,DHYSIOLDDICAL ' or: DISORDERS 0? APPLE :I-‘IIUIT, PECTSi SOME NUTRITIONALASV I Thesis for the Degree of PD D vIEIIsmI MICHIGAN STATE UNI MICHAEL w, IIILDYT 1971 i A 35%. . an}??? wen» our? . . an,“ . an” Wwfififf g. .fig 7%.? a?” .fifixuq...” .wfimmrawfimyfi .4.» 4. figurfi, D £3? 4 4. ”Vanna? . \r munfiu...fi,¢r.y. I flfiquflr “fa?!“ LI 3:7: I .- .nrnir. M53955 1!. £131.11}. IJRPARY t E. Midng, I 363:8 ti 5/ :1.f."i?‘f '\ y ""91; zmvisa'x - ‘Dullu This is to certify that the I thesis entitled l SOME NUTRITIONAL ASPECTS OF PHYSIOLOGICAL DISORDERS OF APPLE FRUIT presented by Michael w. Kilby has been accepted towards fulfillment of the requirements for Eh .13. _degree inHomimmuxe flfW Major professor mam 0-7639 ABSTRACT SOME NUTRITIONAL ASPECTS OF PHYSIOLOGICAL DISORDERS OF APPLE FRUIT By Michael W. Kilby A study concerning the effect of nutrient sprays on the chemical composition and disorder incidence of se— lected apple cultivars was conducted in 1969 and 1970. In 1969 experiments_were designed to evaluate the effect of Ca sprays on fruit and leaf composition and physiological disorders of the apple cultivars 'Northern Spy', 'Jonathan' and 'Delicious'. A series of four foliar applications of Ca(NO3)2 at a concentration of .60% during May and June did not significantly alter Ca content of the fruit or leaves nor did they affect physiological disorders of any cultivar. Two applications of CaCl2 applied during August at a concentration of .60 and .8U% with the addi— tion of the chelating agent, Rayplex, significantly re— duced the incidence and severity of bitter pit in 'Northern Spy' apple fruit. Leaf scorch was prevalent one week after application. There was a significant positive correlation between bitter pit incidence and fruit size as measured by weight. The results indicated that the Ca content of the Michael W. Kilby peel appeared to be the dominant factor in reduction of pit formation. The microprobe was used to examine various tissues of 'Northern Spy' apple fruit with and without bitter pit symptoms. Results showed that necrotic—free tissue from apples exhibiting bitter pit symptoms was low in Ca and Mn and high in K and Mg relative to the content of the tissue from bitter pit free apples. In apples showing bitter pit symptoms, necrotic tissue was higher in K, Ca and Mg than adjacent tissue which appeared to be normal. In 1970 experiments were designed to determine the effect of foliar applications of Ca(NO MgSOu, KZSOA’ 3)2, Succinic Acid 2,2-Dimethyl Hydrazide and Triodobenzoic Acid on the nutrition and disorder incidence of 'Jonathan' apple trees and fruit. Three sprays of .60% Ca(NO3)2 applied at 2 week intervals beginning June 16 signifi- cantly reduced internal breakdown (IB) incidence of fruit during storage regardless of type of storage (CA or cold). K230“ sprays increased fruit K and were the only treatments influencing fruit composition values. However, some spray injury to leaves was prevalent. Addition of the adjuvant, Regulaid, to each of the nutrient spray treatments re- sulted in a small increase in leaf absorption of the re— spective element. Internal breakdown incidence was accentuated when harvest was delayed one week beyond the optimum harvest date. Ca(NO3)2 plus Regulaid reduced IB even when harvest Michael W. Kilby was delayed. SADH and TIBA had no effect on IE when fruit were examined after 3 months of cold storage. SADH re- sulted in a firmer fruit at each harvest date. SADH re— sulted in a reduction of IB at the later harvest after fruit were kept in CA storage. Simple linear correlations revealed that IE was nega- tively correlated with Ca and positively correlated with titratable acidity, fruit K/Ca, Mg/Ca and (K + Mg)/Ca ratios. There was a negative relationship between Ca and titratable acidity. Multiple correlations showed that Ca and titratable acidity was strongly related to IE at Opti- mum harvest and water core was an important factor when harvest was delayed. SOME NUTRITIONAL ASPECTS OF PHYSIOLOGICAL DISORDERS OF APPLE FRUIT By w Michael wl Kilby A THESIS SUBMITTED TO Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Horticulture 1971 ACKNOWLEDGMENTS The author wishes to express his sincere appreciation to Dr. A. L. Kenworthy for his guidance and counsel during the course of these studies and in preparation for the manuscript. Appreciation is expressed to Dr. D. H. Dewey for the use of laboratory facilities and assistance in handling of fruit. Appreciation is expressed also to Dr. Jerome Hull, Jr., Dr. C. M. Harrison and Dr. C. J. Pollard for their suggestions in editing the manuscript. Special appreciation is expressed to my wife, Judy, for her patience and encouragement throughout the course of graduate studies. ii TABLE OF CONTENTS INTRODUCTION Section I. EFFECT OF CALCIUM SPRAYS ON MINERAL COMPOSI— TION AND BITTER PIT OF SELECTED APPLE CULTIVARS . . . . . . . Section Abstract Introduction . . . Material and Methods Results . . Discussion . . Literature Cited II. EFFECT OF NUTRIENT AND GROWTH REGULATOR SPRAYS ON INTERNAL BREAKDOWN OF 'JONATHAN' APPLE FRUIT . . . . . . . APPENDIX Abstract Introduction . . . Material and Methods Results . . Discussion . . Literature Cited iii Table LIST OF TABLES Section I The effect of four applications of Ca(NO )2 at .60% during May and June on leaf an fruit composition of 'Northern Spy' apple (1969) . . . . The effect of four applications of Ca(NO ) at .60% during May and June on leaf an fruit composition of 'Delicious' apple (1969) . . . . . . . The effect of four applications of Ca(NO )2 at .60% during May and June on leaf and fruit composition of 'Jonathan' apple (1969) . . . . . . . . The effect of four applications of Ca(NO ) at .60% during May and June on bitter 31% of 'Northern Spy' and 'Delicious' apples (1969) . . . . . . . . . . The effect of four applications of Ca(NO at .60% during May and June on the incidénce of internal breakdown in 'Jonathan' apples (1969) . . . . . . . . . . . . The effect of three applications of Ca(NO3)2 and two applications of CaCl during August and September on the nutrient com- position of 'Northern Spy' apples (1969) 2 The effect of three applications of Ca(NO3 ) and two applications of CaCl on bitter 3pit of 'Northern Spy' apples (1989) The relative amounts of nutrient elements found in cortical tissue of 'Northern Spy' apple fruit with and without bitter pit as determined by microprobe analysis . . iv Page 11 12 13 in 15 l7 18 2O Table Section II I. Effect of nutrient and growth regulator sprays on leaf composition of 'Jonathan' apple trees sampled on July 31, 1970 . 2. Effect of nutrient and growth regulator sprays on nutrient composition of 'Jonathan' apples harvested on October 5, 1970 . 3. Effect of nutrient and growth regulator sprays on weight, lenticel spot, titratable acidity, and soluble solids of 'Jonathan' apples harvested on October 5, 1970 A. Comparison of harvest date and nutrient and growth regulator sprays on internal break- down (IB) of 'Jonathan' apples after 3 months of cold storage (36F) followed by 2 weeks at 70F . . . . 5. Effect of nutrient and growth regulator sprays on internal breakdown (IB) of 'Jonathan' apples after 5 months in CA storage (32F) followed by 2 weeks at 70F 6. Effect of nutrient and growth regulator sprays on brown heart (BH) and core brown- ing of 'Jonathan' apples after 5 months of CA storage (32F) followed by 2 weeks at 70F . . . . . . . . 7. Effect of delayed harvest on disorder inci— dence irrespective of treatments from both CA and cold storage 8. Significant correlation coefficients showing the association between leaf analysis and various physiological disorders of 'Jona- than' apples measured before or after cold storage (36F) 9. Significant correlation coefficients between leaf analysis and various disorders of 'Jonathan' apples after 5 months of CA storage (32F) followed by 2 weeks at 70F Page 39 Al “2 44 45 H6 #8 “9 50 Table 10. 11. 12. 13. 14. 15. Section II con't. Significant correlation coefficients showing the associations between fruit analysis and various disorders of 'Jonathan' apples after 3 months of cold storage (36F) Significant correlation coefficients showing the association between fruit analysis and various disorders of 'Jonathan' apples after 5 months of CA storage (32F) followed by 2 weeks at 70F . . . . . . . . Significant correlation coefficients showing the association between various factors measured at harvest or after cold storage. Disorder indices were used in calculation of correlation coefficients . . . . . . Significant correlation coefficients showing the association between fruit analysis and parameter other than disorder inCidence Significant correlation coefficients showing the relationship between disorders from fruit examined after 5 months in CA storage (32F) . . . . . . . . . . . . Multiple correlation and regression coeffi- cients with internal breakdown and titratable acidity as dependent variables vi Page 51 52 5M 55 57 61 Table A—1. A-3. A-u. A-S. A-6. A-7. APPENDIX Leaf composition values of 'Jonathan' trees from the Ray Klackle orchard, Belding, Michigan collected July 31, 1970 . Leaf composition values of 'Jonathan' trees from the John Schaefer orchard, Sparta, Michigan collected July 31, 1970 Fruit composition values of 'Jonathan' apple fruit harvested from the Ray Klackle orchard, Belding, Michigan collected October 5, 1970 . . . . . . Fruit composition values of 'Jonathan' apples harvested from the John Schaefer orchard, Sparta, Michigan collected October 5, 1970 . . . . . Internal breakdown and water core incidence of fruit harvested on October 5, 1970 and placed in cold storage (36F) followed by 2 weeks at 70F . . Internal breakdown incidence of fruit har- vested on October 5,1970 and placed in CA storage (32F) followed by 2 weeks at 70F . . Variation in fruit and leaf nutrient elements for overall Jonathan experiment-- 2 orchards (40 trees), 1970 vii Page 71 72 73 7A 75 76 77 INTRODUCTION Annual production of apples in Michigan is approxi- mately 17 million bushels. Michigan ranks third in total U.S. production. The leading cultivar in terms of pro- duction is 'Jonathan' which accounts for about A million bushels annually. Michigan produces about 40 percent of the nation's 'Jonathan' crop. 'Northern Spy' is the lead- ing processing cultivar in the state. Growers usually suffer economic losses brought about by low prices, inadequate storage facilities, poor grower management and packing. Losses involved in packing in— clude those caused by physiological disorders which affect primarily 'Jonathan', 'Delicious' and 'Northern Spy' fruit in Michigan. Two disorders which have been of economic importance are bitter pit and internal breakdown. Internal breakdown is more serious with 'Jonathan'. Internal break- down is a storage disorder and affects the cortical regions of the fruit. Bitter pit is more severe on 'Delicious' and 'Northern Spy'. Fruit affected with bitter pit show dark pits on the surface of the fruit or just beneath the peel or throughout the flesh. Bitter pit may develop on the tree or during storage. Symptoms for both of these disorders usually occur at the calyx end of the fruit and in severe cases may affect the entire fruit. Cultural practices which have been implicated as possible causes are over—fertilization with nitrogen, severe pruning, and severe thinning. In recent years studies involving the chemical analy- sis of fruit have revealed that a possible cause for these disorders is manifested in the nutrient content of the fruit specifically related to calcium shortage. However, a cause-effect relationship for this phenomenon has not been established. Since the cause of internal breakdown and bitter pit have been designated as possible nutrient abnormalities, experiments were conducted to determine the effect of foliar sprays on the nutrient composition and disorder development of the fruit. EFFECT OF CALCIUM SPRAYS ON MINERAL COMPOSITION AND BITTER PIT OF SELECTED APPLE CULTIVARS Abstract: In 1969 experiments were designed to eval- uate the effect of Ca sprays on fruit and leaf composition and physiological disorders of the apple cultivars 'North— ern Spy', 'Jonathan' and 'Delicious'. A series of four foliar applications of Ca(N03)2 at a concentration of .60% during May and June did not significantly alter Ca content of the fruit or leaves nor did they affect physiological disorders of any cultivar. Two applications of CaCl2 ap- plied during August at a concentration of .60 and .8H% with the addition of the chelating agent, Rayplex, signif- icantly reduced the incidence and severity of bitter pit in 'Northern Spy' apple fruit. Leaf scorch was prevalent one week after application. There was a significant posi— tive correlation between bitter pit incidence and fruit size as measured by weight. The results indicated that the Ca content of the peel appeared to be the dominant factor in reduction of pit formation. The microprobe was used to examine various tissues of 'Northern Spy' apple fruit with and without bitter pit symptoms. Results showed that necrotic free tissue from apples exhibiting bitter pit symptoms was low in Ca and Mn and high in K and Mg relative to the content of tissue from bitter pit free apples. In apples showing bitter pit symptoms, necrotic tissue was higher in K, Ca and Mg than adjacent tissue which appeared to be normal. EFFECT OF CALCIUM SPRAYS ON MINERAL COMPOSITION AND BITTER PIT OF SELECTED APPLE CULTIVARS By Michael W. Kilby Introduction Physiological disorders of apples such as bitter pit and internal breakdown have been associated with low levels of calcium in fruit tissues (lO,ll,l3,lA,2l,23,29). DeLong (IO) and Garman and Mathis (1“) reported that apples from the 'Stark' and 'Baldwin' cultivars showing bitter pit symptoms were lower in calcium than fruit free of pit. Askew at al. (I) reported that discolored tissue was higher in total ash, Ca, Mg, K, Na, P and N than neighboring healthy tissue in 'Cox's Orange' apples affected with bit— ter pit. In addition to low Ca content of fruit, high levels of K have been related to bitter pit incidence. In a two year survey of 'Northern Spy' apple orchards in Michigan, Oberly and Kenworthy (21) found that increased fruit K was associated with bitter pit incidence. Askew at al. (I), Garman and Mathis (14) and Martin (19) analysed bitter pit affected and non—affected fruit from 'Cox's Orange', 'Baldwin' and 'Sturmer' cultivars, respectively, and concluded that fruit showing bitter pit symptoms had a higher K level when compared to fruit free of pitting. Also, these investigators showed a similar relationship with K/Ca ratios. The application of calcium salts in the form of foliar sprays (5,6,8,11,1A,26,30), fruit injections (5, 1H) and fruit dips (14,26) have resulted in a reduction in the incidence of bitter pit. Baxter (5) working in Australia, reported that six foliar applications of Ca(NO3)2 (.5%) to 'Cleopatra' apples would reduce bitter pit. The initial spray was applied in December. Applications to the leaves only, had no effect on pit incidence. Research in South Africa by Beyers (6) showed that four foliar applications of Ca(N03)2 at a concentration of 1% beginning in December, to 'Golden Delicious' apples reduced both tree and storage pit but did not affect Ca content of the fruit. Drake at a1. (11) obtained a highly significant correlation between Ca con- tent of the peel of 'Baldwin' apple and bitter pit free fruit. They suggested that a peel content of .07% Ca would prevent bitter pit occurrence. Stevenson (30) applied 12 sprays of Ca(NO3)2 (.6%) to 'Granny Smith' apples in Aus- tralia. Bitter pit was significantly reduced in treated fruit. The Ca content of the peel was significantly in- creased with Ca(NO3)2 sprays but cortical tissue was not significantly altered. No other combinations of sprays were used, therefore, it is not known which applications were the most effective. Injections of Ca acetate (5) and Ca(NO3)2 (1”) into 'Cleopatra' and 'Baldwin' apple fruit, respectively, reduced bitter pit. These various methods of calcium application usually result in an increase of Ca in the cortical region and peel of the fruit; hence the association of disorder ap- pearance with low levels of Ca in the fruit. Calcium salts which have resulted in the greatest reduction of bitter pit, when applied as foliar sprays, are Ca(NO3)2 and CaCl2 with the former being widely used because of possible foliage injury with CaC12. These salts are usually applied as multiple applications in mid— to late-season with concentrations ranging from 3 to 10 lb/lOO gallons (.36 to 1.2%). The highest concentration of Ca in the fruit occurs after pollination and gradually decreases as the season progresses while total Ca content increases until maturity (25,31). The amount of Ca available to the fruit early in the season could be important and could conceivably deter— mine the ultimate level of Ca in the fruit. In view of current theories that low Ca levels in the fruit are associated with bitter pit (l3) and that a pre— disposition to bitter pit is supposed to be decided early in fruit development (27), a series of experiments involv- ing Ca sprays, were initiated in an attempt to alter Ca levels early in fruit development and reduce the occur— rence of disorders. Nutrient—element investigations were conducted on fruit showing bitter pit symptoms. The microprobe was used in these studies. Material and Methods In 1969 experiments utilizingfoliar Ca sprays were conducted on 'Northern Spy', 'Delicious' and 'Jonathan' cultivars. Two series of Ca(NO3)2 sprays (early and late season) were applied to mature 'Northern Spy' trees while only early season sprays were applied to the other two cultivars. Early season sprays consisted of four Ca(NO3)2 appli— cations at the rate of 5 lbs/100 gallons (.60%) with and without an equal amount of Rayplex*, a chelating compound. Dilute sprays were applied at weekly intervals beginning just prior to petal fall. Treatments and rates were the same for late season sprays applied at 2-week intervals beginning August 30, 33 days before harvest. In addition to Ca(N03)2 sprays, 2 late-season, dilute, CaCl2 sprays were applied to 'Northern Spy' trees at the same time as the first 2 late—season Ca(NO3)2 sprays. Rates were 5 and 7 lbs/100 gallons (.60 and .8U%) with and without an equal amount of Rayplex. * Rayplex, ITT Rayonier Incorporated, 161 East A2nd Street, New York, New York. Treatments were applied to single tree plots with 2 replicates for 'Northern Spy' and A for 'Jonathan' and 'Delicious'. On September 20, a random sample of l bushel of fruit from the 'Delicious' cultivar was picked for each treat- ment, weighed and placed in cold storage at 36F. On October 3, the same harvest procedure was followed for 'Jonathan' and 'Northern Spy'. Each bushel consisted of fruit picked from around the periphery of the tree. After 4 months, fruit of all cultivars were transferred to a 70F room for 2 weeks to allow for maximum development of dis— orders. Fruit of the 'Northern Spy' and 'Delicious' culti- vars were examined for bitter pit; 'Jonathan' for internal breakdown. Leaf samples were collected in July and October for early and late season sprays respectively for nutrient analysis. Nitrogen was determined by the Kjeldahl method, K by the flame photometer and P, Ca, Mg, Mn, Fe, Cu, B, Zn and A1 spectrographically. Chemical analysis of flesh and peel of representative samples of MO fruit was performed for 'Northern Spy' and 'Delicious' while only flesh analysis was performed for 'Jonathan'. Fruit peel was obtained by using a hand peeler-corer apparatus. Cortex samples were obtained after peeling by combining l/H inch thick mean longitudinal wedges from each apple. The same elements were determined for these samples as for leaves, using the same procedures. 10 Chemical Investigations of Bitter Pit Tissue: 'North— ern Spy' apples uniform in size with and without bitter pit symptoms were selected for electron microprobe analysis. Necrotic and adjacent normal appearing tissue of bitter pit affected apples and tissue of bitter pit free apples were compared for nutrient element composition. Cortical tissue was selected at the same morphological position for each apple. Blocks consisting of cortical tissue, two centimeters cubed, were cut from each of A apples for analysis. The samples were dried and pressed into 1 l/H inch boric acid discs at a pressure of 40,000 lbs/sq. in. for 30 seconds. The discs were then covered with carbon and surrounded with India ink to facilitate conductivity. Samples were ana- lysed for relative amounts of K, Ca, Al, Mn, Mg, Fe and Cu. Tissues were also analysed for the non-essential elements Ba, Co, Pb, Rb, Sn, Sr, Ni, and Ti. Results Early season Ca(NO3)2 sprays did not significantly alter Ca levels in fruits or leaves nor did they reduce physiological disorders for any cultivar (Tables 1-5). 'Northern Spy' trees receiving the early season Ca(NO3)2 sprays without Rayplex show a significant lower level of K in leaves when compared to the other treatments (Table 11 TABLE l.--The effect of four applications of Ca(NO3)2 at .60% during May and June on leaf and fruit com- position of 'Northern Spy' apple (1969). Plant * Part Treatment N K* % DryPWeightca M Sampled g Control 2.17 1.A7a .19 1.31 .29 Leaves Ca(NO3)2 2.09 1.36 b .20 1.31 .29 Ca(NO ) + 1.96 l.u9a 7.17 1.36 .29 RayBléx NS * NS NS NS Control .30 .8A .077 .028 .025 Fruit Ca(NO3)2 .3A .83 .071 .03“ .030 Flesh Ca(NO ) + .28 .85 .0A6 .023 .020 Rayglgx NS NS NS NS NS Control .54 .82 .092 .069 .093 Fruit Ca(N03)2 .55 .80 .053 .023 .050 Peel Ca(NO ) + .52 .79 .059 .060 .070 Rayglgx NS NS NS NS NS NS = Not significant * Significant (P .05) Means followed by the same letter are not significantly different as determined by Duncan's multiple range test. 12 TABLE 2.—-The effect of four applications of Ca(N0 )2 at .60% during May and June on leaf and fru t com- position of 'Delicious' apple (1969). __ Plant Part Treatment N K % DryPWeightca M Sampled g Control 2.36 1.32 .169 1.22 .193 Leaves Ca(NO3)2 2.28 1.30 .171 .10 .179 Ca(NO ) + 2.30 1.16 .171 1.05 .172 Rayglgx NS NS NS NS NS Control .35 .887 .082 .043 .038 Fruit Ca(NO3)2 .29 .793 .071 .018 .027 Flesh Ca(NO ) + .34 .833 .090 .022 .028 Rayglgx NS NS NS NS NS Control .84 .720 .092 .096 .119a Fruit Ca(NO3)2 .47 .597 .081 .068 .083b Peel Ca(NO ) + .58 .593 .085 .100 .106ab Rayélgx NS NS NS NS *5 NS = Not significant ** Significant (P .01) Means followed by the same letter are not significantly different as determined by Duncan's multiple range test. 13 TABLE 3.--The effect of four applications of Ca(NO )2 at .60% during May and June on leaf and fru t com- position of 'Jonathan' apple (1969). Plant Part Treatment N K% Dry Weight Ca M Sampled g Control 2.44 1.12 .168 1.163 .187 Leaves Ca(NO3)2 2.24 1.21 .164 1.016 .244 Ca(NO ) + 2.34 1.45 .158 1.120 .189 Raygléx NS NS NS NS NS Control .024 .755 .064 .025 .022 Fruit Ca(NO3)2 .023 .840 .064 .021 .016 Flesh Ca(NO ) + .023 .855 .061 .040 .029 Rayglgx NS NS NS NS NS NS = Not significant 14 TABLE 4.--The effect of four applications of Ca(N03)2 at .60% during May and June on bitter pit of 'Northern Spy' and 'Delicious' apples (1969). Weight % Treatment (gm) Bitter Pit Pits/Apple Northern Spy Control 168.0 12.1 19.7 Ca(NO3)2 170.6 17.3 6.4 Ca(N03)2 + Rayplex 182.4 14.1 21.8 NS NS NS Delicious Control 133.1 9.5 7.3 Ca(NO3)2 161.6 4.4 4.8 Ca(NO3)2 + Rayplex 154.4 5.6 5.6 NS NS NS NS = Not significant 15 TABLE 5.--The effect of four applications of Ca(NO3)2 at .60% during May and June on the incidence of internal breakdown in 'Jonathan' apples (1969). % Internal Treatment Breakdown / Control 5.9 Ca(NO3)2 7.3 Ca(NO3)2 + Rayplex 6.5 NS NS = Not significant 16 1). This is not considered to be a treatment induced effect but is probably due to the inherent variability of the trees. None of the late season Ca salt sprays significantly altered the Ca content of fruit tissues, but there was a general increase in Ca content of peel with the CaCl2 treatments, particularly when Rayplex was used (Table 6). The Ca content of leaves was significantly higher with respect to the CaCl2 treatments (Table 7), however, con- siderable leaf scorch was prevalent. No significant dif- ferences in minor elements were detected for any spray treatment with regard to leaves and fruit. Among the late season Ca salt spray applications, only the treatment CaCl2 plus Rayplex significantly re- duced the number of fruit exhibiting bitter pit (Table 7). Disorder severity, as indicated by pits per apple, was significantly reduced with the Ca(N03)2 without Rayplex and both CaCl2 treatments when compared to the control (Table 7). There was a tendency for all of the late sea- son Ca treatments to reduce the number of pits per apple regardless of chemical formulation. I] A brownish colored residue was present at harvest on leaves and fruit where Rayplex was added to the treatments. This was particularly evident for leaves and fruit with late season applications. This residue was difficult to remove from fruit using a water solution containing a strong detergent, Tide. 17 TABLE 6.—-The effect of three applications of Ca(NO3)2 and two applications of CaClg during August and Sep- tember on the nutrient composition of 'Northern Spy' apples (1969). Lfi Plant Part Treatment N K % DryPWeightca M Sampled g Control 2.49 1.16 .17 .91 b .15 Ca(NO3)2 2.38 1.27 .16 .88 b .13 Leaves Ca(NO ) + 2.42 1.22 .17 1.00 b .14 Rayglgx CaCl2 2.45 1.15 .16 1.15 a .14 CaCl + 2.42 1.16 .16 1.05 a .14 Rafiplex NS NS NS II’ NS Control .33 .85a .079 .035 .022 Ca(NO3)2 .32 .79 b .072 .014 .045 Fruit Ca(NO ) + .31 .74 b .080 .045 .042 Flesh Rayglgx CaCl2 .30 .82 b .089 .022 .030 CaCl + .39 .93a .086 .036 .032 Rayplex NS 7¥ NS NS NS Control .65 .79 .089 .099 .10 Ca(NO3)2 .60 .75 .080 .065 .09 Fruit Ca(NO ) + .60 .73 .094 .060 .07 Peel Rayélgx CaCl2 .60 .65 .082 .110 .09 CaCl + .63 .88 .096 .200 .10 Ra§plex NS NS NS NS NS NS = Not significant * Significant (P .05) Means followed by the same letter are not significantly different as determined by Duncan's multiple range test. 18 TABLE 7.-—The effect of three applications of Ca(N0 )2 and two applications of CaC12 on bitter pit of 'Northern Spy' apples (1969). Weight % Treatment (gm) Bitter Pit Pits/Apple Control 188.25a 17.2a 9.7 b Ca(N03)2 183.82a 21.1a 2.4a Ca(N03)2 + Rayplex 157.60 b 17.5a 4.1ab CaCl2 l80.l2a 16.1a 1.2a CaCl2 + Rayplex 147.00 b 5.2 b 0.5a f? ¥¥' ¥¥ ** Significant (P .01) Means followed by the same letter are not significantly different as determined by Duncan's multiple range test. 19 In an attempt to relate some nutritional elements to l the incidence of bitter pit, simple linear correlations between bitter pit and mineral composition of leaves and fruit (combining 'Northern Spy' and 'Delicious' cultivars) were determined. Included in the correlations were various ratios between Ca, Mg and K. No significant correlations ! were obtained between any expression of bitter pit and nu— I trient composition of leaves or fruit. The correlation between percent pit and fruit size was significant (r = 0.55). The same statistical procedure was used for 'Jonathan' in relation to internal breakdown. Again, no significant correlations were present. Microprobe Investigations: Healthy cortical tissue of bitter pit affected apples when compared to tissue from non-affected apples was generally higher in all elements, with the exception of Mn and Ca which were lower, (Table 8). Those elements significantly higher for normal appear- ing tissue from pitted fruit were K, Cu and A1. The pitted tissue contained significantly higher amounts of Ca and Mg than adjacent normal appearing tissue or tissue of non- affected fruits. l, Elemental ratios of K/Ca, (K + Mg)/Ca and Mg/Ca were higher in healthy tissue of pit affected apples when com— pared to non-affected apples (Table 8). K/Ca and (K + Mg)/Ca ratios were significantly higher in pitted tissue compared to non-affected apple tissue. The Mg/Ca ratio 20 TABLE 8.--The relative amounts of nutrient elements found in cortical tissue of 'Northern Spy' apple fruit with and without bitter pit as determined by microprobe analysis. Source of Counts/10 sec. Tissue K Ca Mg Mn Fe Cu A1 Sigflofigpéi: 2461 b 151 b 32 b 26 84 25 b 58 b From apples showing pit F ti wigfloutsgfifis 4396a 122 b 75 b 12 134 55a 293a :13? giisues 5771a 364a 443a 30 111 47a 281a 3* ¥’ F¥7 NS NS fl ¥¥ K/Ca (K + Mg)/Ca Mg/Ca From apples without pit 17 b 17 b .22 b From apples showing pit igggofiisgggs 46a 46a .80ab From tissues 24 b 26 b 1 64 with pit a a ' a i ”ii i NS~= Not significant * Significant (P .05) ** Significant (P .01) Means followed by the same letter are not significantly different as determined by Duncan's multiple range test. 21 was significantly higher in the pit affected fruit tissue when compared to non—affected apple tissue but did not significantly differ from adjacent tissue which appeared to be normal. Analysis of each tissue for Ba, Co, Pb, Rb, Sn, Sr, Ni, and Ti was negative in that these elements were not present or the amounts present were not detectable. Discussion Early season Ca(NO3)2 sprays failed to reduce the incidence of physiological disorders in 'Northern Spy', 'Delicious' and 'Jonathan' fruit. The growing season of 1969 did not seem to be conducive for development of physiological disorders in apples as the incidence was low compared to other years. This low incidence of the disorders made comparisons of treatments difficult and in some instances the disorder was higher in treated plots than control (Tables 4, 5 and 7). Also, experimental re- sults of other research work conducted over a period of years have been complicated by variation in years brought about by climatic conditions (20). In general, cool, wet seasons result in less physiological disorders than hot, dry seasons (32). The 1969 growing season was somewhat cool when compared to average Michigan conditions (12), particularly during May and June. 22 The Ca content of apple peel or cortex was not sig- nificantly altered with early or late season Ca salt sprays. Early season Ca(N03)2 sprays have been shown to reduce bitter pit (16) but Ca content of the fruit was not~ determined. Also, the rates used (8 lbs/100 gallons or .96%) were higher than the rates used in this experiment and the percentage reductions in bitter pit associated with the sprays was higher than the controls reported herein. This may indicate that the reduction in bitter pit obtained with the use of Ca(N03)2 sprays may be proportional to the severity of pit incidence since Ca(NO3)2 sprays have never been reported to eliminate the disorder. This was graphi- cally illustrated in 6 years continuous research conducted by Martin using Ca(NO3)2 sprays (20). The late season application of CaCl2 + Rayplex sig- nificantly reduced bitter pit in 'Northern Spy' apples but did not result in complete elimination of the disorder. Ca content of the cortex was not appreciably higher than control fruit and was lower than the Ca(NO3)2 + Rayplex treatment. Furthermore, differences in bitter pit inci— dence did not seem to be related to Ca content of cortical tissue even though past research indicates that apples affected with the disorder have a low Ca level in the fruit (1,11,14,21). Others have reported that use of Ca salt sprays have not increased Ca in fruit flesh but sig— nificantly reduced bitter pit (11,17,30). This was the 23 case with the CaCl2 + Rayplex treatments in these experiments. Ca content of fruit peel tissue has been implicated as the primary nutritional factor related to bitter pit incidence when compared to other fruit and plant parts sampled (11,17,30). CaCl2 + Rayplex was the only treat- ment which significantly reduced bitter pit; and the Ca content of the peel was almost double the other treatments (Table 6). Fruit size must be considered when discussing bitter pit, as larger fruit are generally more susceptible to pitting (5,13,18.20). Overall correlations, regardless of treatment, showed a positive correlation between percent pit and fruit weight indicating that fruit size was im- portant in the apparent reduction of bitter pit by the CaCl2 + Rayplex treatment since the lowest fruit weight was contained in this treatment. However, fruit weight was low also with respect to the Ca(NO3)2 + Rayplex treat- ment which did not have a low pit incidence. Furthermore, Ca content of peel from fruit treated with CaCl2 + Rayplex was more than 3 times greater than the Ca(N03)2 + Rayplex treatment indicating that Ca nutrition of the peel, rather than fruit weight, was the dominant factor in reduction of pit. The severity of pit incidence as indicated by the number of pits per apple was reduced by all of the late season Ca sprays. The CaCl2 sprays tended to be more 24 effective than Ca(NO3)2 sprays which was probably due to a larger and more concentrated application of Ca. How- ever, applications of Ca in the Cl form are questionable due to chance of leaf scorch especially at high tempera— tures. Addition of Rayplex to CaCl2 seemed to increase the effectiveness in reducing the severity of pit but had no effect with Ca(NO3)2. Previous use of chelating chemicals and surfactants failed to increase the effectiveness of any form of Ca used as a spray material (2,16,24). Microprobe investigations confirmed the work of others that fruit affected with bitter pit have a lower Ca and higher K content than healthy fruit (1,10,11,14,17,l9,22, 30). The higher ratios of K/Ca, Mg/Ca and (K + Mg)/Ca in pitted fruit (healthy tissue) indicate that a high level of K or Mg or low levels of Ca in the fruit could result in pit occurrence. Not only would the absolute levels of each element be important but a balance should be main- tained among the 3 major cations. The effect of high Ca levels on reduction of pit could be overcome by abnormally large levels of K and Mg resulting in an increase in K/Ca and (K + Mg)/Ca ratios which would be conducive to pit development. Therefore, establishing a high Ca content of the fruit, without maintaining proper levels of K or Mg for a balanced situation, would be futile. In fact, indiscriminate use of K fertilizers has been implicated 25 as a possible cause for bitter pit and the idea that K may be the main operative nutritional element in bitter pit development (21). Invariably, K is always higher in fruit of pitted tissue in comparison to healthy tissue (1,3,14, 19,22). There were relative high values of Ca, K and Mg pres- ent in necrotic tissues of affected apples. These elements could have accumulated as necrotic areas developed. How- ever, artificially induced pitting does not contain high amounts of K, Mg or organic acids peculiar to naturally occurring pit (4). Another possible explanation for a high amount of these elements is that the pit may be mani- fested during early fruit development resulting in an ab— normal metabolic functioning of cells. These abnormalities could prevent proper functioning of cells such as growth and absorption of nutrients, resulting in these elements being "physiologically trapped" in affected cells in early stages of fruit growth. Symptoms may not become present until late in the season when environmental stresses pre- vail. Anatomical studies have shown that abnormal growth of bitter pit cells may be indicative of some stress occurring early in the growth of the fruit (28). Water relations and weather conditions play a major part in incidence of pitting (28,32). Conversely, mineral nutrition has been implicated as the primary area of im- portance in cause-effect relationships. ‘I- 26 The role of Ca in reducing this disorder is not known. Ca is contained in the middle lamella as Ca-pectate and helps to strengthen cell walls. Ca also affects the perme- ability of cell membranes, and complexes with toxic com— pounds such as oxalic acid. An increased synthesis of organic anions could be the cause of pitting as an increase in total and titratable acidity is common to pitted tissue (4). Furthermore, Ca could complex with organic anions produced during periods of environmental stress during the fruit enlargement stage. Environmental stress agents, such as drought and high night temperatures, could result in synthesis or increased concentration of organic anions gig respiration. Low levels of Ca in the fruit would not be able to remove the increased toxic anions and continue with other functions such as membrane permeability control. Improper nutrient balance in the fruit is another possibility of a causal factor related to bitter pit inci- dence. This nutrient imbalance has been explained on the basis of ratios among the 3 major cations (Mg, K, Ca) in the fruit (1,3,14,19,20). The most common ratio used in determining the nutri- ent imbalance phenomena is the (K + Mg)/Ca ratio. This ratio is much higher in pitted apples than in healthy ones. Bangerth (3) showed in a comparison of two susceptible cultivars that the (K + Mg)/Ca ratio in one cultivar (af- fected with pit) was higher than the other cultivar (no 27 pitting present) but little difference in Ca was evident. This would again implicate K as the main operative element in bitter pit incident. With respect to acid formation, excess K results in an excess production of acid, particularly citric acid (4, 9) which has been shown to increase soluble Ca in pitted tissue (15). This solubilization process may be depleting Ca from cell membranes or preventing Ca from performing other necessary physiological functions resulting in cell collapse or malfunction. Furthermore, this soluble Ca might translocate out of cells under conditions of moisture stress as Ca has been shown to move out of the apple under conditions of water stress (31). Water supply and fruit temperature are two environ- mental factors which can be altered for practical use. Sprinkler irrigation systems have been used to reduce fruit temperatures, add water and reduce bitter pit (33). This effect could have been mediated by reducing respira- tion of fruit as fruit temperature was lowered from 10- 20F. Since treatments other than Ca sprays, dips and in- jections have been successful in reducing pit, perhaps a low level of Ca in the fruit is not the causal factor, but must be maintained in sufficient quantities during periods of environmental stress to prevent pitting. Investigations concerning environmental stress and fruit composition with 28 respect to bitter pit incidence demand further study be- fore a definite single cause-effect relationship can be established, if one exists. LITERATURE CITED Askew, H. 0., E. T. Chittenden, R. J. Monk and Joyce Watson. 1960. Chemical investigations on bitter pit of apples. III. Chemical composition of affected and neighbouring healthy tissues. N. Z. J. Agr. Res. 3(1):l69-178. Bangerth, F. 1969. Utersuchungen zur ursache der Entstehung der Sippigkeit bei Apfelfruchten und Moglichkeiten zur Verhinderung. Angewandte Botanik. 42:240—262. (English Summary) Bangerth, F. and M. Mostafami. 1969. Einflub der Wasserversorgung und des Fruchtgewichtes auf den Mineralstoffgehalt und die Stippigkeit von Apfelfruchten. Der Erwerbsob stbau. 11:101—104. (English Summary) Bangerth, F. 1970. Die Stippigkeit der Apfel, ein noch immer ungelostes Problem der Fruchtphysiologie. Gartenbauwissenschaft. 35:91-120. (English Summary) Baxter, P. 1960. Bitter pit of apples: effect of calcium sprays. J. Dept. Agr. Victoria, Aust. 58:801-811. Beyers, E. 1963. Control of bitter pit and other dis- orders of apples with calcium sprays. Deciduous Fruit Grower. 13:319-335. Chittenden, E. T., D. J. Stanton and J. Watson. 1968. Bitter pit in Cox's Orange apples. N. Z. J. Agr. Res. 12(1):240—247. Cline, R. A. and A. Hutchinson. 1969. Calcium sprays to control bitter pit in Northern Spy apples. Rept. Hort. Res. Instit. Ontario for 1969. pp. 15-22. DeKock, P. C. 1969. The physiological significance of the potassium—calcium relationship in plant growth. Outlook on Agric. 4(2):93-98. 29 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 30 DeLong, Walter A. 1936. Variations in the chief ash constituents of apples affected with blotchy cork. Plant Physiol. 11:453-456. Drake, Mack, W. D. Weeks, J. H. Baker, D. L. Field and G. W. Olanyk. 1966. Bitter pit as related to calcium level in Baldwin apple fruit and leaves. Proc. Amer. Soc. Hort. Sci. 89:23-29. Environmental Science Service Administration. 1969. Climatology Data. Environmental Data Service. U.S. Dept. Commerce. Faust, Miklos and C. B. Shear. 1968. Corking dis-p orders of apples: a physiological and biochemical review. Bot. Rev. 34(4):441—469. Garman, P. and W. J. Mathis. 1956. Studies of mineral balance of Baldwin Spot in Connecticut. Conn. Agr. Exp. Sta. Bull. 601. Hilkenbaumer, F., G. Buchloh and A. Zachariae. 1960. Zur Atiologie der Stippigkeit von Apfelfruchten. Angew. Bot. 34:38-45. (Translation) Jackson, D. I. 1962. The effects of calcium and other minerals on incidence of bitter pit in Cox's Orange apples. N. Z. J. Agr. Res. 5:302-309. Kidson, E. B., E. T. Chittenden and J. M. Brooks. 1963. Chemical investigations on bitter pit of apples. IV. The calcium content of skin and flesh of apples in relation bitter pit. N. Z. J. Agr. Res. 6:43-46. Martin, D. 1954. Variations between apple fruits and its relation to keeping quality. II. Aust. J. Agr. Res. 5:9-36. Martin, P., G. C. Wagde and K. Stockhouse. 1962. Bit- ter pit in the apple variety Sturmer in a pot experiment using low levels of major elements. Aust. J. Expt. Am. Hus. 2:92-96. Martin, D., T. L. Lewis and J. Cerny. 1965. Experi— ments with orchard spray treatments for the con- trol of bitter pit is Tasmania. Div. Pl. Ind. CSIRO. Aust. Tech. Paper. No. 22. Oberly, G. H. and A. L. Kenworthy. 1961. Effect of mineral nutrition on the occurrence of bitter pit in Northern Spy apples. Proc. Amer. Soc. Hort. Sci. 77:29-34. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 31 Perring, M. A. 1968. Mineral composition of apples. VIII. Further investigations into the relation- ship between composition and disorders of the fruit. J. Sci. Fd. Agric. 19:640—645. Pienaar, W. J., P. E. Le R. Van Niekerk, Snr. and J. J. A. Bester. 1964. The role played by calcium in the incidence of bitter pit in Golden Delicious apples. The Deciduous Fruit Grower. l4(8):22l-225. Raphael, T. D. and R. R. Richards. 1962. Bitter pit- control by calcium nitrate sprays. Tasm. J. Agr. Rogers, B. L. and L. P. Batjer. 1954. Seasonal trends of six nutrient elements in the flesh of Winesap and Delicious apple fruits. Proc. Amer. Soc. Hort. Sci. 63:67-73. Sharples, R. O. and R. C. Little. 1970. Experiments on the use of calcium sprays for bitter pit control in apples. J. Hort. Sci. 45:49-56. Simons, Roy K. 1962. Anatomical studies of the bitter pit area of apples. Proc. Amer. Soc. Hort. Sci. 81:41-50. Smock. 1941. Studies on bitter pit of the apple. Cornell Agr. Expt. Sta. Memoir. 234. Stebbins, R. L. 1970. Orchard factors affecting the internal breakdown disorder of Jonathan apples. Ph.D. Thesis, Michigan State University. Stevenson, C. D. 1967. Chemical investigations on bitter pit of Granny Smith apples. Queen. J. Agr. Ani. Sci. 24:59-67. Wilkinson, B. G. 1968. Mineral composition of apples. IX. Uptake of calcium by the fruit. J. Sci. Fd. Agr. 19:646-647. Wilkinson, B. G. 1970. Physiological disorders of fruit after harvesting. "In the Biochemistry of Fruits and their Products". Vol. 1. Woodbridge, C. G. 1968. Bitter pit. Proc. Wash. State Hort. Assoc. EFFECT OF NUTRIENT AND GROWTH REGULATOR SPRAYS ON INTERNAL BREAKDOWN OF 'JONATHAN' APPLE FRUIT Abstract: In 1970 experiments were designed to deter- mine the effect of foliar applications of Ca(NO MgSOu, 3)? K2804, SADH and TIBA on the nutrition and disorder inci- dence of 'Jonathan' apple trees and fruit. Three sprays of .60% Ca(N03)2 applied at 2 week intervals beginning June 16 significantly reduced internal breakdown (IB) in— cidence of fruit during storage regardless of type of storage (CA or cold). K280” sprays increased fruit K and were the only treatments influencing fruit composition values. However, some spray injury to leaves was prevalent. Addition of the adjuvant, Regulaid, to each of the nutrient spray treatments resulted in increased leaf absorption of the respective element. Internal breakdown incidence was accentuated when harvest was delayed one week beyond the optimum harvest date. Ca(N03)2 plus Regulaid reduced IB even when harvest was delayed. SADH and TIBA had no effect on IB when fruit were examined after 3 months of cold storage. SADH re- sulted in a firmer fruit at each harvest date. SADH re- sulted in a reduction of 1B at the later harvest after fruit were kept in CA storage. 32 33 Simple linear correlations revealed that IB was nega- tively correlated with Ca and positively correlated with titratable acidity, fruit K/Ca, Mg/Ca and (K + Mg)/Ca ratios. There was a negative relationship between Ca and titratable acidity. Multiple correlations showed that Ca and titratable acidity was strongly related to IB at Opti— mum harvest and water core was an important factor when harvest was delayed. EFFECT OF NUTRIENT AND GROWTH REGULATOR SPRAYS ON INTERNAL BREAKDOWN OF 'JONATHAN' APPLE FRUIT Introduction In 1970 the 'Jonathan' cultivar represented approxi- mately 27 percent of the total apple production in Michi- gan. 'Jonathan' is susceptible to numerous storage disorders in prolonged cold or controlled atmosphere (CA) storage. A major storage disorder is internal breakdown (IB) which is characterized by a light brown discoloration of the flesh near the skin and around vascular bundles and in severe cases the whole fruit may exhibit browning (7). Symptoms are usually present at the calyx end of the apple and in severe cases extends throughout the fruit. Delayed harvest, delayed cooling after picking and extending the storage period can result in IB. IB has been related to the nutritional status of the tree and fruit (5,19,23,24,30). Bunemann gt a1. (5) found that 'Jonathan' fruit with highest incidence of IB had K contents considerably lower than the fruit from the trees yielding small quantities of fruit susceptible to IB. Perring (23,24) concluded that fruit affected with TB was low in Ca and that a Ca content of 5 mg/lOO gm fresh 34 35 weight in the flesh would prevent IB of 'Cox's Orange'. However, from further inspection of the data one might conclude that high K concentrations could be implicated as the causal element just as well as low Ca values. I Stebbins (30) after concluding a two year survey of 'Jonathan' apple orchards in Michigan concluded that either low fruit K or Ca was associated with IB incidence. Martin gt a1. (19) in Australia reported a negative correlation between IB and Ca content of the fruit in 'Jonathan' apples grown in pots. Titratable acidity of apple fruit has been associated with IB incidence (12,15,18). ‘Research in New Zealand by Letham (15) revealed that 1B of 'Sturmer' apple fruit was positively correlated with titratable acidity. Haynes (12) found that there was a direct association between high titratable acidity and 1B of 'Spalding Bramley's' apple fruit. Nutrient sprays have been used to correct or reduce deficiencies in deciduous orchards for many years. Since IB has been related to the nutritional status of the fruit and tree, specifically with Ca and K, a series of sprays containing N, Ca, K and Mg and two growth regulators were evaluated for their effect on IB of 'Jonathan' fruit. Titratable acidity was measured also to determine its relationship to IB and mineral nutrition of the fruit. 36 Material and Methods Two 'Jonathan' apple orchards in the mid-Michigan area with a previous history of IB incidence as described by Stebbins (23) were selected. Spray treatments con- sisted of Ca(No3)2 (.6o%), MgSOu (1.2%) and K280” (1.9%); each of the separate treatments with and without the non- ionic adjuvant Regulaidl (.25%), Ca(No3)2 plus urea (.60% + .36%), Succinic Acid 2,2-Dimethy1 Hydrazide (SADH) (2000 ppm) and Triodobenzoic acid (TIBA) (50 ppm). The nutrient element treatments were applied as dilute foliar sprays 3 times at 2 week intervals beginning June 16, 1970. SADH and TIBA were applied only on the June 16 date. Treatments were duplicated on single tree plots in each orchard. Leaf samples were collected from mid-terminal shoots at shoulder height from each tree on July 31. On October 5, two bushels of fruit were harvested from each tree at both locations. Each bushel container was lined with a plastic bag to minimize fruit moisture loss. One bushel was placed in cold storage at 36F and the other in con— trolled atmospheric (CA) storage at 32F with atmospheric concentrations of 3% O2 and 5% C02. A 20-fruit sample was collected from each tree for weight, water core (WC), per— cent soluble solids, firmness, titratable acidity and 1Formerly known as collodial SG, Collodial Products Cor- poration, Petaluma, California. Treatments including Regulaid will be designated with CSG following the chemi- cal formula of salt used. '37 nutrient element determinations. Sampling procedures for nutrient element determinations of fruits were made as described by Perring (25). Two thin longitudinal sections were cut from each of 20 fruit, one each from the blushed and unblushed side of the fruit. A second harvest was made on October 12 and the storage procedures for the October 5 harvest were followed. After 3 and 5 months, fruit were removed from cold and CA storage respectively, and placed in a warm room (70F) for two weeks to facilitate maximum development of TB symptoms. Removal of fruit from storage was sequential to harvest dates. From each bushel, 75 fruit were selected for inspection for various physiological disorders. Approx— imately 90 percent of fruit examined were 2 1/2 inches and larger. Fruit removed from cold storage were examined for lenticel spot (LS) and IB while those removed from CA stor— age were examined for IB, core browning (CB) and brown heart (BH). To facilitate calculation of analysis of var- iance and to eliminate zeros in the data, an index number for disorder severity was used for each disorder except for lenticel spot which was calculated as percent of fruit affected. During examination, fruit were grouped into categories depending on disorder severity. Categories were as follows: 1 = none, 2 = trace, 3 = slight, 4 = moderate and 5 = severe. The number of fruit in each category was 38 multiplied by the category number and then all categories were added together to produce an index number. Fruit and leaf analyses were conducted using the following procedures: Nitrogen was determined by the Kjeldahl method, K by the flame photometer, and P, Ca, Mg, Mn, Fe, Cu, B, Zn and Al spectrographically (11). The data were analyzed statistically as a split plot using orchards as a final split. For comparisons between harvest, data were analysed as a split plot design with harvest as sub plots. Simple linear correlations were determined for all parameters measured by combining param- eter analysis for all trees regardless of location or treatment. Multiple correlations were conducted using a least squares delete procedure (8). Variables used in the final least squares equation were fruit parameters which showed significant linear correlations with the independent variable. Results Leaf composition values revealed that trees receiving the K280“ treatments had the highest K content which were significantly larger than the Ca(NO3)2 + CSG treatment where K was lowest (Table 1). Mg content was highest in leaves from trees receiving the MgSOu treatments. Only the MgSOu + CSG treatment was significantly greater than 39 TABLE l.--Effect of nutrient and growth regulator sprays on leaf composition of 'Jonathan' sampled on July 31, 1970. % Dry Weight j apple trees Treatment N K P Ca Mg Control 1.92 1.09ab .24 1.35 .26a Ca(NO3)2 1.93 1.01ab .26 1.46 .26a Ca(NO3)2 + urea 1.98 1.00ab .29 1.48 .27a Ca(NO3)2 + CSG 1.96 0.84a .30 1.68 .31ab MgSOu 1.86 0.96ab .26 1.50 .36ab MgSOu + CSG 1.94 0.99ab .30 1.63 .40 b K280“ 1.83 1.22 b .27 1.51 .27a K280” + CSG 1.88 1.19 b .41 1.69 .3lab SADH 1.87 1.04ab .29 1.72 .32ab TIBA 1.88 1.08ab .31 1.70 .28a Means followed by the same letter are not significantly different at the 5% level. 40 the control. There were no significant differences in leaf N, P, Ca or the minor elements. The addition of Regulaid to Ca, K and Mg sprays re- sulted in a slight but non-significant increase in leaf composition values for Ca, K and Mg. The addition of Regulaid to K280“ and_MgSOu sprays resulted in some leaf abnormalities. Leaves sprayed with MgSOu + CSG showed a slight marginal scorch which was not considered serious. One week following the initial K2304 + CSG application, leaves showed a complete yellowing with subsequent abscission. This symptom was randomly distrib- uted throughout the tree. Later, symptoms appeared as circular necrotic spots distributed on the lamina but did not appear to be a nutrient toxicity or deficiency symptom since no consistent pattern of injury occurred. Potassium was the only element which varied signifi- cantly in fruit composition (Table 2). Fruit from the control and K280” treatment were significantly higher in K than fruit from any of the Ca(NO MgSOu or TIBA treat- 3),. ments. Fruit at harvest showed no significant differences between treatments for weight (size), lenticel spot, water core, and soluble solids (Table 3). Titratable acidity was significantly lower in fruit from the Ca(NO3)2, Ca(NO3)2 + urea and TIBA treatments when compared to the MgSOu + CSG or SADH treatment (Table 3). Theuse of SADH resulted in a significantly firmer fruit at both harvest dates. 41 TABLE 2.--Effect of nutrient and growth regulator sprays on nutrient composition of 'Jonathan' apples harvested on October 5, 1970. Treatment 1.% Dry Weight N K P Ca Mg Control .23 .67a .09 .07 .04 Ca(NO3)2 .22 .59 b .08 .07 .04 Ca(NO3)2 + urea .24 .61 b .09 .07 .04 Ca(NO3)2 + CSG .22 .60 b .09 .07 .04 MgSOu .20 .59 b .09 .06 .03 MgSOu + CSG .20 .60 b .10 .06 .03 K280” .20 .68a .10 .06 .04 K230“ + CSG .20 .62ab .10 .07 .04 SADH .21 .62ab .09 .06 .03 TIBA .20 .58 b .09 .06 .03 Means followed by the same letter are not significantly different at the 5% level. 42 TABLE 3.—-Effect of nutrient and growth regulator sprays on weight, lenticel spot, titratable acidity, and soluble solids of 'Jonathan' apples har- vested on October 5, 1970. Weight 1 WC Firm. Treatment (gm) % LS Index TA % SS (lbs) Control 105.58 16.50 47.4 9.84ab 12.2 17.80a Ca(NO3)2 96.03 11.50 46.9 8.86a 11.8 17.22a Ca(N0 )2 + 99.14 18.75 46.9 9.00a 12.0 17.30a ure Ca(NO3)2 + 94.48 12.75 42.9 9.52ab 12.2 17.42a CSG MgSOu 97.59 11.75 48.2 9.47ab 12.5 17.50a MgSOu + CSG 92.16 17.50 48.1 10.88 b 13.2 18.12a K2304 99.30 13.00 44.4 9.89ab 12.0 16.95a K2804 + CSG 90.81 12.75 46.9 10.18ab 12.6 18.00a SADH 90.75 15.00 44.8 10.61 b 13.6 19.88 b TIBA 87.15 15.25 44.5 8.74a 12.1 17.52a Means followed by the same letter are not significantly different at the 5% level. LS = Lenticel spot, WC = Water core, TA = Titratable Soluble acidity reported as meq./100 gm fr. wt., SS solids. l50 fruits were examined for each plot. 43 Evaluation of Fruit Removed from Cold Storage: The IB index and number of fruit exhibiting IB, for fruit har- vested on October 5, was significantly reduced by each of the Ca(N03)2 treatments when compared to the control or MgSO)4 treatment (Table 4). The Ca(NO3)2 treatment ex- hibited the greatest reduction in IE expressed as IB index, number of fruit affected or percent of control. By delaying harvest one week, only the Ca(NO3)2 + CSG treat— ment retained a significant effect in reducing IB incidence. Evaluation of Fruit Removed from CA Storage: Examina- tion of fruit harvested on October 5, showed that Ca(NO3)2 and Ca(NO + CSG treatments significantly reduced IB 3)2 incidence when compared to the MgSOu and TIBA treatments (Table 5). Results were similar to those obtained from cold storage in that Ca(N03)2 alone resulted in the greatest reduction of TB incidence. SADH had a moderate effect on reducing IB. A 1-week delay in harvest eliminated the sig- nificant reduction by Ca treatments at the first harvest. However, the Ca(NO3)2, SADH and Ca(NO + CSG treatments 3)2 retained their relative effectiveness in reducing IB inci- dence. Increased incidence of CB occurred with applications of MgSOu and TIBA when compared to Ca(NO and Ca(NO 342 3)2 + CSG sprays (Table 6). The lowest incidence of the disorder was present in fruit from the Ca(NO3)2 + CSG treatment. Fruit from the SADH treatment had the lowest CB index when 44 wcfizzopn mpficfieme < .mpowmpmo comm :H Um>pomno mm: .m com a .m mmfipowome xmocfi axocxmmpn ca pass“ mo .o: proe H .Ho>ma &m on» pm pcmpmmMHU meCMoHMchHm no: mum poppma 05mm on» ma cmzoaaom mammz n om.H: w.moa n om.:mm nmom.mm H.55 nmmm.sma amHe n wm.om m.:m nmmm.mam awoo.mm m.:s nmoo.ama mmam pmom.mm m.mm nmom.oam ommN.Hm m.mo nmoo.HmH wmo + a0me nmmm.om m.om ommm.mmH swam.mm 0.0» nmmm.mmH sommm cams.sm m.mm pmmN.mHm n om.Hm m.mw pmom.mmH umo + a0%: a 00.0: :.moa n mm.amm a om.zm m.am n ms.mma 30mm: mom.HH m.Hm wmm.mHH ems.m :.m: mmm.s0H cmo + mfimozvmo pmoo.sa 0.0m omom.mmH moo.=H N.Nm me.mmH «mg: + mflmozvmo nmoo.mH 3.5m nmom.mma moo.m 3.5: amp.moa mflmozvmo a ms.mm o.ooa n ms.mmm a ms.mm 0.00H n oo.sam Hopscoo palm swamo $2... may.” HOMWGMO 55 2.5.89 pmo>pmm NH moQOpoo pwmbpwm m Monopoo mmem¢m H 'l [I I‘ {II [I I, 1' .mou pm mxmmz m an bosoaaom Ammmv mmeOpm vaoo mo mnucoe m mmpmm moaamm .cmnpmnom. mo AmHv czocxmmmp Hmcpmpcfi so mmmnom nonmaswop susomw cam escapes: paw bump pmm>pm£ mo somemQEooul.: mqm¢e 45 .zuowome sumo 2H Uo>mmmno was wcficzonn mpficfimmu ¢ .m com a .m mmfipowmpmo xovsfi czooxmomn CH paupm mo .0: Hmuoea .Hm>mH mm map pm pcomomMHo meSQOHMHCme no: man pmpuma 08mm 039 an pozoaaom mumps C} nmm.mm H.wm m.mmH nmm.sm o.OMH n o.mmH amHe amo.HH H.mo m.mHH nmo.mH o.mm omm.HmH mmmmm NH monouoo pmm>pmm m meOpoo mmedm Emm>m00,0m map 00 020000000 000c00000c000 pom 000 000000 0600 030 mp vmzoaaom 0:002 0.00 0.000 0.00 00.000 0.0 0.00 0.00 00 0.000 0000 0.0 0.00 0.00 0 0.000 0.0 0.00 0.00 0000.000 0000 0.0 0.00 0.00 000 0.000 0.0 0.00 0.00 0000.000 000 + 00000 0.0 0.00 0.00 00000.000 0.0 0.00 0.00 0000.000 00000 0.0 0.00 0.00 00000.000 0.0 0.00 0.00 0000.000 000 + 00002 0.00 0.000 0.00 000.000 0.0 0.000 0.00 0 0.000 00002 0 0000 0.0 0.00 0.00 00 0.000 0.0 0.00 0.00 00.000 + A 02000 N mean: 0.00 0.000 0.00 00.000 0.0 0.00 0.00 0000.000 + A 02000 0.0 0.000 0.00 00000.000 0.0 0.00 0.00 00.000 00002000 0.0 0.00 0.00 0000.000 0.0 0.00 0.00 0 00.000 0000000 00000000 00000000 00000000 00000000 00000 00000 00000 00000 00000 00000 00000 00000 mo .oz 00 .02 mo .02 mo .02 mm 00 mm 00 000000000 00 0000000 0 0000000 mB¢Q me>m¢m .mo0 00 00003 0 mm 00300000 Ammmv mwmno00 <0 mo 000coe m 00000 000900 .cmnmeOh. wo wGHGzomn mace 000 Ammv 00000 zzopn no 000000 0o000swmp apzonw 000 00000050 mo pommmmuu.0 m0m¢9 “7 harvest was delayed 1 week but was not significantly dif— ferent from the Ca(NO + CSG treatment. The relationship 3’2 between the MgSOu, TIBA and Ca(NO3)2 treatments was similar to the first harvest. Brown heart did not vary significantly among treat- ments but a greater occurrence was observed in fruit from the MgSOu treatment (Table 6). A delayed harvest of 1 week accentuated the disorder incidence irrespective of disorder, treatment or type of storage (Table 7). Simple Linear Correlations: Fruit showing water core symptoms had a positive correlation with leaf Mn and Al and a negative correlation with leaf K and fruit N, K and Cu at each harvest date (Tables 8 and 10). Also, water core determined on October 5 harvest date was negatively correlated with leaf Cu and on October 12 was negatively correlated with fruit Ca and Mn. Fruit affected with lenticel spot were positively correlated with both leaf and fruit K, leaf Fe and fruit N, Cu, Zn, K/Ca, Mg/Ca and (K + Mg)/Ca and negatively cor- related with leaf Mn, Al and fruit Fe (Tables 8 and 10). No significant correlations occurred between fruit affected with internal breakdown and leaf nutrient elements. However, internal breakdown incidence showed a negative relationship with fruit Ca and a positive relationship with fruit K/Ca, Mg/Ca and (K + Mg)/Ca ratios at each har- vest and with both storage operations (Tables 10 and 11). 48 TABLE 7.-—Effect of delayed harvest on disorder incidence irrespective of treatments from both CA and cold storage. CA Storage Cold Storage Disorder Harvest Date Harvest Date Oct. 5 Oct. 12 Oct. 5 Oct. 12 IBI 137.95 149.4* 156.9 189.u** IB N0.l 16.45 19.u 23.7 3o.u** w012 uu.8 u7.3** wc N0. u.u 7.2** CBI 1N2.3 159.0* BHI 81.8 §9.8** * Significant at the 5% level. 0* Significant at the 1% level. 1Total of breakdown index categories 3, U and 5. A defi- nite browning was observed in each category. 2Evaluated at harvest. “9 TABLE 8.--Significant correlation coefficients showing the association between leaf analysis and various physiological disorders of 'Jonathan' apples measured before or after cold storage (36F). Oct. 5 Harvest Oct. 12 Harvest Element WCl Index % LS W01 Index N K _ 527** .715** —.U88** P Ca Mg Mn .655** -.763** -633** Fe '329* Cu --366* B Zn A1 .631** -.72H** .626** * Significant at the 5% level. * * Significant at the 1% level. lWater core evaluated at harvest. 50 TABLE 9.-—Significant correlation coefficients between leaf analysis and various disorders of 'Jonathan' apples after 5 months of CA storage (32F) followed by 2 weeks at 70F. Oct. 5 Harvest Oct. 12 Harvest Element Disorder Index Brown Core Brown Core Heart Browning Heart Browning N K -.“”3** -.597** -.557** P Ca Mg Mn .HO2** .55h** .5H6**' Fe Cu -.3u0* B Zn A1 .393* .502** -“93** * Significant at the 5% level. ** Significant at the 1% level. 51 TABLE lO.—-Significant correlation coefficients showing the associations between fruit analysis and of 'Jonathan' apples after 3 months of cold storage (36F). various disorders October 5 Harvest October 12 Harvest Disorder Index Element Internal Water1 Lenticel Internal Water Breakdown Core Spot Breakdown Core N —.513** .578** -.363* K —.H9l** .589** —.383* P Ca -.52l** -.513** -.360* Mg A Mn —.u15** Fe —.321* Cu -.U83** .32u* —.375* B Zn .312* Al K/Ca .5u9** .366“ .3H8* Mg/Ca .u78** .362* .371* (K+Mg)/Ca .553** .357* -35“* * . Significant at the 5% level. ** Significant at the 1% level. lEvaluated at harvest. 52 .Hm>mH RH map pm pamOHchmHm ** .Hm>ma Rm ms» at undeficficwfim* **mmz. **Hm:. m0\AmS+MV **mzm. **mmz. w0\wz **maz. **::z. w0\m H< EN m *mmm.l do *Nmz. . **:Hm. mm CS w: **mm:.l **nmm.l **Hom.l mu m **NHm.I **mam.l **HN:.I M *mmm.l z mcficzomm pmmmm szooxmonm wcHCSOAm pmmom czocxwmmm whoo czopm chmmwmwcH moomommmoo cachm HammopCH pCoEmHm pmm>pmm NH monouoo pmo>pmm m monouoo .mou pm mxoms m mp omonHom Ammmv mwwLOpm <0 mo mspcoe m mound moamom .smzpmnoh. no whoopomfiv mSOHpm> cam mfimzawcm paupm somzpwn soapmfioommm map mcfizonm mpqmfiOHmuooo COHumHmppoo pGMOHchmeII.HH mqm<9 53 The brown heart index calculated for fruit from the October 5 harvest was negatively correlated with both leaf and fruit K and positively correlated with leaf Mn, Al and fruit Fe (Tables 9 and 11). On the October 12 harvest date, brown heart incidence was positively correlated with leaf and fruit K and fruit N. Fruit exhibiting core browning symptoms from the October 5 harvest showed a negative correlation with leaf and fruit Cu and fruit Ca (Tables 9 and 11). A l—week delay in harvest resulted in core browning being negatively correlated with leaf and fruit K and positively correlated with leaf Mn and Al. Internal breakdown incidence, when determined after 3 months of cold storage, showed a positive relationship with water core, titratable acidity and fruit weight regardless of harvest date (Table 12). There was a higher positive correlation between internal breakdown and water core with delayed harvest. Water core incidence was negatively correlated with lenticel spot and positively correlated with firmness at both harvest dates. Additional positive correlations with water core after a delayed harvest were obtained with titratable acidity and fruit weight (Table 12). Titratable acidity showed a positive relationship with fruit weight, firmness, and fruit K and a negative relationship with fruit Ca (Tables 12 and 13). 54 .Hm>ma RH who pm pcmoacficwfim ** .Hm>mH am map at pcmOHchme .3 .pmo>aw£ NH hmoopoo spa: oopmfioommm coflumsam>m .pmo>pmn m hobouoo npwz ompmwoommm GOHQMSHm>m m H .mmocapfim u .Ehflm .pnwfimz uflspm u 3m .mpaofiom manwpmspfle u <9 .poam HmOHpcoq n ma .mnoo mmpmz n 03 nczooxmmhn anchopCH n mH *NHM. **0Hm.l **Nm:. **Nm:. *mam. .Ehfim **mo:. *mmm. *mam. **wm:. 3m *mdm. **mo:. *Nmm. *xwwz. *xmmm. <9 **Hfim.l **m:m.l *xmmm.l mg a **>m:. *mmm. *mmm. **m:m.l **mmw. *mmaw. **m::. NH .pmm **mm:. **mmm.l **mmw. *xmmm. *me. m .pwm *mam. *mam. **w>:. *mmam. **mmm. **mw>. NH .pmm **mm:. **mmm. **m::. *Ham. **mmg. m .pmm .Ehfim 3m ¢B mg R N03 H03 NmH HmH hopowm .mpcmHOHmmooo soapmaompoo mo soapmasoamo :a com: who: mmoHUQH sophomflm .mwmQOpm oaoo nmpwm so pmo>mm£ pm oopzmmme mAOpowm macamm> cmozpmn COflpmHoommm map wcflzosm mpCoHOfimmooo coapwaopmoo pcwowmflcwfimln.ma mqmpm£ NH LmDOpoo QuHB UopmHOOmmm COHpmsz>mN .pmo>pm£ m LoQOpoo csz UmuMHoommm COHpmsz>mH .HmeeH RH men he unwefieecmfimee .HeeeH em esp pm hemoececmem* .pmmmc szoam mm “@900 hopwz n 03 eczooxmoho HmCLopQH n mH .wnHQBohn 0900 u mo **MNw. **Nwm. **mmm. *mzm. Nmm **mNm. **om:. *xmmm. **sz. Hmm *kwum. **om:. *mew. **mm:. *Nwm. **mwm. **mmm. N03 **mmm. **mmm. **me. *ozm. **mmm. *xzmn. H03 *zzm. **mm:. *qu. **m:>. *xazz. *mem. NmH *Nwm. **m:>. *sz. **owm. HmH *mzm. **sz. **m>m. *xmmm. **:::. *Nnm. **m:m. Nmo **o~:. **mmm. *zmz. **mHm. **omm. **m:n. Hmo Nmm Hmm N03 H03 NmH HmH NmO Hmo .Amva mwmpoum <0 CH mnucoE m popmw omcHwam pH5pm Scam nymphoch comzpmn QHnmsoHpmHmp on» wcHzocm mucmHOHmmmoo coHpmHmppoo meOHMchHmII.:H mamHE 58 cations. This suggests that Ca is the major cation to be considered in a nutritional relationship with respect to IB. Further evidence for this relationship was shown with IB being negatively correlated with fruit Ca and positively correlated with K/Ca, Mg/Ca and (K + Mg)/Ca fruit ratios. These relationships suggest that an increase in fruit Ca or a decrease in fruit K or Mg would reduce internal break- down. These relationships and analysis substantiate’ research of others with respect to analysis of fruit affected with IE (19,23,2U,26,28,30). It has been generally accepted that high levels of K in leaves or fruit would result in a reduced incidence of breakdown in affected fruits. This concept has been sup- ported by soil applications (19,22) and survey data (5,30). However, there have been occasions when increased fruit K was associated with an increase in fruit breakdown (28,“1). By virtue of simple correlations these experiments imply that K may be a possible cause or additional factor in relation to IB. Correlations with titratable acidity were most interesting in this respect. Normally, increased fruit K results in increased acid formation (3M) and both were positively related in these experiments. Also, in- creased acidity was associated with increased incidence of IB. Conversely, Ca showed the reciprocal relationship to both acid and IB. In previous years titratable acidity of apple fruit has been associated with IE incidence (12,15, 59 18). Haynes (12) reported that there was a direct associ- ation between high titratable acidity and IB of 'Spalding Barmley's' apple fruit. Other physiological disorders related to Ca shortages such as tipburn of lettuce and blossom end rot of tomatoes have been related to organic acid excess with Ca acting as a postulated neutralizing or complexing agent (9,32). The role of Ca in reducing IB is not clear but may be involved in organic anion metabolism similar to the above mentioned disorders. Specific acids may be involved in abnormal metabolic functioning when IB occurs. Hulme et_a1. (13) reported that in air stored apples of 'Cox's Orange Pippin' there was a continuous rise in the oxaloacetic acid content and a rapid onset of low temperature breakdown as the acid reached its maximum level. When the fruit were warmed prior to storage both oxaloacetic acid and low temperature breakdown were reduced. This warming treatment has been reported to reduce IB in 'Bramley's Seedling' (31). Con- versely, Wills and McGlasson (37) found no relationship with development of IE of 'Jonathan' fruit to oxaloacetic acid metabolism. Later work by Wills et a1. (38) showed that high levels of acetic acid in 'Jonathan' fruit were associated with IE incidence. Injections of acetic acid into the fruit increased IB. In 1971 Wills and McGlasson (39) were able to reduce IB of 'Jonathan' fruit by warming 6O them to 15C for 5 days. There was also a reduction in acetic acid with warming. Clijsters (6) concluded that maleic acid was de— carboxylated to acetaldehyde in apple flesh exhibiting breakdown symptoms. When maleic acid was added to fruit tissue acetaldehyde levels increased. Acetaldehyde in- jections into the fruit produced IB. Acetaldehyde has been shown to be very toxic to apple tissue (21). Since maleic acid is the predominant acid measured when titratable acidity is determined, increases in titratable acidity may result in increased acetaldehyde levels in fruits causing IB occurrence. Also, this may indicate that high K content of the fruit may be an additional cause of IE since K is directly associated with titratable acidity (3“). Multiple correlations using a least squares delete procedure, with IB as the dependent variable resulted in titratable acidity and Ca being the most important factors contributing to IE incidence (Table 15) and were negatively correlated with each other. Further delineation by use of multiple correlations with titratable acidity as the de- ‘ pendent variable suggest that a decrease in acidity could be manifested by maintaining proper Ca levels in the fruit (Table 15). The exact amounts of Ca needed in a fruit to prevent excess acidity is not known but flesh Ca content of 5 mg/lOO gm fresh weight will supposedly prevent breakdown 61 .Hm>eH RH whh he hthHhthHm ** .He>eH am the he hhwoehflhwem * :w.l m:.mNI mo pHShm speeeeh we as. aw. em.HH hhwhnhoo ethhmthe mm. mH.m whoo pmpmz 03.: mm.mm:N| mo pHsnm csooxwopm * 5:. mm. . Hm.OHH pcmpmcoo Hampoch pmo>mmm NH ponchoo mpHoHo< mz. om.HN oHnprMpHB H:.I Nm.mMNN| mo pHSpm czooxwopm * Hz. no. m:.HOH unnumcoo Hospoch .mmmoo mam p p coHpmHopmoo wucmHonmmoo mmHanpm> oHQmem> . N HmHupmm COHmmmpwmm unoccodmocH pSoUCoamm pmm>pmm m nonopoo .moHQMHhm> pcmvcmawfi mm mpHUHom manmpmmpwp flaw czooxmmhn HMCLOPQH SPHB mpCOHOHhmwoo Coammmhwmk USN Coapmfimhh o Q . o eh hhhs z-.. 62 in'Cox's Orange Pippin' (18). In the experiments reported hmmin only 1 tree out of #0 had a fruit Ca content below .mfl or 500 ppm. However, both peel and flesh were ana— lmwd for each sample which would tend to result in a humer Ca content compared to flesh analysis alone. One of the most important factors to be considered IWEn discussing IB is fruit weight or size. Large sized fmflt tend to result in an increased fruit susceptibility ‘MJphysiological disorders (1U,l8,l9,27,30). Increases in fruit size may be accompanied by increased K, Mg and titratable acidity (l8,l9,27,30) but may not have the ef- fect of increased Ca. In fact, increase in fruit size would have a tendency to reduce Ca concentration; thereby reducing the apparent beneficial Ca effect in reducing This relationship was shown by the negative disorders. If the correlation of fruit weight and Ca (Table 13). assumptions with titratable acidity are valid and the ef- fect of fruit size on K and Ca is justified, it would seem 'that a.balance of K and Ca would be desirable to maintain a.rders. This concept has been thoroughly examined for Lnternal breakdown with water core (l6,17,28,30) and almost ilways water core was related to internal breakdown inci- lence. Factors which contribute to water core development are 1aturity, temperature, sorbitol and orchard practices. [ore mature fruit is likely to have more severe water core. This was true in these experiments (Table 7). If a delay ;n harvest results in increased water core, a concomitant anrease in IE should occur. This happened in these ex- >eriments as denoted by an increase in correlation coeffi— :ients when harvest was delayed 1 week. Fruit exposed to aunlight and high temperatures have been found to develop rater core quickly and intensely (H). Sorbitol is one of :he major translocatable carbohydrates in apple leaves and 1as been associated with water core development (40). Iilliams (40) reported that water cored tissue of 'Delicious' Lpples was higher in sorbitol than adject non-water cored :issue. Also, as sorbitol decreased in leaves it increased .n the fruit. Smagula gt 1;. (29) reported that apple tissue showing rater core conditions was higher in acetaldehyde, ethanol Lnd ethylacetate than adjacent non-water cored tissues and >ersisted in the fruit if water core disappeared. 65 SMmequently browning occurred following water core. TMNe results are consistent with Clijsters (6) who found Umt acetaldehyde accumulation in 'Jonathan' fruit re- smted in IE symptoms. Also, multiple correlations showed thm;water core became a significant factor in IE develop— mmm when harvest was delayed (Table 15). Ca sprays have bemureported to reduce water core (3). This would sup— port the negative correlation between water core and Ca reported herein. It would seem that conditions conducive for high photosynthesis activity may be an important factor in WC development and subsequent IB incidence. This suggests that nutritional factors may be secondary to environmental stress factors in regard to the occurrence of physiological disorders. Environmental stress factors that tend to increase respiration, in the balance of photo- synthesis—respiration, would tend to increase titratable acidity and thereby increase the incidence of disorders. Control of these stress factors may prove to be as criti— cal as control of nutritional conditions. The correlations obtained with leaf analysis were ccnisidered to be of little importance since the fruit was true plant part exhibiting symptoms. However, leaf N srnyuld be used in assessing tree vigor. Correlations be- tvweeri leaf and fruit analysis resulted in only 2 correla- txioris being significant (Mn, r = -.56, K, r = +.82). In general there was a lower incidence of IE in fruit ffironi CA storage than from cold storage and SADH had a 66 ubstantial effect in reducing .IB. This may be attributed o a lower respiration rate and a delay in the natural enescence of the fruit. In conclusion, it appears that to establish a cause— ffect relationship for future control of IE is difficult. ruit nutrient composition, fruit size, fruit maturity, 'ater core incidence and environmental conditions play an mportant part in causes of IB. Most of these factors are .nterrelated, with fruit size being an important feature. increases in fruit size affect the nutrient balance in the 'ruit and are conducive to water core development. Exces— iive tree vigor caused by thinning, light crops, heavy >runing or excessive N applications contribute substan— ;ially to IB. Improved storage performance may, therefore, >e obtained by suitable adjustment of cultural practices ind use of supplementary Ca sprays. LITERATURE CITED Albrigo, L. G. and N. F. Childers. 1970. Effect of Succinamic Acid, 2—2-Dimethyl Hydrazide and late— season night temperature on the maturity indices of 'Stayman' apples. J. Amer. Soc. Hort. Sci. 95(U):M82—48H. Bernstein, Paul and Roy E. Marshall. 1942. A study of internal breakdown on Northern Spy apples in storage. Mich. Agr. Expt. Sta. Quar. Bul. 25: 156—162. Beyers, E. 1963. Control of bitter pit and other dis— orders of apples with calcium sprays. The Decid. Fruit Grower. 13:319—335. Brooks, C. and D. F. Fisher. 1926. Water core of apples. J. Agric. Res. 32:223—260. Bunemann, D. H. Dewey and A. L. Kenworthy. 1959. The storage quality of Jonathan apples in relation to the nutrient levels of the leaves and fruits. gich. Agri. Expt. Sta. Quart. Bull. Ul(4):820— 33. Clijsters, H. 1965. Maleic Acid metabolism and initiation of the internal breakdown in Jonathan apples. Physiol. Plant. 18:85—93. Dewey, D. H. and D. R. Dilley. 1968. Jonathan apple quality and storage life. Extension Bull. 627. Michigan State Univ. Draper, N. R. and H. Smith. 1966. "Applied Regression Analysis". John Wiley & Sons, Inc., New York— London-Sydney. Evans, H. J. and R. V. Troxler. 1953. Relation of calcium nutrition to the incidence of Blossom—End Rot in tomatoes. Proc. Amer. Soc. Hort. Sci. 61: 3A6-352. 67 10. ll. 12. 13. 1“. 15. l6. 17. 18. 19. 20. 68 Fukuda, H. 1968.‘ Control of internal breakdown of Jonathan with calcium sprays. Kajutsu-Nihon. 23:50-52. Kenworthy, A. L. 1960. Photoelectric spectrometer analysis of plant materials. Proc. 36 Ann. Meet- ing Council Fert. Appl. pp. 39-50. Haynes, D. 1925. Chemical studies in the physiology of apples. I. Change in the acid content of stored apples and its physiological significance. Ann. Bot. 39:77-96. Hulme, A. C., W. H. Smith and L. S. C. Wooltorton. 1964. Biochemical changes associated with the development of low-temperature breakdown in apples. J. Sci. Fd. Agric. 15:303-307. Letham, D. S. 1961. Influence of fertilizer treat— ment on apple fruit composition and physiology. Aust. J. Agr. Res. 12:600-611. Letham, D. S. 1969. Influence of fertilizer treat- ment on apple fruit composition and physiology. II. Influence on respiration rate and contents of nitrogen, phosphorus, and titratable acidity. Aust. J. Agric. Res. 20: 1073- 1085. Lord, W. J. and F. W. Southwick. 196“. The suscepti— bility of two Delicious strains to some pre- and post-harvest physiological disorders. Proc. Amer. Soc. Hort. Sci. 8flz65-7l. Lord, William J. and R. A. Damon, Jr. 1966. (Internal breakdown development in water-cored Delicious apples during storage. Proc. Amer. Soc. Hort. Sci. 88:94—97. Martin, K. 1954. Variation between apple fruits and its relation to keeping quality. II. Between—tree variations due to cropping factors. Aust. J. Agric. Res. 5:9-30. Martin, D., T. L. Lewis, J. Cerny, and A. Grassia. . 1970. Effect of high levels of nitrogen on mineral content and disorder incidence in Jonathan apples in pot culture. CSIRO Division of Plant Industry Technical Paper No. 29. Montgomery, H. B. S. and B. G. Wilkinson. 1962. Stor— age experiments with Cox's Orange Pippin apples from a manurial trail. J. Hort. Sci. 37. 150— 158. 21. 22. 23. 2A. 25. 26. 27. 28. 29. 30. 31. 32. 69 Neal, G. E. and A. C. Hulme. 1958. The organic acid metabolism of Bramley's Seedling apple peel. “i; Exp. Bot. 92142-157. Overley, F. L. and E. L. Overholser. 1931. Some effects of fertilizer upon storage response of Jonathan apples. Proc. Amer. Soc. Hort. Sci. 28: 572-577. Perring, M. A. 1968. Mineral composition of apples. VIII. Further investigations into the relationship between composition and disorders of the fruit. J; Sci. Fd. Agric. 19:6H0—6H5. . 1968. Mineral composition of apples. VII. The relationship between fruit composition and some storage disorders. J. Sci. Fd. Agric. 19:186—192. and B. G. Wilkinson. 1965. The mineral composition of apples. IV. The radial distribu— tion of chemical constituents in apples, and its significance in sampling for analysis. J. Sci. Fd. Agric. 16:535-5H1. Sharples. 1968. The structure and composition of apples in relation to storage quality. Rep. E. Malling Res. Stn. for 1967 (1968). . 196“. The effects of fruit thinning on the development of Cox's Orange Pippin apples in rela— tion to the incidence of storage disorders. J; Hort. Sci. 39:22u—235. 1967. A note on the occurrence of water core breakdown in apples during 1966. P1. Path. 16:119—120. Smagula, J. M., W. J. Bramlage, R. A. Southwick and H. V. Marsh, Jr. 1968. Effects of water core on respiration and mitochondrial activity in 'Richared Delicious' apples. Proc. Amer. Soc. Hort. Sci. 93:753-761. Stebbins, R. L. 1970. Orchard factors affecting the internal breakdown disorder of Jonathan apples. Ph.D. Thesis, Michigan State Univ. East Lansing, Mich. Smith, W. H. 1958. Nature, Lond. 181:275. Thibodeau, P. O. and P. L. Minatti. 1969. The influ— ence of calcium on the development of lettuce tipburn. J. Amer. Soc. Hort. Sci. 9U(u):372—376. 33. 3A. 35- 36. 37. 38. 39. A0. Al. 70 Tiller, L. W., H. S. Roberts and E. G. Ballard. 1959. The Appleby Experiments. N. Z. Dept. Sci. and Ind. Res. Bul. 129 Wilkinson, B. G. 1958. The effect of orchard factors on the chemical composition of apples. II. The relationship between potassium and titratable acidity and between potassium and magnesium, in the fruit. J. Hort. Sci. 33:“9-57. . 1965. The effect of orchard factors on the storage behaviour of Cox's Orange Pippin apples. Rep. Ditton and Covent Garden Laboratories for 1964-65. . 1968. Mineral composition of apples. IX. Uptake of calcium by the fruit. J. Sci. Fd. Agric. 19:6A6-6A7. Wills, R. B. H. and W. B. McGlasson. 1968. Changes in the organic acids of Jonathan apples during cool storage in relation to the development of breakdown. K. J. Scott and W. B. McGlasson. 1970. A role for acetate in the development of low—tem— perature breakdown in apples. J. Sci. Fd. Agric. 21:u2—uu. and W. B. McGlasson. 1971. Effect of storage temperature on apple volatiles associated with low temperature breakdown. J. Hort. Sci. 46:115—120. Williams, Max W. 1966. Relationship of sugars and sorbitol to water core in apples. Proc. Amer. Soc. Hort. Sci. 88:67—75. Woodbridge, C. G. 1970. Is there an answer to bitter pit? Proc. Sixty—Sixth Annual Meet. Wash. State Hort. Assn. 71 OOO OH OO O OO OOH Om. OO.H OO. OO. 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