deep in which the seed was placed and covered only 1.3 centimeters. The shallow seeding was also covered only 1.3 centimeters. Increasing the tension of the seeding shoes placed the seed 7.5 centimeters deep. On November 18, 1965 when the seedlings were six weeks old, half of the deep furrow plots were closed by leveling the ridges into the furrows. This caused the seed in the closed furrows to be covered 5.3 centimeters. .Figure 8 shows the tillering and size of plants when the deep furrow plots were leveled. Winter survival was determined by estimating the percent of stand in each plot on March 1, 1966. Tiller counts and crown measurements were made by digging plants on April 21, 1966. Only tillers exceeding 2.54 centimeters in length were counted. The location of tillers on the crown were identified by grouping them in order of origin, as described by Sarvella _E__l, (1962). Group one, primary tillers, are main culms and the first tillers attached to them. Group 2 tillers arise from a node just above the primary tillers. Those tillers coming from above the 36 Figure 8. Size and tillering of seedlings of Hudson (H), Wong (W) and Avon (A) at time of closing half the deep furrow plots. Seeding treatmehts are (S) shallow seeded, (F) deep furrow and (D) deep seeded. 37 secondary tillers are group three. In this study, the latest tillers develOped from a fourth group. Data and Results Differential winterkilling occurred between vari- eties. .Avon survived 100 percent, Hudson averaged 55 per~ cent and Wong had 50 percent survival. Winter survival data are shown in Table 11. No difference occurred between deep furrow and shallow seeded plots. The seed covering was the same in these two treatments and in the absence of a protec- tive snow cover in the deep furrows there was no difference in plant survival. Plant density was less in closed deep furrow plots than in open deep furrows but higher than in deep seeded plots. The reduction in stand of the closed deep furrow plots may be due to the covering of the crown as Table 11. Average plant survival of varieties in plot treat- ment on March 1, 1966 Plot Treatment Deep Shallow Closed Deep Varietal Variety _Furrow Seeded Deep Furrow Seeded ,Average Hudson 75.0 76.5 37.5 37.5 55.6 Wong 62.5 67.5 47.5 23.8 50.8 Avon 100.0 100.0 100.0 100.0 100.0 Treatment . V Average 79.2 80.0 . 61.7 53.8 38 the survival is intermediate between deep seeded and Open deep furrow plots. Thermocouples were placed near the crowns of plants in three treatments; closed deep furrow, Open deep furrows, and in the shallow seeded plots. Temperatures were auto- matically recorded on a Brown Honeywell Electronik(T) Strip Chart Recorder during the winter months. Figure 9 shows the E___- plot treatments immediately after installing the thermo- couples and closing the deep furrow plots. Tiller counts are reported in Table 12. The deep H“? w._". h.- furrow and the shallow seeded plots produced the greatest number of tillers per plant. These two treatments also had the best winter survival. Normally tiller production and plant density are expected to be negatively correlated. The positive association in this instance is explained by winter- killing of tillers and/or tiller buds. Greater tillering in the shallow seeded plots was due to more tillers at the group one level, the most protected group. In the deep seeded plots a lack of tillering is evident at the group four level, eSpecially in barley. Group four are later tillers formed closer to the soil surface where they are more exPosed to winter damage. (A varietal difference in tillering is apparent by Wong having the least number of tillers. Wong is the least winterhardy variety. Winter- killing could account for the fewer number of tillers. 39 Figure 9. Plot treatments after closing the deep furrows lower left. The Open deep furrows are shown directly above them. The deep seeded plot is at the lower right and the shallow seeded plot is adjacent to the Open deep furrow plot. 40 Table 12. Average number of tillers and their location on ten plants produced with different seeding methods, counted April 21, 1966 Tiller Group** Seeding Variety Treatment* 1 2 3 4 Total Hudson F 2.6 3.3 3.1 2.0 11.0 S 2.3 1.7 2.0 1.1 7.1 D 1.0 1.4 1.1 ... 3.5 I C1 1.4 1.4 2.1 ... 4.9 , I Variety Average*** 6.8a Wong F 1.6 1.4 0.9 0.1 4.0 S 1.5 1.3 1.3 1.0 5.1 D 1.1 0.8 0.6 0.3 2.8 C1 1u3 0.9 0.6 ... 2.8 L1- - Variety Average*** 3.6b Avon F 1.6 1.7 1.7 0.4 5.4 S 2.6 2.7 2.0 1.3 8.6 D 1.4 1.4 1.3 1.4 5.5 Cl 1.6 1.6 2.0 0.4 5.6 Variety Average*** 6.2a Treatment F 1.9 2.1 1.9 0.7 6.6ab Average*** S 2.2 2.1 1.8 1.1 7.13 D 1.2 1.3 1.1 0.6 4.2b Cl 1.4 1.3 1.6 0.1 4.4b *F = deep furrow; S = shallow seeded; D = deep seeded: C1 = closed deep furrow. **Tiller groups according to node of origin (Sarvella _£__1,, 1962). ***L.S.D. (5% level) between: ~ varieties 0.83 tillers per plant treatments 2.47 tillers per plant. Averages with different letters are significantly different at the 5%.leve1. 41 The depth of crown formation from the soil surface is shown in Table 13. The crown formation in the deep furrow and shallow seeded plots was less than one centimeter from the soil surface. Seeding depth was 1.3 centimeters. Plants in the deep seeded plots (7.5 centimeters) produced crowns at 1.62 centimeters below the soil surface. The leveling of ridges and covering of seedlings in the closed deep furrow plots caused plants to produce a second crown. The first crown formed close to the depth of crowns in deep seeded plots and the second crown formed closer to the sur- face than crowns in shallow seeded plots. Temperature readings as measured by thermocouples placed near the plant crown did not reveal a significant protective effect in the deep furrow plots. The lack of snow during the colder periods might eXplain the lack of insulative protection. Temperatures for two different periods are shown in Figures 10 and 11. Crowns in the closed deep furrows were consistently warmer than the other treatments during the cold weather period from January 24 to .February 2, 1966 (Figure 10). The Open deep furrow plots had slightly warmer temperatures than the shallow seeded plots in the early and very late portions of the period when temperatures were relatively moderate. In the middle of this period, air temperatures drOpped to below —20 C and the Open deep furrow temperatures became the lowest of the treat- ments. The differences in temperature did not affect plant 42 Table 13. Average depth of crown formation of wheat and barley grown with different seeding methods as measured April 21, 1966 Seeding Method Closed Deep Furrow* Deep Shallow Deep Varietal Variety Furrow Seeded Seeded Upper Bottom Average** centimeters "" Hudson 1.13 0.90 1.61 0.61 4.49 1.06 Wong 0.69 0.80 1.71 0.70 3.86 0.98 Avon 1.34 0.83 1.67 0.70 4.02 1.14 Treatment Aver- age*** 0.96b 0.85b 1.62a 0.67c 4.09 *A second crown often formed after seedling was covered by closing the deep furrow--bottom is the depth of original crown and upper is the depth of the second crown. **Does not include bottom node of closed deep furrow plots. ***L.S.D. (5% level) between: treatments .... 0.17 cm treatment within a variety .... 0.30 cm. Averages with different letters are significantly different at the 5%,1evel. 43 .oooa .N mumsunmm Op mm mumocmb .ucofifluomxo uoam Bowman mo monoumummfimu HHOm tam. HEN .OH oudmflm «\m H\m Hm\H om\H m~\H m~\a h~\a o~\a m~\HIImumn a mans ed 2m :4 2m ze 2m :4 2m :4 2m z< 2m :4 2m ze an 24 AWIIWII . 1i. 4 . 1 in . . _ . ill . Jl . . . m mNI I. OHSDMHOQEOH HEN 1 ¢.mml W. I I.m.hHI : I IIIII\\\>////\\\\III/<\\\\//// I.~.NHI LI \ .l\ \A\ .I .4/ ..ommI\\w.~HI L , , , fl 1. / .I e.HHI , a s / m. I \ I.o.oau i z \ / u e.mI m I i \ II \ / a I x \ I ma. m 8 I I m.>I m x w Pm- I I H.0I v .... p 9 I I o.mI .I NNmmmmmu loo zonesm ammoHo moo . l E 5...... a x as- I E re 8:25 . 4 44 \ \ uazrgzuua I‘\“i\\\i ) ) ‘Cl. Furrow (C) "I'll/ll. .4 HM.— Vuunilnnsu 7!!!!”14 I“\\\\‘\‘ IIII’ll,Ill'l’IIIIIIIIIIIIIIIIIIIII ‘\‘\\\\\\\‘\\\\\‘\\\\\\““\\\“\\\\\~ VII!!(IIA \‘ ' "\Kfi _ , , XIII/I!Illlllllill/IA 5iéiseiiiécnéiufifisfiéfiifiifieenna VIII/1114 n§\\\ Shallow (S Jeep Furrow (F ””nlll'lln/Ilnllllllllll F ‘ . I" M I I l l J l I l l \l | I _ 1 o m e m N H o a N o Is .4 h '3 o In e «I «v a 0 r4 N o w .4 o a I I H I l w (epezfirqueo) sznqexadmem ITOS ITV 2 w-l E 1 AM 2/15 2/16 AM PM AM PM 2/14 I AM PM 2/13 2/12 I_ AM PM AM PM 2/11 AMPMAMPM 2/10 Air Temperature 2/9 I AM PM 2/8 Air and soil temperatures of furrow plot experiment, February 8 to 16, 1966. Figure 11. 45 survival as stands in shallow and deep furrow plots survived equally well. As air temperatures warmed during the second period, February 7 to 16, 1966 (Figure 11) a change in the relation of temperatures in the plots occurred. Temperatures at the crown level in shallow seeded plots reacted quicker to the change of the air temperature and were the highest. The temperatures in the closed deep furrow reacted slower and were recorded as the coldest. The relationship of tempera- ture to growth would thus indicate those plots warming quickest would begin develOpment earlier. EXPERIMENT IV THE EFFECT OF SEEDING RATE AND FURROW TREATMENT ON TILLER FORMATION AND CROWN LOCATION Methods A factorial eXperiment was designed involving four varieties, three seeding rates, and three furrow treatments to determine their effect on tiller formation, location of crown and grain yield. .A drill was obtained that permitted accurate adjustments of seeding rate and the placement of seed in deep furrows or in a smooth surface.1 Seeding rates were 80, 120 and 160 pounds per acre. Avon, Gaines and Genesee winter wheat and Hudson winter barley were used. Seeding was done either in deep furrows or in a normal manner in a smooth surface. After plant emergence, half of the deep furrow plots were closed by leveling the ridges and covering the crowns of the emerged seedlings. Figure 12 shows furrows approximately eight centi- meters deep and the result of "closing" the furrows by 1Grateful acknowledgment is made to the Department of Agricultural Engineering, Michigan State University and the Agricultural Engineering section, A.R.S., U.S.D.A., Washington, D.C. for providing a Special research drill and tractor Operator. 46 .GOADMOOH czouo Go uuwmwo on» OCHEHmumo Cu >oaumn tam umm£3 Heucfl3 Ou omfladmm mucoEummHu zouusw 038 .NH oudmwm .EU em.m Snowmen .so em.s IxOHAQG couo>oo 30c ma comm .momoau touo>oo mm3 3ouu3q mo EOouon :H teem mcaao>oH noun: bean 3Ouusw door tomoHo .momtbu EU m cud3 ana sounsb door :01: “f3”- 48 leveling the ridges and covering the crowns of the plants. Recovery and continued growth was as good in the closed deep furrow plots as in other treatments as shown in Figure 13. Yield was determined on the center two rows of the four row plots. Harvest was accomplished with the nursery combine thresher. Just prior to harvest, three-foot por- tions of a guard row were dug to determine plant and tiller density. Data and Results Table 14 shows the plants per three-foot row for the varieties at the different seeding rates and furrow treat- ments. Plant density was influenced mainly by seeding rate. Covering Of the emerged plants by closing, or leveling the deep furrows, did not reduce the plant density Significantly. Table 15 Shows the tillers per three-foot row pro— duced by the varieties at different seeding rates and furrow treatments. Again only the seeding rate made a significant difference in the number of tillers produced. Statistical analysis of the data Showed Significantly fewertillers per square foot in the 80 pound per acre seeding rate. There was no difference in the tiller density in 120 and 160 pound seeding rates. If there were more plants per three-foot row in the 160 pounds per acre rate than at 120 pounds and no signifi- cant difference in the number of tillers between the two rates, there must be more tillers per plant produced at the 49 Figure 13. Hudson barley in the foreground where ridges were leveled and crowns covered. The Open deep furrow plots are in the rear. The ridges have sloughed down somewhat during the winter season. Stands in both plots were considered the same. In“; Table 14. 50 Average number of plants per three foot row from different seeding rates and furrow treatments, July 21, 1966 Average Number of Plants per Three Foot Row Average Deep for Shallow Deep Furrow Seeding Seeding Rate Variety Seeded Furrow Leveled Rate* 80 lbs/A Hudson 52 50 48 Avon 46 44 22 Gaines 61 56 38 Genesee 36 36 36 Average for Rate x Treatment 48.8 46.5 36.0 43.8c 120 lbs/A Hudson 74 95 73 Avon 83 67 78 Gaines 68 89 80 Genesee 101 82 73 Average for Rate x Treatment 81.5 83.3 76.0 80.3b 160 lbs/A Hudson 140 107 126 Avon 99 121 112 Gaines 101 89 93 Genesee 108 123 84 Average for Rate x Treatment 112.0 110.0 103.8 108.6a Average for Treatment 80.8 79.9 71.9 .Average for Average Variety x for Treatment Variety Hudson 82 84 88 85.0 Avon 70 77 76 74.6 Gaines 70 78 76 75.0 Genesee 64 80 81 75.4 *Averages with different letters are significantly different at the 5% level. 51 Table 15. Average number of tillers per three foot row produced by different seeding rates and furrow treatments, July 21, 1966 Average Tillers per Three Foot Row Average Deep for Shallow Deep Furrow Seeding Seeding Rate Variety Seeded Furrow Leveled Rate* 80 lbs/A Hudson 92 82 69 Avon 83 82 44 Gaines 114 110 90 Genesee 75 93 103 Average for Rate x Treatment 91.0 91.8 76.5 86.4b 120 lbs/A Hudson 136 152 123 Avon 139 125 155 Gaines 131 174 128 Genesee 154 166 124 Average for Rate x Treatment 140.0 154.3 132.5 142.3a 160 lbs/A Hudson 183 140 199 Avon 124 160 151 Gaines 154 135 136 Genesee 162 170 120 Average for Rate x Treatment 155.8 151.3 151.5 152.8a Average for Treatment Average for Variety x Treatment 128.9 132.4 120.2 Average for Variety Hudson 137 124 130 130.7 Avon 115 122 117 118.1 Gaines 133 140 118 130.2 Genesee 130 143 116 129.7 *Averages with different letters are significantly different a t the 5%.leve1. 52 lower seeding rate. This is confirmed by the data in Table 16. Each increase in the seeding rate significantly lowered the number of tillers per plant. The furrow treat- ments had no effect on the number of tillers per plant. The yield of grain differed Significantly between furrow treatments as shown in Table 17. A relationship between tillers and yield is shown by the high yielding treatment which had the most tillers per three-foot row. Varietal yields also differed significantly. Genesee which ranked first with Gaines for tillers per three-foot row and tillers per plant was the highest yielding. 53 Table 16. Average tillers per plant produced by varieties in different rate of seeding and furrow treat- ments, July 21, 1966 Average Tillers per Plant Average Deep for Shallow Deep Furrow Seeding Seeding Rate Variety Seeded Furrow Leveled Rate* 80 lbs/A Hudson 1.8 1.6 1.4 Avon 1.8 1.9 2.0 Gaines 1.9 2.0 2.4 Genesee 2.0 2.6 2.9 Average for Rate x Treatment 1.88 2.03 2.18 2.03a 120 lbs/A Hudson 1.8 1.6 1.7 Avon 1.7 1.9 2.0 Gaines 1.9 2.0 1.6 Genesee 1.5 2.0 1.7 Average for Rate x Treatment 1.73 1.88 1.75 1.78b 160 lbs/A Hudson 1.3 1.3 1.6 Avon 1.3 1.3 1.3 Gaines 1.5 1.5 1.5 Genesee 1.5 1.4 1.4 Average for Rate x Treatment 1.40 1.38 1.45 1.4lc Average for Treatment 1.67 1.76 1.79 Average for Average Variety x for Treatment Variety Hudson 1.6 1.5’ 1.6 1.57b Avon 1.6 1.7 1.8 1.69ab Gaines 1.8 1.8 1.8 1.81a Genesee 1.7 2.0 2.0 1.89a *Averages with different letters are significantly different at the 5%Ileve1. Table 17. 54 seeding rates and furrow treatments Average yield of grain produced by different Grain Yield Average for Shallow Deep Closed Seeding Seeding Rate Variety Seeded Furrow Furrow Rate grams per plot 80 lbs/A Hudson 383.50 498.50 242.50 Avon 589.75 523.00 390.25 Gaines 553.00 550.50 329.50 Genesee 598.75 603.00 452.75 Average for Rate x Treatment 531.25 543.75 353.75 476.25 120 lbs/A Hudson 394.75 487.25 404.00 Avon 601.25 703.75 490.00 Gaines 495.50 519.75 334.25 Genesee 535.25 827.75 535.25 -Average for Rate x Treatment 506.69 634.63 445.38 528.90 160 lbs/A Hudson 510.50 644.25 380.00 Avon 530.50 635.75 504.75 Gaines 430.50 522.00 383.75 Genesee 621.00 745.50 592.50 Average for Rate x Treatment 523.13 636.88 465.25 541.75 Average for Treatment* 520.35b 605.08a 421.46c Average for Average Variety x for Treatment Variety* Hudson 429.59 543.33 342.17 438.36c Avon 573.83 620.83 461.67 552.11b Gaines 493.00 530.75 349.17 457.64c Genesee 585.00 725.42 532.83 614.42a *Averages with different letters are significantly different at the 5% level. EXPERIMENT V DETERMINATION OF WAVE LENGTH OF LIGHT AFFECTING CROWN LOCATION Since EXperiment III indicated that the absence of daylight caused an elevation of the plant crown, restricting the color of light received by the coleOptile might help to identify which wave length was concerned. Methods Colored beads were used to vary the light intensity and wave length striking the coleOptile of wheat as it emerged from the soil. If the light wave penetrating the beads was effective, the crown would be formed deeper in the soil as the coleOptile received the light at bottom of the beads. If the light wave was noneffective in triggering the plant to form a crown, the coleOptile would have to pene- trate the surface of the beads before the crown would be formed, presumably at a Shallow depth. Six Avon seeds were accurately placed in soil five centimeters below the level of a layer Of glass beads three centimeters deep, making the overall planting depth eight centimeters. Seedlings emerged in four days as Shown in Figure 14. The seedlings were thinned to five per pot. 55 56 Figure 14. Wheat seedlings emerging through colored beads from seeding depths of eight centi— meters. Bead colors (left to right: first row = blue, white, green; second row = black, yellow, red). 57 The percent of light transmission through the three centimeters of beads was determined by use of a Carl Zeizz SpectrOphotometer PMO II prior to placing the beads in the pots. The percent transmission of different wave lengths through the 3-centimeter layer (fl? beads is shown in Figure 15. Density of beads reduced transmission to less than 8 percent for all colors including the clear glass. Red and yellow colors attained 8 percent transmission at the longer wave lengths (yellow, 6500A and red, 7250A). The clear glass allowed 2.3 percent transmission at the 5250A length. Less than 1 percent transmission occurred in the blue and green beads at the shorter wave lengths Of 4500A and 5200A, reSpectively. Data and Results .All seedlings emerged four days after seeding. Heat and energy differences between bead colors thus appeared negligible. However, different plant heights were obtained with the different colored beads. Figure 16 represents graphically the average height of plants and the location of the crowns of plants grown through the colored beads. Fig- ure 17 Shows the difference in crown location between plants grown through red beads and black beads. The crown formed 3.5 centimeters under the red beads and at 1.0 centimeter I under the black beads. Figure 1£3compares the location of the crown in relation to the bead layer of all colored beads. 58 .momon mmmam smoonnu mcumcoa o>m3 econommao um OOammHEmcmHu unmaa mo unmoumm .ma onsmflm A5 598; 963 comb ooow oomm oooo oomm ooom come oooe comm _ e ops? t I t Bum. Iooow. t - o > > I \\ . II Iowan comma l. .L H d a m. .I II N a u moao 1 .l .H m 0 II J ..1 um. I II .v U. 1 n. I. II m e u S m. I. II o s s To 0 1 com II b u . sedan» II m centimeters Figure 16. 59 47 i— er 46 45" 44" 43‘— 42“ 41'— 40 — 39*— 38'— 37'— 36'- 35" 34'- 33'— 32*’ ‘r 31'— 30‘— Tallest Leaf 8" ‘Bead Surface 7 '- 2“ ,_ 6" /’ ‘xw o —-- -ChlorOphyll Line 5I— » " -'-'--SO11 Surface 4 P 0" ’ ‘i>\ I \qb’1D-_ ...-Crwn g'_ .-4’ Developed l I— 0 - ---Seeding_Depth ‘1 n A A A A '0 8 .54 H C: (D Bead Colors—_) 3" H (a), g 8 3 r4 H PI u m :2 In 0 (9 Average height, location of chlorOphyll and crown develOpment On wheat plants grown through colored beads. III—‘— 6O Figure 17. Location of crown develOpment on wheat plants grown through red beads on the left and black beads on the right. 61 Figure 18. Comparison of location of crown develOpment of Avon wheat plants in relation to layer of beads. 62 Table 18 records the average measurement on five plants of the subcrown internode, the distance from crown to chlorOphyll develOpment and the length of the tallest leaf of wheat seedlings grown through the colored beads. The longest subcrown internode was found on plants grown through the clear and black beads. Totaling the length of the sub- crown internode and the distance from the crown to chloro— phyll develOpment Shows light penetration was least through these two layers of beads. Table 18. Average measurements of subcrown internode, crown to chlorOphyll, and length of tallest leaf of wheat plants grown through colored beads, May, 1969 Measurement From Bead Peak Light Seed Depth Crown to Tallest Color Transmission to Crown* ChlorOphyll Leaf (A) centimeters Red ' 7400 2.5b 1.8 46.5 Yellow 6600 2.5b 1.9 31.9 Clear 5500 4.2a 2.3 30.2 Green 5250 3.2b 2.1 46.8 Blue 4500 3.2b 2.6 29.6 Black none 4.6a 2.5 37.5 *L.S.D. (5%.level) between colors, 1.0 cm. Averages with different letters are significantly different at the 5% level. 63 The shortest subcrown internode was found on plants grown through the red and yellow beads. Totaling the length of the subcrown internode and the distance from the crown to chlorOphyll develOpment Shows that chlorOphyll developed 4.3 centimeters above the seeding depth, and that the light penetrated the bead layer to a depth of 2.7 centimeters. The green and blue light waves were intermediate in their ..n effect. Seedlings growing through the red and green beads 5. ‘ III-3 1“ _x- produced the tallest plants, while those under the blue and clear beads produced the Shortest plants. EXPERIMENT VI TO DETERMINE IF LIGHT QUALITY ON THE SOIL SURFACE INFLUENCES CROWN LOCATION The objective of this eXperiment was to determine if the wave length responsible for crown formation could be identified by its penetration of the soil and the effect of light energy on crown location. Methods Avon wheat and Hudson barley were used. Seed was accurately placed in large lZ-inch clay pots and covered with eight centimeters of coarse sandy soil. Soil particle analysis showed particle Size distribution as: 54 percent larger than 1.00 mm 21 percent 0.53 to 1.00 mm 20 percent 0.25 to 0.53 mm 5 percent less than 0.25 mm Various colored cellOphane papers were used as filters over the tOpS of the pots to produce a range of wave lengths (Figure 19). The Optical density and percent of light transmission of the cellOphane was measured with a Hitachi-Perkin-Elmer UV-Vis SpectrOphotometer. The percent 64 Figure 19. 65 Colored cellOphane paper used as filters to restrict wave length reaching soil surface in pots. Colors from left to right: (front row) clear and green, (second row) double layers of yellow, blue and red, (third row) single layers of yellow, blue and red. 66 of light transmission for the different colors at various wave lengths is shown in Figure 20. The radiation energy received by the plants in each pot was balanced by altering the light intensity with multi- ple layers of cellOphane. The green cellOphane had the highest Optical density (.2542) at its peak of tranSmission (5000A). The Optical density of the other colors was adjusted utilizing the principle of Beer's law which states that light intensity through a material is prOportional to the absorbency and density of the material. Table 19 gives the Spectral photometric data for the cellOphane filters and the calculations for equating the Optical densities. The pots were placed in a Sherer Controlled Envi- ronmental Laboratory where a constant 20 C temperature-was maintained. Light was received from Ken-Rad T12 Extra white florescent bulbs. Light intensity at the tOp of the pots was measured as 2500 foot-candles with a Weston Illumination Meter MOdel-NO. 756. Watering was through the bottom of the pots. Plants were pulled and location of the crown deter- mined after four weeks of growth. Figure 21 Shows the growth made by the plants under the cellOphane filters prior to removal from the pots. The greatest morphological differ- ence in plants occurred under the red, Single layer filter where plants were more etiolated than plants under other filters. Comparable growth occurred between plants under IJ 67 .muouafim ocmcmOHHoo Smoounu mnumcoa o>m3 ucmHOMMHe mo :memHEmsmnu unmouom .ON onsmflm Adv summon o>m3 0005 00mm oooo 00mm ooom oomw ooog 00mm ooom ommN PI _ _ .h I _ _ C _ o 4 5 \ I cum 73 soaamw quaoxad T ammuo .Iom . Hmoao on ll 1|. 03m Iom cam .63 a» .TI FIOOH 68 .mDOOSm mo Hogan: M“Muamcoo Hmowum0\muflmcoo Hmoaumo poumsvmo .Asmonm mo muflmcoo Hmoaumov NmN. x Oaumu Noumea .meouummc< CH numcoa m>m3 .ummer oaoa x oo.m names «0 ommmm . m m com H bNI OH x s~o.o unnumcoo m.xo:mam A U a Q “muon3 EOImHo maloa x K\hmma u EOImHo maloa x K\U£ u .omm\Educmsv meow ONm. m mam. mNH hm.¢ ONH. ooog msam NmN. H NmN. OOH mm.m NmN. ooom somuo OHN. m mHN. hm m¢.m ooo. ombm BOHHOM omH. N dad. Nb mo.m moo. comm com axe Adv muamson omuoonm muwmcon somuo AEOImev abandon numcmq HOHOU Hmowumo ocmcmoaaoo moaumo Ou Owumm m.oom\musmso Hmoaumo o>m3 emcnmuno omumsvm mmnocm cofimmHEmcmuu unmfia xmom um ooumasoamo one Hmumeouonm Iouuoomm >3 OOGHEHoumo mm muouaam ocmnmoaamo mo muOHoo HON mumo vauuoeouonm .ma manna Figure 21. 69 Growth of wheat and barley seedlings made under colored cellOphane filters. Comparable growth was made between filters of the same color, but different energy values due to multigle layers of cellOphane except for the red filters, Colors from front to rear are: green (front left), clear (front right), blue, yellow and red. Single layer filters (higher energy) covered the pots on the right. 70 filters of the same color but with different energy levels due to multiple cellOphane layers, except for the red filters. Data and Results The attempt to balance the energy received through all filters was not entirely successful. However the range Of energy between colors was much less than had no adjust- ment been made. Table 20 shows the percent of light trans- mitted and the energy values received from the 2500 fOot- candle illumination as determined from the Optical density of each filter. The first five represent the filters adjusted for energy with additional layers of cellophane. The energy values range from 495 for red to 694 erg-centimeters for the clear filter. This is a 40 percent increase in energy value. If a single layer of cellOphane had been used, the range would have been from 557 for green to 944 erg-centimeters for the blue filter, or nearly a 70 percent increase. Figure 22 shows the percent emergence of seedlings in the different potscovered by filters. Emergence was poor in most pots, especially with barley seedlings where only 10 to 20 percent emerged. This appeared to be due to the extreme seeding depth and the tendency for barley to have shorter subcrown internodes so that the coleOptile failed to penetrate to the surface of the soil. 71 Table 20. Percent of light transmitted, foot-candles and energy values received from 2500 foot-candle light source as determined by measured Optical density of each cellOphane filter Cello- Percent Energy Filter phane Optical Trans- Foot-cand e Values Color Layers Density mission Received (erg-cm) Red 2 .190 65 1625 495 Yellow 3 .210 62 1550 535 Green 1 .252 56 1400 557 Blue 3 .320 48 1200 596 Clear 1 .244d 57d 1794d 694d Red 1 .065 86 2150 656 Yellow 1 .060 87 2175 750 Blue 1 .120 76 1900 944 aTransmission = l/Log O.D. x 100. b2500 x percent of transmission. cFoot-candles x quanta per second. dValues for clear filter are averages of data obtained at four wave lengths: 4000, 5000, 5750 and 6500A. 72 100 '- ‘ 7. — ‘1 .LJ a 8 so " H o m . 25 '— L] 0 I I I I I I I I Energy Value 3 t?) g} 3 3 g g g (erg-cm) <- o w) b In m as 0 Filter Color Red Yellow Green Blue Clear Figure 22. Percent of seedling emer ence of wheat and barley sown under colore cellOphane filters. 73 Most barley plants produced at least two subcrown internodes with root formation occurring at the lower node as well as at the crown. .Figure 23 Shows typical wheat and barley seedlings produced under the various colored filters. The lower node on the barley seedlings can be seen usually less than four centimeters from the seeding depth. The wheat seedlings on the other hand produced only the crown node between five and seven centimeters above the seed. Table 21 shows the average distance from the seed to (l) the crown, (2) to the area of first chlorOphyll devel- Opment and (3) to the tip of the tallest leaf of the plants grown under the cellOphane filters. Multiple layers of blue, yellow and red cellOphane were used to balance the energy transmitted with the light. Thus the lower energy values of these colors represent multiple layers of cellOphane and the higher energy values are from single layers. The crown location on seedlings tended to be higher in pots under filters with the lower energy values, particularly between plants in pots with filters of the same color. The upper— most crown node of barley followed this pattern, but it was not true for the lower node. Figure 24 Shows graphically the locations of the crowns, area of chlorOphyll formation and height of seedlings produced under colored filters. The area of chlorOphyll develOpment was also higher in the plants receiving lower energy. There is a parallel between 74 Figure 23. Wheat and barley seedlings grown under colored cellOphane filters from seeding depth of eight centimetGLS. Bailey (on the right of each pair) had at least two SUDClOMn inteinodes, wheat (left plant of each pair) had only one. 75 .floomo paw .omhm .ooom .ooow mnumcma m>m3 MO mmmnm>¢e¢ .Ho>oa.Xm ozu um ucmuommao Naucmoflmwdoam mum mnouuoa ucmnowmao nuflz mommum>< .Eo m.o .mucmEummHu soo3umn Aao>mH.va .Q.m.q£ m.MN m.m m.m m.m o.mm m.h oom.m doe *«NHmm Hmoao o.¢m m.o v.h o.m m.a¢ N.o ma.h mod oomo pom m.om m.m m.m m.N h.om m.m em.m omo oomo pom m.HN o.m m.o o.¢ o.N¢ m.o poo.m mum omhm zoaamw o.mN o.h H.o m.m N.mm H.h onmm.o omb omnm sedan» o.mm m.m o.h N.¢ ¢.N¢ m.m Amm.o hmm ooom qmouo o.mm o.m ¢.m ¢.¢ m.om v.m oono.o mom oooe osam o.mm m.m b.m m.m m.o¢ «.5 och.m sea oooe moam muoumfiauaoo AEUImHoV Adv mama ucmEmOHo>oQ Home: Hosea mmoq undemoam>mn czouo. oon> sumcoq HOHOO umoaaea HamnmonoHno czono umoaama Hamnmouoazo. Noumea mhmz moaumm umng Ii $3 Sm: .muouaam mamnmoHHoo Hoods czoum mmcflaooom moaumn one umon3 mo mama umoaamu no man one .ucmEmOHo>oo Hamnmouoazo mo mono .csono Op comm Eoum moamumao ommno>¢ .HN magma 76 .muouafiw mamanHHmo oouoaoo Hood: szoum mmcwaoomm hoaumn new umo£3 mo mama umoaamu mo unmade one unmEmOHo>oo Hamzmouoaso 0%» ohm.» «\MM. 89» 82v .Nk 30\\9\A18 50.1% ka g . , _. .. 30¢ mmaumm 4v numsoq o>m3 HOHOO spawn mcaooom E 982 GBOHU oommnsm u memoao> a ansemouonao gunman Honowmv S‘s momma mHmGHm Ammuocm ooocmammv mumhmq oamfluasz coho ohm“ SM.“ 000“. OOoxv 3o 3* t8 O 50.6 u3\Q .czouo mo mGONumooq .eN mwsmflm o N w o o O a on m. m. a N 1 a 1 g s om mm ow me om 77 the line of chlorOphyll develOpment and the location of the crown across the colors for wheat. Variation in growth Of the seedlings appeared to be associated with the energy level received at each wave length, as Shown by comparisons of crown formation, chloro- phyll develOpment and height of tallest leaf. There are differences in location of these points between plants grOwn Fl under single or multiple layers of cellOphane. The Single layer permitting higher energy radiation, resulted in decreased elongation Of the plants and a compressing of the Li points measured. - The difference in response to energy levels is most evident within the same color wave length, eSpecially in the red area where a difference in energy level from 500 to 650 erg-centimeters made a striking morphological change. .In the blue area where the energy difference was from 600 to 950 erg-centimeters the reSponse was less noticeable. As shown in Figure 25 there was a general lowering of the crown and chlorOphyll line as energy radiation increased. 78 .ocmnmoaaoo ooHOHoo nmsounu cowumwomu moaned NA ooodosHm:H mm mmcflaommm moaumn new ummnz an undemoam>oo HamanHoHno «0 meme can GodumOOH :3ouo one .mN musmflm A A . .. .... m n ...... .... I a m m a p e a m p I I I .L e .1 Z a Z Z AEOImHov mosam> Noumea evo omh saw one can hmm mmm mod 15 Ln < < LT ( < ( \\./ .I...|.ll..\\ / F \\ \\ II II. I \ / IIII..\ / “a .II... / \. can 302333 / sxeasmrquao DISCUSSION The crown of small grain plants is considered as that region of the plant where tillers and secondary roots 1 originate. It is a succession of nodes and teleSCOped :1,- internodes, generally occurring near the soil surface. After germination, as growth of the seedling occurred, the '3:- apical meristem surrounded by the coleOptile was carried ‘1 upward by elongation of the internode or internodes beneath the growing point. In some cases with deep seeding, more than one internode was formed below the crown. The inter- nodes continued to elongate until emergence of the coleOp- tile or foliar leaf. Thus it may be more apprOpriate to refer to the growth as a subcrown "stem" with nodes and internodes similar to an above ground stem. The bud at each node could develOp into a crown under prOper environmental conditions. The name "crown" however should be reserved for the node where tiller buds are produced and elongate and the secondary root system develOps. .When the seedling received light, elongation of the internode halted and foliar leaves with axillary buds develOped at the uppermost node. Minimum tillage created a soft seedbed resulting in deeper seeding of barley. The normal seedbed preparation I 79 I 80 resulted in a firm seedbed and shallow seeding. NO elonga- tion of the subcrown internode occurred in the Shallow seed— ing because the coleOptile emerged and received light before elongation of the apical meristem. With deeper seeding, the meristem became active and elongation of the internode occurred before the coleOptile emerged. As long as the coleOptile was kept in the dark, either by soil or by a tar paper lid, the one or more subcrown internodes elongated. Light seemed the principle factor in determining the loca- tion of the crown. Soil moisture and oxygen content were considered as factors in crown location. ‘While they are undoubtedly important, the fact that the crown was formed above the level of the soil surface in darkness eliminates these as determinant factors in crown location. The possibility of manipulating the location of the crown by covering the emerged seedlings of wheat and barley was investigated. A second crown was formed by seedlings of both Species by covering them with soil after they had emerged and formed the first crown. The second crown formed at a node closer to the soil surface than the crown of shallow seeded plants. »Apparently the covering of the crown allowed a temporary resumption of hormone production needed by the growing point for elongation purposes. Light was not completely removed from the seedlings as some leaf area always remained above the leveled soil surface. Very few tiller buds at the first crown elongated. 81 The influence of light intensity on crown formation has a practical application in eXplaining observations of Ferguson and Boatwright (1968) that wheat grown under stub- ble mulch produced crowns nearer the surface of the soil. The blanket of stubble litter would have reduced light intensity, as did the dark beads in the present eXperiments, elevating the location of the crown. Long wave lengths of red and yellow light (6600 and 7000A) permitted greater light transmission and effectively triggered the reSponse for crown formation at a lower depth than the shorter wave lengths of blue and green (4600 and 5200A). The finding of varietal differences in tillering confirms previous reports. 'Wong produced more tillers from the coleOptile node than did Hudson. However Hudson Showed a depth of seeding—variety interaction to coleOptile tiller- ing by producing more tillers at the coleOptile node when seeded deeper. Gaines also exhibited more tiller production capacity than other wheat varieties. Other factors were more important in tiller production than depth of crown formation. However there was a slight association between depth of crown formation and number of tillers produced per plant. Generally plants with deeper crowns produced more tillers than those with shallow crowns. The environment for tiller survival might be better at the lower depth. There ‘would be less ground action from*winter freezing and better protection from cold temperatures. CONCLUS IONS Light played a major role in determining the crown location of wheat and barley seedlings. During and after germination the apical meristem of wheat and barley seed- lings elongated to form the subcrown stem until growth was halted by plant emergence into light, or food reserves of the seedling were exhausted. In normal conditions the sub- crown stem consisted of a Single internode, the axillary bud at the tOp node develOping into the crown. With excessive seeding depth, the subcrown stem contained a series of nodes and internodes, the crown forming at the uppermost node. The subcrown stem of wheat and barley ceased elongation when the seedling received light. When the coleOptile emerged and elongation of the subcrown stem ceased, foliar leaves with axillary (tiller) buds and the secondary root system develOped to form the crown. The location of the crown was manipulated at least to a small degree by seeding depth. Seeding at lower depths permitted some elongation of the subcrown internodes and permitted the crown to be formed at a lower depth than with shallow seeding where no internode elongation occurred. 82 83 Barley had shorter subcrown internodes than wheat increasing the probability of it producing more than one subcrown internode. The shorter subcrown internodes also makes deeper seeding of barley more susceptible to failure of emergence. Leveling of ridges between deep furrows to cover emerged seedlings can be used to manipulate the crown loca- tion. A second crown above the original crown was formed near the leveled soil surface. The possibility of rejuve- nating the lower crown in case of winter damage to the upper crown was not eXplored but offers interesting Speculation. The number of tillers and yield were not increased by this practice. Varietal differences in tiller production and the point of tiller origin were Observed. Wong produced more tillers from the coleOptile node than Hudson. Gaines produced more tillers than Avon or Genesee. _111 BIBLIOGRAPHY Aamodt, O. S., J. A. Torrie, and A. Wilson. 1935. Studies of the inheritance of and relationships between kernel texture, grain yield and tiller survival in crosses between Spring wheats. J. Am. Soc. Agron. 27:456-466. Allen, R. E., O. A. Vogel, and C. 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