‘1 u‘»\\‘~‘.\\\\\ l l V *W \\‘~\\\\\\\\\‘\\* Wu K t f -7! _. ’d’ , l \ \ W \ M FACTORS ENVGLVSNG SQLATEQN [N FROQUCTON G»? HYBRiD SEED CQRN Thesis {of {he E39351: :24. 3A. 3. :ViiCi’iiGAN STATE CCLLEGE Sfméew R. Afi§~man 294:9 'THESES V t This is to certifg that the ~ . thesis entitled "Factors Involving I 0 Production of Hybrid elation in Seed Corn" presented bl] Stanley R. Anderson has been arrepted towards fulfillment of the requirements for - MS degree in F?” Crows t I l t l E Z W 1 Major profesmr IMHO- Y_y 35tg. 1949* ,1 M~7tos l i I i . FACTORS INVOLVING ISOLATION IN PRODUCTION OF HYBRID SEED CORN by Stanley R. Anderson A THESIS Submitted to the School! 31' Graduate Studies of Michigan State College of Agriculture and Applied Science in partial fulfilment of the requirements for the degree of MASTER OF SCIENCE Department of Farm Crops 19h9 THESIS FACTORS INVOLVING ISOLATION IN PRODUCTION OF HYBRID SEED CORN ACKNOWLEDGEMENTS The author is grateful to Dr. E. E. Down for his assistance throughout this experiment and the preparation of this thesis and to Dr. M. D. Springer and Mr. H. M. Brown for their assistance with the statistical analysis. The author also wishes to express his appre- ciation to Dr. C. M. Harrison and Mr. H. M. Brown for their construc- tive criticisms of this thesis. TABLE OF CONTENTS INTRODUCTION REVIEW OF LITERATURE METHODS OF EXPERIMENTATION PRESENTATION AND DISCUSSION OF DATA SUMMARY LITERATURE CITED TABLES Page N con-w 10 ll INTRODUCTION Contamination in the commercial production of hybrid seed corn is of major importance. There are a number of factors that cause contam- ination, among which insufficient isolation and inadequate detasseling are the most important. Requirements for isolation of the seed field may be influenced by the relative amounts of pollen produced by both the male pollinating parent in the seed field and nearby corn of another variety or type. Likewise, the wind direction and velocity during the period of pollen shedding may cause variations in contamination. The relative time of silking and pollen shedding of the male parent, climatic conditions which may effect the longevity of the pollen, and isolation brought about by male border rows or natural barriers between the seed field and.possible contaminating fields bring about problems which must be answered, if effective isolation is to be brought about. In addition, topography which may influence air currents carrying contaminating pollen and size of seed field are factors that influence possible con- tamination. A study of the factors which influence contamination under actual production conditions is the objective of this thesis. An attempt is herein made to simulate the actual conditions under which hybrid seed corn is produced. Since one of the problems of crap improvement is to keep and main- tain genetic purity of varieties, proper isolation of hybrid seed fields becomes a problem of considerable importance and.economic significance to growers. -2- REVIEW OF LITERATURE LPRussell (h) planted contaminating corn directly adjoining seed fields which were not detasseled. Less than five percent contamination was found after 20 rows of corn in the seed field.when contamination. was from the north, after to rows when the contaminating field was on the south, and after 20 rows when east and southeast contamination was present. Isolation required for a low level of contamination depended greatly on the direction the contaminating corn was from the seed ifield. Sufficient male parent border rows were found to be beneficial in decreasing the percentage contamination.v He concluded that more male parent border rows and less isolation distance served to lessen the percentage contamination. Jones and.Newell (1) in determining the concentration of pollen of corn and other grasses, found that there was a rapid decrease due to gravity and dispersal acting on the pollen load as it is blown from the field. Using the average amount of pollen caught in the center of the field as 100%, approximately 31.0% was caught per unit area at S rods away from the field, 10.0% at 15 rods, h.h% at 25 rods, 1.2% at to rods, and 0.8% at 60 rods. At 25 rods from the field considerable quantities of pollen remained.dispersed in the air. Not until hO rods was reached was the amount reduced to relatively small quantities. At 60 rods the amount was further reduced to about one percent of that caught at the center of the field. One percent of pollen is the equivalent of several thousand.pollen grains per square foot, which would be sufficient to effect much fertilization in absence of com- petition. -3... METHODS OF EXPERIMENTATION This experiment consisted of three fields of yellow dent corn that were located directly east of contaminating fields of Folk's white cap yellow dent corn. The fields were handled similarly to seed fields and the four rows designated as females were detasseled daily, while a fifth row designated as male was left with the tassels on. Folk's White Cap corn gives a white characteristic to the F1 crosses (2). Field 1 was located to rods from the contaminating white cap field to the first female seed row. Two male border rows were planted around the field to meet the requirements of the Michigan Crop Improvement Association (Table 6). Table 6 is taken from those requirements. Field 2 was located 20 rods from.the contaminating white cap corn to the first female seed row. Ten male border rows were planted on the side facing the contaminating corn and.two male border rows sur- rounded the other sides of the field (5). Field 3 was located 10 rods from the contaminating white cap corn to the first female seed row. Fourteen male border rows were planted on the side facing the white cap corn and two male border rows sur- rounded.the other sides of the field (5). The contaminating fields of white cap corn were planted to the west of the seed fields since the prevailing winds are from southwest to west over the area where these fields were located. Wind data were secured during the pollination. Data from Field 1 were obtained.prior to silage harvest when the corn was in the early dent stage. The primary ear from.every fifth 4,- stalk in each row of female and male corn was sampled and the data were recorded as to the number of white cap kernels per ear. The corn was also sampled for the average number of total kernels per ear. 0n Fields 2 and 3, data were taken as to the number of white cap kernels per ear when the corn was mature. Counts were made on every primary ear of the male border rows and female seed rows. No counts were made on the male pollen parent in the main part of the crossing field. Each individual male border row and female series were sampled for the average number of total kernels per ear. In Field 1, data were taken on the first 20 series of female rows. In Fields 2 and 3, data were taken on all of the female series of rows in the field.which consisted of 22 and 12 series, respectively. By "series of female rows" is meant the four rows between two consecutive male pollen rows. PRESENTATION AND DISCUSSION OF DATA The data obtained in this experiment is presented in table form on pages 11 through 17. Data were obtained as to the amount of con- tamination in each field for both the male border rows and the female seed rows. This information is presented in Tables 1, 3, and h. Table 2 shows the effect of contamination on different female rows within a series of four female rows. In Table 5, the wind data is given for the period during which pollination took place in the experiment. Table 6, is taken from the Field.Requirements for isolation of hybrid seed corn production of the Michigan Crop Improvement Association (5). When each four rows of corn designated as female were analysed, there was found a significant difference in contamination in the center choc mo caofiu weapmcwaopnoo scum meow an .n on ad ad pd «a mu ru 3 «N 3 ad D b ‘ mouaom oaoaom much Ezemmnonomwesssp .2 .2 .2 ¢¢ s. s. .2 .a c; ¢s s. s. odes. .wou nodded oaoe mason uohaon mane Hounoaanon_no :2: .m oanna ooao oom .ooa=0m nonponwaopnoo on» scum moon ON ma nownw w eaofim scum ohm anon .ooanom o no anon oaoaou neon one mo omouopo one one son 7 pounce oaoa huo>o ca goo oaani Mo noaaondaopnoo mo owopnoo anon anaconm neoao .H oaamam uotqeutmeiuoo yo efiequaoaed /_~ UH nnoo no caofiu mcaaondaovnoo apnu atom ml». Mn an 0n ow mu sud ed ha rs nu MN 3 on 2 9 2 2 n. I. n. a. z b ilrlllllr D b D D p P r . uoanon odoaom uneaseteflzen22mphboon..." SiiEiEiiiSiEiiiiEs—SSEE 0‘ l1 DIOR _ $23 one: .son noaaon oaoe npnooonnon onus Hoocouanon so an: .n canoe onao oom .oonsom nonaonaaoanoo onv aonu moon OH on nonns n eaoan aonu one upon .aonnoo o no nwon oaoaou neon on» no owonona on» one son noenon oame hno>o :4 duo opnnn no nonponnaopnoo no owopnoonon weakenm neono .m onswau mméw/fi mwfiomgmmao :13 UOIQBUIWBQUOO JO 9331!:an -7- two rows as compared to the outer two rows adjacent to the male parent rows. This analysis was done on only the first ten series of the field, since there was relatively little contamination beyond this point. Applying "Students" method to the first ten series of Field 1, the odds are highly significant (h82zl) that rows 2 and 3 of a female series of four rows have more white kernels (due to con- taminating pollen) than do rows 1 and h of the female series. In the case of Fields 2 and 3, the first male border row facing the contaminating corn exhibited about twice as much contamination as did the second row (Figures 1 and 2 and Tables 3 and h). Contamina- tion on the next two male border rows decreased rapidly with the re- maining male border rows only slightly affected. Apparently the male border rows were effective as barriers. Likewise, the proportion of pollen shed by the male border rows, in relation to the contaminating pollen, increased from the outside to the inside of the male border rows. In the first few female series the contamination increased very no- ticeably.‘ This was probably due to the decrease in the number of male parent rows and the consequent decrease in amount of male pollen be- cause only every fifth row was a male pollen row with tassels remain- ing. Results of these findings are illustrated in Figures 1 and.2. Distance is evidently quite important as all three fields Showed that the amount of contamination decreased with respect to increased distance between female seed rows and the contaminating field of white cap corn. However, only in Field 3, where the isolation distance was but ten rods, did the contamination exceed one percent. Less than one percent of contamination was found in this field after a distance of 16 rods. This degree of contamination may seem trivial, but this -8- amount would be disasterous in the maintenance of the genetic identity of a variety of corn. The winds during the period of pollination in l9h8 for all three fields at the time of pollination, were medium to light when from the southwest to westerly directions (Table 5). Some increase in velocity was recorded when the winds shifted to northerly and easterly direc- tions. SUMMARY In an attempt to establish, experimentally, the safe isolation requirements for production of hybrid seed corn, three fields of yellow dent corn were planted and handled according to the regulations of the Michigan Crop Improvement Association. Each field was exposed from the west to Folk's White Cap yellow dent corn. This white cap corn gives a white cap characteristic to the F1 crosses. Male border rows seemed to act effectively as barriers protecting against contamination in only the male border rows. A rapid decrease in contamination from.white cap corn was found in the inner group of male border rows in comparison to the male border rows facing the con- taminating field of corn. A marked increase in contamination was found where the detasseled female series began. A significant increase in the contamination by the white cap source was found in the inner two rows of the female series of four rows than was found in the outer two rows adjacent to the male pollen parent. The amount of contamination decreased as the distance from the contaminating corn increased. It appears that male border rows are not as effective as distance in preventing contamination in seed production of hybrid corn. It is also evident that large quantities of the corn pollen drop near the source and that smaller portions are dispersed by the wind. The evidence shows that where isolation distance must be forfeited and male border rows used, that there is an increase in contamination _ for the first few series of female corn. l. 2. 3. -10- LITERATURE CITED Jones, M. D. and.Newell, L. C. Pollination cycles and.pollen dis- persal in relation to grass improvement. Res. Bul. 1&8, Univ. of Nebr. Col. of Agr., Agr. Exp. Sta. l9h6. Kulkarni, Chandrakant G. Inheritance studies of white-capping in yellow dent maize. A thesis. Michigan State College, 1926. Love, H. H. and Brunson, A. M. Students method for interpreting paired experiments. Jour. of Amer. Soc. of Agron., Vol. 16, No. 1 pp. 60-68 incl. Jan. 192h. L-Russell, Herman Gacitua. Factors which determine the importance of contamination in corn. A thesis. Iowa State College, l9h6. Michigan Cr0p Improvement Association. Field requirements for certification of corn hybrids. Michigan State College. pp 2-3. 19h9. mo. mm. mm mm a as so. mm. mm om a mu so. mm. mm mm a an mo. om. so. am. an an a * Hm mo. mm. mm mm * om mo. ma. AH om * ma mo. OH. m mm * ma no. co. m mm * AH no. mm. No. an. on om m s on :0. mm. mm mm . a ma mo. mm. mm om * na mo. we. on om * ma :0. mm. mm mm * NH no. we. mo. mm. mm om m s an no. as. mm mm s on so. am. we mm s a 50. m4. mm mm * m . so. me. an om * n n“ NH. as. oa. mm. mm mm H * o . S. on. we as s m an. em. n» mm s a ma. we. mm mm a m ma. as. aw as s N an. mm. we we a H a .02 n a n a n a n 2 .02 n a m .02 mHonnox moo ooaaaom mownom tom .02 mwfihmm mHflEwh Rom mpflé HO nhwm mflmfimh Ho 30$ .02 Hanan no .02 mane noo nod mHonnox moo open: mo nomad: omono>< .eoaaeoo mob hon nooo cw naopo name.“ mnopo no noo angina one .oabn oaoeom one oaoe neon. no eopooflnoo onok H paofim Eon.“ open .H manna -12- 00. Ho. 00. oo. 0 mm HH * em 00. Ho. H mm * mm 00. oo. 0 mm a 3m oo. Ho. H om * mm 00. No. N mm * Nm 00. Ho. oo. oo. o om 0H * Hm Ho. no. H mm s cm 00. oo. 0 cm s an ac. Ho. H mm a we 00. oo. o om * en Ho. no. 00. No. N om m s on Ho. mo. n so a ma Ho. :0. 4 om * an ac. mo. m mm # m: 00. No. N mm a Na Ho. no. Ho. no. a mm m s H; No. mo. m as s on Ho. co. m an * mm .8. No. 0 mm a. an Ho. :0. n om * pm Ho. so. Ho. so. 4 mm N * em Ho. so. 0 om * mm Ho. mo. A am a an Ho. no. 4 om * mm Ho. mo. m mm * Nm Ho. mo. Ho. no. 3 om o * Hm «0. 0H. m Hm * 0m Ho. 50. 0 mm * mN Ho. mo. m om * mN Ho. mo. N am * AN no. 0N. mo. mH. 0H . mm m * 0N mo. Nm. mN om s mN .e.p:oo H mHnmn -13- oo. oo. oo. oo. 00. Ho. 00. Ho. Ho. 00. Ho. 8. oo. 00. 8. 8. OO. oo. OO. oo. oo. oo. 8. oo. oo. oo. oo. oo. oo. 8. 8. oo. 8. 00. Ho. 8. 8. 00. CO. 00. oo. 8. 00. Ho. 00. 00. Ho. 8. 8. oo. 00. Ho. 8. oo. oo. 8. No. No. 00. 8. Ho. 00. 8. 8. 00. 00. mo. 00. oo. oo. oo. 8. 00. Ho. 00. OH OHOO OOHO NOOO COMO OOOO r-IOON mm mm mm mm mm mm om NH 0H ma 2H ma NH *4: a>o\ QDQ) * t * * n: a) * * * * <3 as * * * * * * * # * * # * e s a sews 9a e um .U.pcoo H wanes -1h- 00. oo. 0 ww * MOH oo. oo. o om * NOH oo. oo. oo. oo. 0 mm oN * HOH oo. oo. 0 mm s 00H 00. oo. 0 mm * mm 00. oo. 0 mm a mm 00. oo. 0 mm a pm 00. oo. 00. Ho. H mm mH * em 00. oo. 0 mm a mm 00. oo. o mm s as oo. oo. 0 om * mm 00. oo. 0 mm a Na 00. oo. oo. oo. 0 mm mH * Hm oo. oo. 0 mm * om .U.¢:oo H manna Table 2 o (1, h) of each female series in Table 1 to show comparison of re- -15. Pairing of inner two rows (2, 3) and outer two rows lative amounts of contamination in pairs of rows. No. of Ears Total White Cap Average White Cap Sampled kernels kernels Rows Rows Rowe Rows Rows Rowe Series No. 2, 3 1, h 2, 3 1, h 2, 3 1, h 1 177 177 1h2 121 .80 .68 2 177 178 87 62 .h9 .35 3 179 180 52 26 .29 .1h h 179 177 32 28 .18 .16 S 179 178 Sh 39 .30 .22 6 180 180 15 7 .08 .0h 7 179 179 13 8 .07 .oh 8 178 177 13 10 .07 .06 9 179 177 11 S .06 .03 10 178 179 3 l .02 .01 11 177 178 1 1 .01 .01 13 180 178 O 0 .00 .00 lb 178 179 0 3 .00 .02 15 179 177 o 2 .oo .01 16 179 177 1 0 .01 .00 17 178 179 l 0 .01 .00 18 177 176 l 0 .01 .00 19 177 178 0 l .00 .01 20 177 178 0 0 .00 .00 Applying ”Students" pairing method (3) to the first 10 series, the odds are highly significant (h82sl) that rows 2 and 3 have more white cap kernels (due to contaminating pollen) than do rows 1 and.h of each This analysis was done on only the first ten series of the field, since there was relatively little contamination beyond.this female series. pOinto ~16- Table 3. This table shows the average total number of kernels per ear of corn, the total and average number of white cap kernels per ear, the percentage of white cap kernels per ear, and the number of ears sampled for both the male border rows and the female parent rows in Field 2. . Total Male Female. kernels No. of Total White White cap kernels Border row Series per ears Cap kernels per ear No. No. ear Sampled per ear Ave. 1 5h2 29 867 29.90 5.52 2 608 2b 392 16.33 2.69 3 628 27 222 8.22 1.31 h SAC 28 115 n.11 .76 S 512 26 32 1.23 .2h 6 552 25 36 1.hh .26 7 566 25 11.11 1.76 931 8 Sh8 25 25 1.00 .18 9 S92 26 8 .31 .05 10 610 27 O .00 .00 1 590 100 231 2.31 .39 2 586 102 172 1.69 .29 3 608 101 9b .93 .15 h 590 106 38 .36 .06 5 566 101 29 .29 .05 6 58h 107 19 .18 .03 7 590 109 13 .12 .02 8 582 10b 5 .05 .01 9 60h 105 1 .01 .00 10 556 110 0 .00 .00 11 566 102 O .00 .00 12 572 100 O .00 .00 .17- Table h. This table shows the average total number of kernels per ear of corn, the total and average number of white cap kernels per ear, the percentage of white cap kernels per ear, and the number of ears sampled for both the male border rows and the female parent rows in Field 3. Total Male Female kernels No. of Total White White cap kernels Border row' Series per ears Cap kernels (per ear No. No. ear Sampled per ear Ave. % 1 6h8 27 h,782 177.11 27.33 2 510 25 1,850 7h.00 13.70 3 602 25 627 25.08 h.17 h 590 26 A95 19.0h 3.23 5 576 30 339 11.30 1.96 6 598 21 336 1h.00 2.3u 7 512 27 251 9.30 1.82 8 570 28 116 8.11 .73 9 578 26 115 h.h2 .76 10 632 29 116 1.00 .79 11 578 28 88 3.00 .52 12 612 29 59 2.03 .33 13 621 26 51 1.96 .31 1h 516 27 27 1.00 .19 1 588 102 1,111 13.83 2.35 2 601 99 1,551 15.67 2.61 3 591 107 1,53h 1h.33 2.h2 h 575 10b 1,282 12.33 2.11 5 576 108 883 8.17 1.h2 6 593 106 300 2 .83 .118 7 592 111 129 1.17 .20 8 576 10b 70 .67 .12 9 597 105 70 .67 .11 10 589 102 51 .50 .08 11 588 100 83 .83 .1h 12 556 107 52 .50 .09 13 596 110 36 .33 .06 1h 590 103 BA .33 .06 15 588 105 18 .17 .03 16 590 107 6 .05 .01 17 608 109 3 .03 .00 18 592 100 1 .01 .00 19 566 100 1 .01 .00 20 581; 101 0 .00 .00 21 590 101; o .00 .00 22 578 108 o .00 .00 -13- Table 5. The wind direction and velocity for the pollination period covering August 6, 19h8 through August 22, 19h8, in the area where the experiment took place. Readings were recorded" at four intervals during the day: 6 A.M., 10 A.M., 2 P.M., and 6 P.M. Directionfi and VelocityH-w of Wind Date Time of'Day August, 1918 6 1.11. 10 11.11. 2 P.M. 6 ma. 6 w 10 Nw 22 Nw 22 Nw 8 7 N 6 Nw 5 NW 7 Nw 3 8 Nw 10 NW 8 NW 10 NE 1L 9 SE 26 SE 30 SE 16 SE 8 10 SE A SE 1 SE .114 SE 17 11 SN 8 Sw 10 sw 8 Sw 5 12 sw 5 SN 10 SN 6 sw 6 13 SN 5 Sw 12 w 8 Nw 7 1h N 8 NW 16 NW 10 NW 7 15 w 2 NW 5 N 5 NE 5 16 ' sw 5 SW 10 SW 11 SW 5 17 sw 6 SN 11 sw 8 sw 6 18 sw 13 w 8 NW 15 NW 12 19 N 26 N 3h NE 19 NE 10 20 E 10 SE 18 SE 12 SE 6 21 S 3 SW 11. SI 9 SN 11 22 S 7 9 SE 11 S 9 SW' * Data collected by the Soil Conservation Service for the Michigan Hydrologis Survey by G. A. Crabb. ** N-north E-east S-south Wewest «ma-Velocity is given in miles per hour. .19- Table 6. This table applies to all sides of the crossing field exposed to contamination from another field, whether located directly It indicates the minimum number of male border rows required when sufficient isolation distance is lacking. opposite of diagonally. When the number of acres in the crossing field is 9 or less 10-19 20-29 30-39 hO or more This is the minimum number of outside rows of "pollen” parent acres acres , acres required. and the distance of the seed rows from the other corn is at least Rods Rods Rods Rods Rods hO 38 35 3h 33 2 35 33 31 29 28 h 30 28 26 zh 23 6 25 23 21 19 18 8 20 18 16 1h 13 10 15 13 11 10 10 12 7 h h 1h 10 9 This was taken from "Certification Service", Hybrid Field Corn, published by the Michigan Crop Improvement Association, Michigan State Reprint, 19h9. ‘ College, East Lansing, Michigan. -20- Figure 3. This photo illustrates the white cap contamina- tion on a yellow dent ear of corn. Figure h. White cap contamination on the male border rows in Field 2. Ears represent rows 1, 3, 5, 7, and 9. -21- Figure 5. White cap contamination on the male border rows in Field 3. Ears represent rows 1, 2, 5, 6, 9, 10, 13, and 11.. Figure 6. White cap contamination within the first series of female rows in Field 3. These are representative ears of from all four female rows. -22- Figure 7. White cap contamination within the second series of female rows in Field 3. These are representative ears of from all four female rows. Figure 8. ‘White cap contamination within the third series of female rows in Field 3. These are representative ears of from.a11 four female rows. -23- Figure 9. White cap contamination within the fourth series of female rows in Field 3. These are representative ears of from.a11 four female rows. ' Figure 10. White cap contamination within the fifth series of female rows in Field 3. These are representative ears of from.a11 four female rows. -zh- Figure 11. White cap contamination within the sixth series of female rows in Field 3. 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