FOT EXPERIMENTS WITH STRAWBARRIES Thesis for Degree of M. 5. Robert Ear] Loree I 9 2 5 IL”: I. .. . tlto? JJAI? "5!1 L "TR. 1...? 1-1.. w,n..l.t.\.r.fi~f (3.; r.» .17..." ‘I F:‘ 6.1.. .. x .r. . . I ‘n‘... 1 1. i. u .1. 1|... .. .10. Gun.- . 4PT.. "rt: tint: u..- .7! cair‘ ..¢....«Y ....fl‘..y. i1. .Iu . r . . ......r,...J.p.s.......n.,h.. .l e......w_... n 1... ...a.t...-“l,.... 1.13: .. e . 4 1 .(. : .. . . ., .‘. I ..|I| [It L LP . .HI. ...‘ I.“ I'.LI..¥u .\ol ...ah.s3~4..K-I.: ..v 14.1., \I lkikb 7‘. r)~..,1.f#7v;4tf ‘rli.l.)~_’V7\.nuN.U.ua..sVIP}. ..-...‘: 1.31111 \ -.f .i. 02.3.1513... u.: . 5.. A . . V . . , ELI-I I; It Na. 4-.. . . m . ! I.flrfln~¥rerJEEEEB£EIQ. :— .l [.3 .Q . . m x. - . < 0 1 3w I\ a / .. - . r . I: I .. C .1 .. ' q. I 1.... .l l ; .\ .1 . I A]. . .\\ o n . v c . Pot Experiments With Strawberries The Effect on Growth and Fruit Production of Nutrients Applied at Various Seasons THESIS Submitted to the Faculty cf'the Michigan State College of Agriculture and Applied Science in partial fulfillment of the require- ments for the degree of Master of Science By Robert Earl Lore June 192 THESIS TABLE OF CONTENTS Introduction --------------- ~ - 1 Review of Literature ------------- 2 Statement of Problem ------ ~ ------ 10 Materials and Methods- - - - - - 4 ------ 11 Presentation of Data - - - - - é ------- 17 Influence of Nutrients on Vegetative Growth 17 Nitrogen, Mineral and Carbohydrate Content of Plants ----------------- 28 Relation of Potash and Sugars ------- 55 Total Intake of Elements - ~«- - - - - - - 35 Flowering and Setting of Fruit - ----- 37 Total Yield and Size of Fruit - - ----- 4O Relation of NitrOgen and Carbohydrates ‘- - 45 Pistid Abortion - - - - - - - - - - - - - - 52 Moisture Content of Berry ----- -- - - - 53 Discussion - ----- - ........... 55 Summary---- --------------- 59 Acknowledgments ................ 54 Literature Cited ............... 65 109:3.“33: ‘ W K“ - 1 - iggeonucrrom With the exception of moisture there is, perhaps, no factor which more often limits fruit produc- tion by the strawberry plant than the supply of nitrogen and mineral nutrients in the soil. A soil may possess all the physical qualities which make it suitable for the strawberry, but unless there is a proper proportion and amount of the essential elements readily available for the plants the results in growth and fruit produce tion are likely to be unsatisfactory. The nutrient requirements of the straw- berry are not well understood. The limited data which are available on the subject are conflicting and the recommendations for the use of fertilizers equally con- tradictory. Commercial fertilizers are often used in strawberry growing, and they are sometimes applied with little definite knowledge of the results that may be ex- pected from the use of different amounts, different com- binations, or different times of application. In the past the interpretation of the results of fertilizer experiments have been based al- most entirely upcn the yield and grade of fruit. Very little attention has been given to the nutritive condi- tions within the plant and their relationship to the various manifestations of growth such as runner pro- duction, crown develOpment, number of flower clusters, the flowering and the setting of the fruit.. Few care- fully conducted experiments have been recorded in which an attemot has been made to control experimental condi- tions so as to measure accurately the various responses of the strawberry plant to known variations in the supply of available nutrients in the soil. Consequently, though the yield of fruit is the ultimate test of the value of any fertilization program the results obtained in terms of yield only are empirical and of limited range of applicability. Review of;;iterature The data which are available on straw- berry nutrition are largely the results of field ex- periments with fertilizers which have been conducted under variable soil and climatic conditions in differ- ent sections of the country, and a few analyses of the plant and of the fruit. Analyses of the fruit indicate that the amount of nutrients removed from the soil by the straw- berry when compared with some other crops is relatively small. Shaw (15) in Oregon found that the average amounts of the essential elements which would be re- moved in 1000 pounds of fruit was 1.9 pounds of nitrogen, .59 pounds of phoSphoric acid and 1.67 pounds of potash. Van Slyke (18) in New York calculated that a crop of 5000 quarts per acre will remove from the soil approx- imately 7.5 pounds of nitrogen, 3 pounds of phosphoric acid and 12 pounds of potash. However, the total in- take, or the amounts of these constituents which are actually removed from the soil by the plants in the pro- duction of a crop of fruit is much larger than these figures indicate. According to Willie (28) one acre of strawberry plants with a crop of 10,000 pounds of fruit will require more than 100 pounds of nitrogen and nearly 500 pounds of mineral elements to sustain them during growth. He points out that though the loss of nutrients from the soil through the harvesting of a crop of fruit is small, the soil must provide, in addition to the elements which are required by the fruit, a very liberal supply of the constituents which are necessary for the plants. Further, "That a soil to be well manured must contain a large excess of avail- able plant food over and above the amount that can be utilized by the strawberry crop since it cannot by virtue of its root disposition in the soil absorb more than a small proportion of such fertilizing ingredients". A study of the literature shows that the reaponse of the strawberry to fertilizer treatments is extremely variable in different localities, parti- cularly where there are differences in soil composition; and that there are many conflicting Opinions regarding the kind and amounts of materials carrying the limit- ing elements which may be profitably employed. There is also a considerable diversity of opinion regarding the influence of nutritive conditions in the soil, as affected by fertilizer applications, at different seasons. The use of fertilizers in the spring of the fruiting year is thought by many to be particul- arly beneficial. Fletcher (7) emphasizes the import- ance of a large amount of available plant nutrients in the "short time between the blossom and the ripe fruit". He states (8) that "gains of 500 to 1000 quarts an acre from a spring dressing of nitrate of soda are not infrequent”. It is applied as the plants come into bloem. If used late in the spring there is danger that it will produce a rank growth and the berries will be soft and of poor quality and flavor". According to Darrow (6) "The use of nitrogen has been found profitable in the growing of certain varieties for they seem to need the stimulating effect of this element in the spring. Applications of nitrate of soda are made in the spring of each year following the one in which the plants are set". White (31) in New Jersey reported an increase of 31 per cent in yield from a Spring dressing of 200 pounds of nitrate of soda. The soil was a sandy loam and had not previously been fertilized with nitrogen though well supplied with potash and phosphoric acid. A similar application (22) of nitrate of soda to plants which were well fertilized with complete for- tilizer a year before, when they were set, gave an increase of only 18 per cent. The gains in yield were due to an increase in the size of the fruit and apparently not to any increase in numbers. Brown (3) at the Hood River Station in Oregon found that heavy applications of nitrogen greatly increased the yield but that the results from the use of either potash or phosphoric acid alone were disappointing. The use of sodium nitrate combined with phosphoric acid resulted in yields smaller than those where no fertilizer was used, but when combined with sulphate of potash the yields were increased. Highest yields were secured when heavy applications of sodium ni- trate were made, one-half in early spring and the other half at blossoming time. Quaintance (15) in Georgia found that an early spring application of complete fertilizer supplemented by 200 pounds of sodium nitrate at blooming time increased the yield sufficiently to warrant its use. He also tried the effects of doubling the essential elements in a normal fertilizer formula. In plots that received a double dose of potash the yield was lessened con- siderably below the normal. Doubling the amount of -6- sodium nitrate resulted in a slightly increased yield but not enough to make it financially profitable. At the Woburn Experimental Farms (2) in England, liquid dressings of manure and commercial fertilizers were applied to strawberry plants during the fruiting season. The dressings had a retarding influence on the ripening of the fruit, but otherwise had no appreciable effect on the crop. Von Brehmer (19) gives an account of forcing strawberries in pots filled with the same kind of soil but differently fertilized with chemical fertilizers applied once each week in water solutions. With a complete for- tilizer and an additional application of calcium ni- trate the yield was more than ten times greater than that with no fertilizer and the fruit ripened nearly two weeks earlier. Chandler (4) in Missouri feund that nitrogen either in the form of sodium nitrate or dried blood applied in the spring before the crop was harvested gave injurious results in every case. They caused excessive weed growth and greatly re- duced the crop. The berries were larger but fewer in number, and they were soft and of poor color and quality. The data presented by Gardner (10) in Mdssouri indicate that there is little, if any, effect upon yield from applications of fertilizer in the spring of the fruiting year. He states, "When moisture and temperature are not limiting factors the number of flower clusters, number of flowers and size of berries are dependent on nutritive conditions with- in the plant the preceding fall and winter, and they are practically independent of soil fertility condi- tions during the spring and at the time of fruiting". Size of berry was found to be correlated with the number of pistils per flower and the percentage of these which develOped akenes in the resultant fruit. These were influenced but little by fertilizer treat- ments shortly before fruiting. He further states that .'the nutrition question as it relates to the strawberry is a late summer and fall question to a much greater extent than has been generally suspected". Few experiments have been reported which furnish definite data on the effect of fertilizers when applied in the spring a year before the harvesting of the crop. Bailey (1) in summarizing the results of a series of coOperative experiments conducted on various types of soil in Oswego County, New York, reported that the use of both potash and phosphoric acid was benefi- cial, but with commercial nitrogen the increase in returns failed to repay the outlay. The fertilizers were applied to young plantations after the first tillage and after the plants bloomed, but a year before any records were taken on the crop. 'The use of potash and phosphoric acid increased productiveness, and the berries were firmer and better colored. When nitrogenous fertilizers were used there was too much plant growth and an inferior quality of fruit. Chandler (4) gives the results of a number of exper- iments in.Missouri which were conducted on both old and on new beds. "Acid phosphate used alone at the rate of 150 to 440 pounds to the acre gave a profit- able increase in five trials out of six. In six trials out of seven when used in combination with either sodium nitrate or dried blood the yields were increased over the yields that were obtained when either of the latter were used alone. Nitrogen applied in the spring a year before the crop was harvested gave an increase in yield over the unfer- tilized plots in only one trial out of nine". Keffer (11) in Tennessee working with a clay loam soil found that with muriate of potash, acid phos- phate, and cottonseed meal singly and in combination, some of the fertilized plots yielded less than the unfertilized, and that the results, as a whole, were negative. Experimental data on the influence of summer and fall applications of fertilizers in the nutrition of the strawberry are also meager. Fletcher (9) states that "many growers in the northern and central states apply one-third of the fertilizer be- fore the plants are set, one-third during the summer, and one-third early the following spring", and that "throughout the South three or four applications of fertilizer commonly are made; the first when the plants are set and the last four or five weeks before the plants bloom" (8). However, no references to ex- perimental data are given. Bailey (1) reports that in one of the tests in Oswego County, New York, the fertilizer was not applied until August. The ferti- lizers were sodium nitrate and acid phoSphate, and the plot yielded almost 1000 quarts less per acre than the plots which were fertilized with potash in combina- tion with nitrate of soda or potash alone. He attri- butes the small yield, in part, to the lateness of the fertilizer application. Close (5) in Maryland applied commercial fertilizers to strawberry beds in the fall at the time when they were ordinarily mulched. The yields from the fall fertilized plots were smaller than from the check plot which received no fertilizer or mulch. Chandler (4) found that when sodium nitrate or dried blood is applied in small quantities during the early summer one year before the crop is harvested they do not cause excessive plant or weed growth the following Spring. However, when dried blood is applied in large quantities, even a year before the crop is harvested, it tends to cause excessive plant growth, to reduce the yield and to cause the berries to wilt worse during droughts at picking time. Brown (3) in Oregon conducted some experiments on an old bed to determine the value of applications made after the harvesting season as compared with similar applica- tions made at blossoming time. The yields though small consistently favored'late summer applications. As a rule the plants receiving nitrogen alone pro- duced larger berries than those receiving nitrogen in combination with potash or phosphoric acid. Where com- plete fertilizers were used, the plants which were fertilized in the fall produced somewhat larger berr- ies than those which were similarly treated in the Spring. Statement of Problem. Considerable information has been se- cured as a result of the investigations which have been cited, but as yet some of the more fundamental pro- blems relating to the nutrition of the strawberry are not well understood. Gardner (10) has shown that where moisture and temperature are not limiting factors the crap of any season is determined largely by the nutritive conditions existing within the plants during the preceding fall, particularly at the time of fruit bud formation. A study of the nutrition problem brings to attention two questions. First, what are the .conditions which are essential for the growth and fruit- -11- ing of the strawberry; is a certain nutritive condition or balance of the elements existing within the plant necessary or best at the time of fruit bud formation, or is it more important to obtain certain growth con- ditions or a certain size of plant or crown? Second,. what are the best methods of bringing about the desir- able conditions? The first can be answered only by a chemical examination of the plants grown under various nutritive conditions, and careful observations on the behavior of the plants during the blossoming and fruit- ing period. The second, obviously is a question of soil management and the preper selection and uSe of nutrient materials. The objects of this investigation have been to determine (1) the particular conditions which are most favorable for fruit bud formation and the develOpment of the fruit in the strawberry; and (2) the influence of certain nutrient materials, particularly those containing nitrogen, phOSphoric acid and potash on the growth and the nutritive con- ditions in the plant when applied at different times of the year. Materials and Methods. Young runner plants were dug from a bed of Senator Dunlap strawberries early in the spring of 1923 and planted in six inch pots. These were -12- first set on boards which were laid on the bottom of a shallow trench, and then surrounded with ordinary garden soil. Later this soil was covered with sand to prevent it from splashing onto the soil in the pots. The soil used for growing the plants during that experiment was a very light sand. The use of a soil of this type was intended to provide a medium which would offer favorable physical conditions for growth, and at the same time one very low in plant nutrients. The composition of the soil is shown by the following analysis: Moisture 0.16% Loss on ignition .36 Phosphorous pentcxide Sodium oxide (Na 0) 1.07 Potassium Oxide (K20) 1.29 Silicon dioxide (SiOg)86.75 Calcium Oxide (CaO) .98 Magnesium Oxide (M80) .90 Iron and aluminum oxides (Fezogand A1205)9.29 Titanium dioxide (T102) trace Manganous oxide (Mp0) trace Sulphate (303) bare trace Nitrogen (N) 0.02 The amounts of nitrogen, phosphoric acid, sulphur and some other elements seem small when compared with the amounts present in a common productive soil, and there was very little organic matter present. The supply of potash was moderate but inasmuch as an abundance of organic matter - 15 - is thought to be essential for the liberation of potash (13) it is possible that snly a small per- centage of it was available. When the plants had become estab- lished in the pots they were divided into lots of thirty-five each and treated with fertilizers accord- ing to the outline in Table 1. With the exception of Lot 18 the nutrient elements were applied in the form of commercial ammonium sulphate containing 20. per cent. nitrogen, acid phosphate containing 16 per cent. P205and potassium chloride containing 50 per cent. K20. In Lot 18 chemically pure monocalcium phoSphate and commercial sodium nitrate were used. The fertilizer applications were calculated on the basis of an application of 200 pounds of ammonium sulphate, 400 pounds of acid phosphate and 150 pounds of potassium chloride per acre, assuming the plants to be grown under field conditions in hills 15 x 30 inches apart. During the first season the spring applications of acid ph08phate and potassium chloride were made on May 10 and the summer applications on August 1. In the case of the nitrogen-carrying ferti- lizers applications of one gram per plant were made once each month to avoid excessive concentration in the soil and consequent injury to the plants. These for the spring period were made on May 10, June 1, - 14 - and July 1 and those for the summer period on August 1, September 1, and October 1. When fertilizers were applied in the spring of the second year a single application was made soon after the plants started to grow, (about May 1). So far as possible, uniform conditions favorable for the growth of the plants were maintained during the course of the experiment. Water was supplied whenever necessary by means of an overhead system of irrigation, and rarely did any of the plants show symptoms which indicated that they were suffering from the lack of moisture in the soil. Some trouble was eXperienced with strawberry leaf spot but the foliage was kept in a healthy condition by spraying with Bordeaux Mixture. There was some root growth outside of the pots but usually the boards underneath prevented any pene- tration into the soil in which the pots were plunged. The pots were lifted occasionally and any roots found protruding from them were out. All runners were removed as they appear- ed throughout the season and the number and total length of those from each lot of plants recorded. On August 1 and on October 26 three representative plants were selected from each of the lots which had previously received different treatments. These were carefully washed, the fresh weights of the teps and roots deter- mined, and afterward dried and saved for the prrpose -15- Table 1. -- Outline of Treatments used in Strawberry Nutrition Experiment. Lot No. Nutrients Total amount Tmme of Used applied per plant application. 1 No fertilizer 2 Ammonium Sulphate 3 grams Spring 3 " ” 3 ” Summer 4 " " 6 " Spring and summer 5 (Ammonium Sulphate 5 . Spring (Acid Phosphate 15 " Summer 6 Acid PhoSphate l5 " Spring 7 " " l5 " Summer 8 (Acid Phosphate 15 " Spring (Ammonium Sulphate 3 ” Summer 9 (Acid Phosphate 15 " Summer (Ammonium Sulphate 2 " Spring (2nd yr.) 10 (Ammonium Sulphate Z " Spring (Acid Phosphate l5 " Spring 11 (Ammonium Sulphate 3 ” Summer (Acid Phosphate l5 " Summer 12 (Ammonium Sulphate 6 " Summer (Acid Phosphate 15 n 1/2 Spring, 1/2 summer 13 (Ammonium Sulphate 8 " 1/3 Spring, 1/5 (Acid Phosphate l5 " summer, 1/3 foll- , owing spring. 14 ( Ammonium Sulphate 5 " Spring (Acid Phosphate l5 " Spring (Potassium Muriate 5 " Spring 15 (Ammonium Sulphate 3 " Summer (Acid Phosphate l5 " Summer (Potassium Muriate 5 " Summer 16 (Ammonium Sulphate 6 " 1/2 spring, 1/2 (Acid PhOSphate l5 " summer (Potassium Muriate 5 " 17 (ammonium Sulphate 8 ” 1/5 spring, (Acid PhOSphate 15 " 1/z summer, 1/3 (Potassium' Muriate 5 " following spring 18 (Sodium Nitrate 8 " 1/3 Spring, 1/5 (Monocalcium PhOSpha- 4 (Potassium.Muriate(te 5 summer, 1/5 foll- owing Spring. _ . I v.3 ~ - 15 - of determining the dry weight, free reducing sugars, sucrose, starch, total polysaccharides, nitrogen and mineral content. When the plant samples were collected samples of the soil in which they were grown were taken and Submitted for hydrogen-ion determinations. These were made colorometrically against standard buffer solutions. The untreated soil showed a pH of 7.5, indicating a slight degree of alkalinity and apparently it remained unchanged throughout the season. The use of fertilizers resulted in some modification of the pH, but the differences were small and there was no indication that the hydrogen-ion concentration in the soil had any definite influence on the behavior of the plants in this experiment. During the winter the plants were pro- tected with several inches of straw and with the exception of a few from each hot which were taken into the green- house for observation during the winter months, all were left under natural out-door conditions until spring. During the Spring and summer of the fruiting year records were taken of the number of flower clusters, number of flowers per cluster, and the number and weight of the berries from each individual plant. Moisture determina- tions of the berries were made and the fruit dried and saved for analysis. Records were made also of the number of abortive pistils and fully develOped akenes per berry for each of the different lots. After all the fruit was - 17 - harvested three representative plants were collected from each lot and the fresh and the dry weights determined and recorded. The determinations of nitrogen and mineral content of the plants, as well as the hydrogen-ion deter- minations of the soil, were made by the experiment station chemists. All carbohydrate determinations were made in the research laboratory of the horticultural department. The Allihn method,(14) with Slight modification, was employed in making all the carbohydrate determinations. Digestion with diastase (20) preceded the hydrolysis of the starch. The results of all chemical analyses were calculated on the basis of even dry material. PRESENTATION OF DATA ghe Influenceof Nutrients Applied During the Spring and Summer on Vegetative Growth. -- When the plants were dug from the field in the spring considerable care was taken to select those which were nearly the same in size and vigor, and after they were planted in the pots they appeared to be very uniform in these respects. At the end of the third week differences in the character of the plants were noticeable, particularly in the lots to which nitrogen had been applied. At the end of the Spring period (August 1) these differences, especially in the size and vigor of the plants, were very pronounced. - 18 - Table 2. -- Effect of Spring and Summer Applications of Fertilizer on the Size of the Strawberry Plant. w —fi ~— V ‘ fl. w fl _‘ ——fi w Lot Total average weight Total average weight Increase Aug. 1 No. Treatment per plant, Aug. 1. per plant, Oct. 26. to Oct. 26. (gms.) (gms.) (gms.) Ffeéh Dry FrSSh "‘Dry Fresh *ny l Unfertilized 21.0 6.52 20.14 6.01 -.86 -.51 2 N Spring 56.0 10.4 58.0 V 11.4 2.0 1.0 10 at Spring 45.75 14.5 49.1 15.29 5.56 (.8 l4 NPK Spring 42.45 15.57 54.58 15.78 11.94 2.4 6 P spring 21.4 6.48 18.82 5.8 ~2.58 -.68 5 N summer 21.0 6.52 44 .07 12.65 25.06 2.25 11 NP summer 21.0 6.52 49.92 15.9 28.92 7.57 15 NPK summer 21.0 6.52 56.5 15.87 55.5 9.54 7 P summer 21.0 6.52 20.25 5.65 -.77 -.67 4 N Spring-summer 56.0 10.4 58.7 18.79 22.7 8.59 12 NP Spring-summer 45.75 14.5 76.5 22.86 51.56 8.56 16 NPK Spring-summer 42.45 15.57 60.25 18.69 17.79 5.52 18 NPK-S Spring-summer 54.25 9.71 51.0 15.45 16.76 5.74 5 N Spring, P summer 56. 10.4 51.8 16.05 15.8 5.65 8 P Spring, N summer 21.4 6.48 42.7 12.5 21.5 5.8 - 19- SpringgApplications. -- The data in Table 2 Show the average total fresh and dry weights of the plants which were collected from the various lots on August 1 and on October 26. The average fresh weight of the unfertilized plants on August 1 was 21 gms. and of those which were fertilized with nitrogen alone 56 gms., a gain of 70 per cent. over the unfertilized plants during this period. In the lots which were fertilized with nitrogen and phOSphoric acid the average weight was 45.7 grams or a gain of nearly 118 per cent. The gain in weight from the use of nitrogen and phosphoric acid with potash in combination was slightly less. Phosphoric acid alone did not increase the growth appreciably over that of the unfertilized plants. The gains of the same plants during the summer period are Significant. There was a slight de- crease in the fresh weight and the dry weight of the plants in the unfertilized and in the acid phOSphate fertilized lots. This was due to a failure of the plants to produce new growth and the loss of some of the older leaves in the fall. The effect of withholding nitrogen during the summer period was an almost immediate check in growth of the crowns. In Lots 2 and 10 the increases in fresh weight per plant after August 1 were only 2 gms. and 5.56 gms. reapectively. In Lot 14 which was ferti- lized with nitrogen, phosphoric acid and potash there was a larger increase of 11.94 grams. -20.- Summer Applications. -- The results with the plants which were fertilized during the summer period only are also significant. Here again phOSphoric acid alone failed to produce any effect on vegetative growth, but when used in combination with nitrogen or with nitro- gen and potash the growth was greater than with the use of nitrogen alone. The effect of fertilizers on the growth of the plants in Lots 5, 11, and 15 which had re- ceived no previous fertilizer treatment during the spring period was almost immediate. The leaves changed from a light green to a dark green color and the plants grew vigorously until the close of the season. The data Show that the plants were slightly larger at the close of the season than those which received similar treatments dur- ing the Spring period only. Spring and Summer Application. -- Plants which were treated with fertilizers containing nitrogen during both the Spring and summer periods were all larger at the close of the season than the plants whichhad been treated during the Spring period or the summer period only. The plants in Lot 12 which were treated with ni- trogen and phOSphoric acid were larger and more vigorous than those of any other lot. The average green weight of these plants on October 26 was 76.5 grams. Those fer- tilized with nitrogen weighed 58.7 grams and those ferti- lized with nitrogen, phosphoric acid and potash 60.25 grams. In Lot 18 the same elements were applied and in the same amount as in Lot 16, but as indicated in the out- line in Table l the phosphorous was applied as chemically pure monocalcium phOSphate and the nitrogen as commercial sodium nitrate. The treatment was designed to determine the importance of sulphur in strawberry nutrition. Since no sulphur was added to the soil in the form of fertili- zers and there was only a bare trace of sulphates present in the soil, the amount of sulphur available for the plants was extremely small. The plants grown under this treatment were not as large and vigorous as those of the other lots which received a complete fertilizer treatment. The leaf petioles were shorter and the plants lower and more Spreading in habit. During a portion of the season there was a characteristic crinkling of the leaves some- what resembling the disease known in some of the southern states as "strawberry crimp". However, it is not certain whether the differences noted were entirely due to the fertilizer treatment given or to some other factor for an analysis of the plants given later shows that the tissues contained nearly as much sulphur as those grown under any other treatment. The Effect of Fertilizer Treatments on Runner Production. -- Records of the number and length of runners produced by each lot of plants with the date of their removal are Shown in Table 5. This table gives some idea of the distribution of runner production through- out the season. A summary of the total number, length, -22- Table 5. Record of Number and Total Length of Runners Removed. (Length recorded in inches). 8878 5/8_ 8/15 6/25 7/5 _Z/l8 i 7/24 fiwje/E 8/15 8/20 8/29 9/5 Total_ No. No. Length No. Length No. Length No. Length No. Length Noi Length No. Length No. Length No. Length No. Length No. Length No. Length 1 l 5 4 28 12 85 5 14 l 6 ”l 6 .5 14 .21 10 0 l 10 0 ‘ 27 ing 2 5 25 10 53 15 75 42 268 22 120 50 242 48 '270 25 101 50 155 2 15 251 1504 t 5 12 8 51 3 18 4 26 5 17 4 18 l 8 5 12 10 51 6 41 45 254 4 19 98 17 44 45 275 50 174 42 140 55 178 27 82 55 155 5 24 255 1148 5 7 57 9 so 17 55 51 214 25 150 58 255 51 179 24 80 25 77 5 17 224 - 1105 8 5 18 1 4 7 49 2 8 6 l6 5 11 5 24 1 5 26 156 7 7 58 10 87 5 15 5 29 5 18 2 12 5 14 1 5 55 194 8 1 5 1 5 5 29 1 4 5 28 1 5 5 22 9 25 28 98 7 48 61 270 9 2 6f 5 10 2 8 2 7 1 6.5 1 4 11 42 10 4 56 10 4c 42 280 22 148 56 505 28 160 ’6 521 40 226 12 42 20 77 5 18 283 1655 ll 5 8 5 15 8 49 1 5 1 4 2 4.5 5 20 2 12 11 29 6 45.5 38 1885 12 7 57 48 272 58 350 82 444 55 128 77 551 58 275 54 115 88 265 10 57 455 2288 15 5 27 11 50 59 227 59 502 58 588 45 178 74 568 66 560 54 108 59 259 8 55 456 2282 14 5 l2 8 44 50 196 54 258 27 158 28 122 62 275 48 565 25 95 28 156 2 14 295 1649 15 5 45 5 51 1 15 1 9 1 5 2 19 16 140 16 6 42 16 80 40 248 40 227 36 256 56 181 70 586 45 279 25 8O 28 111 6 45 544 1955 H \7 ()3 H ,p. (‘3 l--’ CC CI) .45 F)“ (‘0 'n to ()7 9 228 52 554 25 _106 65 525 45 271 59 164 51 125 15 108 575 2042 H (‘3 (‘3 (Y) 03 H (‘3 ,5. ' Tl CD 9 s *0 O H (D 18 8 42 25 91 57 278 48 284 20 88 15 :5 1 10 277 1455 - 25 - and fresh weight of the runners produced, together with the average production per plant is given in Table 4. The data show some interesting facts regarding this feature of vegetative growth. The unfertilized plants produced only 27 runners with a total length of 176 inches and a total weight of 10.2 grams. About 75 per cent. of these were produced during June. Spring applications of nitrogen either alone or in combination with phosphoric acid or potash greatly stimulated runner production and apparently at the expense of other parts of the plant for runners were produced freely throughout the season even though no nitrogen was applied after July 1, and the growth of the tops was checked. Contin- ued applications of nitrogen during the summer period particularly when in combination with phOSphoric acid andpotash stimulated still greater runner production. In Lot 15 the total number of runners produced was 456 with a total length of 2282 inches and a total weight of 215.4 grams. When nitrogen was applied during the summer period only, fewer runners were produced as shown in Lots 5, 11 and 15 while the total weight of the plants slightly exceeded that of the plants in the Spring- treated lots. However,1when the weight of runners per plant is taken into account the total amount of vegeta- tive growth produced per plant was nearly the same in the Spring and the summer-treated lots. The average total fresh weight of the plants with runners in the spring-treated lots (2, 10 and 14) was 41 gms., 52.9 gms. and 58.58 grams reSpectively and in Lots 5, 11 and 15 which were similarly treated during the summer period 44.71 gms., 50.42 gms. and 56.8 grams reSpectively. The data show that the nutrients which were applied in the spring induced nearly the same total amount of new tissue formation as equal amounts of the same nutrients lapplied in the summer, but in one case, it was utilized to a considerable extent in runner production, and in the other for the develOpment of the crowns. Eglation of Top and Root Development. -- The average dry weights of the tops and roots of the plants in the various lots on August 1 and on October 26 are tabulated in Table 5. The growth of the tops and roots previous to August 1 in the plants of the un- fertilized lot and of those which were treated with acid phosphate were nearly equal, but when the plants were treated with nitrogen the tops were much larger than the roots. When nitrogen was used alone the ratio of tops to roots was 5 to 2 and when it was used in combination with phosPhoric acid and potash the ratio was 2 to 1. The weights of the plants which were collected in October show that there were increases in the root growth in all the Spring-fertilized lots and decreases in the weight of the tops. Very little top growth, except the production of runners, was made by the plants in these lots after august 1. Some of the outer leaves dried up and were lost from the - 25 Table 4. Summary of Runner Production. Total no. Total length Total fresh weight fresh‘wt. Av. fresn wt. runners runners re- of runners of plant of runners Lot. raucved moved (gms.) Oct. 26. per plant No. Treatment (inches) £gms.) {gms.) 1 No fertilizer 27 176 10.2 20.14 .5 2 N spring 251 1504 106.9 58.0 5.0 10 HP spring 285 1655 152.2 49.1 5.8 14 HPK spring 2 5 1649 140.0 5 .58 4.0 6 P spring 26 156 9.5 18.82 2.8 5 N summer 45 254 22.4 44.07 .64 11 HP summer 28 188 17.4 49.92 ,5 15 JFK summer 16 140 10.0 56.5 .5 7 P summer 55 194 15.5 20.25 .4 8 P Spring, N summer 61 270 27.5 42.7 .8 5 N Spring, P summer 224 1105 90.4 51.8 2.6 4 H Spring & summer 224 1105 101.4 58.7 2.9 12 NP Spring & summer 455 2288 208. 76.5 6. 15 UP Spring & summer 456 2282 215.4 61 6.2 16 JFK spring & summer E44 1955 191.5 60.25 5.5 17 LUflisypring & sunmun? 575 2042 200. 60.25 6. 18 UPK-S spring & summer 277 1455 158. 51. 4. - 26 - plants and this, with the larger number of runners produced, accounts for the loss in weight between August 1 and October 26. The data show, however, that there was a considerable increase in the growth of the roots after August 1 and that the amount of living tissue in the tops at the close of the growing season was less than in the roots. In the summer treated lots which had not been treated with nutrients previous to August 1 the develOpment of the roots was less in proportion to the amount of teps produced than in the spring ferti- lized lots. In the lots which had been treated with nu- trigts during both the spring and the summer periods, the tops were all larger than the roots. It will be noticed, however, that with nitrogen alone the weight of the tops did not greatly exceed that of the roots, while with the addition of phOSphoric acid and potash the prOportion of tops Wasmuch larger. Apparently, the phosphoric acid or the potash, or perhaps both, have had some influence in the development of larger crowns with relatively small root systems. The most import- ant point to be observed, however, is that when the supply of nutrients in the soil is small the plants de- velOp an extensive root system, and with a very limited amount of nutrients a correspondingly small crown. On the other hand, with a moderate supply of readily available nutrients in the soil the root system Nutrients Table 5. The Effect of Av. dry wt. of teps and roots Nutrients on TOp and Root Deve10pment in the Strawberry Plant. Av. dry wt. of tops and roots, October 26. Applied Aug. 1 (gms.) tgms.) Spring treatment Summer Treatment Spring & summer treatment Ratio Of tops to roots Tops Roots T/R Teps Roots T/R TOps Roots T/R TOps Roots T/R No fertilizer 5.27 2.95 1.11 1.82 4.19 .45 P 5.5 2.98 1.17 1.96 2.85 .5 2.17 5.48 .6 H 6.24 4.16 1.47 5.56 5.84 .93 6.94 5.71 1.2 9.72 9.07 1.07 NP 9.77 4.75 2.06 6.95 8.54 .85 7.02 6.88 1.02 12.5 10.56 1.16 NPK 9.08 4.29 2.11 7.66 8.12 .94 8.14 7.7 1.06 11.2 7.21 .55 NPKt—S) 6.54 5.57 1.88 8.76 6.68 1.5 is less extensive and the crowns preportionally larger. The Influence of Fertilizer Treatments on Vegetative Growth Turing_the Spring_and Summer of the FruitingiYear. -- Considerable differences were observed in the growth of the plants during the Spring and summer of the second (fruiting) year. The unfertilized plants develOped very little new foliage, some of them producing only one or two very small flower clusters. The growth of the plants of the various lots which were fertilized during the preceding season was variable, but in general, the plants which were treated with fer- tilizers containing nitrogen during the summer period grew more vigorously than those which were similarly treated during the spring period only. Whenever ni- trogen was applied in the spring of the fruiting year there was a quick response in the vegetative growth, not only in the develOpment of new foliage but in runner production. The response in new growth was much greater in the plants of Lot 9 which were grown under rather low nutritive conditions than in those of Lots 13 and l? which were well supplied with nitrogen and the mineral nutrients during the preceding season. The Influence of Fertilizer Treatments on the NitrogenL_Minera1, and Carbohydrate Content of the Plants. -- Still more significant perhaps than the morphological characters which have been discussed were the differences in the nitrogen, mineral and carbohy- - 29 - Table. 6. Percentage Composition of Strawberry Plants Collected October 26. (Oven Dry Material) Lot Total Total 30. Treatment Ash S N 1205 K20 Reducing Sucros Total Starch poly- carbohy— 4 5 5 5 % sugars % sugars fl sacchar- drates 5 g ides 4 /" z 1‘- m TOPS l Unfertilized .25 .82 -5 . 5.44 1.24 6.68 22.26 28.94 2 N spring 11.64 .97 .45 .87 7.6 5.92 11.52 1.52 10.98 22.5 10 HP spring 11.48 .71 .42 .99 9.76 1.4 11.16 16.04 27.2 14 NFK spring 11.88 .84 .48 .99 9.95 .7 10.65 12.70 25.55 6 P spring 16.16 .20 Jfli .75 1.10 - 7.8 7.8 8.24 16.04 5 H spring, P sumnmr 14.24 .66 .52 .98 10.15 1.2 11.55 .90 15.74 25.07 5 N smear 11.89 1.59 .49 1.10 9.1 .8 9.9 7.5 17.4 11 NP summer 9.40 2.02 .76 .55 2.9 4.65 .55 9.87 17.4 15 fiPK summer 11.05 2.09 .84 1.5' 7.49 4.68 12.17 .80 11.18 25.55 8 P Spg., H summer‘ 15.15 1.79 .67 1.11 2.61 8.11 10.72 11.26 21.98 4 N spg., summer 15.54 .26 1.55 .24 .98 6.66 5.09 9.75 1.45 11.64 21.59 12 HP spg., summer 10.88 .26 1.79 .66 1.00 5.4 4.9 10.5 1.0 10.29 20.59 16 NPK spg., summer 11.89 .22 1.65 .62 1.01 5.91 5.95 9.86 1.05 12.00 21.86 18 JFK-S Spg., summer 2.86 .19 1.55 .65 1.25 4.55 7.72 12.05 .72 12.45 24.48 ROOTS 1 Unfertilired. 27.21 .19 .69 .50 .87 5.17 1.97 7.14 15.54 22.48 4 H spg., summer 18.72 .21 1.64 .59 .86 5.72 .50 6.22 4.14 18.81 5.05 6 P spring 50.85 .24 .84 .87 1.06 5.27 1.0 6.55 . 14.67 21.0 12 m: '4 4.; surmer 19.18 .41 2.22: .69 1.05 8.79 .75 9.54 14.0 11.87 21.41 '15 1m: '4ng sumier 15.89 .27 2.02 .67 1.01 18 JTK(~S) spg., summer12.27 .19 1.72 .68 1.15 Table 7. Absolute Amounts of Nitrogen, Minerals and Carbohydrates Per Plant in Strawberry Plants Collected October 26. AV. dry wt. of Free re— rotal Lot tons oer S N 2205 K20 ducing bucrose sugars starch volysacchar- Total 30- plant ens. ans. 5ms. gms. sugars gms. gms. gms. ides carbohyirates isms.) gms. gms. gms. 1 1.67 .004 .014 .009 .091 .021 .112 .572 .485 2 5.05 .049 .025 .044 .582 .197 .579 .066 .552 1.152 10 6.59 .045 .027 .065 .325 .089 .712 1,050 1.758 14 7.09 .060 .054 .070 .705 .050 .755 .900 1.655 6 1.82 .004 .016 .015 .020 .142 142 .150 .292 5 7.26 .052 .058 .071 .755 .088 .825 .065 .998 1.820 5 6. L .102 . 52 .071 .585 .0.2 .657 .482 1.119 11 6.55 .122 .049 .087 .189 .505 .492 .644 1.156 15 7.47 .156 .065 .112 .559 .550 .909 .059 .855 1.744 8 5.85 .046 .059 .065 .152 .475 .625 .660 1.281 4 8.97 .025 .159 .051 .087 .597 .278 .875 .092 1.044 1.918 12 11.4 .050 .204 .075 .114 .61. .559 1.174 .114 1.170 2.547 16 10.56 .050 .169 .064 .105 .405 .616 1.021 .106 1.245 2.264 18 8.04 .015 .125 .055 .100 .548 .621 .969 .058 1,000 1.968 49.919. 1 5.89 .0075 .0268 .0194 .0558 .201 .0766 .277 .596 .875 4 8.42 .0178 .158 .0528 .0858 .481 .043 . 594 .548 1.585 2.107 6 5.61 .0086 .0505 .0514 .0582 .190 .058 .228 .529 .757 12 9.79 .05 .217 .0675 .1007 .860 .074 .934 .295 1.162 2.096 I Q] H I drate content of the plants in the different lots. The analyses of the plants taken October 26 are shown in Tables 6 and 7. The amounts of the various sub- stances in percentage of dry matter are tabulated in Table 6 and the absolute amounts in grams per plant in Table 7. Some of the samples were too small to make all determinations, and for this reason the analyses in several cases, particularly for sulphur and starch are incomplete. Only a few analyses of the roots are given. These show that the ash and starch content was larger in the roots than in the tops. There were some differences in the percentages of nitrogen, and of car- bohydrates other than starch, but the data in Table 7 show that, in general, the absolute amounts in propor- tion to the amount of dry matter were nearly the same. The percentage of ash in the tops varied from 9.4 per cent. in Lot 11 to 16.16 per cent. in Lot 6. It will he noticed, however, that the plants with the lowest ash content contained larger amounts of nitrogen, phos- phoric acid, and potash than those with the highest ash content. The unfertilized plants and those which had been treated with fertilizers containing nitrogen in the spring period only, contained lower percentages of nitrogen, phOSphoric acid, and potash, and a higher percentage of carbohydrates than those which had been similarly treated dur- ing the summer period. The greatest differences were found in the nitrogen content. Then the nutrients were aPPlied in the summer period only, the percentage of nitrogen was larger than when corresponding treatments were given during both the spring and summer periods. In the spring-treated lots the amount of nitrogen ranged from 0.66 to 0.97 per cent; in the summer-treated lots 1.59 to 2.02 per cent. and in the spring- and summer- treated lots 1.55 to 1.79 per cent. Reference to Table 7 shows, however, that the absolute amounts of nitrogen and carbohydrates per plant were the largest in Lots 4, 12, 16 which were well supplied with nutrients during the entire season. The analyses of the plants at the close of the spring period (august 1) are given in Table 8. A comparison of these analyses with those of the plants which were taken October 26 shows that considerable amounts of nitrogen and potash which were absorbed by the plants dur- ing the early stages of growth were 163 from the plants later in the season. The data show that in Lots 1 and 6 there was an increase in the percentage of nitrogen and phosphoric acid but a decrease in potash during the summer period. In Lots 2, 10 and 14 the phOSphoric acid remained nearly constant but there were large decreases in nitrogen and potash. Reference to Table 2 shows that the total dry weights of the plants on August 1 and on October 26 were nearly the same, therefore the loss in percentage cannot be accounted for by an increase in bulk or growth of plant. There were probably some losses of these elements from the crowns through runner production and the death n.0m $12“ 37m hem moon moon we. no...” ma. Awnvmmz ma H.mm Hm.ma mm.na me.a em.aa om.” me. mn.a ma. manage Mme «a mm.mm mm.mfi mm.nn mm.H rm.afi em.a me. mn.a mm. menace ma oa an.om ma.ma ma.m mo.m pm.o mo.a we. mu.a ma. manage a a 8." ‘3. 3. 3. mafia; m a mm...“ mm. mm. 3". douadapnmuflb H '1 1 In? ' I. ’ If '..II 'I 'I': r» t r t R a o “Nam R R 93an R are R m. en es as one . oz moneys»: Iguana Human omonoum masons 0mm 0mm 2 m won nopmso $me LnHon Hmoa no.” oonFr [ .H pmemee empomaaoo I wanna E93333 .Ho 33:00 mpmnnchnonado and agenda .Qmmonfia .m 0.."de I (Q “a I of some of the outer leaves during the summer period. It is also conceivable that certain amounts may have been returned to the soil and that there were losses from the plants by leaching. A further comparison of the analyses in Tables 6 and 8 brings out still another interesting fact. The nitrogen-carbohydrate content of the plants on August 1 was nearly identical with that of the summer treated plants on October 26. The re- sponse to this condition in the spring-treated plants, however, was manifested chiefly by a vigorous runner production and as will be shown later, no fruit bud differentiation at the time, and very little fruit bud differentiation in late fall, while under similar conditiOns in the summer treated plants there was less tendency for runner production and a greater response in fruit bud formation. The analyses of the spring treated plants taken on October 26 show that there was a decrease in the percentage of nitrogen after August 1 and a slight increase in carbohydrate content. In Lot 18 which received nitrogen during both the Spring and summer period the percentage of nitrogen on August 1 and October 26 was nearly the same and there was a slight increase in the percentage of carbohydrates. - 55 - The Relation of Potash and Sugars -~ One of the general effects of the fertilizer treatments in this experiment was an increase in the amount of sugars and a decrease in polysaccharides. The unfer- tilized plants contained 6.68 per cent. sugar and 22.26 per cent. polysaccharides. With the exception of Lots 6 and 11 the amounts of sugar in the fertilized lots ranged from 9.75 to 12.17 per cent. Lot 5 was lowest in polysaccharides with 7.5 per cent. and Lot 10 highest with 16.04 per cent. Spring-treated plants contained more free reducing sugars and less sucrose than the summer-treated plants. The data presented in Table 9 show that there is, apparently, some relationship be- tween the intake of potash and the amount of sugars found in the plant. Tne potash content varies from 20 to 114 mgms. and the sugar content from 142 to 1174 mgms. per plant. The ratio of potash to sugars (S/KgO) in the tops varies from 1.0 : 5.6 to 1.0 : 13.5. The average ratio is 1:8.7 and the most common ratio about 1:10. In the roots the ratio is approximately 1:8. The data indicate that even if no definite ratio of potash to sugars exists in the strawberry the amount of sugars pro- duced is closely associated with the intake of potash by the plant. The Total Intake of Nitrogen.and Mineral Elements by the Strawberry Plant. Calculations from the data in Table 6 show that the typical ash content of the Table 9. The Ratio of Potash and Sugar in Jer wt. per plant €gms.? TOPS_ (‘3 (>3 C31 0‘) 5.05 6.45 8.97 t 3 , Pa 7. 1.82 5.85 PotashéKgO) __Sugarhv % Mgms. per plant per plant .87 43 1.10 70 .98 87 .98 71 1.10 20 the Strawberry Plant. Ration of potash to plants at the termination of growth in the fall was approximately 12.4 per cent., and that the plants con- tained an average of 1.75 per cent. nitrogen, .64 per cent. phOSphoric acid, and 1.16 per cent potash. Though these figures are not necessarily indicative of the requirements of the strawberry, they furnish a measure- ment of the amounts of the various nutrients absorbed from the soil by the plants. Analyses of the berries indicate that the amounts of nitrogen, phosphoric acid, and potash present in the fruit is small and that the strawberry is not a soil depleting crOp. However, the data show that the actual intake of nutrients by the plant, though only temporarily removed from the soil, is considerable; and while the strawberry is not an exhausting crOp its requirements particularly during the period of vegetative growth are relatively high. The-Influence of Egrtilizer Treatments on the Flowering and Setting of Fruit. -- Table 10 summarizes the data on flower production and the set of fruit in the different lots. The records show that the total number of flowers is determined chiefly by the number of flower clusters and only to a small extent by the number of flowers per cluster. The general effect of the fertilizers containing nitrogen has been an in- crease in the number of clusters per plant and in some cases a slight increase in the number of flowers per cluster. The plants which were treated during the summer Table 10. The Influence of‘Fertilizer Treatments on Flowering and the Setting of Fruit in the Strawberry. AV. no. flower Av. no. flowers Av. no. flowers Per cent. of flowers Per cent. of Lot Treatment clusters per per cluster setting fruit. setting fruit. "set" matured. N0. plant ‘ l Unfertilized 5.3 5. 76 22.7 86.8 1A Unfertilized lst. yr. 4.0 7.2 57 40 84.2 N spring 2nd yr. . 2 N spring 1st yr. 6.4 6.5 208 50.8 5.1 10 LIP Spl‘i 11g 5- .0 7 .4 225 55 . 84.4 14 HPK spring 4.7 7.8 198 28.4 84.8 6 l?ssprir¥? 4.4 5.7 115 27.9 92.9 5 H srnring, I>snumner 4.9 7.5 201 27.8 88.5 5 N summer 11.7 6.8 596 57.1 5.5 11 NP summer 9.7 9.1 648 58.4 76.5 15 UPK mummd‘ 10.5 7.4 740 46.0 85.5 8 P Spring, N summer 11.5 7.5 626 56.8 85.5 7 P summer 5.8 6.6 141 27.0 89.5 9 P summer, N second 5.2 7.0 544 61.5 88.1 Spring, 4 N spring & summer 12.2 7.1 717 59 76.5 2 8? spring & sunmmr 14.4 8.8 910 40 75°1 5 ”“ spring, summer, & 15.2 8.8 1328 52 74-5 sprinsiind yr.; 6 nkh spring, 8 summer 11.7 8.2 685 57.6 81.9 17 NPK Spring;-summer~> 10.5 9.1 1091 47.5 81.4 spring, 2nd yr. 18 NFK-S spring, summer, 7.6 8.9 565' 45.5 88.4 Spring,fihmier period only, produced nearly twice as many flower clus- ters as those which received corresgonding treatments during the spring period though they were but little, if any, larger. The average number of flower clusters per plant in the spring fertilized lots ranged from 4.7 to 6.4, and in the summer fertilized lots from 9.7 to 11.7. The average number of clusters per plant in the lots which received both Spring and summer treatments was somewhat larger, ranging from 10.5 to 14.4 and there was a slightly larger number of flowers per cluster. The applications of fertilizers in the spring of the fruiting year had no effect on the number of clusters per plant or the number of flowers per cluster. The percentage of flowers which set fruit is also shown in Table 10. From these data it appears that the percentage of set may be influenced by nutri- tive conditions which exist in the plant, and to a con- siderable extent by nutritive conditions in the soil during the blooming season. Plants which had been fer- tilized during the spring period only, did not set as many flowers as those which had been fertilized during the summer period. The average set of all spring (first year) -fertilized lots was 29.6 per cent., of all summer-fertilized lots 57 per cent., and of those which had been fertilized during both the spring and the summer periods 59 per cent. Reference to Table 6 shows that the summer-fertilized plants had more reserve nitrogen in the tissues in the fall, which may account for the better set of fruit the following Spring. Applications of nitrogen in the spring of the fruiting year greatly increased the set of fruit, particularly, with those plants which were grown under low nutritive conditions the preceding summer and fall. In Lot 1 (unfertilized), 22.7 per cent. of the blossoms set fruit, while in those of the same lot which had re- ceived an application of sodium nitrate Just before blossoming there was a 40 per cent. set. In Lot 9, which had been treated with acid phosphate during the summer period and with nitrogen the following spring, 61.5 per cent. of the blossoms set fruit while the set was only 27.6 per cent when no spring application of nitrogen was used. Spring applications of nitrogen before blooming in the lots which had previously been well fertilized during the preceding season also resulted in an increase in the set of fruit, as shown in Lots 15 and 17, but the increase was not as large as in those which had been grown under less favorable nutritive conditions. The Influence of Fertilizer Treatments on ‘Ehe Total Yield and Size of Fruit. -- Table 11 presents a summary of the average total yield and the number and the weight of berries from the plants of the different lots. Nitrogen, when used alone or in combina- tion with phosphorous and potash has in every instance -41- greatly increased the yield. The yields due to the in- fluence of spring applications of fertilizer the first year have been doubled and in some cases trebled by the same treatment with fertilizers during the summer period. Fertilizers applied during both Spring and summer periods have in only one instance given increased yields over those which were applied in the summer period only. The largest yields were secured from plants in lots 15 and 17 which were fertilized during both the spring and summer periods and again in the spring of the fruiting year. Applications of nitrogen in the spring of the fruiting year increased the yields by inducing a better setting of the flowers and an increase in the size of the berries. In Table 12 the data which has already been presented in Table 9, is arranged in a different manner to show the number and size of the berries which ripened in different periods during the harvesting season. It will be noticed that the berries which ripened in the first period (June 20 - 25) were the largest and that there was a decrease in size until at the end of the sea- son many of them were very small. However, this seems to be characteristic of the Senator Dunlap and was to be SXpected. Valleau (17) has shown that there is a definite relationship between the position of the flower in the cluster and the size as well as the degree of setting of - 42 Table 11. Number and Size of berries per Plant as Influenced by Different Fertilizer Treatments. Lot No. Treatment no. berries Av. total wt. of berries Av. wt. per plant per plant per berry (gms.) (gms.) l Unfertilized 5. 9.8 2,5 1A Unfertilized (1st yr.) 9.0 24.2 2,5 NitrOgen( 2nd Spri ng) 6 P Spring (1st year) 6.56 14.5 2.18 7 P summer 6.0 14.4 2, 9 (P summer 12.1 55.0 2.88 (N 2nd spring 2 N spring (1st yr.) 10.8 25.7 2.57 10 NP spring 10.6 22,6 2,14 14 m: Spring 8.74 20.8 2.25 5 (N Spring 8.9 20.6 2.5 (P summer 5 N summer 24.8 55.5 2.2 11 HP summer 26.0 58.1 2.25 15 HPK sunmu r 51.0 71.5 2.45 8 (P Spring 26.1 60.5 2.55 (N summer 4 N Spring-5, 26.1 55-2 “-04 summer . 12 HP Spring and 58.0 7407 1.97 summer 12 HP Spring, summer 45.8 95-3 2.1 spring (2nd yr.) 16 NPK Spring, 29.65 57-1 2.25 summer 17 ITK synurmg 57. 91-5 2045 summer. spring (2nd yr.) 18 NPK-S Spring, summer, 26.2 54.7 2.09 spring (2nd yr.), - 43 - of the fruit. With Senator Dunlap in particular, he found that a very large percentage of the primary flowers set perfect fruit, and that there was a gradual decrease in the number of perfect fruits and the total number of berries set from the primary to the last flowers which opened in the cluster. The data in Table 12 show that the number of eardy berries depends more on the number of flower clusters than any other factor. Nitrogen app- lied in the spring of the fruiting year slightly increased the number as shown in Lots 1A, 9, 15 and 1?, probably by a better setting of the primary flowers. The early berries were usually larger when they were few in number. In Lots 1, 2, 10 and 14 which bore a small number of clusters the berries were larger than those from the sum- mer—treated plants in Lots 5, 11 and 15, which bore a large number of clusters. In the second period (June 27 to July 2) a larger number of berries in pr0portion to the number of clusters was harvested from the summer-fer- tilized plants, and the fruit was larger in size. Ni- trogen applied in the Spring before fruiting was most effective during this period. Apparently it influenced a much larger setting of the secondary and tertiary flowers in the clusters for 5.8 clusters per plant in Lot 7 ripened only 2 berries with an average weight of 2 grams each while 5.2 clusters in Lot 9 ripened 6.1 berries with an average weight of 2.8 grams each. Corres- ponding increases in the number and size of berries during this period may be shown by a comiarison of Lots 12 and 15 Table 12. The Influence of Fertilizer Treatments on the Number and Size of Berries at Different Periods During the Harvesting Season. Berries harvested June Berries harvested June Perries harvested July 20 to 25. 27 to July 2. 2 to 10. AV. no. Av. no. n5} total Av. wt. Av. no. .Av. total Av. wt. Av. no. Av. total Av. wt. Clusters berries wt. berries of berries wt. berries of berries wt. berries of Lot Treatment per per per plant berry per per plant berry per per plant berry no. plant plant (gms.) (gms.) plant (gms.) (gms.) plant (gms. ) (gms.) 1 Unfertilized 2.5 .6 2.7 4.5 1.4 5.8 2.7 2 5 1.51 12 N spg. 2nd yr. 4.0 2.0 9.2 4.6 4.4 9.6 2.2 5.2 5.4 1.7 6 P Spring 4.4 1.5 4.2 2.1 2.1 5.0 2.4 5.C 5. 1.65 "' r sewer 5.8 1.86 5.1 2.2 2.0 4.0 2.0 2.2 4.5 1.95 9 P summer 2.2 2.9 11.7 4.1 6.1 17.5 2.8 5.1 5.9 1.9 N 2nd spg. ~ ~ 2 N spring 3.4 2.9 10.5 5.65 4.2 9.5 2.26 5.7 5.7 1.54 10 JP spring 5.0 2.55 .5 5.26 4.0 9.4 2.55 4. 4.9 1.22 14 RPK Spring 4.7 2.26 7.8 5.44 2.0— 3.6 2.2 5.5 2.4 1.54 5 3 spring, P 4.9 2.15 7.8 5.65 5.65 8.5 2.4 5.1 4.1 1.52 summer 5 N summer 11.7 4.9 18.8 2.8 10. 25. 2.5~ 9.8 14.8 1.5~ 11 HP summer 9.7 5.C 16.0 2. 10.7 28.0 2-5 10.5 15.1 1.56 15 SP2 summer 10.5 5.5 11.1 5.4 15. 37.6 2.9 15.‘ 25.0 1.75 8 P Spring, N 11.5 5.0 16.0 5.2 11.7 52.0 2.7 9.4 15.4 1.42 summer 4: 3 37171113 (9? lpoo 5.5 15. 50L 15-90 2505 400 900 1109 1053 summer ‘ ~ 12 HP spring 8 14.4 5.6 16.0 2.9 18. 41.6 2.5 14.5 17.0 1.2 summer 1 15 NP snring, 15.5 7.65 24.0 2.14 25.5 57.2 2.24 12.7 5.0 1.2 summer & 811711" 2 16 UTE garing 8 11.7 6.0 17.8 2.97 14.0 55.4 2.5 10 14.0 1-4 summer * 17 NP gpring, sum- 10.5 7.0 25.0 5.50 18.7 51.0 2.7 11.4 18.0 1.6 1 i ‘ 71:: {Shrlf .. 18 {315-8 Ste”? 7.6 4.8 15.7 2.85 10. 24.7 2.47 11.4 16.5 1'45 summng spg. and of Lots 16 and 17. In the third period which included the last four pickings nearly all the fruit was small. How- ever, the size of berry in Lots 7, 9 and 15 held up well to the end of the season. The number of berries ripened in this period was about equal to the number ripened in the second season except in Lots 4, 12, 15, 16 and 17 which ripened about fifty per cent of the entire crop during the second period. . The Relation of Nitrogen and Carbohy; drates to Fruit Bud Formation and Yield in the Strawbergz Plant. -- The results of recent investigations indicate that the proportion of nitrogen and carbohydrates exist- ing in the plant at certain times of the year bears an important relationship to fruit bud differentiation and to blossom and fruit production the following Spring and summer. Krause and Kraybill (12) in their studies of the response in vegetative growth and fruit setting of the tomato concluded that "fruitfulness is associated neither with highest nitrates nor highest carbohydrates but with a condition or balance between them. Fertilizers containing available nitrogen are mainly effective in pro- ducing vegetative response. They may either increase or decrease fruitfulness according to the relative available carbohydrate supply". -46- The analysis of the plants grown under the various treatments in this eXperiment show that very extreme ranges in the nitrogen and in the carbohydrate contents have been produced, which afford Opportunity for examination of the applicability of this concept to the strawberry. In Table 15 the data from the different lots have been arranged in five groups according to the dry weight of the tops of the plants in order that some direct comparisons may be made. The data shows that four dis- tinct sets of conditions have been produced so far as the amounts of nitrogen and carbohydrates are concerned: (1) a low nitrogen content with high carbohydrates; (2) a low nitrogen content with low carbohydrates; (5) a high nitrogen content with low carbohydrates; and (4) a high nitrogen content with high carbohydrates. Comparison of the data from Lots 1 and 6 show that both have a low nitrogen content, but that the carbohydrate content is high in Lot 1 and low in Lot 6. However, the number of clusters and the total yield of fruit in Lot 6 was larger than in Lot 1. No definite cause can be assigned for the difference in yield in the two lots. It is evident that high carbo- hydrate alone was not resoonsible for the relatively low yield in Lot 1 for other lots nearly as high in carbohydrates yielded well. However, high carbohydrates with low nitrogen has apparently inhibited fruit bud information, for Lots 5, 10 and 14 were all low in ni- Table 5. Nitrogen and Carbohydrates and their Relation to Fruit Bud Formation and Yield in the Strawberry Plant. Lot Dry wt. of Nitrogen Total carbo- Av} no.01usters Av. no. clusters Av. no berries Av. total wt. AV. total w» No. tops per phydrates. per plant per gm. dry wt. per plant of berries of berries plant 2 Mgms. " Mgms. of plant per plant per gm. dry gms. 3 per 6 per (gms.) wt. of plant plant. plant. ii ‘iotflr ‘ .82 14 243.94 485 “' '5 .5 —‘ 2 6.9 i 9.8 I 5.27 6 1.82 .86 16 16.04 292 4.4 2.4 6.56 14.5 7.85 2 5-03 .97 49 22.5 1152 6.4 1.27 10.8 25.7 5.1 8 5-83 1.79 104 21.98 1281 11.5 2 26.1 60.5 10.4 10 6.39 .71 45 27.19 1768 5.0 .8 10.6 22.6 5.5 5 6.46 1.59 102 17.4 1119 . 11.7 1.8 24.8 55.5 8.6 11 6.55 2.02 162 17.4 1166 9.7 1.5 26.0 58.1 8.8 14 7-£** .84 ex) 2 .55 1655 4.7 .66 8.74 20.8 2.9 5 7-26 .66 52 26.07 1820 4.9 .67 8.9 20.6 2.8 15 7.47 2.09 -6 25.55 1744 10.6 1.68 61.0 71.5 9.6 18 8.04 1.55 125 24.48 1968 7.6 ..94 26.2 54.7 6.8 4 8.97 1.55 169 2 .69 1918 12.2 1.66 26.1 5:.2 6.0 16 10.66 1.66 169 21.86 2264 11.7 1.16 29.6 67.1 6.5 12 11-4 1.79 204 20.59 2547 14.4 1.26 58. 74.7 6.6 . trogen and high in carbohydrates and their relative pro- duction in number of clusters and yield of fruit in pro- portion to their size is even less than in Lot 1. In Lot 6 which was fertilized with acid phosphate the plants contained larger amounts of phosphoric acid, potash, and sugars than those in Lot 1, and it is pose- ible that these factors may have had some influence on the formation of fruit buds. Lots 2 and 8 both had a moderately high carbohydrate content but there was twice as much nitrogen in Lot 8 as in Lot 2. Here the nitrogen content appears to be the limiting factor in fruit production for in Lot 2 with(197 per cent. nitrogen there were 6.4 clusters and the total yield was 25.7 grams per plant, while in Lot 8 with 1.79 per cent. nitrogen the number of clusters was 11.5 and the yield of fruit 60.5 grams per plant. The data from Lots 3, 10 and l1 also indicate that nitrogen was the governing factor in fruit production for in Lot 10 which had a low nitrogen content -- 0.71 per cent. -- and a high carbohydrate content, the number of clusters and the total yield of fruit was less than one-half that from Lots 5 and 11 which had a high percentage of nitrogen and a comparatively low carbohy- drate content. Similar comparisons may be made with the remaining groups. It will be noticed that the carbohy- drate content is moderately high in all the lots in these - 49 - groups, but that there are extremes in the nitrogen content. Low nitrogen content in Lots 5 and 14 is associated with low yields. On the other hand, high nitrogen with high carbohydrates as in Lot 15 is assoc- iated with high yields. In general, the data show clearly the importance of nitrogen in the nutrition of the strawberry. a large accumulation of carbohydrates is desirable, but a relatively large amount of nitrogen is very important for fruit bud differentiation and the development of the fruit the following spring. However, the data show that fruit bud differentiation is due to, or is controlled by, some factor or factors other than a certain proportion of nitrogen and carbohydrates in the plant. It has been pointed out that though in this eXperiment extreme ranges have been produced both in the nitrogen and in the carbohydrate content in the various lots of plants at the time of fruit bud differentiation, some fruit bud formation has always taken place -- better in some lots than in others -- but nevertheless it has never been entirely inhibited. Furthermore, in the discus- sion of the data presented in Table 7, it has been shown that the nitrogen-carbohydrate content of the Spring- fertilized plants on August 1 was very similar to that of the summer-fertilized plants on October 26. Sometime after august 1, the nitrogen-carbohydrate conditions of the summer-fertilized plants must have become identical -50.. with that of the Spring-fertilized plants earlier in the season. The response to this condition in the Spring-fertilized plants was manifested by a vigorous runner production. 0n the other hand, when the same con- dition obtained in the summer-fertilized plants it did not start a vigorous runner production, but gave rise to fruit bud formation. In other words, the same nu- tritive condition in the plants which was reSponsible for a vigorous runner production at one time of the year did not induce a vigorous runner production at another time, but instead gave rise to fruit bud differentiation. Fruit bud differentiation in the straw- berry, therefore, is not due entirely to a certain nitrogen- carbohydrate ratio within the plant, but is modified, per- haps, by temperature, length of day, rest period phenomena or some other associated factor. However, the data from this experiment show that though fruit bud formation has not been entirely inhibited by the extremes in the nitro- gen and in the carbohydrate content of the various lots of plants, yet there are certain conditions which are more favorable than others during late summer and fall when fruit bud differentiation does take place. Extreme varia- tions in the nitrogen content have had a greater effect on fruit bud formation than extremes in carbohydrate con- tent. High carbohydrates with low nitrogen have an in- hibiting effect on fruit bud formation. Low nitrogen has always been associated with low yields; high nitrogen with Table 14. The Influence ofFertilizer Treatments on Pistil Abortion. Lot No. Treatment Av.. total no. of Av.. no. of Av. no. aborted Per cent. of pistils per berry anenes pistils pistils 1 1 fi_ 11 w 1 . aborting. 1 Unfertilized 217 197 20 9.12 2 H SpriUF 242 212 51 12.7 10 UP spring 158 167 21 15.6 14 JFK spring 225 197 26 11.5 5 N Spring, P summer 247 225 24 9.7 6 P Spring 235 215 18 7.7 5 N summer 28? 208 27 11.5 11 HP summer 258 215 25 10.5 15 HPK summer 261 226 55 15.4 8 P spring, N summer 252 221 52 12.5 7 P summer 204 185 21 10.5 4 LI spring &- summer 24; 20/4 58 15 .7 12 HP Spring & summer 228 210 18 8.0 16 NPK Spring & summer 253 250 23 9.1 18 JFK-S spring & summer 215 171 42 19.7 9 P summer, N following 192 170 22 11.5 s,‘1' 15 JP spring, sumgirni 268 244 24 8.2 . _,2 . , a 3»? umzsgiii‘ifléluéiei & 266 224 22 8.2 spring 2nd year. - 52 - with high yields. The best condition in the plant at the time of fruit bud differentiation is a high nitrogen con- tent associated with a moderately high, or a high percentage of carbohydrates. The Influence of Fertilizer Treatments on Pistil Abortion. -- Gardner (10) has shown that the number of pistils per flower and the setting of the individual pistils bears an important relationship to the size of the fruit, and that the nutritive conditions in the plant during the fall particularly at the time of fruit bud differentiation has considerable influence on the setting of the pistils the following spring. No attempt has been made in this investigation to study this re- lation other than to determine the influence of the diff- erent treatments on this factor in the develOpment of the fruit. Counts were made of the number of akenes and of the aborted pistils in berries from each of the different lots. Some of the berries were collected early in the season, and some from the midseason crop. None of the small late berries were saved for this purpose. The data re presented in Table 11. The differences in the number of pistils per berry were not as large as might be expected considering the wide range of the different treatments. In general the number of pistils was larger in the berries from the plants which had received summer treatments than from those of the spring-treated lots, but the differences are not sufficiently consistent to warrant any definite -53.. conclusions. Furthermore, there is no evidence that there has been any definite influence of the different treatments, on the setting of the individual pistils. The Moisture Content of Berry As Influenced py Fertilizer Treatments. -- In the field eXperiments which have been reported from different sections of the country, frequent mention has been made of the effect of fertilizers on the texture and quality of the fruit. Chandler (4), in particular, reported that whenever nitrogen was applied in the Spring before the cr0p was harvested it tended to make the berries soft and of poor color and quality. Some- what similar results are reported by Bailey (1) from the use of nitrogenous fertilizers when applied in the spring a year before the crop was harvested. Brown (3) found that when the weather was extremely warm during a large portion of the season the plants which had received heavy applications of nitrogen produced berries that were inclined to be soft and that plants receiving sulphate of potash produced somewhat firmer but not more attractive berries. However, in the years when there was a long cool picking season there was practically no difference in the firmness, size, and appearance ofifruit. Moisture determinations were made for three samples of fruit which were taken at different times during the harvesting period, from each of the different lots of plants in this experiment. 54 - Table 15. Moisture Content of Berries as Influenced by Fertilizer Treatments. Lot No. Treatment Wt.fiof H20 per of‘dry matter. Average wt. Sample 1 Sample 2 Sample 5 perogmgggry matter 1 Unfertilized 9.1 7.6 8.86 8.52 2 N Spring 9.7 8.25 8,77 8.91 10 HF Spring 9.7 8.15 8.6 8.82 14 HEX Spring 8,7 7,4 9.0 8.05 6 P Spring. 10.5 7.2 7.84 8.44 5 [Isummer 10.7 8.86 9.04 9.55 11 NP 8 mmer 10.2 .2 9.5 9.5 15 JFK summer 11,0 8,44 9.5 9.58 7 l?summer 9.5, 7.5 8.6 8.49 4 N Spring & Sumnnr 10,7 8,5 9.8 9.53 12 NP Spring & sunmmr 12.1 9.0 8.8 9.97 16 NPK spring & summer 10.9 8.87 9.6 9.79 5 N Spring, P summer 9.7 7.6 7.61 8.5 8 P storing, H summer 9.17 8.7 8.8 8.89 9 I>Emhmner, 11.next 8.9 7.55 6.6 7.61 8331‘“? 15 LU‘Spring,smummr 10.6 8.5 8.0 8.95 and following Spring 17 133113351574an3?” 81101.4 7.9 8.6 8.97 18 2188-8 Spring, sunmmr'zhn 561166166 spring. 10.6 9.6 9.4 9.7 The data are summarized in Table 12. The figures indicate the weight of water in grams for each gram of dry matter. Berries from the unfertilized plants and those which were treated with acid phOSphate alone,show a lower moisture content than those from the other fertilized lots. Plants which had been fertilized with nitrogen during the summer period produced berries with a higher moisture content than those which had been similarly treated during the spring period only. How- ever, there was practically no difference in the appear- ance and texture of the fruit at the time of harvesting. Acid phosPhate and potash when used in combination with nitrogen have had no effect on the moisture content. The use of fertilizers applied in the spring of the fruiting - year, as shown in Lots 9, 15 and 17 , has not resulted in any increase in moisture content though the berries were somewhat larger than those from the plants which were not fertilized at that time. - 56 - 11180036ng; While strawberries are actually planted in soils of practically every kind they are seldom grown in a medium‘that is of. lower productivity than the one usd in this experiment -- a dune or "blow" sand. The evidence indicates, however, that even such a soil will provide the strawberry plant with an ample supply of most of the essential nutrient elements. Furthermore, applications of fertilizers carrying nutrient elements other than nitrogen would seem to be of little value, though perhaps in some cases phosphorous containing materials may be of some use. On the other hand, the data show that a deficiency in available nitrogen at any period during the growing season profoundly influences the growth and development of the fruit and observation leads to the belief that such deficiencies are of common occurrence in strawberry production. From a practical standpoint, then, nitrogen is the nutrient element to which the grower needs to give the most of his attention. Plants grown with a limited supply of available nitrogen during the spring and early summer and with more liberal supply later will produce crowns about as large as those in which nutrient conditions are reversed and they are much more productive. On light soils which are likely to be deficient in nitrogen, the application of quickly available nitrogenous fertilizers in the Spring when the plants are set may stimulate a - 57 - vigorous vegetative growth with an abundant runner pro- duction. This may result in a condition which will arrest the deve10pment of the crowns and reduce fruit bud formation. Therefore, such applications, if made at all, should be light in the case of those plantations intended for fruit production. In the case of plantations intended principally for plant or runner production more liberal spring applications are warranted. In many cases both spring and summer applications of nutrients may be necessary for the development of crowns of suffi- cient size for maximum fruit production and to obtain the best conditions for fruit bud differentiation.~ How- ever, if only one application is to be given the summer treatment is to be preferred. Fruit bud formation and total yield of fruit depend largely on nutritive conditions within the slant in late fall. More Specifically, they seem to be associated with a rather high nitrogen and carbohydrate content within the plant at that particular time. These in turn depend largely on soil nutrient conditions, parti- cularly the supply of available nitrogen during the late summer and early fall. Without doubt, many soils that are.being well cultivated naturally provide conditions that approach the Optimum in this respect, and fertilizer applications would not be useful. They might even be harmful. On the other hand, it is evident that in many cases light or moderate summer and early fall applications of quickly available nitrogen carrying fertilizers would -58.. be of value. No definite statement can be made that will enable the grower to decide exactly when or where fertilizer applications are reasonably sure to prove profitable; nor can a definite statement be made as to how heavy such applications should be. However, obser- vations on the appearance of the different lots under eXperimental study in this investigation, the data fur- nished by the analyses, and the later fruiting records, together with many field observations lead to the belief that any considerable purpling of the foliage excluding that which is obviously caused by firouth or leaf spot, in summer or early fall, indicates a deficiency of avail- able soil nitrogen that is very likely to interfere with fruit bud differentiation and correspondingly to reduce subsequent yield. This should be a signal for Judicious applications of nitrogen carrying fertilizers, or better still, the grower should so handle his strawberry plan— tation as to prevent this condition from developing. It is, of course, possible that applications of amounts over and above those required to prevent such purpling may sometimes be desirable. Applications of nitrogen in the Spring of the fruiting year may increase yields by inducing a better setting of the flowers and an increase in the size of the berries, However, the greatest response from an application at this time may be eXpected from those plants which have been grown under low nutritive conditions during the preceding summer and fall. - 59- SUMMARY ANQ_CONCLUSIOHS 1. Large variations have occurred in the size of the plants as a result of receiving the various treatments in this experiment. The summer-treated plants were slightly larger than the spring-treated plants. The largest plants were obtained when the nutrients were applied during both the epring and the summer periods. 2. Nitrogen has been the chief limiting element. It is an important factor in promoting vegeta- tive growth and is particularly important at the time of fruit bud differentiation. 3. Phosphorous alone has, apparently had no effect on vegetative growth. In combination with nitrogen it has promoted a larger vegetative growth and fruit production than was secured with nitrogen alone. 4. Plants treated with sodium nitrate, monocalcium phosphate and potash were not as large or as productive as those treated with ammonium sulphate, acid phosphate and potash. 5. Spring applications of nitrogen, alone or in combination with phosphoric acid or phosphoric acid and potash, caused a vigorous runner production. When equal amounts of the same nutrients were applied during the summer period, few runners were produced and there was a better develOpment of the crowns. 6. With a limited supply of nutrients in - so - the soil the roots were large in prOportion to the tops. With a moderate supply of nutrients the root system was less extensive and the teps prOportionally larger. When phosphoric acid and potash were used in combination with nitrogen the preportion of tops to roots was larger than when nitrogen was used alone. 7. Plants which had been treated with nitrogen during the previous summer period grew better in the spring of the fruiting year than the unfertilized, or the spring-treated (first year) plants. The response in vegetative growth was greater in plants grown under low nutritive conditions the preceding summer and fall. 8. The ash content of the roots was larger than that of the tops. There were some differences in the percentages of nitrogen, and carbohydrates in the tOps and roots, but the absolute amounts of the various constituents in proportion to the amount of dry matter were nearly the same. 9. The amount of ash in the tops varied from 9.4 to 16.16 per cent., but the plants with the lowest percentage of ash contained higher percentages of nitrogen, phOSphoric acid and potash than those with the highest ash content. 10. The unfertilized plants and the Spring-treated plants were lower in nitrogen, phosphoric acid and potash and higher in percentage of carbohydrates, than the summer-treated plants. - 51 - 11. One of the effects of the fertilizer treatments was an increase in sugars and a decrease in polysaccharides. Spring-treated plants contained more free reducing sugars than the summer-treated plants. The amount of sugars in the plants appears to be closely associated with the potash content. 12. Calculations from the data of this experiment show that an acre of strawberyy plants in hills 15 by 30 inches apart will produce, during the per-. iod of vegetative growth and fruit bud formation, approx- imately 2500 pounds of dry matter which will contain 41.75 pounds of nitrogen, 16 pounds of phosphoric acid, 29 pounds of potash and 225 pounds of other mineral con- stituents. 15. The total number of flowers per plant as modified by fertilizer treatments is determined chiefly by the number of clusters, and to a very limited extent by the number of flowers per cluster. Fertilizers containing nitrogen increased the number of flower clus- ters per plant. The summer-treated plants produced nearly twice as many clusters as the spring-treated plants. A slightly larger number of clusters was borne by the Spring- and summer-treated plants. Applications of fertilizers in the spring of the fruiting year have no effect on the number of clusters or the number of flowers per cluster. '14. The preportion of flowers which set fruit is influenced to some extent by nutritive condi- 1 tions Which exist in the plant the preceding fall, and to a considerable extent by nutritive conditions in the soil at blooming time. Summer-treated plants, which con- tained more nitrogen at the termination of growth in the fall, set a larger percentage of blossoms than the Spring— fertilized plants which were low in nitrogen. applications of nitrogen in the spring of the fruiting year caused a better setting of the blossoms and an increase in the size of the berries. l5. Nitrogen alone or in combination with phosphoric acid and potash has in every instance increased the total yield. The yield of the summer- fertilized plants was larger than that of the Spring- fertilized plants. Largest yields were obtained from plants which were fertilized during both the Spring and the summer periods and again in the spring of the fruit- ing year. 16. Fruit bud differentiation in the strawberry does not depend on a particular nitrogen- carbohydrate ratio in the plant. However, fruit buds are formed more readily when certain quantitative re- lationships of the nitrogen and carbohydrates exist at the time differentiation takes place. 17. Variations in the nitrogen content of the plants at the time of fruit bud differentiation have a greater effect on the yield of fruit than varia- tions in carbohydrate content. Low nitrogen is associated - 55 - with low yields, high nitrogen with high yields. Plants with a high nitrogen content and a high carbohydrate content are most productive. 18. The size of the crown is not an index of the fruitfulness of the strawberry plant. Total production is determined by the number of flower clusters and the number of blossoms which set and develop into fruitSa These are determined chiefly by nutritive conditions Within the plant at the time of fruit bud differentiation during the late summer and fall. 19. There is no indication that ferti- lizer treatments have materially affected the moisture content, the texture, or the quality of the fruit. ACKHOVLEDGMENTS The writer wishes to make acknowledg- ment to Professor V. 3. Gardner for many criticisms and suggestions in planning and conducting the work outlined in this experiment, and for assistance in the preparation of the manuscript; to Dr. John W. Grist for assistance in making carbohydrate analyses; to the members of the Agricultural Chemistry Depart- ment for making the mineral analyses; and to Professors F. 0. Bradford and R. E. Marshall fer reviewing the manuscript. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. l4. 15. 16. 17. 18. LITERATURE CITED Bailey, L. H. Cornell Univ. Agr. Exp. Bul. 189. 1901. Bedford, H. A. R., and Pickering, S. V. Woburn Exp. Farms Rept. 1900, pp. 85-92. (abs. from Exp. Sta. Rec. Vol. 12 p. 645. 1900-1901). Brown, G. G. Oreg. Agr. Exp. Sta. Bul. 159. 1919. Chandler, W. H. Mo. Agr. Exp. Sta. Bul. 115. 1915. Close, 0. P., Ballard, W. R. and White, T. H. Md. Agr. Exp. Sta. Bul. 124. 1907. Darrow, Geo. M. U.S.D.A. Farmers' Bul. 1028. 1919. Fletcher, S. W. Strawberry Growing p. 55. New York. 1917. ibid. p. 59. ibid. p. 58. Gardner, V. R. Mo. Agr. Exp. Sta. Res. Bul. 57. 1925. Keffer, C. A. Tenn. Agr. Exp. Sta. Bul. XVIII:2. 1905. Kraus, E. J., and Kraybill, H. R. Oreg. Agr. Exp. Sta. Bul. 149. 1918. Lyon, T. L., and Buckman, H. 0. The Nature and Pr0perties of Soils, p. 15. New York. 1925. Methods of Analysis, A. O. A. 0., p. 90. Washington, D. C. 1921. Quaintance, A. L. Ga. agr. EXp. Sta. Bul. 48. 1900. Shaw, G. W. Oreg. Agr. Exp. Sta. Bul. 62. 1900. Valleau, W. D. U. S. Dept. Agr. Jour. Agr. Hes. XII : 10. p. 615. 1918. Van Slyke, L. L. Fertilizers and Crops. p. 694. New York. 1912. 19. 20. 21. 22. You Brehmer, -- , Gartenwelt, 11 (1906) No. 7, pp. 78-79. (Abs. from Exp. Sta. Rec. Vol. 18. p. 549. 1906-1907) Walton, G. P., and Coe, M. R. U. S. Dept. Agr. Jour. Agr. Res. XXIII : 12, p. 995. 1925. White, J. M. N. J. Agr. Exp. Sta. Rept., 1891. p. 141. White, J. M. N. J. Agr. Exp. Sta. Rept., 1892. p. 127. Willis, J. J. Gardener's Chronicle, 5 : XX : 590. 1896.