THE RELATIONSHIP OF STRAWBERRY LEAF NUTRIENT CONTENT TO PLANT PERFORMANCE By Lloyd Wayne Martin AN ABSTRACT OF A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Horticulture I967 ABSTRACT THE RELATIONSHIP OF STRAWBERRY LEAF NUTRIENT CONTENT T0 PLANT PERFORMANCE By Lloyd Wayne Martin Field plots of Midway and Robinson strawberries were established in a complete factorial design using single applications of O, 100 and 200 pounds per acre of N, P205 and K20 at time of planting. Plots were established in l964 at East Lansing on a Hillsdale sandy-loam and in l965 at Sodus, Michigan on a Genesee silt-loam. Leaf samples collected in July and August the year of transplanting and at flowering and harvest the following spring were analyzed for nutrient content. Total fruit weight and number were determined on a three to five day interval as fruit matured. Applications of N and K20 significantly reduced yields in the East Lansing experiment. Yields at Sodus were not altered by applications of N, K20 or P205. Correlation coefficients for yield verSus leaf composition was calculated for each sampling period. Yield potential may be more accu- rately estimated from leaf samples taken in July, considering the numer- ical size‘of the correlation coefficients and the number of eIements significantly correlated with yield. Leaf N concentration was highest in leaf samples collected at bloom whereas leaf P was highest in August samples. Leaf K concentra- tion was approximately the same at bloom as the previous August. Leaf concentrations of N, P, and K were lowest in foliage sampled at harvest. I'I-II- lutf.ll r I. III . - 2 Lloyd Wayne Martin Soil applications of N, P205, and K20 caused significant increases in leaf concentrations of N, P, and K. Differences between application rates diminished with time. Available Ca, Mg and K in the soil at harvest were significantly related to yield, but available P was not. Nutrients were not related to firmness or color of fruit. Neither was nutrient content of fruit related to color intensity. A number of fruit nutrient elements were correlated to firmness, however none were consistently related. Correlation coefficients for leaf composition versus soil test val- ues, from samples taken immediately below the plants from which leaf ~samples were taken, indicated that available P and K in the soil were not correlated to P and K found in the leaves. Available Ca and Mg were significantly correlated to the Ca and Mg found in the plant leaves. A survey of 42 commercial strawberry plantings revealed wide var- iations in fertilizer use. COmmercial applications of N, K20 and P205 exceeded rates probably necessary for maximum yield. Leaf K content was higher in some plantings than necessary for Optimum yield according to data from this experiment. Other leaf composition values were within a range at which optimum yields would be expected to occur. Mg content in the soils tested from Manistee County is believed to be lower than desired. THE RELATIONSHIP OF STRAWBERRY LEAF NUTRIENT CONTENT TO PLANT PERFORMANCE By Lloyd Wayne Martin A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Horticulture l967 ACKNOWLEDGEMENTS The author wishes to express his sincere thanks and appreciation to Drs. Jerome Hull and A. L. Kenworthy for their assistance in carrying out the experimental work and preparing the manuscript; to Drs. R. P. Larsen, H. D. Path and C. M. I Harrison for their suggestions in editing the manuscript; to Dr. J. D. Downes for his Suggestions in design of the experi- i ment; to Dr. H. K. Bell for assistance in outlining the problem. Special appreciation is due my wife, Sharon, and three sons, Mitch, Mike and Monty, for their patience and sacrifice during the course of graduate study. TABLE OF CONTENTS ACKNOWLEDGEMENTS OOOOIOUIIOIUOIIt.0....IICIOICIOOOOOIOOOUOOIII TABLE OF CONTENTS coo...oooouooooonanooloooloo-noooolttnooouta LIST OF TABLES ontoot-Olen...Cocoa-oto.oloooooooooooooooonoo-I LIST OF F'GURES OIDOOOOOIIICOIOIIIOOIO.IIOOOOUIIOOOIOOOOOIIJOQO LIST OF APPENDICES ........................................... INTRODUCTION ................................................. REVIEW OF LITERATURE ......................................... EXPERIMENTAL PROCEDURE ....................................... RESULTS ...................................................... Leaf Analysis and Yield ............................. Soil Analysis ....................................... Plant Density ....................................... Crown Analysis ...................................... Fruit Composition ................................... Fruit Firmness ...................................... Size ................................................ Percent Sugar ....................................... Color ............................................... Survey Data ......................................... DI SCUSSION ................................................... SUMWRY.u.n.n.u.u.n.u.u.u.u.u.u.n.n.u.u.u.u L ITERATURE CITED ............................................. APPENDlx TABLES IIOIOCOOOOIOIOCOIO.II.....;OIIIOIIOOOOIIOI...- IS IS 38 1+5 1+5 49 54 55 6i 61 69 75 8| 83 87 Table LIST OF TABLES Effect of rate of applied N, P, and K on leaf composition of Midway strawberry leaves at selected Sampling times II...0.0...IQOIOOOIIOIOOOOOOOOIOIOOIO. Effect of rate of applied N, P, and K on leaf com- position of Robinson strawberry leaves at selected Sampling times OOIIOOIOIOICIOOOOIOIOIUC0.0-0.IOOOIICI Correlation coefficients for I965 Midway strawberry yield versus leaf composition at selected sampling times IOOOIOIOOOOIIOIOIIOO0.00.0...OCIOIOOIOOIOIOCCOO Correlation coefficients for I966 Midway strawberry yield versus leaf composition at selected sampling times nooooooooolooooooolouoooDoolotolooootccoon-oo- Correlation coefficients for I966 Robinson strawberry yield versus leaf composition at selected sampling times Itouts-cocooooolonuocooo-oooocnoouoooolooooool- Average soil test values from Midway and Robinson strawberry plots taken in May prior to fertilizer application OD.OI.OIOOOCIOIOOIOOOOIOOII.IOOOOOOUOIUI Average soil test values from Midway and Robinson strawberry plots at last harvest .................... Correlation coefficients for total yield versus soil test Values at last harvest o...DOOCCOIOOOOOOOOOCOODI Effect of three rates each of N, P, and K in l965 on nutrient composition of Midway and Robinson runner crowns in March, 1966 0....O...OOOIIOOOIOIICIDOOOIOI. Correlation coefficients for l966 Midway and Robinson strawberry yield versus nutrient composition of runner Crowns in March, 1966 OOOII.00....COCO-0.0.0.0000...- Effect of three rates each of N, P, and K applied in I964 on composition of Midway strawberry fruit at three 1965 harvest dates I.IICOIOOOCOOOOCOIOCIOOCQDCU Effect of three rates each of N, P, and K applied in l965 on composition of Midway strawberry fruit at two 1966 harvest dates OI.O...-0.0.0.0000...00.00.0000..- Page 25 26 28 39 41 1+2 #8 50 SI 52 Table 13. IA. IS. l6. I7. 18. I9. 20. 2I. 22. 23. 2h. Effect of three rates each of N, P, and K applied in l965 on composition of Robinson fruit at two 1966 harvest dates OOIOOOOOOOOOOOOOOOOOOOO0.0.0.0.... Effect of three rates of N, P, and K applied in I96A on firmness of Midway strawberry fruit at selected 1965 harvests O0.0.0.........OOOCOCOOOOOOOOO Effect of three rates each of N, P, and K applied in I965 on firmness of Midway strawberry fruit at selected harvests in l966 ........................... Effect of three rates each of N, P, and K applied in I965 on firmness of Robinson strawberry fruit at se‘eCted harvests in l966 O0.000000.........OOCIOOOOO Correlation coefficients for firmness of Midway straw- berry fruit versus nutrient composition of fruit at selected harvest dates in I965 and l966 ............. Correlation coefficients for firmness of Robinson strawberry fruit versus nutrient composition of fruit at selected harvest dates in I966 ............. Effect of three rates each of N, P, and K on Size of Midway strawberry fruit at each I965 harvest date ... Effect of three rates each of N, P, and K on Size of Midway strawberry fruit at each I966 harvest date ... Effect of three rates each of N, P, and K on Size of Robinson strawberry fruit at each l966 harvest date . Effect of three rates each of N, P, and K applied in I969 on percent sugar in Midway strawberry fruit at two harvests in I965 ............................. Effect of three rates each of N, P, and K applied in I965 on percent sugar in Midway strawberry frunt at two harvests in “966 O......CCOCOCCCOCCOCOO0.00.00... Effect of three rates each of N, P, and K applied in I965 on percent sugar in Robinson strawberry frunt at two harvests in 1966 O......OCCOOOO......IOOOOOOO Page 53 55 56 57 58 59 6O 62 63 6h 65 66 Table 25. 26. 27. 28. 29. 30. 3]- Effect of three rates each of N, P, and K applied in 1964 on pigmentation of Midway strawberry fruit at four harvests in 1965 ............................ Correlation coefficients for Midway strawberry fruit pigmentation versus nutrient composition of fruit at different I965 dates of harvest .................. Composition of strawberry leaves sampled in July of planting year from commercial planting in southwestern MiChigan to...cocoa-...Ooooooooonooocoonoonooocoo-oo- Composition of strawberry leaves sampled in August of planting year from commercial planting in southwestern MlChlgan .00....O.Ioooonoouoaooooooooooocooooouoooooo Composition of strawberry leaves sampled in July of planting year from commercial plantings in Manistee county, Michigan ...IIOIOCIOIOIOOOI......OOCIIODCOCOO Composition of strawberry leaves sampled in August of planting year from commercial plantings at Manistee county, MIChigan ......OCUCCUICOIIOIC......IIIIOIOIOO Soil test finding from commercial strawberry planting from samples taken in August of planting year ....... vi Page 67 68 70 71 72 73 7h Figure ‘0 LIST OF FIGURES The effect of three rates of N applied at time of planting on N content of Robinson strawberry leaves in July and August of the planting year and at bloom and harvest the following year ................ The effect of three rates of N applied at time of planting on N content of Midway strawberry leaves in July and August of the planting year and at bloom and harvest the following year ...................... The effect of three rates of K applied at time of planting on K content of Robinson strawberry leaves in July and August of the planting year and at bloom and harvest the following year ...................... The effect of three rates of K applied at time of planting on K content of Midway strawberry leaves in July and August of the planting year and at bloom and harvest the following year .......................... The effect of three rates of P applied at time of planting on P content of Robinson strawberry leaves in July and August of the planting year and at bloom and harvest the following year ...................... The effect of three rates of P applied at time of planting on P content of Midway strawberry leaves in July and August of the planting year and at bloom and harvest the following year ...................... Total 1965 Midway strawberry yield as a function of a single application of three rates of N in I964 and of percent of N in the leaves at selected periods of plant development .............................. ..... Total 1966 Midway strawberry yield as a function of a single application of three rates of N in 1965 and of percent N in the leaves at selected periods of plant development ................................ Total 1966 Robinson strawberry yield as a function of a single application of three rates of N in 1965 and of percent of N in the leaves at selected periods of plant development ................................... Page 20 21 22 23 29 3O 3] i. illiwll'lll FEigure 10. Total 1965 Midway strawberry yield as a function of a single application of three rates of K in 196A and of percent of K in the leaves at selected per- iods of plant development ........................... Total 1966 Midway strawberry yield as a function of a single application of three rates of K in 1965 and of percent K in the leaves at selected periods of plant devel0pment ................................ Total 1966 Robinson strawberry yield as a function of a single application of three rates of K in 1965 and of percent K in the leaves following last harvest cocoon.loo...lance-catooooooooooooouooooooooo Total 1965 Midway strawberry yield as a function of a single application of three rates of P in l96h and of percent P in the leaves at selected periods of plant development ................................... Total 1966 Midway strawberry yield as a function of a single application of three rates of P in 1965 and of percent P in the leaves in July of planting year Total 1966 Robinson strawberry yield as a function of a single application of three rates of P in 1965 and of percent P in the leaves at selected periods of plant development ................................... Total I965 and 1966 Midway strawberry yields as a function of available K in soil following last harvest uoooolooooooooooooo'oooOlooooolololIOIooooolo Total yield of Midway and Robinson strawberries as a function of available Ca in soil following last harvest 0.00....IOIIIOOOIOIIIIOOOCOOOO.IIIOIOIOOICIOO Total yield of Midway and Robinson strawberries as a function of available Mg in soil following last harvest lI.......IDIOOOOIIIOOIOOOCCOOIOIIOOCCOC...... Total 1965 and 1966 Midway strawberry yield as a function of plant density in August following trans- planting olooooooooolGoo-ooonocnooooooooooOno-coon..- viii Page 32 33 34 35 36 37 “3 #6 47 3A. AA 0 6A. 7A. 8A. 9A. LIST or APPENDICES Effect of three rates each of N, P, and K on yield of Midway strawberries .IIOOOIOO......CQOCOIIOCIOIOOO Effect of three rates each of N, P, and K on yield of Robinson strawberries in l966 .................... Nutrient content of Midway strawberry fruit at SeIeCted harvest dates ...!‘IOI.........CCCIIOCC.I.OO Nutrient content of Robinson strawberry fruit at selected l966 harvest dates ......................... Average nutrient composition of runner plant crowns from Midway and Robinson strawberry plants in March . Nutrient composition of youngest mature leaves from Midway strawberry plants at selected periods of deve'opment I...CIIIICO.....CIIOCIDIIO......OOOIIDIII Nutrient composition of youngest mature leaves from Robinson strawberry plants at Selected periods of deve‘opment a.....IOII‘OOCCIOOUOIIOI......ICICOIOIIOD Total units of N, P, and K applied from transplanting to harvest in commercial plantings of Midway and Robinson strawberries 0IO.It.......OIOOOOIOOOOCIQOO.I Correlation of strawberry leaf composition versus soil composition from #2 commercial plantings in Michigan loco-I.a...OIt.o...I000.000.000.000000000000 Page 88 89 90 9l 92 93 9h 95 96 I NTRODU CTI 0N Mineral nutrition of the strawberry plant has been extensively studied but findings from numerous field and greenhouse studies have often been contradictory. The strawberry is one of the most widely adapted fruit crops and has been investigated under widely different soil, climatic and cultural conditions. Greenhouse investigations with individual plants may not apply to field conditions utilizing matted- row culture. The lack of agreement among various investigations may be a reflec- tion of the nutritional status of the field plots before some experiments \Nere initiated. Recently a symbiotic relationship between strawberry plants and soil mycorrhiza has been demonstrated.1 This enables plants to more efficiently extract P from the soil. Obviously a more precise rnethod for determining the plants nutritional status and development <>f associated fertilizer practices should be possible. Foliar analysis has been successfully utilized in Michigan for cietermining the nutritional status of tree fruits, grapes and blueber- ries. Soil tests have not been Sufficiently reliable for these craps, F>artly because it is difficult to sample the entire plant root zone. 1'his may explain why most plant analysis research has concentrated on Cieep-rooted perennial crops rather than shallowbrooted plants such as the strawberry. Kenworthy has established standard leaf values for a number of IPersonal communication, C. Bould, Long Ashton Research Station, Llniversity of Bristol, 1967. .IEN lltl'iil. ..Ia Pdichigan fruit crops by collecting a great mass of samples from a number of selected orchards.2 Bould (6), however, contends that ”because non- nutritional factors often limit crop yield under field conditions, the survey method of establishing standard leaf nutrient values is not gen- erally satisfactory.” He has conducted precisely controlled greenhouse and nutrient solution studies to establish his standard values. Smith (“5) points out that "artificial cultures and field surveys are helpful in setting tentative leaf value standards, but they have serious short- comings in that they do not fully integrate all of the factors affecting growth and fruit quality.” A successful leaf analysis approach to plant nutrition problems re- quires proper sampling procedures, sample preparation, analytical proce- ciures and establishment of standard values for evaluating results. The r>rimary objective of this research has been establishment of standard leaf nutrient values incorporating some of the procedures of Kenworthy and Bould. 2 Personal communication, A. L. Kenworthy, Department of Horticulture, r1ichigan State University, I967. REVIEW OF LITERATURE Foliar analysis has been successfully utilized as a tool for determining nutritional status of many tree fruit species, grapes and blueberries. Plant analysis research on the strawberry, how- ever has been largely restricted to investigations comparing time of sampling and determining most satisfactory plant parts to analyze. Lineberry E£.§l (3l) working on new lands in North Carolina compared the mineral content of fresh tissue extractions for mature leaves, young leaves and runners. K and P levels were higher in the immature leaves than in the mature leaves. Conversely, calcium (Ca) and Mg levels were lower in the immature leaves. Both the mature and immature leaves reflected the P and K applications previously imposed, vvhereas foliage from runners did not. They concluded that expanded rnature leaves were most satisfactory for determining nutrient defi- <:iencies by tissue analysis. Kwong and Boynton (26) studied the effect (f sampling time, leaf iage and leaf fractions on nutrient composition of Catskill and Sparkle strawberry plants. They found that leaflets were a more desirable sampling media than petioles and observed no difference in chemical czomposition between terminal and lateral leaflets. During the first Six weeks of leaf growth, foliar concentrations of nitrogen, phOSphorus Eind potassium declined and calcium increased. They Suggested the "youngest mature“ leaves for nutritional analysis. No consistent difference in chemical composition was found between Catskill and Sparkle varieties. Ballinger and Mason (3) concluded from a study with Albritton strawberry plants that the tissue best suited for analysis depended on the element in which one is interested. They found leaflets most satisfactory for nitrogen and calcium determinations, crowns or leaf- lets for phOSphorus, petioles for potassium, and roots for magnesium. Leaflets were recommended as the one plant part most satisfactory for an analysis for all the elements investigated. Anderson §£.§l_(2) found the 3rd and hth oldest leaves of the Catskill variety lower in P and K and higher in Ca and Mg than the youngest mature leaves. The P content of new leaf tissue was greatly increased by each increment of P added whereas older leaves were much less sensitive in reflecting the P fertilizer treatments. In- creased N fertilizer levels also increased leaf P, suggesting an N/P interaction. Lanning and Garabedian (27) found that Ca was highest in the crowns while Fe was highest in the roots and lowest in the petioles and crowns. They found little difference in Fe and Ca content between Dixieland, Surecrop, Armore and Blakemore varieties. Fe averaged 0.20% and Ca 0.85% in the leaves. Lineberry and Burkhart (29) reported soluble Ca in strawberry leaf blades more than four times as great as in any other plant part tested. Gruppe and Nurbachach (l7, 18) sampled recently matured leaves at time of flowering and found no yield increase with K levels above 0.7%, Mg above 0.4%, N above 2.35 - 2.40% and P above 0.28 - 0.32% Emmmmmprena suggesting that additional increases in these elements would fail to further increaSe yield in the Climax variety. Optimum foliar nutrient concentration immediately following harvest is reported by Naumann (38) to be l.8 - 2.0% for N, 0.28 - 0.30% for P, l.8 - 2.0% for K and l.0% for calcium. Bould (5) suggests nutrient composition of recently matured strawberry leaves be above 2.0% N, 0.20% P, 1.0% K and 0.15% Mg after fruiting the first year. Cline (9) found leaf blades preferable to petioles as an indicator of nutrient status of both fruiting and non-fruiting plants. Under Ontario conditions, early August was considered the nwost desirable time to collect leaf samples from non-fruiting plant- ings. June is to 30 was suggested as the time for sampling during fruiting year. Bould (6) suggests sampling at a specific physiological stage <>f deveIOpment. From time of flowering until immediately after har- \/est, he found that N, P, and K decreased whereas Mg increased. The l eaves contained more Ca at harvest than at flowering or following l1arvest. When leaf composition was correlated with yield, those Siamples taken at harvest time gave the best reflection of total yield. A more practical time to sample would be sufficiently early in cievelopment of the plant to allow time for corrective measures pre- <2eding fruiting. Strawberry flower primordia are defferentiated in *1ichigan under short day c0nditions in late August and early September. ‘rhe nutritional status of plants at this time has a decided effect on 3/ield the following Spring (ll, 32). Gardner (16) found the number c>f flower stalks, flowers and Size of the berries depend to a large extent on the nutritional condition the preceding fall. Strawberry plant numbers, height and spread measurements taken in the fall are significantly related to yield the following spring (46). Morrow and Darrow (37) found a close relationship between number of leaves in November and number of flowers the following Spring. Thus, it appears that a plant analysis program that considers nutritional condition the year preceding fruiting has merit. Matlock's extensive review of strawberry nutrition (35) makes - -r—4-.L-r:- cm 4 it clear that reSUlts of strawberry fertilizer experiments are quite (:ontradictory. A number of investigations (ll, 2i, 28, 43, 48) l1ave reported reduced yields from N applications; others (40, 50) l1ave reported no significant yield re5ponse to N fertilizer; and sstill others (24, 30, 47) have shown an increase in yield with N applications. Strawberries are apparently very tolerant of excessive P ap- F>lications. No reports indicating reduced yield from P fertilizers Eire evident. In some experiments (ll, l4, 30) yield has been in- czreased, whereas in others (4, 2], 40) it was not significantly (:hanged with applicatiOns of P. Response apparently depends on 1<3cal environment and soil conditions. Yield response to K applications is also contradictory. In Smome investigations (25, 40) yield has been increased; others (8, 28, 31) report decreased yields; and still others (33, 4l) report '10 yield differences from applications of K fertilizers. 7 Relatively little has been reported in relation to quality 'factors and foliar nutrient composition. Relationship between foliar concentrations of N, P, and K at Start of harvest and fruit charac- teristics during harvest were recently investigated by Ricketson and Hill (42) in greenhouse, sand-culture studies. Nitrogen levels above .about 2.4% generally adversely affected berry characteristics evaluated — fruit were smaller, lower in soluble solids and matured later. Berry size and earliness increased as leaf composition of P increased from O.l6 to 0.60%. Soluble solids, titratable acids, and earliness increased as K levels increased from 0.5 to 2.0%. A number of investigations have studied the relationship between various fruit quality factors and plant growth rate, crop size, ferti- l izer treatments, etc. However, most fruit quality investigations have been primarily concerned with fruit firmness. Sistrunk (44) studied the relationship between fertilizer level, berry firmness and freezing quality of strawberries. He found Spring applications of fertilizer decreased firmness of the fresh fruit and increased solubility of cell wall constituents. The firmness meaSure- ments on fresh fruit were directly related to quality of strawberries which had been frozen and thawed. A number of publications indicate nitrogen applied in the Spring of the fruiting year caused softer fruit. Among such studies are those Of Chandler (8), Brown (7), Anchter and Knapp (l) and Loree (34). oVerholzer and Claypool (39) found N fertilization increased fruit size and reSpiration rate while firmness decreased. Darrow (l3) reported 0 u.’MxKlm__-_——— no consistent difference in firmness of berries from plots receiving different rates and kinds of fertilizer. Others (20, 36) have found firmness related to dry weight and rate of respiration. Cochran and Webster (l0), working in Oklahoma, concluded that added nitrogen fertilizer was not associated with any reduction in fruit firmness. These same findings were later substantiated by Webster and Gray (49). Application of K are not normally associated with fruit firm- ness. Kimbrough (23), Darrow (l3), Cochran and Webster (l0) and others, reported no beneficial effect on fruit firmness or shipping quality from use of potash. Haut gt a1 (22) found that neither N, P, or K affected the firmness of Strawberries. Strawberry fruit firmness has been determined by several dif- ferent methods, probably explaining some of the wide variation in results. Eaves and Leefe (l5) measured firmness of strawberries through the use of a “penetrometer.” Such a meter basically consists of a pinion - operated plunger eight millimeters in diameter tapered to four millimeters and mounted on a Spring scale. Pressure for a given distance of penetration is read from the scale. A similar device was used by Culpepper at El (l2), however, compression was determined rather than penetration. Shoemaker and Greve (43) modified a pressure tester commonly used with apples to determine berry firmness. The 7/l6 inch plunger was replaced by a l/4 inch plunger. Grams pres- 5ure required to force the plunger 3/8 inch into the fruit was deter- ruined. Scott suggested a probe type pressure meaSure sufficiently sensitive to detect differences in toughness of Skin and actual firmness of the flesh.3 A complete review (l9) of the different pressure testers used on various fruits indicates relatively little work in this regard with respect to the strawberry. ‘ 3Personal communication, 0. H. Scott, Agricultural Research SService, U. S. Department of Agriculture, l965. EXPERIMENTAL PROCEDURE EaSt Lansing Field Plots Field plots of Midway and Robinson varieties were established on the Michigan State University horticultural farm at East Lansing in the spring of 1964 to Study plant composition in relation to strawberry yield and fruit quality. Plants were spaced two feet apart in rows Spaced four feet apart. The experimental design was a factorial with replicates. Treat- ments were single applications of three rates of fertilizer: O, 100, and 200 pounds each of nitrogen (N), phosphorus (P205), and potassium (K20). Hereafter P205 and K20 treatments may be referred to as P and K treatments. Two replicates of each variety were grown, giving a total of 108 plots. Each plot contained 10 mother plants spaced two feet apart. Nitrogen was applied as ammonium nitrate; potassium as muriate of potash; and phosphorus as concentrated super phosphate. Phosphorus was banded five inches deep and four inches to the side of the row one week before planting. The ammonium nitrate and potash were Side-dreSSed one and two weeks respectively following transplanting. Plots were maintained weed-free by cultivation and hand hoeing. Irrigation was applied during the growing season whenever rainfall was less than approximately one inch during any 10 day interval. Detailed records were taken from a Six foot area in each plot. This record area consisted of three representative mother plants and all runner plants developing in the six foot area. 11 Statistical analysis were concentrated on treatment effects and the relationship of plant performance to N, P, and K plant composition. In- teractions were not studied in detail. The following data were collected: Leg: Samples. Nutritional status was evaluated at different stages of plant development through leaf analysis. Leaf samples were taken from each of the plots in July and August of the planting year and at bloom and harvest the following Spring. Youngest, mature leaves were collected at random from established mother and runner plants for chemical analysis. No effort was made to separate the leaves of runner plants from those of mother plants. The fresh leaf samples were taken to the laboratory, washed in mild detergent solution, thoroughly rinsed with tap water, and then oven-dried at 180° F. The dried samples were ground in a Wiley mill through a 20 mesh screen and analyzed for 11 elements. Nitrogen was determined by a modi- fied Kjeldahl method, potassium by flame spectrophotometer, and P by photoelectric Spectrometer. Ca, Mg, Mn, Fe, Cu, 8, Zn, and Al were also determined by photoelectric spectrometer, however were not studied in detail. S211 Samples. Soil samples were collected from the upper six inches of soil from each 108 plots prior to fertilizer applications. A second soil sample was taken the following Spring after the last harvest. >A11 samples were analyzed for available P, K, Ca, and Mg, cation exchange capacity, percent base saturation, pH, and percent Saturation of K, Ca, and Mg, by the Michigan State University Soil Testing 12 laboratory. The soil was a Hillsdale sandy loam with good percolation and drainage. £122; Density. Number of established runner plants was determined by counting all rooted plants in the six foot record area in late August, following tranSplanting. liglg and £551; §15g. Fruit was harvested as it matured at two to five day intervals. All berries from each plot were counted and weighed to determine total yield. Fruit size was calculated as average gram weight per berry for each harvest period. Fruit Quality. Berries were stored at 40°F for 18 to 24 hours after harvest. Ten fruits which were relatively uniform in size, color and degree of maturity were selected from each plot for further evaluation. £521; firmness: Firmness was measured with a Hunter push-pull gauge. A flat tipped plunger, 7/16 inch in diameter, was forced approximately 1/8 inch into the cheek surface of the strawberry. The required force, measured in grams of pressure, was determined for each of 10 fruit. Fruit analysis: Each berry was then cut in half along the longi- tudinal axis. That half of the fruit damaged by the firmness probe was utilized for pitment and percent sugar determinations. The other half was analyzed for nutrient composition in a Similar method utilized for the leaves. Percent 2232;: Percent sugar was determined on a combined juice sample consisting of one drop of juice from each of the 10 berry halves. Refractive index was measured on an Abbee refractometer and converted to percent sucrosa sugar. .5221; 22121: The fruit tissue was ground in a Waring blender after the juice sample was collected. A 25 gram composite sample of the ground tissue was added to 75 ml of 0.5 percent oxalic acid. The samples were sealed in glass bottles and stored in a darkened, 40°F cooler until analyzed. After removal from the cooler, each sample was filtered through No. 5 Whatman filter paper. Fruit pigmentation was determined by meas- uring optical density of the filtrate at 515 millimicrons using an Evelyn calorimeter. 22222 Horticultural 5212.32222 A Second series of plots was established in 1965 at the Sodus Ex- perimental Fann at Sodus, Michigan. The design of the experiment, the fertilizer treatments and measurements taken were the same as those from the East Lansing plots the previous year, with the following exceptions: A more slowly available form of nitrogen, Ureaform, was used in place of ammonium nitrate. In addition to taking leaf samples as previously described, a crown sample was also taken during March. Crowns from run- ner plants near the center of the row were thoroughly washed and ex- panded leaves and roots removed. They were subjected to the same chemical analysis as the leaves. Fruit pigmentation was not measured. The soil type for this second experiment was a Genesee silt loam. Survey 21 Commercial Plantings Leaf samples were taken in July and August of the planting year in ‘42 commercial plantings of Midway and Robinson strawberries in southwest 14 Michigan and Manistee county. Soil samples were taken in August immediately below the plants from which leaf samples were taken. Correlation coeffi- cients for August leaf composition versus soil test values were calculated, A severe infestation of sap beetles made accurate yield records prohibi- tive in the majority of plantings. RESULTS Leaf Analysis egg Yield Table 1 indicates the effect of N, P, and K fertilizer rates on nu- trient composition of Midway strawberry leaves at 4 selected sampling times. Soil applications of N, P, and K caused a significant increase in leaf N, P, and K in July and August at East Lansing. Differences still existed the following spring at bloom. However, the differences between treatments for N and P were less than the previous year. P and K applications resulted in no significant difference in leaf composition for P and K at harvest. Plants fertilized with 200 pounds per acre of N continued higher in leaf-N than those receiving no N. Applications of N were never significantly reflected in leaf com- position for the Sodus experiment. P applications significant increaSed leaf P in July, however this effect was not evident in August or at bloom. At harvest a significant reduction in leaf P occurred in plants receiving P fertilizer. Leaf K was not altered in July as a reSult of treatments, however it was increased at the other three sampling times. Table 2 indicates the effect of fertilizer rate of N, P, and K on nutrient composition of Robinson strawberry leaves at A selected sam- pling times. The same general trends that occurred with Midway were evi- dent. Leaf composition values for each of the two experiments, presented in Tables l and 2, were combined and average values for the two years graphically presented in Figures l through 6. Figure l shows the effect 15 16 Table 1. Effect of Rate of Applied N, P and 1_< on Composition# of Midway Strawberry Leaves at Selected Sampling Times. Sampling Fertilizer East Lansing Sodus Time Rate## 1264-1365 1265-1266 N P K N P K July 0 2.37 0.390 1.58 2.64 0.411 1.37 100 2.62 0.423 1.64 2.71 0.435 1.42 200 3.02 0.470 1.71 2.63 0.471 1.43 ** ** ** N.S. ** N.S. August 0 2.81 0.516 1.79 2.75 0.460 1.28 100 3.09 0.576 1.86 2.82 0.463 1.49 200 3.24 0.580 2.01 2.89 0.481 1.58 id: 4:1: 1H: N.S. N.S. 76‘ Bloom 0 3.03 0.440 1.77 3.09 0.400 1.42 100 3.06 0.452 1.92 3.15 0.406 1.60 200 3.26 0.475 2.06 3.07 0.410 1.61 * k ** N.S. N.S. * Harvest o 2.12 0.11011 1.39 2.22 0.313 0.72 100 2.30 0.360 1.43 2.28 0.275 0.92 200 2.37 0.370 1.49 2.28 0.242 1.00 ** N.S. N.S. N.S. ** ** # % of dry matter. §9# Lb/A of actual N, P205 and K20. * Significant at 5% level. ‘5‘”? Significant at 1% level. Table 2. 17 Effect of Rate of Applied N, P and K on Leaf Composition# of Robinson Strawberry Leaves at Selected Sampling Times. Sampling Fertilizer East Lansing Sodus Time Rate ## 1964-1965 1965-1966 N P K N P K July 0 2.05 0.355 1.44 2.37 0.407 1.17 100 2.29 0.391 1.57 2.40 0.362 1.27 200 2.40 0.401 1.61 2.40 0.420 1.19 ** ** ** N.S. ** N.S. August 0 2.67 0.555 1.77 2.61 0.409 1.20 100 2.78 0.592 1.98 2.60 0.422 1.39 200 2.89 0.636 2.03 2.58 0.419 1.52 ** ** ** N.S. N.S. ** Bloom 0 2.43 0.452 1.60 2.93 0.361 1.41 100 2.43 0.510 1.75 2.96 0.376 1.59 200 2.79 0.517 1.86 2.92 0.392 1.70 1': 321': in? N.S. 5': 723': Harvest 0 1.68 0.338 1.51 2.19 0.312 0.77 100 1.81 0.345 1.54 2.24 0.304 0.90 200 1.86 0.322 1.59 2.23 0.284 0.99 ** N.S. N.S. N.S. * ** #¥ % of dry matter. fi¥ar Lb/A of actual N, P205 and K20. Yb Significant at 5% level. 7%”? Significant at 1% level. Figure 1. The effect of three rates of N applied at time of planting on N content of Robinson strawberry leaves in July and August of the planting year and at bloom and harvest the following year. 23. EST 1 H 2. B A u .. ... ... .. .2. .m ....1. 2 a 2 a a l. «myth! >mo ox; z mmo «8 z ....(mq HARVEST A JULYW || 01 L341 N 100 LBIA N &l\‘ I 200 LB/A N Figure 3. 20 The effect of three rates of K applied at time of planting on K content of Robinson strawberry leaves in July and August of the planting year and at bloom and harvest the following year. ..m 4H . ... . oi. ACMPP10 o\L v— ...(mn— | o LB/A K 100 LB/A K K M B L O O 2 [Pi ..llllllllllllili i F1gure 4. 21 The effect of three rates of K applied at time of planting on K content of Midway strawberry leaves in July and August of the planting year and at bloom and harvest the following year. HARVEST M B fl K K A m m .... B 7- 1. L nu m u. a O WMMW 1. J I . ... . an . 4. . 9. . ofl Eur—k: >mo a}. x "Em.— Figure 5. 22 The effect of three rates of P applied at time of planting on P centent of Robinson strawberry leaves in July and August of the planting year and at bloom and harvest the following year. 0.56 . 3 0 T S J. V E H J 454 ms\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ .521 AUGUST BLOOM Y .381 o. o. o o 33:22 :3 ox... 0. “Eu; 2 8 4. 8 5. A 4 4 3 J 2 O O O I o LB/A P \\\\ loo LB/A P 200 LB/A P Figure 6. 23 The effect of three rates of P applied at time of planting on P content of Midway strawberry leaves in July and August of the planting year and at bloom and harvest the following year. ——___q__. “~— . 3| 7 was HARVEST Q BLOOM .420 T. A . W J .... e... m m w u... $.32: 53 .5. a (228. (324 2 3. 0 uzm z «ox. oz< Zhddma. 30 Figure 8. Total 1966 Midway strawberry yield as a function of a single application of three rates of N in 1965 and of percent N in the leaves at selected periods of plant development. Y* (As a function of N applied) - 2425.518 + 1.359 N W: (July) - 28154.79] + 24679.0204 N 41909215 N2 Y* (Harvest) - 43.593 + 3406.0139 N - 982.499 N2 * Grams per six linear feet of row. 5—— o.n Amp—LR! >mo at z ....431 wwm. hmm>¢<1 1b A<\mm.: ow_1_n_n_< z CON oo. o . - l J a. .00 .0m .3. . mu. 0131A (V/lMO) 31 Total 1966 Robinson strawberry yield as a function of 1965 and Figure 9. a single application of three rates of N in of percent N in the leaves following last harvest. Y* (As a function of N applied) - 2691.833 + 0.462 N w: (Harvest) - - 119114.145 + 45925.0587 N - 10130.491 112 * Grams per six linear feet of row. ——~_— ed «cur—k2 >10 ext 2 m¢¢o 30 v. ...—¢¢o on. .... “3‘0... A<\001: 00.17:; A. 00.0 0¢.0 0¢.0 de vN.0 . 00m 00. 0 . . . lJ. . .1. 000. h0u>¢¢a <00 .... m405 00m 00. .53.: 33...: n. 0 1 .— 00 00 N: 0N. (V/lMO) 0131A 37 Figure 15. Total 1966 Robinson strawberry yield as a function of a single application of three rates of P in 1965 and of percent P in the leaves at selected periods of plant development. Y* (As a function of P applied) = 2769.11 + 0.0733 P 1* (August) . 28320.719 + 224128.385 P - 529265 P2 + 409879.536 93 1* (Harvest) . 8249.722 + 108288.335 P - 344396.511 92 + 356660.630 p3 * Grams per six linear feet of row. 00.0 000. «cur—k! P0303< 0*.0 >m0 <0. .... 00.0 m< 000 00w ‘ 00m. ><392 000. ><3n=2 00m 00. 00. ‘ . 0N. . 0e. 0131A (V/lMO) 44 Figure 17. Total yield of Midway and Robinson strawberries as a function of available Ca in soil following last harvest. Y* (Midway 1965) - 830.194 + 3.236 Ca - 0.000983 Ca2 Y* (Médway 1966) a 1619.603 + 0.760 Ca + 0.0000859 Ca Y* (Rgbinson 1966) a 4§01.362 - 0.787 Ca + 0.000144 Ca - 0.00000001 Ca * Grams per six linear feet of row. A<\0mi: <0 m..m<.:<>< 0000. 0000 0000 000¢ 000m . . . . . J a 00 . 00. woo. zomzaoe com. 2392 .0N. moo. 2392 .0! 0131A (V/lMO) 45 Figure 18 indicates a substantial increase in yield as available Mg increased from 60 to 200 pounds per acre at East Lansing. Midway yield in l966 decreased as available Mg increased from 300 to 700 pounds. 0p- timum yields for Midway occurred between 175 and 300 pounds of available Mg per acre. Maximum Robinson yield occurred between 1000 and 1100 pounds per acre. Plant Density Much of the variation in 1965 Midway yield was related to variation in number of established plants per plot. Figure 19 shows yield in 1965 and 1966 as a function of Midway plant density for the two locations. Peak yields occurred at East Lansing when eight to ten runner plants had been established for each mother plant. A larger number of runner plants was associated with peak yield at Sodus, however the precision of the re- gression was considerably less than for the East Lansing experiment. Variation in number of runner plants explained 62 percent of the varia- tion in yield in East Lansing plots but only seven percent for Sodus. Number of runner plants per mother plant ranged from 3 to 14 in the Robinson variety but was not significantly related to yield. Crown Analysis Table 9 indicates the effect of N, P, and K applied in 1965 on the nutrient composition of Midway and Robinson runner plant crowns in March of 1966. Neither N or K composition in the crowns was affected by the fertilizer applications the previous year. P was increased in the crowns of the Robinson variety as the result of P application but not Figure 18. Total yield of Midway and Robinson strawberries as a function of available Mg in soil following last harvest. 11* (Midway 1965) = 852.734 + 22.268 Mg -0.0473 M92 Y'k (Midway 1966) .. 4798.466 -7.128 Mg + 0.00549 M92 1* (Robinson 1966) a -2489.999 + 10.168 Mg -0.00476 M92 * Grams per six linear feet of row. 3:001: 02 m..m<1:<>< 000. 000 000 00¢ 00w ‘ '1 000. zomzaom 000— ><30_2 000. >439: L 00 00. ON. 0?. 0131A (V/lMO) 47 Figure 19. Total 1965 and 1966 Midway strawberry yield as a function of plant density in August following tranSplanting. 1965 r = .794** v#= -448.159 + 255.248x## -4.287x2 1966 r = .271* v#‘= 1652.918 + 68.184x## -0.975x2 * Significant at 5% level. ** Significant at 1% level. # Yield per six linear feet of row. ## Total number of established plants in six linear feet of row in August. ._.z<1_m «07:02 mun. 00.24.: muzzam .v. N. 0_ 0 0 ¢ 1 8 1‘ 1 N 1.7 C C ' .00 0 £2 (V/lMO) 0713111 000. . 0N. moo. . 0.! 48 Table 9. Effect of Three Rates Each of N, P and K in 1965 on Nutrient Composition of Midway and Robinson Runner Crowns in March, 1966. Element Rate# Midway Robinson a N 0 2.71 2.33 f 100 2.68 2.36 1 200 2.69 2.37 1 Nos. Nose I. p 0 0.381 0.376 100 0.390 0.442 200 0.382 0.443 N.S. * K 0 1.16 1 22 100 1.38 1.29 200 1.23 1.37 N.S. N.S. * Significant at 5% level. # Lb/A of actual N, P205 and K20. 49 for the Midway variety. Table 10 shows the correlation coefficients for yield with each of the 11 elements analyzed in the crowns. Crown N was not related to yield for either variety. P and Ca were the only elements correlated with yield for both varieties. Fruit Composition Composition of N, P, and K in Midway fruit at three selected har- vests in 1965 are shown in Table 11. At each of the three harvests N significantly increased in the fruit as a reSult of applied N. At two of the three harvest periods K increased as a result of K applied the previous year. P was not significantly different in the fruit in any of the three harvests. Table 12 shows N, P, and K fruit composition values for the Midway variety in the Sodus experiment. Percentages of N and P in the fruit were not affected whereas K was significantly increased as a result of ferti- lizer applications. Fruit N, P, and K composition values for the Robinson variety are reported in Table 13. As with Midway, N and P in the fruit were not af- fected but K was significantly increased as a result of fertilizer appli- cation. Fruit N and P composition of Robinson were substantially lower than the N and P composition previously shown for Midway fruit. A number of erratic interactions occurred. At one harvest fruit Ca was increased as a result of N applications; at another, applications of N caused increased Mn content. However, no significant interactions were consistently present at all harvest dates. Table 10. Correlation Coefficients for 1966 Midway and Robinson Straw- berry Yield at Sodus Versus Nutrient Composition of Runner Crowns in March, 1966. Element Midway Robinson N ____## ____ K __ .2761 (2)1; P .3787“? (3) .494“ (3) Ca .33973 (I) .2764 (I) M9 , .3074 (2) _ Mn .460“: (2) _ Fe _ __ Cu .2851': (2) _ B _ _ Zn _ __ A1 .2837? (3) * Significant at 5% level. ** Significant at 1% level. # Type of regression: (l) = straight line, (2) = parabola, (3) = cubic parabola. ## Correlation coefficients for straight line, parabola, and cubic para- bola curves below that required for significance. 51 Table 11. Effect of Three Rates Each of N, P and K Applied in 1964 on Composition# of Midway Strawberry Fruit at Three 1965 Harvest Dates at East Lansing. Rate ## N P K T 1 June 22 0 1.20 0.19 2.39 1 100 1.35 0.22 2.46 1 200 1.35 0.24 2.41 1 ** N.S. N.S. 1 1.. June 24 0 1.27 0.22 2.44 100 1.34 0.23 2.50 200 1.38 0.25 3.00 s'n'c N_S. in? June 30 0 1.12 0.19 2.26 100 1.28 0.21 2.38 200 1.28 0.22 2.30 H N.S. fl ** Significant at 1% level. # = % of Dry matter. ## Lb/A of actual N, P205 and K20. Table 12. Effect of Three Rates Each of N, P and K Applied in 1965 on Composition# of Midway Strawberry Fruit at Two 1966 Harvest Dates at Sodus. 52 Rate## N P K June 15 0 1.24 0.70 1.63 100 1.22 0.66 1.84 200 1.16 0.61 1.96 N.S. N.S. ** June 21 0 1.31 0.75 1.59 100 1.32 0.71 1.89 200 1.20 0.68 1.96 N.S.. N.S. ** ** Significant at 1% level. # = % of Dry matter. ## Lb/A of Actual N, P205 and K20 -Q 3" 53 Table 13. Effect of Three Rates Each of N, P and K Applied in 1965 on Composition# of Robinson Strawberry Fruit at Two 1966 Harvest Dates at Sodus. Rate## N P K June 21 0 0.93 0.70 1.45 100 0.92 0.66 1.61 200 0.89 0.63 1.61 N.S. 11.5. M June 23 0 0.93 0.63 1.38 100 0.89 0.66 1.58 200 0.94 0.59 1.64 N.S. Nos. id: ** Significant at 1% level. # a % of dry matter ## Lb/A of actual N, P205 and K20. 54 [gait Finnness. Effect of fertilizer applications on fruit firm- ness of Midway strawberries at four harvest periods in 1965 is shown in Table 14. Fertilizer treatments did not significantly affect fruit firm- ness at any of the harvests. Table 15 lists Midway fruit firmness data for three harvests in 1966. Again, N and K did not affect firmness, but in the first of the three harvests applied P was associated with firmer fruit. P also was found to increase firmness in one harvest of Robinson (Table 16). N and K apparently caused no difference in fruit firmness for this variety either. Table 17 lists correlation coefficients for Midway fruit firmness and fruit nutrient composition. Calcium was more consistently correlated with firmness than the other elements. Correlation coefficients were significant in three of the four harvests evaluated. Although other cor- relation coefficients were significant, none were consistent throughout the harvest. Table 18 lists correlation coefficients for Robinson fruit firm- ness versus fruit composition. Ca was significantly related to firmness for one harvest. Fe and Al were significant at both harvests from which analysis were made. However, in both cases, when the regression lines were plotted, the curve for the Sec0nd date was opposite that of the first. §i§§. Effect of fertilizer treatments on size of Midway fruit at each 1965 harvest are shown in Table 19. Size typically decreased from first to last harvest. Application of N decreased fruit size at the third Table 14. Effect of Three Rates Each of N, P and K Applied in 1964 on Firmness of Midway Strawberry Fruit at Selected 1965 Harvests at East Lansing. 55 Firmness q_fle Element Ra te## 18 21 23 28 N 0 685 802 684 6110 100 6116 778 630 623 200 66k 666 633 646 N.S. N.S. N.S. N.S. P o 662 781 621 609 100 663 785 6119 660 200 671 781 678 641 N.S. N.S. N.S. N.S. K o 683 758 663 629 100 666 813 655 653 200 6A7 775 629 629 N.S. N.S. N.S. N.S. # Grams pressure required to force 7/16" plunger 1/8” into fruit sur- face. ## Lb/A of actual N, P205 and K20. 56 Table 15. Effect of Three Rates Each of N, P and K Applied in 1965 on Firmness of Midway Strawberry Fruit at Selected Harvests in 1966 at Sodus. Firmness VT 4_ge Element Rate## 13 20 22 N 0 994 1006 610 100 993 922 597 200 1043 934 622 N.S. N.S. N.S. P 0 955 942 631 100 1027 962 594 200 1048 959 603 4 N.S. N.S K 0 1009 943 599 100 1012 967 607 200 1009 952 622 N.S. N.S. N.S. * Significant at 5% level. # Grams pressure required to force 7/16” plunger 1/8” into fruit surface. ## Lb/A of actual N, P205 and K20. 57 Table 16. Effect of Three Rates Each of N, P and K Applied in 1965 on Firmness of Robinson Strawberry Fruit at Selected Harvests in 1966 at Sodus. Firmnessfi June Element Rate## 20 22 N o 787 686 100 770 647 200 743 656 N.S. N.S. P 0 734 674 100 808 655 200 757 660 * N.S. K 0 781 654 100 747 667 200 771 668 N.S. N.S. * Significant at 5% level. # Grams pressure required to force 7/16” plunger 1/8” into fruit surface. ## Lb/A of actual N, P205 and K20. 58 Table 17. Correlation Coefficients for Firmness of Midway Strawberry Fruit Ver5us Nutrient Composition of Fruit at Selected Harvest Dates in 1965 and 1966 East ngsinq Sodus Element June 21, 1965 June 23, 1965 June 25, 1965 June 20, 1966 N _ __ _## .2849: (3)# K _ __ _ 1 P _ .273* (3) 1" Ca .308* (3) .268* (2) .2714 (1) Mg 302* (1) ' .2773- (3) _ Mn .307* (3) _ .267* (3) __ Fe .265* (2) __ Cu __ .398an (3) __ .2759: a .2779: (2) _ __ __ Zn _ _ __ A1 .0011... (2) * Significant at 5% level. ** Significant at 1% level. =11: Type of regression: (l) = straight line, (2) = parabola, (3) = cubic parabola ## Correlation coefficients for straight line, parabola and cubic para- bola curves below that required for significance. 59 Table 18. Correlation Coefficients for Firmnes Fruit Versus Nutrient Composition of Dates in 1966. s of Robinson Strawberry Fruit at Selected Harvest M N ____j%9 K ____. P .____ Ca .343* (3)# M9 .4177”r (3) Mn Fe .306* (2) Cu ____ B _ Zn A1 .308* (2) June 22 .828** (2) .816** (2) .448** (2) * Significant at 5% level. ** Significant at 1% level. # Type of regression: (1) a Straight line, (2) = Parabola, (3) = Cubic parabola ## Correlation coefficients for straight line, curves below that required for significance. parabola, and cubic parabola 60 Table 19. Effect of Three Rates Each of N, P and K on Size of Midway Strawberry Fruit at Each 1965 Harvest Date at East Lansing. Size (Gms each) 4_ge July Element Rate # 15 18 21 23 25 28 l 6 N 0 14.2 14.2 13.3 9.9 7.6 6.7 5.1 5.2 100 15.1 14.0 12.6 9.9 8.0 7.4 5.7 6.0 200 13.5 14.9 11.0 7.9 7.2 6.7 6.2 6.4 N.S. N.S. * * N.S. N.S. ** ** P 0 13.2 13.4 11.8 8.0 6.7 5.9 5.4 5.9 100 15.3 15.0 13.0 10.6 8.4 8.0 5.8 5.7 200 14.3 14.7 12.1 9.1 7.9 6.9 5.8 5.9 N.S. N.S. N.S. * ** N.S. N.S. N.S. K 0 15.0 15.7 12.5 10.1 8.2 6.9 5.8 5.9 100 14.2 14.6 12.6 9.0 7.4 7.8 5.6 5.9 200 13.7 12.8 11 7 8.5 7.3 6.1 5.5 5.8 N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. * Significant at 5% level. ** Significant at 1% level. # Lb/A of actual N, P20 5 gand K20. 61 and fourth harvest but resulted in larger fruit for the last two har- vests. In two midseason harvests larger fruit were associated with 100 pounds of P but not with either 0 or 200 pounds per acre. K was not sig- nificantly related to size of Midway fruit. Effect of fertilizer application on size of Midway fruit from the Sodus experiment is shown in Table 20. Although 5% significant dif- ferences in size occurred at three different harvests, no consistent difference in size can be attributed to treatments. The effect of treatment on size of Robinson fruit is shown in Table 21. Applications of N and P did not affect size of fruit at any of the eight harvests. Larger fruit occurred the first harvest in plots receiving 200 pounds of K20, however the effect was not evident in the remaining seven harvests. Percent Sggg_. Applications of P resulted in a slight decrease in percent sugar in Midway fruit at one of the harvests selected for de- tailed evaluation in 1965 (Table 22). Percent sugar of Midway fruit was not affected by applications of N and K in either 1965 (Table 22) or 1966 (Table 23). While Robinson fruit was consistently higher in percent sugar than Midway, the N, P, and K treatments did not significantly change the percent sugar content (Table 24). Egbgg. Table 25 indicates the effect of fertilizer treatments on red pigmentation of Midway fruit. No significant difference in pigmen- tation occurred during any of 1he four selected harvests as a result of fertilizer treatment. Table 26 lists correlation coefficients for optical density readings 62 Table 20. Effect of Three Rates Each of N, P and K on Size of Midway Strawberry Fruit at Each 1966 Harvest Date at Sodus. Size (Gms each) Jfi“; Element Rate # 10 13 15 17 20 22 24 27 N 0 10.6 10 2 8.6 7.5 3.3 4.4 3.8 3.6 100 12.1 10.2 9.9 8.0 2.2 4.7 4.1 3.6 200 11.1 9.7 9.9 8.6 3.4 4.9 4.0 3.7 N.S. N.S. 2: N.S. 11.5. 11.5. N.S. N.S. P 0 12.0 10.4 9.3 8.1 3.4 4.5 3.8 3.5 100 10.7 9.0 9.1 7.8 2.6 4.6 4.0 3.6 200 11.1 10.8 1o.o 8.3 2.8 4.9 4.2 3.8 11.5. + N.S. N.S. 11.5. N.S. N.S. N.S. K 0 11.1 10 2 9.5 7.9 4.7 4.7 4.2 3.6 100 10.8 10.2 9.6 8.1 1.7 4.7 3.9 3.6 200 11.8 9.8 9.2 8.1 2.4 4.6 3.9 3.6 11.5. NS. 11.5. 11.s. 2: N.S. 11.5. 11.5. * Significant at 5% level. # Lb/A of actual N, P205 and K20. 53 Table 21. Effect of Three Rates Each of N, P and K on Size of Robinson Strawberry Fruit at Each 1966 Harvest Date at Sodus. Size (Gms each) gggggge ggly Element Rate# 15 17 20 22 24 27 29 1 N 0 14.6 13.7 8.6 7.7 6.4 6.1 4.9 4.4 100 15.0 13.0 9.3 8.4 6.9 6.3 5.1 4.3 200 15.1 12.9 9.5 8.2 6.7 6.2 5.4 4.6 N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. P 0 15.9 13.0 9.2 8.3 6.8 6.2 5.2 4.6 100 14.4 13.5 9.5 8.1 6.8 6.2 5.0 4.4 200 14.4 13.0 8.6 8.0 6.4 6.3 5.1 4.3 N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. K 0 13.9 12.3 8.6 7.9 6.8 6.2 5.3 4.4 100 14.8 13.6 8.8 8.2 6.6 6.2 5.0 4.5 200 16.0 13.6 10.0 8.2 6.5 6.3 4.9 4.4 * N.S. N.S. N.S. N.S. N.S. N.S. N.S. * Significant at 5% level. # Lb/A of actual N, P205 and K20. 64 Table 22. Effect of Three Rates Each of N, P and K Applied in 1964 on Percent Sugar in Midway Strawberry Fruit At Two Harvests in 1965 at East Lansing W N P K Rate# June 18 June 23 June 18 June 23 June 18 June 23 0 6.77 6.64 7.08 6.86 6.80 6.77 100 6.86 6.83 6.92 6.81 6.88 6.83 200 7.00 6.86 6.64 6.66 6.94 6.72 N.S. N.S. * N.S. N.S. N.S. * Significant at 5% level. # Lb/A of Actual N, P205 and K20 65 Table 23. Effect of Three Rates Each of N, P and K Applied in 1965 on Percent Sugar in Midway Strawberry Fruit at Two Harvests in 1966 at Sodus. N Rate# June 20 June 22 June 20 June 22 P W K June 20 June 22 0 6.82 6.72 100 6.91 6.71 200 6.90 6.91 N.S. N.S. 7.04 6.71 6.87 N.S. 6.93 6.95 6.70 6.53 7.00 6.86 N.S. N.S. # Lb/A of actual N, P205 and K20 66 Table 24. Effect of Three Rates Each of N, P and K Applied in 1965 on Percent Sugar in Robinson Strawberry Fruit at Two Harvests in 1966 at Sodus. N Rate# June 20 June 22 p Nutrient Element June 20 June 22 K June 20 June 22 0 7.47 7.30 100 7.31 7.33 200 7.22 7.29 N.S. N.S. 7.26 7.54 7.21 N.S. 7.28 7.20 7.28 7.36 7.44 7.36 N.S. N.S. # Lb/A of actual N, P205 and K20. Table 25. Effect of Three Rates Each of N, P and K Applied in 1964 on Pigmentation of Midway Strawberry Fruit at Four Harvests in 1965 at East Lansing 67 Optical Density Harvest Application Date Rate # N P K June 18 0 44.9 45.1 44.2 100 45.9 45.1 45.7 200 46.2 47.0 47.2 N.S. N.S. N.S. June 21 0 41.2 40.6 39.7 100 40.6 39.7 41.3 200 39.7 41.3 40.6 N.S. N.S. N.S. June 23 0 38.3 38.9 40.8 100 42.0 39.9 39.1 200 39.7 41.3 40.2 N.S. N.S. N.S. June 28 0 27.3 27.2 27.8 100 29.8 28.4 27.8 200 27.4 28.4 27.8 N.S. N.S. N.S. # Lb/A of actual N, P205 and K20. 68 Table 26. Correlation Coefficients for Midway Strawberry Fruit Pigmenta- tion Versus Nutrient CompositiOn of Fruit at Different 1965 Harvest Dates at East Lansing. Element June 21 June 23 June 28 N ____## .2731: (2)# .428“ (2) K _____ ____ .314* (1) P — _ — Ca _____ .393** (3) .404** (3) M9 __ __ __ Mn __ .387“ (3) _ Fe ____ .353** (3) ____ Cu .3021: (3) _ __ B _ .3091- (2) .437“: (3) Zn .276“: (2) __ __ A1 * Significant at 5% level. ** Significant at 1% level. # Type of regression: (l) = Straight line, (2) = Parabola, (3) = Cubic parabola. ## Correlation coefficients for straight line, parabola, and cubic para- bola curves below that required for significance. 69 versus fruit nutrient composition. Although a number of statistically significant correlations occurred, none were consistent for all three harvests from which optical density readings and composition were cor- related. EELXEX Data. Leaf composition values for July (Table 27) and J August (Table 28) from 29 Southwest Michigan commercial strawberry plant- ings are listed. Leaf composition tends to be higher in August than July, agreeing with findings from controlled plots. Tables 29-and 30 list leaf composition values for July and August from 13 commercial plantings in Manistee county. Again, leaf composi- tion tends to be higher in July than August. Leaf N and K content of strawberries in August from Manistee county Were higher than August sam- ples from Southwestern Michigan. Soil test findings (Table 31) suggest an adequate level of available P, K, and Ca in commercial plantings in Michigan. The availability of these elements is less in Manistee county than Southwestern Michigan. Available Mg in Manistee county was less than half that in Southwestern Michigan. 11111 111 ‘11 Table 27. Composition of Strawberry Leaves Sampled in July of Planting 70 Year From Commercial Plantings in Southwestern Michigan. Migg§y* Robinson** Element Average Range Average Range N (%) 2.52 2.24-2.76 2.37 2.08-2.60 K (11.) 1.58 1.32-1.86 1.75 1.36-2.00 P (%) 0.42 o.30-0.62 0.40 0.34-0.53 ca (%) 0.72 0.58-0.82 0.65 501-659 Mg (20 0.36 0.27-0.43 0.33 0.24-0.44 Mn (ppm) 211 90-562 216 129-368 Fe (ppm) 134 62-306 206 128-326 Cu (ppm) 16 11-42 16 13-21 B (ppm) 33 26-40 30 27-32 Zn (ppm) 26 17-35 26 22-32 A1 (ppm) 165 92-289 218 155-279 * Average of 23 locations. ** Average of 6 locations. 11" Table 28. Composition of Strawberry Leaves Sampled in August of Planting Year From Commercial Plantings in Southwestern Michigan. 71 Midway* Robinson** Element Average Range Average Range :5 N (%) 2.68 2.20-314 2.54 2.04-2.74 K (7.) 1.68 1.44-2.10 1.78 1.62-2.00 P (7.) 0.51 0.39-0.63 0.53 0.43-0.63 Ca (‘11.) 0.79 0.62-0.92 0.73 o.58-0.86 Mg (‘11,) 0.40 0.30-0.51 0.38 0.30-0.47 Mn (ppm) 290 123-854 298 129-430 Fe (ppm) 143 106-188 171 140-203 Cu (ppm) 14 10-23 14 13-16 8 (ppm) 33 26-53 31 28-37 Zn (ppm) 34 29-39 35 32-36 Al (ppm) 136 97-190 145 97-210 * Average from 23 plantings ** Average from 6 plantings. 11111111111" 72 Table 29. Composition of Strawberry Leaves Sampled in July of Planting Year From Commercial Plantings in Manistee County, Michigan. Midway? Robinson** Element Average Range Average Range T11 N (%) 2.39 2.12-2.80 2.49 2.38-2.66 1 K (%) 1.71 1.44-1.94 2.13 1.94-2.52 . P (%) 0.382 0.329-0.443 0.426 0.401-0.443 ;—= Ca (%) 0.71 0.58-0.86 0.63 0.40-0.80 Mg (2) 0.313 0.25-0.35 0.25 0.20-0.32 Mn (Ppm) 241 95-383 399 171-597 Fe (ppm) 81 45-132 141 111-201 Cu (ppm) 12 11-13 13 12-14 8 (ppm) 26 24-28 33 30-38 Zn (ppm) 23 19-30 27 27-28 A1 (ppm) 120 77-151 154 106-195 * Average from 10 locations. ** Average from 3 locations. 11111111111111.1111 73 Table 30. Composition of Strawberry Leaves Sampled in August of Planting Year From Commercial Plantings in Manistee County, Michigan. Midway* Robinson** Element Average Range Average Range N (34) 2.84 2.38-3.26 2.86 2.68-2.96 K (°/.) 1.81 1.52-2.10 2.14 2.00-2.32 P (2.) 0.47 0.385-0.599 0.53 0.454—0.565 Ca (%) 0.76 0.60-0.86 0.61 0.47-0.70 Mg (2.) 0.35 0.25-0.44 0.31 0.27-0._33 Mn (PPm) 369 156-707 593 364-844 Fe (ppm) 124 89-143 141 138-145 Cu (ppm) 15 12-20 18 17-20 B (PPm) 30 28-35 30 27-33 Zn (PPm) 37 30-47 41 38-43 A1 (ppm) 117 97-195 151 126-185 * Average of 10 plantings. ** Average of 3 plantings. 74 Table 31. Soil Test Findings From Commercial Strawberry Planting From Samples Taken in August of Planting Year. Southwestern, Michigan Manistee County, Michigan Midway(23*) Robinson(6) Midway(10) Robinson(3) é 1 PH 6.0 6.3 . 5.7 5.4 L P# 215 186 190 216 K# 206 172 1160 155 Ca# 1075 1305 823 704 ”9# 183 153 77 54 * Number of plantings from which samples were taken. # Pounds available per acre. DISCUSSION An attempt was made in the design of the reported experiments to affect wide variations in leaf composition values. Thus, unuSually large amounts of fertilizer were applied. A single application was made to avoid the time of application variable. Difficulty was encountered in establishing runner plants in some of the East Lansing plots. Apparently the application of ammonium ni- trate and potassium chloride resulted in an excessive accumulation of salts. Ureaform was used as the N source at Sodus to avoid this diffi- culty. A more rigorous irrigation schedule was also followed and the difficulty did not occur. 5— The major objective of this study was to detennine the relation- ship between variations in leaf composition and plant performance. There- fore, much of the data has been subjected to correlation and regression analysis although a statistically significant correlation coefficient may occur when there is no natural relation between the two variables. With most biological data the relationship between two variables can be expressed either as linear or quadratic. Exceptions to this may occur with a very wide range in independent variables. Thus, all corre- lations were calculated as linear, quadratic and cubic. In event correlation coefficients were significant for more than one function a choice was made based on degree of precision indicated by the correlation coefficient, the standard error of estimate and a knowledge of the natural relationship that may be expected to occur. No 75 76 regressions Were presented which did not have a statistical significance of five percent or greater. July appeared a better time to take leaf samples than either August, bloom or harvest, when all elements related to yield are considered and the size of the correlation coefficients compared. Leaf samples taken in July would also have the practical advantage of providing time after chemical analysis for corrective measures before fruit bud differentiation. Harvest appeared the best time to take Robinson leaf samples if only composition of N, P, and K are considered. Determination of nutrient status at harvest precludes corrective meaSures that wOuId alter current yield. However, adjustment of fertilizer practices the following season based on nutrient status at harvest would be possible in plantings to be fruited a second year. In July the optimum range of leaf N for Midway would probably be below 2.6 percent. Yield from Midway plots at East Lansing was a nega- tive linear function of leaf N at harvest. Yield from Midway plots at Sodus was a negative, slightly curvilinear, function of N at harvest. Both regressions tend to suggest that desired leaf N at harvest would probably be below 2.0 percent. This compared favorably to an optimum Robinson range of 2.2 to 2.4 percent N at harvest. An optimum range for P, at any of the four times of sampling, cannot be determined from the data presented. Although percent P in July samples was significantly correlated to Midway yield in both ex-‘ periments, the characteristics of the two curves were quite different. It is impractical to choose an Optimum range or to postulate which of the 77 two curves reflect the true relationship. The P content in August and at harvest sampling periods were correlated with Robinson yield. Both curves were third order and indicate that a relatively wide range in leaf P may occur with little change in yield. Leaf K values found in the two experiments are in closer agreement than those found for N and P. Concentration of K in August samples from Sodus indicate that yield increased as percent K in the leaves increased from 1.2 to 1.8 percent. Samples for the same period at East Lansing suggest that yield decreased as leaf K increased from 1.6 to 2.4 percent. Thus, one may conclude that peak Midway yields occur when leaf K in August is between 1.6 and 1.8 percent. Yield decreased in the East Lansing experiment as leaf K at har- vest increased from 1.0 to 1.8 percent. Yield at Sodus increased as leaf K at harvest increased from 0.5 to 1.2 percent. Optimum yield ap- parently occurred when leaf dry matter content was between 1.0 and 1.2 percent. Peak yield of Robinson also occurred in this same range. Many of the differences in plant composition values between years and varieties can be traced to soil differences. Considerable differ- ences in soil test values were found both in the 1964 East Lansing plots and in 1965 Sodus plots prior to application of treatments, thus, dis- cussion concerning differences in plant composition values between var- ieties is minimized. A Statistical comparison between East Lansing and Sodus plots was not made; however, major soil differences were obvious. Percent K in the leaves was consistently higher at East Lansing than the following year at Sodus (Appendix Tables 6A and 7A). This .—- -q .. ._..> l 1 111 ll‘ll‘i" 78 difference appeared small considering the soil differences reported in Table 6. The same was true for percent P in the leaves. P in the Robin- son leaves taken in August at Sodus was approximately 30 percent less than in the same sampling from East Lansing. Available P in the soil, however, was approximately 90 percent less. This tends to suggest that strawberries may be very efficient in retrieving K and P from soils even 7 7 though soil test indicates a low available supply. Available Ca and Mg were considerably higher in the soils at Sodus than at East Lansing. Percent Ca and Mg in the leaves were only slightly higher. This again may have been the result of efficient ex- ‘E_ traction from the soil. The plants may have been near their maximum capacity for Ca and Mg or there may be an interaction with K. Manganese was approximately three times more concentrated in leaves from the East Lansing plots. Applications of ammonium nitrate caused an increase in leaf manganese, whereas applications of Ureaform did not result in Such an increase. Major differences in manganese leaf content apparently occurred as a result of the source of N applied. A comparison of values in Tables 11 and 12 indicates that the K con- tent of Midway fruit is considerably lower from the soil which was lower in available K. The opposite is true for P; however, no explanation for the higher P content is evident. Attempting to explain leaf concentration of P and K by use of soil test values is probably futile, as Appendix Table 9A tends to confirm. No significant relationship could be established between leaf P and K and available P and K in the soil. This is of particular interest since 79 the soil samples were taken directly beneath the plants from which the leaf samples were taken. Bouldh has recently shown that the presence of certain mycorrhiza greatly enhance the ability of strawberry plants to absorb P. This may partly explain the erratic reSponse of strawberries to applications of P. Symbiosis may also affect the Supply of other elements. There can be little concluded concerning leaf and fruit composition values and its effect on fruit quality as evaluated in this study. The lack of conclusive findings may be the result of working within a luxury range of nutrients. Essentially no differences were found in fruit color 15 and percent sugar despite widely varying leaf nutrient composition values. Fruit meaSurements failed to reveal any striking firmness differ- ences due to fertilizer applications. This is somewhat surprising in view of considerable research findings to the contrary. Firmness of Mid- way fruit was correlated with the calcium content of the fruit in three of the four harvests evaluated for firmness. The correlation coeffi- cients, however, Suggest the regressions are of poor fit and each are of a different order. One must conclude that no differences in fruit firmness actually occurred or that the measurements were not reflecting actual firmness. It is possible that firmness, as evaluated in this study, may not fully reflect treatment effect. Firmness measured with the Hunter spring gauge is more indicative of skin toughness than flesh firmness. Both skin toughness and flesh firmness need to be determined to extensively 1+Personal communication, C. Bould, Long Ashton Research Station, University of Bristol, 1967. 80 study strawberry fruit firmness. A realistic measure should also re- flect firmness and resistance to breakdown following freezing and thawing. SUMMARY Field plots of Midway and Robinson strawberries were established in 1965 and in 1966 to study plant composition in relation to yield and fruit quality factors. Treatments were single applications of 0, 100, and 200 pounds each of nitrogen (N), phosphorus (P205), and potassium (K20) . Leaf N and K composition tended to be highest at bloom whereas P was highest in August. Lowest composition values occurred at harvest. Leaf samples taken in July were more closely correlated to yield than samples taken at other periods. Yield was significantly reduced as a result of N and K applications in the 1965-66 East Lansing experiment. Much of this variation in yield could be traced to variations in plant density. Applications of P did not affect yield. None of the fertilizer applications affected yield in the Sodus experiment. Midway yield was significantly related to plant density, however Robinson yield and plant density were not significantly correlated. Available Ca and M9 in the soil at harvest were significantly corre- lated to yield in each experiment, whereas P was not. Available K was significantly correlated with yield of Midway but not Robinson. Neither N nor K composition in the crowns was affected by fertiliz- er applications the previous year. P was increased in crowns of the Robinson variety as the result of P applications but not in the Midway variety. Soil applications of N and P caused no effect on N and P composition 81 82 of the fruit. K was significantly increased in the fruit as a result of the K application the previous year. Fruit firmness, percent sugar and intensity of red pigment were not affected by fertilizer treatments. Pigmentation was not consistently correlated with any nutrient element in the fruit. Fruit firmness tended to be associated with fruit calcium content. A survey of 42 commercial Michigan strawberry plantings was con- ducted in 1966. Leaf samples were taken in July and August and chemical- ly analyzed. Soil samples were also collected in August. Correlation coefficients for leaf composition versus soil test values indicated that ; available P and K in the soil are not correlated to P and K found in the leaves. Available Ca and Mg were significantly correlated to the Ca and Mg found in the plant leaves. LITERATURE CITED Auchter, E. C. and H. B. Knapp. 1929. Orchard and small fruit culture. John Wiley and Sons, New York. Anderson, J. F., S. J. Bailey, M. Drake, G. W. Olanky and D. L. Field. 1964. Mineral content of strawberry leaves as influenced by rate and placement of fertilizer and lime. Proc. Amer. Soc. Hort. Sci. 85:332-337. Ballinger, W. E. and D. D. Mason. 1960. Selection of a tissue for use in strawberry nutritional studies. Proc. Amer. Soc. Hort. Sci. 76:359-365. Bould, C. 1963. Manurial experiments with fruit. V. A factorial NPK experiment with strawberry, var. Royal Sovereign. A. R. Long Ashton Agr. Res. Sta. for 1963. pp. 79-83. . 1964. Leaf analysis as a guide to the nutrition of fruit crops. V. Sand culture N, P, K, Mg experiments with strawberry (Fragaria spp.). J. Sci. Fd. and Agric. 7:474-487. . 1966. Leaf analysis of deciduous fruits, in Nutrition 2f Fruit Crops, edited by N. F. Childers, Somerset Press, Somer- ville, New Jersey, pp. 651-684. Brown, W. G. 1919. Fertilizer tests for strawberries. Oregon Agri. Expt. Sta. Bul. 159. Chandler, W. H. 1913. Commercial fertilizers for strawberries. Mo. Agri. Exp. Sta. Bul. 113. Cline, R. A. 1961. Sampling techniques for determining leaf nutrient concentrations for strawberries. Report of the Horti- cultural Experiment Station and Products Laboratory, Vineland, Ontario, Canada. 19-27. Cochran, G. W. and J. E. Webster. 1931. The effect of fertilizers on the handling quality and chemical analyses of strawberries and tomatoes. Proc. Amer. Soc. Hort. Sci. 28:236-240. Cooper, J. R. and J. E. Valle. '1945. Effect of fertilizers, soil reaction and texture, and plant stand on the performance of strawberries. Ark. Agric. Expt. Sta. Bul. 454. Culpepper, C. W., and J. S. Caldwell, and H. H. Moon. 1935. A physiological study of development and ripening in the straw- berry. Jour. Agri. Res. 50:645-699. 83 20. 21. 22. 23. 24. 25. 84 Darrow, G. M. 1931. Effect of fertilizers on firmness and flavor of strawberries in North Carolina. Proc. Amer. Soc. Hort. Sci. 28:231-235. . and G. P. Waldo. 1932. Effect of fertilizers on plant growth, yield and decay of strawberries in North Carolina. Proc. Amer. Soc. Hort. Sci. 29:318-324. Eaves, C. A. and J. S. Leefe. 1962. Note on the influence of foliar sprays of calcium on the firmness of strawberries. Canadian Jour. Pl. Sci. 42:746-747. Gardner, V. R. 1923. Studies in the nutrition of strawberry. Mo. Agric. Exp. Sta. Res. Bul. 57. Gruppe, W. von and K. Nurbachsch. Untersuchungen zur mineralischen ernahrung von erdbeeren. l. Stickstoff, Phosphor und Chlorid - Steigerungen. Gartenbau Wissenschaft 26:415-440. Gruppe, W. von and K. Nurbachsch. 1962. Untersuchungen zur mineralischen ernahurng von erdberren. II. Kalium, Kalzium, und Magnesium - Steigerungen. Gartenbau Wissenschaft. 27:64-86. Haller, M. H. 1941. Testers and their practical applications. U.S.D.A. circular 627. Haller, M. H., P. L. Harding and D. H. Rose. 1932. The interre- lation of firmness, dry weight and respiration in strawberries. Proc. Amer. Soc. Hort. Sci. 29:330-334. Hartman, J. D., R. H. White-Stevens, and M. B. Hoffman. 1938. PhOSphorus and N fertilization for strawberries on Long Island, New York. Proc. Amer. Soc. Hort. Sci. 36:473—476. Haut, I. C., J. E. Webster and G. W. Cochran. 1935. The influence of commercial fertilizers upon the firmness and chemical com- position of strawberries and tomatoes. Proc. Amer. Soc. Hort. Sci. 33:405-410. Kimbrough, W. D. 1931. The effect of fertilizer on the quality and on the keeping and carrying qualities of strawberries. Proc. Amer. Soc. Hort. Sci. 28:224-230. Kirsch, R. K. 1959. The importance of interaction effects in fer— tilizer and lime studies with strawberries. Proc. Amer. Soc. Hort. Sci. 73:181-188. Knight, L. 0. M. and T. Wallace. 1932. The effects of various manurial treatments on chemical composition of strawberries. Jour. Pom. Hort. Sci. (England). 10:147-180. W. . .2 ... a .... .2 e 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 85 Kwong, 5. S., and D. Boynton. 1959. Time of sampling, leaf age and leaf fraction as factors influencing the concentrations of nutrient elements in strawberry leaves. Proc. Amer. Soc. Hort. Sci. 73:168-173. Lanning, F. C. and T. Garabedian. 1963. Distribution of Ash, Calcium, Iron and Silica in the tiSSues of strawberry plants. Proc. Amer. Soc. Hort. Sci. 82:287-291. Latimer, L. P. and S. W. Wentworth. 1933. Fertilizer experiments on strawberries. N. H. Agri. Expt. Sta. Tech. Bul. 55. Lineberry, R. A. and L. Burkhart. 1943. Nutrient deficiencies in the strawberry leaf and fruit. Plant Physiol. 18:324-333. Lineberry, R. A. and E. R. Collins. 1942. Fertilizing strawberries in North Carolina. Car. Agri. Expt. Sta. Bul. 332. Lineberry, R. A. and J. J. Skinner, H. 8. Mann and C. B. Williams. 1933. Results of strawberry fertilizer and tilage experiments. N. C. Expt. Sta. Agr. Inform. Circ. 75. Long, J. H. 1939. The use of certain nutrient elements at the time of flower formation in the strawberry. Proc. Amer. Soc. Hort. Sci. 37:553-555- Loree, R. E. 1925. The nutrient requirement of the strawberry. Mich. Agr. Expt. Sta. Tech. Bul. 70. Loree, R. E. 1928. The nutrient requirements of the strawberry. Mich. Agr. Exp. Sta. Tech. Bul. 182. Matlock, D. L. 1966. Strawberry nutrition, in Nutrition 2: fruit crops, edited by N. F. Childers, Somerset Press, Somerville, New Jersey. pp. 518-548. Maxie, E. C., F. G. Mitchell, and A. Greathead. 1959. Studies on strawberry quality. Calif. Agri. 13, No. 2, ll, Morrow, E. B. and G. M. Darrow. 1939. Relation of number of leaves in November to number of flowers the following cropping in the Blakemore strawberry. Proc. Amer. Soc. Hort. Sci. 37:571-573. Naumann, W. D. 1961. On the connection between the mineral con- tent of the leaves and productivity in raspberries and raspberries under different culture. Gartenbau Wissenschaft. 26:33-56. Overholzer, E. L. and L. L. Claypool. 1931. The relation of fer- tilizers to the reSpiration and certain physical properties of strawberries. Proc. Amer. Soc. Hort. Sci. 28:220-224. 86 40. Peacock, N. D. 1939. The relating importance of various factors in- fluencing profits in strawberry production. Mich. Agri. Expt. Sta. Tech. Bul. 162. 41. Proebsting, E. L. and L. C. Benson. 1957. Strawberry Fertilizer trial. Cal. Agr. ll(5):4-15. 42. Ricketson, C. L. and R. G. Hill, Jr. 1966. The relationship between certain berry characteristics of the strawberry and foliar concen- trations of nitrogen, phOSphorus, and potassium at harvest. Proc. XVII Int. Hort. Cong. 1:418. r 43. Shoemaker, J. S. and E. W. Greve. 1930. Relation of nitrogen fer- tilizer to firmness and composition of strawberries. Ohio Agric. Exp. Sta. Bul. 466. ”......‘fisa-aw.» ...- w- ,_ .mrzALn .- 44. Sistrunk, W. A. 1963. Field conditions and processing practices to frozen strawberry quality. Proc. Amer. Soc. Hort. Sci. 83:440- 446. 1 45. Smith, P. F. 1966. Leaf analysis of citrus, in Nutrition 9: fruit crops, edited by N. F. Childers, Somerset Press, Somerville, New Jersey. pp. 208-228. 46. Taylor, J. 1950. Statistical studies on strawberry crop and vigor measurements. Ann. Rept. East Malling Res. Sta. 100-107. 47. Taylor, R. W. 1930. Influence of winter application of fertilizer to strawberries. Proc. Amer. Soc. Hort. Sci. 27:187-189. 48. Waltman, C. S. 1951. Nitrogen and P relationship in strawberries. Ky. Agri. Expt. Sta. Bul. 562. 49. Webster, J. E. and G. F. Gray. 1937. Relation of rate of ferti- i lizer application to firmness and chemical composition of strawb berries and tomatoes. Proc. Amer. Soc. Hort. Sci. 35:204. 50. Wentworth, S. W. 1924. Results on the effect of nitrate of soda on the yield of strawberries. Proc. Amer. Soc. Hort. Sci. 21:358- 362. APPENDIX TABLES 87 . 1111,11 i 1 88 Table 1A. Effect of Three Rates Each of N, P and K on Yield of Midway Strawberries. N P K Rate ## 1965 1966 1965 1966 1965 1966 O 3304 2565 2476 2678 2752 2397 100 2541 2690 2608 2732 2736 2849 200 1735 2837 2497 2682 2091 2846 ** N.S. N.S. N.S. * N.S. # Grams of total season yield from 6 feet of matted row. ## Lb/A of actual N, P205 and K20. * Significant at 5% level. ** Significant at 1% level. Table 2A. Effect of Three Rates Each of N, P and K on Yield of Robinson Strawberries in 1966. Rate ## N P K 0 2736 2671 2661 100 2789 2997 2849 200 ' 2828 2685 2843 N.S. N.S. N.S # Grams per plot. ## Lb/A of actual N, P205 and K20. 90 Table 3A. Nutrient Content of Midway Strawberry Fruit at Different Harvest Dates. 14115 1966 Element # June 22 June 24 June 30 June 15 June 21 N (%) 1.3 1.3 1.2 1.2 1.3 K (%) 2.4 2.6 2.3 1.8 1.8 P (%) 0.21 0.23 0.21 0.66 0.71 Ca (%) 0.12 0.11 0.13 0.52 0.60 Mg (%) 0.10 0.11 0.09 0.27 0.30 Mn (ppm) 60.7 55.3 63.6 86.6 79.0 Fe (ppm) 65.2 76.8 64.1 319.8 231.7 Cu (ppm) 2.6 2.8 2.6 19.0 17.2 8 (ppm) 10.6 11.9 7.5 32.7 32.4 Zn (ppm) 19.9 18.9 15.1 6.0 30.3 Al (ppm) 46.7 44.3 23.1 149.7 84.9 # % or ppm of dry matter Table 4A. Nutrient Content of Robinson Strawberry Fruit at Different 1966 Harvest Dates. 91 Element # June 21 June 23 N (%) 0.91 0.92 K (%) 1.56 1.53 P (%) 0.66 0.63 Ca (%) 0.57 0.58 Mg (%) 0.26 0.27 Mn (ppm) 51.1 52.3 Fe (ppm) 189.6 199.5 Cu (ppm) 12.6 14.9 8 (ppm) 26.7 25.4 Zn (ppm) 30.4 28.1 A1 (ppm) 104.4 92.9 # % or ppm of dry matter #’_:wii :mr - - r Table 5A. Average Nutrient Composition of Runner Plant Crowns From Midway and Robinson Strawberries Prior to Spring Growth. 92 Element# Midway Robinson N (%) 2.70 2.35 K (%) 1.26 1.30 P (%) 0.38 0.42 Ca (%) 1.33 0.97 Mg (%) 0.34 0.45 Mn (PPm) 175 92 Fe (ppm) 455 606 Cu (ppm) 31 30 B (ppm) 31 32 zn (ppm) 80 50 A1 (ppm) 315 380 # % or ppm of dry matter ‘2‘ Fr? ““ ‘i f ”f 1: 1-.-.-.~ Table 6A. Nutrient Composition of Youngest Mature Leaves from Midway Strawberry Plants at Selected Period of Development. July August Bloom HarveSt Element# 1964 1965 1964 1965 1965 1966 1965 1966 N (2) 2.67 2.66 3.05 2.82 3.12 3.10 2.26 2.26 K (%) 1.64 1.41 1.89 1.45 1.92 1.55 1.44 0.88 P (2) 0.43 0.44 0.56 0.47 0.46 0.41 0.38 0.28 Ca (%) 0.79 0.85 0.67 0.89 0.78 1.00 0.86 1.88 Mg (%) 0.33 0.41 0.37 0.47 0.36 0.31 0.34 0.47 Mn (ppm) 625 140 1 722 196 725 157 537 133 Fe (ppm) 168 182 214 216 259 223 132 129 Cu (ppm) l4 13 23 15 19 20 20 13 8 (ppm) 42 38 31 39 38 39 32 37 Zn (ppm) 42 35 52 33 69 35 4o 31 A1 (ppm) 116 114 195 134 236 158 115 123 # % or ppm of dry matter. 94 Table 7A. Nutrient Composition of Youngest Mature Leaves From Robinson Strawberry Plants at Selected Periods of Development. ___July August Bloom Harvest Element# 1964 1965 1964 1965 1965 1966 1965 1966 N (%) 2.25 2.39 2.78 2.60 2.55 2.93 1.78 2.22 K (%) 1.54 1.21 1.92 1.37 1.74 1.57 1.54 0.89 P (%) 0.38 0.40 0.59 0.42 0.49 0.38 0.33 0.30 Ca (%) 0.74 0.98 0.56 0.85 0.67 1.06 0.60 1.88 Mg (%) 0.34 0.49 0.36 0.49 0.33 0.37 0.27 0.57 Mn (ppm) 422 137 509 103 467 136 294 127 Fe (ppm) 177 197 218 231 245 298 128 116 Cu (ppm) l7 13 20 16 16 15 20 14 B (ppm) 37 39 27 35 29 3o 25 37 Zn (ppm) 40 40 48 29 54 35 21 35 A1 (ppm) 134 154 218 156 191 212 102 125 # % or ppm of dry matter. l’1’l'1iliii‘ii1i1i11 95 Table 8A. Total Units of N, P20 and K20 Applied From Transplanting to Harvest in Commercial glantings of Midway and Robinson Strawberries. Pounds Per Acre -* N P205 K20 Average Range Average Range Average Range Southwestern 1 Michigan 5' Midway (19)* 122 43-214 191 43-414 89 0-189 Robinson (5)* 112 54-192 140 54-267 76 54-98 Manistee County Midway (7)* 137 75-196 224 75-493 86 32-196 Robinson (2)* 127 116-129 302 296-309 166 37-296 * Number included in survey. 96 Table 9A. Correlation of Strawberry Leaf Analysis VerSus Soil Analysis Taken from 42 Commercial Plantings in Michigan (Soil Samples Were Taken Immediately Adjacent to Each Plant From Which Leaf Samples Were Taken). Dependent Independent Correlation ; Variab1e# Variable## Coefficient f 1 Leaf P 5011 P N.S. 1 Leaf K 5011 K N.S. Ls! Leaf Ca Soil Ca .402** (2)8 Leaf Mg Soil Mg .582** (l) # % of dry matter. ## Pounds per acre *4 Significant at 1% level * Type of regression: (I) = Straight line, (2) = parabola 11111..