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Zuni. ,.-.‘..;.1...r s... :. ‘eaeéflqfinfiflfimfihflkfi egg; . , ‘ alley. ‘ A. 773.1. .. .nuanr if. .THESR This is to certify that the thesis entitled ENVIRONMENTAL STUDIES ON MATURATION OF THE MCINTOSH APPLE presented by Adnan M. Badran has been accepted towards fulfillment of the requirements for Ph D degree in HOIthUltUI‘e ,. / 7 1' , flex-ac: L’/\ Zia a}; Major professor 7" Date October 31, 1963 0—169 LIBRARY Michigan Sm: University ENVIRONMENTAL STUDIES ON MATURATION OF THE MCINTOSH APPLE BY Adnan M. Badran AN ABSTRACT Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Horticulture 1963 ABSTRACT ENVIRONMENTAL STUDIES ON MATURATION OF THE McINTOSH APPLE by Adnan M. Badran The influence of the post bloom environment on the maturation period of McIntosh apples was investigated. The environmental factors experimentally varied were night temperature, light intensity and day length. Natural envir- onmental variations were obtained by selecting orchards with a wide range of microclimates over a three year period, Observations of growth, cell division, starch accumulation, physiological maturity and storage quality of fruits from trees on seedling and East Malling rootstocks were obtained. High night temperatures during the first month follow- ing bloom increased the rate of vegetative and fruit growth and hastened maturity. Low light intensity enhanced vegeta- tive growth, suppressed fruit growth and delayed maturity, High night temperatures overcame the suppressing effect of low light intensity on fruit growth. Day lengths three hours shorter or longer than tte ambient had no marked effect on fruit growth, Trees which received low light intensities or a short day underwent a secondary flush of terminal growth, Net accumulation of starch was observed in fruits about one month after full bloom and occurred within two Adnan M. Badran - 2 days of the time it was first detected, Temperatures follow- ing bloom did not markedly affect the interval from full bloom to starch accumulation whereas low light intensity lengthened the interval by about one week, The onset of starch accumulation coincided with the cessation of cell division, cessation of shoot and leaf growth and the June drop of fruits in 1°62, while in l063, shoot and leaf gronth continued after starch accumulation commenced, The onset of starch accumulation appears to he the turning point in the growing season when photosynthetic capacity exceeds growth requirements. No relationships were discernible between the post bloom environments and the interval from full lloom to starch acoumulation, The length of this interval bore no relationship to the length ot the interval from full bIOOm to physiological maturity, The premise that starch accumu- lation may serve as a physiological parameter of the influence of the early growing season environment on fruit maturity was therebv invalidated, The interval from full bloom to maturity was shortened in proportion to heat unit accumulation during the first two weeks following bloom, High night as well as high day temp- eratures were effective in advancing maturity, However, high night temperatures during the third and fourth weeks follow- ing bloom had a delaying effect on maturity, Predicting fruit maturity by heat unit summation Adnan M. Badran - 3 methods developing in other apple production areas was not satisfactory for environmental conditions experienced in Michigan in 1961, 1962 or 1963, The interval from full bloom to maturity was inversely proportional to the date of full bloom. This may be related to generally warmer post bloom temperatures which prevail in areas of late bloom. The rate of change in red coloration, ground color, flesh firmness or soluble solids over a three week harvesting period was of little value in determining the proper harvest date for storage. The values of these characteristics varied considerably for fruits of the same physiological maturity from different locations in a single season, Fruits from the harvests closest to the preclimacteric respiratory minimum rated highest in quality following five months storage in air or eight months storage in controlled atmospheres, No relationship was observed between maturity at harvest and the incidence of scald on fruits from CA storage or on fruits from various locations after air stor- age. However, immature fruits from trees grown on a number of East malling rootstocks at the same location generally scalded more severely after air storage than the more mature fruits, Flesh and core browning was not related to maturity of the fruit at harvest, ENVIRONMENTAL STUDIES ON MATURATION OF THE MCINTOSH APPLE BY Adnan M. Badran A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Horticulture 1963 ACKNOWLEDGEMENTS The author wishes to express his sincere appreciation and gratitude to Dr. D, R, Dilley for his assistance in outlining this problem and for his constant guidance and encouragement throughout the duration of the study, Appreciation is also expressed to Dr. D, H, Dewey for his personal assistance in the research work and for his suggestions in editing the manuscript, to Drs, P. Markakis, A. L. Kenworthy, and M, J, Bukovac for reviewing the manu- script. Acknowledgement is made to Mr. D, macLean and Mr, D. Olson for their help in collecting the data; to the Michigan apple growers for providing the McIntosh apples for the study; and to Miss Janet Gassman for typing the manuscript, TABLE OF CONTENTS Page INTRODUCTION . . . . . . . . . . . . . . . . . . . 1 REVIEW OF LITERATURE . , , , , , , , , . , , . . . 3 Introduction . . . . . . . . . . . . . . . . . 3 I, Growth, Maturation and Ripening , , . , . , 3 A. Physical changes . . . . .i. . . . . . 3 B, Chemical changes . . . . . . . . . . . 6 C, Physiological changes . . . . . . . , . 11 D, Environmental modification . . , , . , l3 1], Maturity lndices . . . . . . . . , . . . , 14 A. PthiCal . . . . . . . . . . . . . . . 14 B. Chemical . . . . . . . . . . . . . . . 17 C. Physiological . . . . . . . . . . . . . 20 D, Environmental . . . . . . . . . . . . . 21 nATERIALs AND METHODS . . . . . . . . . . . . . . 25 I, modified Temperature Environmental Study, 1901 . . . . . . . . . . . . . . . . . 25 11, modified Environmental Study, 1962 , , , , 29 111, Natural Environment Study, 1962 , , , , , 31 1V, Post—Storage Quality Evaluation . , , . , . 34 RESULTS . . . . . . . . . . . . . . . . . . . . . 35 1, Modified Environmental Study, 1961 , , , , 35 A, The environment , . , , , , , , , , , , 35 B, Vegetative growth , , , , . , , , , , , 35 C. Fruit growth . . . . . . . . . . . . . 39 iii ‘ II, III. IV, D. E. Modified Environmental Study, A. B. C. I). 5. TABLE OF CONTENTS CONT'D Starch accumulation . . . . Fruit maturity . . . . . . The environment . . . . . . Vegetative growth , , . , , Fruit growth . . . . . . . O 9 Starch accumulation and cell division Fruit maturity . . . . . . Natural Environment Study. 1°62 A. B. O The environment , . . . . . Starch accumulation . . . . Fruit maturity , , . . . . 1, Physical characteristics 2, Respiratory climacteric 3 Storage quality . . . . EM Rootstock Study, 1002 . . . A, B. C. The environment . . = . . . Starch accumulation , . . , Fruit maturity . . . . . . 1, Physical characteristics 2, Respiratory climacteric 3, Storage quality . . . . Predicting MClntosh maturity iv Page 39 43 43 43 45 49 49 a4 68 77 ‘ 77 77 81 81 Cl) H 86 Q3 TABLE OF CONTENTS CONT'D Page DISCUSSION................... 99 SUMMARY..........,......... 106 LITERATURE CITED . . . . . . . . . . . . , , . . 109 APPENDIX O I C O O O O O C I C O O O O O O O O O 119 TA BLE J \l LIST OF TABLES Page Characteristics of natural environment loca- tions in 1962 I O O O O I O Q 0 C O O C O D 31 Average weekly temperature ('F) regimes obtained for five weeks following petal fall in 1961 at the M,S,U, Horticulture Farm, East LanS-ing - o o o o o o o o e o o o o o o o o 36 Summation of maturity characteristics for McIntosh under modified environmental treat- ments. 1°61 . . . . . . . . . . . . . . . . 41 C‘ . - Average temperature ( F) regimes obtained for five weeks following petal {all in 1962 at the M,S,F, Horticulture Firm, East Lansing, id Infinence ot modified env"‘umentq on the “alqrrtxon of Mclntosh at *:«t Raising in I)": s o c o o o o o o e a o o o o o e o o 50 The relationship between the date of the cessation of cell divi51on in fruits, cessa- tion of shoot elongation, June drop and starch accumuhnicn in fruits ot mcrntosh from trees subjected to modified environments at East Lansing in 1962 , , , , , , , , , , , 51 Relationship between post-bloom temperatures and the elapsed interval from full bloom to starch accumulation and the preclimacteric minimum for mclntosh fruits from ten locations in 1002 a o o e e o o o o o v e o o o o o o 54 Relationship between post-bloom temperatures and the elapsed interval from full bloom to starch accumulation and the preclimacterir mininuw for McIntosh fruits from ten locations in 1062 o o o o o o o c o o o o o e o o o o 55 w Relationship between post-bloom temperatures and the elapsed interval from full bloom to starch acoumulation and the precliwacteric minimum tor Mclntosh fruits grown at three locations for the 1961, 1962, and 1963 seasons 55 14 1b 18 LIST OF TABLES CONT‘D Relationship between post-bloom temperatures and the elapsed interval from full bloom to starch accumulation and the preclimacteric minimum for McIntosh fruits grown at three locations for the 1961, 1962 and 1963 seasons Hourly and daily changes in starch content in McIntosh apples during initial stage of accumulation in 1962 , , , , , , , , , , , , The relationship between the date of full bloom, starch accumulation and harvest of several apple varieties at East Lansing in 1062000000000¢0000000000 Physical characteristics of mclntosh fruits from ten locations at the onset of the respiratory climacteric . , , , . , , , O O llhaluation of red coloration (fl) of Mclntosh fruits from seven harvests at ten locations it} 1962 I C C 0 O O O O C C . . C O O . O . ”nirud‘uvl post-storage e ilnati l of ground role: “atlng ot mclntosh ":itm from seven harvests 1t ten locations '1 196?. The fruits were stored in air for fi A m-2ths or CA «tar;~v tlr eight months . . . . , Harvest and post-storage evaluation of flesh firmness (lts,) of mclntosh fruits from seven harvests at ten locations in 1962, The fruits were stored in air for five months or CA storage for eight months . . . . . , . . , , Harvest and postnstorage evaluation of solu- solids (%) of McIntosh fruits from seven harvests at ten locations in 1962, The fruits were stored in air for five months or CA storage for eight months . , . . , , , , , , Appearance rating of post-storage Mclntosh fruits from seven harvests at ten locations in 1962. The fruits were stored in air for five months or CA storage for eight months 66 DO 70 LIST OF TABLES CONT'D TABLE Page 1° Eating quality rating of post-storage Mc- Intosh fruits from seven harvests at ten locations in 1962. The fruits were stored in air for five months or CA storage for eight months 0 Q 0 O D O O O O O C O O O O 74 20 Summation of maturity characteristics for Mclntosh from ten locations in 1962 , . , 75 21 Post-storage evaluation of scald (%) on MC~ 1ntosh fruits from seven harvests at ten locations in 1962, The fruits were stored in air for five months or CA storage for eight months . . . . . . . . . . . . . . . 7o 22 Post-storage evaluation of core browning (%) of McIntosh fruits from seven harvests at ten locations in 1962, The fruits were stored in air for five months or CA storage for eight months , , . . , . , . . , . . . 78 23 Post-storage evaluation of flesh browning %) of MCJntosh fruits from seven harvests at ten locations in 1962, The fruits were stored in air for five months or CA storage for eight months , _ . . . , . . . . . . . 7O 74 Summation of maturity characteristics for MCIntosh grown on East Malling rootstocks in 1962 . O O O O O O O O C O 0 O O O I O 80 25 Physical characteristics of mclntosh fruits grown on seven East Malling rootstocks at the onset of the respiratory climacteric , 82 20 Evaluation of red coloration (fl) of McIntosh fruits from seven harvests from trees 0n seven EM rootstocks in 1962, The fruits were stored in air for five months or CA storage for eight months . , , , , , , , , 54 27 Harvest and post-storage evaluation of ground color rating of McIntosh fruits from seven harvests from trees on seven EM rootstocks in 1962, The fruits were stored in air for five months or CA storage for eight months 8? viii TABLE 28 29 'vJ .4 32 33 LIST OF TABLES CONT'D Harvest and post~storage evaluation of flesh firmness (lbs.) of McIntosh fruits from seven harvests from trees on seven EM root- stocks in 1962. The fruits were stored in air for five months or CA storage for eight months . . . . . . . . . . . . . . . . . . . Harvest and post-storage evaluation of solu- ble solids (%) of McIntosh fruits from seven harvests from trees on seven EM rootstocks in 1962, The fruits were stored in air for five months or CA storage for eight months . Appearance rating of post-storage McIntosh fruits from seven harvests from trees on seven EM rootstocks in 1962, The fruits were stored in air for five months or CA storage for eight months , . , , , , , , , . Eating quality rating of post-storage MC— Intosh fruits from seven harvests from trees on seven EM rootstocks in 1962, The fruits were stored in air for five months or CA storage for eight months . . , . , , , , , , Post-storage evaluation of scald (%) on McIntosh fruits from seven harvests from trees on seven an rootstocks in 1062, The fruits were stored in air for five months or CA storage for eight months . . . , , , , Post-storage evaluation of core browning (%) of mclntosh fruits from seven harvests from trees on seven EM rootstocks in 1062, The fruits were stored in air for five months or CA storage for eight months . . , , , , , , Post-storage evaluation ot flesh browning (%) of mclntosh fruits from seven harvests from trees on seven EM rootstocks in 1062, The fruits were stored in air for five months or CA storage for eight months . . , , ix Page 89 90 91 94 95 06 Figure 1 LIST OF FIGURES Technique employed to obtain night temp- erature control , , , , , , , , , , , , Photomicrographs of apple starch granules at the initial stage of accumulation , . The influence of night temperatures on Mclntosh shoot elongation at East Lansing in 1961 O O O O O 0 O O O O O O D O O C I Influence of night temperature on Mclntosh leaf growth at East Lansing in 1961 . , , influence of night temperature on McIntosh fruit growth at East Lansing in 1°61 , , Respiratory climacteric of Mclntosh fruits from modified temperature treatments at East Lansing in 1061 , , , , , , , , lnfluence of night temperatures, light intensity and day length on McIntosh shoot elongation at East Lansing in 1962 , influence of night temperature, light in- tensity and day length on Mclntosh leaf growth at East Lansing in 1962 , , , , , inlluence of night temperature, light in- ten31ty and day length on mclntosh fruit growth at East Lansing in 1962 , Respiratory climacteric of mclntosh fruits from modified environmental treatments at East Lansing in 1962 . . . . . . . . . . 5? Change in red coloration, ground color= flesh firmness and soluble solids of mo. Intosh fruits over a sequence of seven har- vests at ten locations in 1062 . . . 05 Respiratory behavior of mclntosh fruits from seven harvests at ten locations in Michigan in 1962, Fruits were harvested at 3-day intervals , , , A? a o a o o t n o v 0 o o 0 Figure 13 LIST OF FIGURES CONT'D Change in red coloration, ground color, flesh firmness and soluble solids of Mclntosh fruits over a sequence of seven harvests from seven EM rootstocks in 1902 Respiratory behavior of McIntosh apples grown on seven EM rootstocks in 1002, Fruits were taken from seven harvests at 3-day intervals . INTRODUCTION During the past 50 years the merchandising period for fresh apples has expanded from a few months to the entire year, The departure from a harvest season surplus to year around availability has been made possible through the appli- cation of refrigeration and more recently controlled atmos- phere storage. Fruit quality after long periods under optimum storage conditions is strongly dependent upon the maturity of the fruit at harvest, Immature fruits are subject to excessive shrivelling, physiological disorders associated with immaturity and are generally of low dessert quality as they fail to ripen properly during storage, Over- mature fruits are subject to several physiological disorders associated with senescence and are of low dessert quality after an extended period in storage. Determining the proper harvest maturity becomes more critical as the length of the intended storage season increases and is one of the most important annual decisions made in the apple industry. The elapsed interval from full bloom to maturity varies according to the growing season environment, parti- cularly during the first month following bloom, The first month is important in terms of fruit development since total fruit cell number is determined during this period. Starch accumulation in developing fruits begins approximately one month after full bloom, The elapsed interval from full bloom to the onset of starch accumulation may be related to the cessation of cell division and hence be related to environ- ment during this period. This thesis was based on the hypothesis that the onset of starch accumulation in the developing fruits may serve as a physiological parameter of the influence of the post bloom environment and hence a new basis for predicting fruit maturity, REVIEW OF LITERATURE Introduction The problem of fruit maturity has been studied for several decades and many methods for predicting and estimating maturity have evolved. Methods used with some success in one apple production area are often not successful in other areas. Maturity indices based on physical characteristics of the fruit are generally quite subjective in nature but are commonly employed, Predicting methods are generally based on records of past seasons for a particular area and may not be applicable to other areas. The following review of liter- ature contains some of the methods currently in use and provides the basis for the importance of the early growing season environment on fruit growth and development, Growth, Maturation and Ripening A, Physical changes The physiology of growth in apple fruits has been studied extensively in recent years by a group of Australian investigators under the direction of Dr, R, N, Robertson, Their initial studies (Bain and Robertson, 1°51) confirmed the observations of other investigators (Tetley, 1930, 1931; Tukey and Young, 1942; Smith, 1950) that cell division in developing apple fruits ceased within four weeks after ferti- lization and subsequent growth was due to cell enlargment, Variation in size of fruit at maturity was shown by Rain and 3 Robertson (1951) to be due primarily to variations in cell number and to a small extent by mean cell size, Their con- clusions were at variance with observations by Smith (1950) that either or both cell size and cell number may be the determining factor in fruit size in any given season. Smith (1950) has shown that the characteristic varietal size was determined primarily by the cell number and that variations in degree of cell enlargement were of secondary importance, Cell enlargement continued in a linear manner as long as the fruit remained attached to the tree while intercellular air space increased at a decreasing rate over the same period (Bain and Robertson, 1951), Color in apple fruits is a varietal characteristic, but the rate of development can be hastened or delayed by environmental conditions, The pigment responsible for color in the red varieties was found to be the anthocyanin, idaein (3-i-galactosidylcyanidin) (Sando, 1937; Duncan and Dustman, 1036), A precursor of this anthocyanin is synthesized in the leaves and moves to the fruits in the same manner as sugars (Cnslow, 1025), Light is required for the development of red color (Overholser, 1917; Schrader and Marth, 1931) and the ideal temperature required for color development was found by Magness (1925) to be warm days for maximum photosynthesis and cool nights during the latter part of the ripening season, Seigleman and Hendricks (1958) demonstrated the photocontrol of anthocyanin formation in the apple skin and found two distinct radiationodependent phases. The first phase was an induction period while the second phase was the anthocyanin formation which was a linear function of time of irradiation at constant irradiance. The action spectrum of the two phases was in the region of 6000 to 7500 A°, They concluded that the photoreceptor was probably a flavoprotein similar to acyl coenzyme A dehydrogenase, which was later termed "Phytochrome," Most of the red pigment was found in the hypodermis with some in the epidermis; and in some varieties, anthocyanin was found in the flesh particularly in the over- ripe fruits (Smock and Neubert, 1950). The underlying green color of apple fades out when fruits approach maturity due to chlorophyll destruction in the chloroplasts of the cell, while xanthophyll and caro- tenoid pigments remain relatively constant and are responsible for the yellow grOund color of apples (Biale and Young, 1962), Ground color development was influenced by the leaf-fruit ratio with fewer leaves per fruit resulting in greener fruits (Haller and Magness, 1925), As the apple matures, the cortical tissue becomes softer and the cells become less firmly cemented together as protopectin is enzymatically hydrolyzed into soluble pectin (Griffin and Kertesz, 1946), Increase in cell size, inter- cellular spaces and water content were among the important factors uhi:b affect the textu" (Runemann, 1959), The specific gravity of the apple decreased through- out the period of fruit development (Simpson, 1953) and was primarily the result of the increase in the volume of intercellular spaces, Decrease of juice viscosity also followed a similar pattern (Rasmussen, 1962; Truscott and wickson, 1954), B, Chemical changes Mineral composition of apple fruit has been reviewed adequately by Askew (1935) and Smock and Neubert (1950), In general, the mineral content of the apple flesh increased during the first six weeks after full bloom (Brown, 1920), The total nitrogen in apple fruits increased during fruit development (Gourley and Hopkins, 1929), English workers led by Dr, A, C, Hulme (1936) have shown that total nitrogen per fruit increased rapidly during the first six weeks, The organic acid fraction of the fruit is of interest because it affects the eating quality of the apple, The organic acids increased steadily as the fruit enlarged on the tree until Just before harvest when there was a slight decline (Hulme, 1936), The titratable acidity steadily decreased as the fruit matured on the tree (Caldwell, 1°28; Lopez, 1958), The pH rose steadily as the fruit developed and remained unchanged for several weeks and dropped to a lower value just before harvest (Heimlich, 1953; Powrie and Asselberges, 1956). Comin and Sullivan (1953, 1954) have shown that the degree of dissociation of acids in the Rome Beauty apple increased rapidly throughout apple develop- ment, and rapidly decreased two weeks before picking maturity, Accumulation of cations, mainly potassium, may account for the increased dissociation of the acids with a concommitant increase in the pH (Richmond, 1903). Malic acid was tound to be the dominant organic acid in the apple by many workers (Bigelow and Dunbar, 1917; Krotkov and Helson, 1946; Thimann and Bonner, 1°50). Since the develop- ment of ion exchange and paper chromatography analytical techniques, several investigators (Hulme, 1°58; Krotkov 33 31,, 1951) have shown that malic acid was not the dominant acid during the early stage of development, Quinic acid was found to be the dominant acid in the early stage of develop— ment of the yowug fruit (Hulme l058)_ The relationship between acid and carbohydrate meta- bolism was studied by Krotkov £5 31. (1°51), They found that organic acids did not contribute to the increase in sugars during the climacteric and were not formed during the decrease in sugars in the postclimacteric period, Acidity of the apple fruits was high in years when climatic conditions were favorable for carbohydrate accumulation (Haller and Magness, 1°26; Brown, 1036), Robertson and Turner (1051) Suggested that organic acids are formed in the leaves and transported to the fruits in the same proportion as they are formed, Hulme (1054b; 1958) has shown that citramalic acid appears only at maturity in the peel tissues, and quinic and shikimic acids may have a possible role as precursors of aromatic ring compounds. An extensive study on the changes in the nitrogenous compounds of apples during growth and ripening was conducted by Hulme (1058), Archbold (1932 ), Askew (1935), Robertson and Turner (1951), and Pearson and Robertson (1953), Hulme (1958) summarized the amino acids which he and others identified by chromatographic methods. (1949) serine by paper chromatography, Joslyn and Stepka were the first to identify asparagine, aspartic and Robertson and Turner (1951) found that protein in Granny steady the rate was slower, Smith apples increased per apple and per cell at a rate until about 135 days from full bloom after which Studies on the lipids from the peel of Granny Smith apples were conducted by Huelin and Gallop (1951), They found that oil content increased with maturity, and the iodine number of the oil increased with oil concentration, Ioodwin (1952) reviewed the literature on changes in carotenoids in fruits during ripening and cnnuluded that the carotene content increased destruction was taking place, peel and flesh was dw3 to this Sugars are an important storage life, and serve as the ation, Sugars are synthesized and translocated to the fruits ratio may affect the concentration of (Haller and Magness, 1926), increase as the fruit develops Seedling apples, Glucose, fructose content was at the time when chlorophyll The yellow color of the apple pigment, factor in fruit quality and primary substrate for respir- in the leaves by photosynthesis (Evans, 1028), The leaf-fruit sugars in the fruits fructose and sucrose on the tree, In Bramley found to be twice that of glucose at harvest time (Archbold, 1932), Archbold and Barter (1934) reported that total sugars increased from the core to the outside and from the stem to the caylx end, Sugar content varied from season to season and by location (Evans, 1928). Extensive investigations on sugar changes during fruit development were conducted by Archbold (1932); Caldwell (1934); Krotkov and Helson (1946); Eggenberger (1949); Griffiths £1 at, (1950); Hulme (1950); and Robert- son's group in Australia (l951), Archbold (1932) showed that the concentration of glucose remained constant during the cell division 5: ge, and fructose remained the most abundant sugar when the apples were removed from the tree, Hulme (1950) explained that starch synthesis and hydrolysis were not directly related to die increase or decrease in reducing sugars. Total sugars increased for a short period after harvest due to starch hydrolysis (Krotkov and Helson, 1046) and declined gradually during senescence, Haynes and Archbold (1928) reported that death of the apple followed the exhaustion of sucrose, the respirable material. Starch is formed in the early part of the apple development primarily from the sugars transported from the leaves and partially from sugars formed in the fruits (Smock and Neubert, 1950), Gerhardt (1926) provided evi- dence for the presence of a small amount of starch degrad- ation products in apples at certain stages of development, White t 1, (1959) described starches as polysaccharides which serve as nutritional reservoirs in plants. The starch itself is a mixture of a straight-chained amylose component and a branched-chained amylopectin fraction; amy- lose gives an intensely blue-colored complex with iodine while the color of the amylopectin—iodine compound is blue- violet, and on the basis of these color differences, the relative proportions of amylose and amylopectin in apple starch has been estimated (Hulme, 1958), Microscopic exam- ination reveals the starch grain is a series of concentric layers of starch deposits around a hilum (Bonner, 1950), and the layering is believed due to the alteration of day and night, with the denser layer being deposited during the day, Starch deposition begins near the skin and proceeds toward the core (Archbold and Barter, 1934) and as the fruits mature, starch hydrolysis proceeds from the core outward, Deter- mination of starch content is dependent on the ratio of amylose and amylopectin which varies with plant species (Bonner, 1950) and from season to season (Carter and Neubert, 1954). Changes in starch content of the apple fruit during development have been studied by many workers (Haller and Magness, 1944; Haller and Smith, 1950; Kidd 3: 21,, 1950; Phillips and Poapst, 1950; Poapst g: 31,, 1957), Hulme (1958) reported that starch may not be hydrolyzed or syn- thesized in the metabolizing cell by the amylase enzyme but rather by a phosphorylation process. The pectic compounds of the developing apples are comprised of protopectin (insoluble pectin) which is the main constituent of the middle lamella of the cell wall (Smock and Neubert, 1950). As the apple matures, protopectin is hydrolyzed by the pectinase enzyme into soluble pectinic acid and pectin (Griffin and Kertesz, 1946; Kertesz, 1943), Pectic changes in apples were influenced by different condi- tions and were not always constant, Kertesz (1951) has written an extensive review of pectic substances. C, Physiological changes Transpiration of Baldwin apples during the growing season was studied by Pieniazek (1943); transpiration was found to be rapid when fruits were small and was directly related to the surface area and the amount of epidermal hairs. Pieniazek (1943) also attributed the transpiration to the small quantity of cuticle present on voung fruits, Transpiration rate dropped steadily throughout the fruit development and started to increase again at matud.ty, However, fruits harvested early transpired faster than more mature fruits (Smock and Neubert, 1950), Photosynthesis is believed to occur in young fruit since chlorophyll is present in the epidermal tissue. The amount of the green pigment present in the cortical tissue is much less than that in the epidermis or in leaves, Fur- thermore, the fruit is not structurally adapted for photo~ SYnthesis. This may explain the limited amount of sugar SYUthesis in the fruits (Smock and Neubert, 1950), The apple fruit is metabolically active throughout its development, Krotkov (1941) has shown that the respiration rate of McIntosh apples decreased rapidly in early summer and less rapidly in late summer, The period of rapid respiration rate coincided with the period of active cell division. Kidd and West (1926) observed a rise in the respiration rate of English apples after detachment at the commercial harvesting time and referred to this phenomena as the respiratory climacteric, They showed later (1945) that the climacteric rise in respiration also occurred while the fruits were attached to the tree, They demonstrated that detached fruits had the same respiration rate ror a short period of time as those attached to the tree. The respiratory climacteric was fOund to be a general phenomenon in fruits (Biale, 1951) and was looked upon as a transition phase between ontogeny and senescense (Bialv and Young, 1°62), Kidd and West (1930) attributed the onset of cli- macteric to protoplasmic changes. They also showed that treatment of apples with ethylene induced the climacteric, The mechanism responsible for the climacteric has been extensively investigated and has been reviewed by Hulme (1958), Hulme (1936) observed that a rise in the net pro- tein was associated with the climacteric in apples, These findings were confirmed byPearson and Robertson (1953, 1954), Robertson and Turner (1951) explained the :limacteric in terms of phosphorylations coupled with electron transport system, Protein synthesis provides a rapid turnover of phosphate acceptors which cauSe a rise in respiration rate, according to the Robertson theory (1954), 13 D. Environmental modification In general, a high level of nitrogen nutrition re- sulted in larger fruits, decreased the firmness, retarded chlorophyll degradation, delayed the development of antho- cyanin and a high potassium level tended to increase fruit color (Gourley and Hopkins, 1929; Overly and Overholser, 1932; Hill and Heeney, 1952; Hill, 1953, Weeks st 31,, 1952; Beatie, 1954; Collins, 1957), Eggert (1961) found a positive correlation between P content and firmness at harvest, and between Ca content and firmness after storage, High nitrogen reduced soluble solids content of the fruit (Smock and Boyn- ton, 1944), Smock and Neubert (1950) reported that water was a limiting factor in photosynthesis and fruit quality, The rate of red coloration development at the end of the growing ‘ season was diminished when moisture was limited, Heinicke and Childers (1936) have shown that respira— tion during the night increased with increase in temperature, Tukey (1956) concluded that the growth of M Intosh apples exposed to controlled night temperatures and natural day temperature for approximately a month following petal fall was stimulated mainly by high night temperatunz, Day temper— ature influenced the daily growth, Later (1960) he reported that growth was more sensitive to night and day temperature conditions prevailing for a month after petal fall than to similar conditions following this period, Fruit grOwth may also be influenced by light intensity and duration, Piringer and Downs (1959) found that vegeta- tive growth was greatest on trees provided a 16 hour photo— period, This conclusion was at variance with Hoyle (1955) who found that growth and flowering of Cox's Orange Pippin and Worcester Pearmin were not affected by photoperiod, She used a combination of low intensity incandescent and fluore- scent lights supplementing the basic 8 hour day, Visser (1956) found greater elongation and better growth of apple seedlings grown in continuous light, Apples were found to grow more rapidly under a 10 hour day regime than with the full length of day at midsummer (Garner and Allard, 1923), II. flgggfity Indices A, Physical It was stated earlier that developing apples soften as they approach maturity, Magness and Taylor (1925) de— veloped a preSSure tester to indicate the flesh firmness of apple as a possible index of maturity, Firmness of a given variety varied from season to season and from one location to another (Smock and Neubert, 1950), Furthermore, the firmness varied at different locations on the same apple, In general, the red area of an apple was firmer than the non-red area, Moisture, temperature and nutrient intensity may affect fruit firmness (Haller and Magness, 1944; Smock and Boynton, 1944; Haller, 1937), The pressure tester is a better measure of fruit condition than it is a measure of fruit maturity, A marked disadvantage of the pressure 15 tester is that the fruit is spoiled for further use. A recent innovation in pressure testing has been the develop- ment of the "mechanical thumb" by workers in the USDA (Schomer and Olsen, 1963), It is a modification of the Magness-Taylor pressure tester to measure compression of the fruit flesh. The use of the "mechanical thumb" does not mutilate the fruit, Surface red color of apple fruit has been studied as a maturity index, since color continues to develop as the fruit remains on the tree, However, color development is very much influenced by environmental conditions such as night temperature, sunlight and nutrition, Thus, color was not reliable as a maturity index (smock, 1948, Blanpied, 1000), As the apple ripens on the tree the underlying green coloration in the skin changes to yellow as a result of chlorophyll degradation and the resultant appearance of the yellow carotenoid pigments, Magness 31 31. (1°26) and Smock (1048) prepared color charts to assist in describing the ground color, In some varieties ground color does not change mark-ll! as the fruit matuven_ Ground color is in- fluenced by the level of nitrogen nutrition which limits its usefulness as a maturity index, Smock (1948) reported that despite the ground color test limitations, it was the best useful measure for McIntosh maturity, As fruits approach full maturity, the seeds change color from white to brown, However, the rate of seed coloration varied from season to season which made this observation of little value as a maturity index (Haller and Magness, 1944; Smock and Neubert, 1950), Flesh color (Yeatman st 31,, 1962) was studied in relation to maturity of Red and Golden Delicious apples by using the light-transmittance technique which measures optical density difference GAO,D,) between wave lengths of 740 - 695 mu, Low 0,0, differences indicated high chloro- phyll content in the apple, while high O,D, differences indicated low chlorophyll content, Low chlorophyll content was correlated with better apple quality, The light trans— mittance technique was studied also by Olsen and Schomer (1°62) who feund a good rorrelation between the sererity of water core and light transmittance, The ease of abscission of apple fruit from the spur has been used as an index of maturity, As the apple matures on the tree, it separates more easily from the spur, but some varieties such as McIntosh may abscise before attaining maturity, Environmental conditions markedly affect the ease of fruit abscission, Furthermore, the use of chemicals to prevent pre-harvest drop complicates the use of abscission as a maturity index (Smock, 1948; Blanpied, 1060), Apple fruits increased in size as long as they re- mained on the tree (Magness st 31,, 1926: Haller and Magness, 1944), The rate of size increase may be influenced by soil moisture and by any factor which influences the photosynthe- tic rate, The use of size increase as a maturity index was 17 of limited value (Haller and Magness, 1944), Truscott and wickson (1954) studied juice viscosity in relation to apple maturity and suggested that changes in viscosity of fruit juice might be used as an indication of fruit maturity, As apple fruits approach maturity, the lenticels be- come filled with cork cells; however, the rate of change was too gradual to make this observation a valuable index for maturity (Haller and Magness, 1944), Flavor and eating :nrality are used by many persons in the apple industry as a subjective index of fruit maturity, Extreme variability between different individuals as to what constitutes good eating quality makes this observation of little general value, The McIntosh variety has a very distinctive odor which contributes to its eating quality (Smock and Neubert, 1950), Gas chromatographic identification of the volatile components of the apple fruits was studied by USDA personnel (1962), Chemical constituents responsible for odor were esters, essential oils, and aldehydes, Astringent materials in apples are one of the most important factors contributing to the eating quality. As fruits mature on the tree, astringency declines, Astringent materials are composed chiefly of tannin and its derivatives and flavones, B, Chemical The sugar content of the apple increased as the fruit 18 matured on the tree (Heimlich, 1953), Sugars were the main constituents of the soluble solids, Soluble solids as measured by a refractometer has been used as a maturity index (Smock, 1948: Smock and Neubert, 1950), The sugar content varied with crop load, cultural practices, and en- vironmental conditions during the season (Caldwell, 1928: Blanpied, 1960), The change in soluble solids was too gradual to be useful as a guide to maturity (Smock, 1948), The titratable acidity steadily decreased as the fruit matured on the tree (Bigelow and Dunbar, 1917; Cald- well, 1928), The pH rose steadily as the fruit developed, but the rise was not striking (Archbold, 1932), Smock and Neubert (1950) reported a considerable fluctuation as the fruit matured, but in general there was an increase, Acid- ity varied between varieties (Askew, 1935) and from one season to another (Caldwell, 1928), Statistical correlation was fOund between the PH and the titratable acidity, Haller and Magness (1926) reported the influence of leaf-fruit ratio on the total acidity, Sugar-acid ratio showed a continuous increase with maturity (lopez, 1958), Reyneke and Reinecke (1939) reported that solids—acid ratio was a suitable maturity index because it more effectively reflected small changes in maturity, In general, total acidity decreased with loss of firmness, pH and soluble solids-acid ratio increased (Lopez, 1958), The sugar-acid ratio was used successfully as a maturity index for citrus fruit, Comin and Sullivan (1953, 1954) have shown that the degree of dissociation of acids in the Rome Beauty apple increased at a rapid rate until about two weeks before picking maturity and then rapidly decreased, It was suggested that the peak of this dissociation occurred at a point in the relation between anabolic and catabolic processes where the fruits were at maximum quality standard of taste, tlavor and appearance, and hence may prove useful as an index on proper maturity, Blanpied (1960) concluded that acid changes were not consistent enough to be used as a reliable maturity index , As the apples mature on the tree, the starch grad- ually decreases in the fruit, Canadian workers have attempted to make use of the starch disappearance in the apple fruits as a criterion of picking maturity (Phillips and Poapst, 1950; Poapst 3: El,, 1957), Hesse and Nita (1939) suggested a correlation between starch disappearance and maturity of the apple fruits, Phillips and Poapst (1950) studied the starch disappearance in relation to maturity quite exten- sively and found the starch loss was linear, and this linearity appeared to be independent from day—to~day weather conditions but varied from season to season (Poapst Si 31,, 1054). Poapst 31 El. (1959) concluded that the picking time in McIntosh apples was related to starch content and starch— iodine reaction may be used as an index, Although this test was recommended as a useful maturity index in Canada, it has not been found reliable in the United states (Smock, 1948; Blanpjed, 1960), The dependence of starch conversion on 20 climatic and cultural conditions has diminished the import- ance placed on starch disappearance as a guide to maturity (Tiller, 1936; Ward, 1054; Smock, 1°48; Hulme, 1958). The pectic changes seem to vary considerably with different varieties and under different conditions. Such changes cannot be used as a good index of softening rate for maturity (Smock and Neubert, 1950). C. Physiological Apple fruit respiration rate varies with the age of the fruit, Kidd and West (1°2fi) indicated that some apple varities should be picked just before the climacteric rise begins, Smock (13483 in the United States confirmed this relation with McIntosh in New York State. Some workers have raised crit'cism at this respiratory technique and expressed the climacteric rise as a physiological artifact resulting from the fruit detachment (bzell and Gerhardt, IGJJ) but Kidd (1058) proved that attached fruits on the tree pass through the climacteric rise of respiration. It was also found that fruits after detachment had 1 similar respiration rate to the attached fruits for a short period (kiddfi 1035). This test is valuable, but only of experimental interest since it is not adaptable to the orchard, Hulme (1054) studied the respiration behavior of Cox'x Orange Pippin apples ”ad found the difference in time between the omiet of the climacteric at 125C, and at 150 C, varied with the picking date, but had a minimal value which varied from season to season, He suggested that this minimal gap may reflect a definite physiological state of the fruit which could be a guide to maturity. Enzymatic studies on the apple fruits indicated that polyphenolase plays the most important role in darkening of apple tissues upon exposure to air. The oxidase activity of apples was found to decrease with increasing maturity on the tree (Ezell and Gerhardt, 1942), Catalase activity was found by the same authors to increase steadily with maturity within a given variety, This increase varied from one variety to another (Draine, 1926), The biochemical changes which take place during the climacteric were studied as possible maturity criteria. Addition of malate to peel tissues caused an increase in carbon dioxide output but not in the oxygen uptake during the respiration climacteric and this resulted in an increase in the respiratory quotient (Neal and Hulme, 1058; Dilley, 1062), It was suggested that this decarboxylation process takes place at the expense of some Kreb cycle acids and does not require oxygen (Neal and Hulme, 1058; Pearson and Robert- son, 1054), The net increase in protein, which occurred during the climacteric, was interpreted as a result of malic enzyme development which was required in the reaction, 0 Environmental Smock (1048) reported that harvesting by calendar date proved to be a more reliable index of fruit maturity than elapsed days from full bloom, Blanpied (1060) studied the optimum picking dates for a 10 year period, and found that for seven years out of ten the optimum harvest date was within three calendar days, and concluded that the cal- endar date may serve as a rough guide though not a very accurate one. It is well known that different varieties of apples have different lengths of growing season, Tukey (1942) made a comparison of different varieties and different seasons and found that the interval between full bloom and maturity differed slightly due to seasonal varim ions, while Haller (l942) concluded from three years experiments that regard- less of locality and seasonal variations, the number of days from bloom to maturity was rather constant, and was a more reliable index than others studied. The average number of days from full bloom to maturity was given by other workers in the areas of uniform growing conditions (Haller and mag- ness, 1044: Haller and Smith, 1°50; Ellenwood, 1041; Ryall 2!. 9.1..- 1041). Date of full bloom was studied as a basis for pre- dicting maturity. Magness st 31. (1026) and Blanpied (1°60) reported a fairly close relationship between the time of full bloom in different varieties and the picking date, The validity of the elapsed days from bloom to matur- itY is questionable because of the seasonal environmental variations, When heat units were calculated with 3 45°F base temperature, a better prediction of harvest was made (Brooks, 1045). Osterwalder (1949) reported the importance of temperature distribution through the season in addition to heat unit accumulation, Haller and Smith (1950) found an inverse relationship between the early growing season temp- erature and the growth rate, High night temperatures were found to decrease the number of days from full bloom to harvest (Baker and Brooks, 1044). Gunnawav and Cremin (1950) developed a means of forecasting maturity of Elberta peaches by a method based on maximum daily temperatures from full bloom until the beginning of Julv, It was found (Radu t 1., 1060) that the temperature sum during the first 10 days after fruit set was the main factor in determining the apple growth and length of time from bloom to harvest, ngert (1060) summarized the reSults of eight years and concluded that the temperature prevailing during the early part of the growing Season exerted a greater influenre on time of maturity than the temperature during the latter part of the growing season. He found that the variability in heat units accumulated during the 40 days after petal fall accounted for 9.% of the variability found in the total elapsed days from petal fall to harvest, and that accumulation of heat units immediately prior to harvest did not markedly inFIJence maturity, Tukey and Young (1042) and others (Smith, 1050; Bain and Robertson, 1051) reported that cell division ceased within four weeks after full bloom. Several investigators (Krotkov and Helson, 1946; Archbold, 1932; Robertson and rurner, 1051; Pearson and Robertson, 1954) have observed that starch accumulation commences approximately one month after full bloom. MATERIALS AND METHODS 1. Modified Temperature Environmental Study. 1961. Eight five-year-cld McIntosh trees were selected for study from a rootstock-variety orchard at the Horticulture Farm at East Lansing, Four of the trees were grown on East Malling II rootstocks while the remaining four were on East Malling VII, Wooden pole frame and electrical conduit structures were built over two trees on each rootstock, The remaining four trees were left uncovered to serve as con- trols, A white nylon parachute with white canvas affixed to the periphery was fastened to the frame structure and served as an easily removed canopy enclosing the tree (Fig, 1), Portable electric heaters with auxillary fans were placed under the canopy to provide a source of heat, The two trees, one each of EM II and VII, receiving the 750F night temperature were supplied with heaters totalling 1650 watts while the two receiving the 65 F night temperature were supplied with 1300 watts, The heaters were wired for control through a Fenwal thermostat located in the center of each tree, Thermocouples were placed at three elevations within the heated and control trees and the temperatures were monitored at four minute intervals during the night by a recording potentiometer, Commencing on May 19, 1961, four days after full bloom, the trees receiving the modified night temperatures 25 III-III-____llu,, ,Ea_44 Figure 1 Technique employed to obtain night temperature control. Pl.» were covered with the parachute canopies and heated during the night. The canopies were placed over the trees at about 7:00 p.m. when the heaters and recorder were turned on and were removed at 6:00 a.m. the following morning. This sched- ule continued for about 30 days following full bloom or until starch accumulation was observed in the developing fruits. Terminal shoot growth, leaf size and fruit diameter measurements were taken at three day intervals until starch aCCumulation was observed and then at weekly intervals for the remainder of the season. Ten shoots, leaves and fruits were selected at random around the perimeter of each tree and tagged for identification to insure that the successive measurements were taken on the same samples, A metric rule and a direct reading metric micrometer (Model 49P-l-Rl, Federal Products Corporation, Providence» R,I,) were used to take the growth measurements. The presence of starch was determined subjectively in ten developing fruits at each sampling period with IZ-KI reagent (Phillips and Poapst, 1952) on a midadaily basis starting two weeks after full bloom, Measurements ceased after starch began to accumulate, Both a laboratory and a field test for starch were employed. The laboratroy test consisted of macerating a small quantity of fruit cortical tissue on a glass slide in the presence of a small quantity 0f IZ-KI solution and observing the first appearance of starch granules at a magnification of 500x (Fig, 2). The field test consisted of cutting fruits longitudinally and 26’ Figure 2 Photomicrographs of apple starch granules at the initial stage of accumulation, Magnification: Top-- 1 inch = 4.0"”L Bottom-- 1 inch = ZOAL .d d. saw: .4... m! 0.. ' a. f . v c PU. vanes £89.. O...» ...” ., .. ‘9 - as ..«anmuf mlafiodfiffiu . . .. ..c m e. .. u. 3.3%.: J .5... we. coy.» e. 3m“. W. mm s. as“- are. . w... «3.4. ...... .,. flu. taro .3. yo ...0 “Jaw/eon. 3&5? on.“ 0 now 9 ‘ o ...... H5.“ 0 ... (.9 ..c. . a: :0. 1.... 1» .... .... ...: ‘& 0:000..¢0.0wu«m...r cam”... .... ., . . . t 9 .. . .C 9 mm... o o.- be...» bOnu! 0.. O C ”Wen-vii. . . x... . 3 observing the blue-stained starch granules after applying a few drops of IZ-KI solution. Respiration rates of fruits at three harvest dates, 127, 135, and 143 days from full bloom, were obtained at 70 F as CO2 evolution from approximately a 1500 g, sample of fruits (Claypool and Keefer, 1952) to determine the time of the climacteric, Additional meteorological information was obtained during the growing season from the Official U.S, Weather Bureau station located at a similar elevation about 1/4 mile from the site of the experimental trees. These observations included daily maximum and minimum temperatures. II. Modified Environmental Study, 1902, The same Mclntosh trees that were used in 1961 were used in 1962 but the conditions were modified to include the effects of high day and night temperaturesa light intensity and photoperiod as follows: 1. One tree on EM VII was provided a night temperature of 75'F as in 1961, 2. One tree on EM II was Provided 75 F minimum day and night temperature by keeping the tree covered with a white parachute both day and night and provided supplemental heat as before. This resulted in a reduction of light intensity during the day of approximately 4000 ft, candles less than the light intensity received by the uncovered trees. 3, One tree on EM II was covered continuously with a green stained parachute and provided circulation and venti- lation at the top and bottom of the tree to prevent heat accumulation during the day. The light intensity obtained varied from that of the uncovered trees by about 5000 ft. candles. 4. One tree on EM VlI was left uncovered and provided supplemental light for three hours after sunset from four 150 watt incandescent lamps located near the upper periphery of the tree and provided the long day treatment, 5, Two trees on EM VII were enclosed in wood frames and provided with removable dark cloths which were placed in position at night and removed at 9:00 and 10:30 a.m, and thus provided two short day treatments. 6, Two other trees were left uncovered and served as controls. Temperature records were obtained with thermocouples and a recording potentiometer as in 1961, The modified environmental conditions were commenced four days after full bloom (May 11) and continued until after starch accumulation was observed, Growth measurements and starch accumulation tests were taken as in 1961. Samples of fruit were selected at random every three days from May 27 to June 19, 1962 from the various treatment trees for cell division observations. The fruits were fixed in formalinacetic acidoalcohol (FAA) solution immediately after harvest, imbedded in paraffin and sectioned with a rotary microtome, The tissue sections from 31 the same position (near the calyx) on all fruits were stained with safranin-heamatoxylin (Sass, 1961) and examined mico- scopically for dividing or newly divided cells. 111. Natural Environment Study, 1962. To ascertain the variability in starch accumulation and maturation of McIntosh under a wide range of natural environmental conditions trees were selected in orchards at various locations in the western Michigan fruit belt, Two McIntosh trees were selected in each orchard with the characteristics listed in the following Table, TABLE 1. Characteristics of natural environment locations in Altitude Distance from Loca- Latitude Longitude (ft, above Lake Michigan Soil tion (’) (') ( ) (') sea level) (miles) Type A 41 59 86 16 773 16 Miami silt loam B 42 20 86 10 670 8 Miami silt loam C 42 36 86 9 680 5 Miami silt loam D 43 5 85 11 850 49 McBride sandy loam E 43 13 85 15 870 47 McBride sandy loam F 43 7 85 18 850 46 Montcalm sandy loam G 43 41 86 24 760 5 Kent silt loam H 43 41 86 24 760 5 Kent silt loam 1 43 43 86 10 980 17 Emmet sandy loam J 42 43 84 225 860 82 Coloma loamy sand 32 Maximum and minimum orchard temperature records were obtained by the grower for at least a 30-day period follow- ing bloom using a standardized thermometer located in a field crate at a height of five feet. Data of full bloom, petal fall, and starch appearance date (date of positive IZ-KI test) were obtained with the help of the grower and visits to the various orchards. A sequence of seven consecutive harvests were made at each location at three-day intervals in an attempt to bracket the onset of the respiratory climacteric and the optimum harvest date for storage in conventional and controlled atmosphere storage (CA), One bushel of fruit was taken from the periphery of opposite sectors of each tree at each har- vest. The two bushels of fruit per harvest per orchard, thus obtained, were randomized and sub-divided into three samples as follows: 1, 1/2 bu, for quality evaluation and measurement of respiration at harvest, 2, 3/4 bu. for conventional storage in air at 32 F, 3, 3/4 bu, for CA-storage in 5% €02 and 3% 02 at 38F, An additional 3/4 bushel sample of fruits were obtained from orchards A and E (high nitrogen orchards) for CA storage in 5% 002 and 3% 02 at 32’F, The fruits were transferred to the laboratory the day of harvest. The fruits destined for storage were placed under refrigeration at 32 F immediately while those for quality evaluation and respiration determinations were IV. Post-Storage Quality Evaluation: The McIntosh fruit samples from the 1962 season placed in conventional storage at 32 F were examined in February, while the fruit from CA storage were examined in April. The same parameters used to judge quality at harvest were employed as described earlier. In addition, all fruits were examined for incidence and severity of scald immediately after storage and after one week at 70‘F. Fifty randomly selected fruits were examined for internal disorders (core and flesh browning and mealy breakdown) after one week at 70 F. General appearance and eating quality of ten fruits from each harvest of each orchard from the two storage types was judged by a panel of three individuals. Supplementary data on temperature, starch accumula— tion and respiratory climacteric for three locations was obtained in 1963, 33 placed at 70 F. Approximately ZSOOS samples of fruits were employed for respiration determinations as described earlier. Evaluation of flesh firmness as measured by a Magness-Taylor pressure tester with 7/16" tip, soluble solids as measured by a Zeiss Opton hand refractometer, and evaluation of fruit size, ground color with Cornell color chart (Smock and Mark- wardt, 1955) and percentage red coloration were made one day following harvest on 25 randomly selected fruits. A study of starch accumulation and maturation of McIntosh as influenced by rootstocks under the natural environment was also undertaken in 1962. McIntosh on EM 1, II, 1V, V, VII, X11 and XIII (17 years of age) located on the Horticulture Farm at East Lansing were employed, Starch accumulation was measured as described earlier, Harvests and measurements were made as described in the two previous paragraphs. A study of the variability in starch accumulation date of 11 different varieties of apples located in an adjoining 36-yearoold orchard was examined in 1962 and 1963, In addition, the diurnal fluctuation of starch content during the period between incipient starch appearance and net accumulation was investigated in 1962, Leaf samples were collected from all orchards and were analyzed for nitrogen and mineral composition in the Plant Analysis Laboratory, Horticulture Department, RESULTS I. Modified Envirggmental StudyA 1961. A. The environment McIntosh trees grown on BM 11 and VII rootstocks received the average weekly night temperature regimes shown in Table 2, The average minimum night temperature for the five week period following bloom was 49.2 F which was 1.9'F below normal for the East Lansing area. The percentage of possible sunshine received during this same period was 73% which was 7% above normal, The average daily maximum temperature for this period was 73,0FF which was O,7*F above normal, Soil moisture was adequate for growth during this period. B, Vegetative growth The influence of the various night temperature regimes on shoot elongation and leaf expansion is shown in Figures 3 and 4, Shoot elongation and leaf expansion were considerably greater on trees which received the 753E night temperature than on trees which received 05 F or the ambient night temperature, Growth at 65 F night temperature was slightly greater than that at the ambient temperature. Shoot elongation and leaf expansion ceased for all treatments on June 14 which was 28 days after full bloom, The apparent failure of the McIntosh VII 65 F night temperature treatment tree to respond to treatment was related to injury to the tree reSulting from repositioning the tree after a Windstorm. 35 TABLE 2, Average weekly temperature (VF) regimes obtained for five weeks following petal fall in 1961 at the M.S.U. Horticulture Farm, East Lansing. Treatment . n Avg. Avg. Control-a—/ 65 F2/ 75 " FE/ Daily Daily Week (night) (night) (night) maximum minimum 1 63 7! 65 d? 2 55 64 75 72 46 3 65 66 77 79 53 4 68 68 78 80 56 5 62 65 75 74 so 2/ average of hourly night temperatures between 9 p,m. and 6 a.m. mucoEumou» on» mo dump acmumacmucoommo wouwomocm Bouu< .fioog cm wemmceq «mom «a acmummcodo poocm swepcmoz :o mouspauoasmu «ammo mo mucosamcm och m ousmmm 29,; one 5302 null. 22$ 08 EEO: Tub .2200 ago: Oil. 22: a one Hm .Hos To 225. one u .32 T4 Bel—coo HH .32 I 59 9 ON mm on mm 0? av ("19) wbua7 Joous .wucwfiwamuw onu mo open acmumacmucoowmo mouaowoem zouu< .HbOa em wemwcmq «mam an nuzoum mama cwowcuoz :o muoumumdeou pcmmc mo ooeoaamcm v munwmm 29:... one 5302 Tu:- zgf 0mm H302 Tuna 6.28 as: on}. 29:“. owe. H Hos To EEC“. one u .32 «Ila .8250 D .Hos. 0'0 69 (we) wbua7 yoa 7 C. Fruit growth High night temperature resulted in a more rapid increase in fruit size compared to the ambient temperature as shown in Figure 5, The 75cF treatment yielded larger fruits than either the 65'F or the ambient temperature, The leaf to fruit ratio was considerably in excess of that con- sidered limiting to fruit growth since the total fruit load was very light for all treatments. D. Starch accumulation The influence of the various environmental treat- ments on starch accumulation in 1961 is given in Table 3, Starch accumulation was evident in fruits from all treatments on essentially the same date, The elapsed interval from full bloom to starch accumulation was essentially the same regard- less of fruit size differences imposed by the different night temperature environments. E, Fruit maturity Fruit maturity was estimated by determining the reSpiratory behavior of samples collected from all treatments at three harvests at 8-day intervals. An insufficient num— ber Of fruits were present within each treatment to provide more than three determinations. The course of the respira- tOFY (:limacteric of fruits from the various treatments is ShOWn in Figure 6, The 75”F night temperature treatment reSUIted in a slight advancement of maturity. This was more eVident with EM VII than with EM 11, However, the exact date 0f preclimacteric minimum could not be obtained from so few .mucos vwmouu on» we mean acmumscmucoommo monsomocm zouu< .Hoofi cm mcmmcwq anew «a :uBOum «menu anewcmoz :o eunumuomsow usmma wo mocoaamca n whammm ON x.— v. 29: u. on» “Haas. nun:- zoe ... 08 H532 7:1 .228 5.32 on}... 29: u one. u .3: oils 29: u 08 u .32 «la .928 d .Hoiolo 5m. (we) J9$8LUDIG “an TABLE 3. Summation of maturity characteristics for McIntosh under modified environmental treatments, Full Starch Climac- Full Bloom Starch to ,F.B. to Treatmentfi/ Bloom Accum, teric to Starch Climacteric Climacteric Date Date Date Days Days Days Mc/VII 75 F, night 5/15 6/14 9/24 30 102 132 Mc/VII 65 F, night 5/15 6/15 10/2 31 109 140 Mc/VII Control 5/15 6/15 10/2 31 109 140 Mc/II 75 F, night 5/15 6/15 9/24 31 101 132 Mc/II 65 F, night 5/15 6/15 9/28 31 105 136 Mc/II Control 5/15 6/15 9/28 31 105 136 a/ Temperature treatments were started one week after full bloom and were discontinued one week after the starch accumulation date .HooH :m mcwwcoq «mom «a mucoEuooua ounumuomEmu omfimmooe Eoum mumaum cucucaoz mo omnowumfimao aneumumawom o muzmmm goo N. e .60 En 8 NM .56 > — _ — 1— _ _ _ _ _ — _ _ _ _ _ < V A - -m. o - - o 18 I o I. - 232 n. on» :36: -on v AV I 10. OquQ/Q/O/O/fu 0 w o o 1 #8 - 232 ... .8 :36: 1.8 V .2280 __> \02 5Q. 1w 6v 20:) 6w ) _ L, .l ~1_1.. O N 29.2 a .9. :22 _1_ 0 r0 _ _ 1 _ o On 292 n. .no :32 1‘ O O iON 1 i N _ ,_ On 0 1 1. 3.5.00 =qu 5m. _ _ _ _ _ _ _ _ _ 1— 1w 611/ zoo 0“! 43 harvests. Fruits from all treatments with BM 11 and those frrnn trees on EM VII which received the 75”F night tempera- ture were more advanCed in maturity than those from the EM VII control and the EM VII 65'F night temperature treatments. No marked differences were observed in the physical characteristics of the fruit at harvest as a result of the high post-bloom night temperatures, 11, Modified Environment Study, 1962. A. The environment The modified environment study in 1962 employed the same trees as were used in the 1961 study, The 75 F night temperature treatment was retained, the 65 F night tempera- ture treatment deleted and day length and light intensity treatments were added, The environmental conditions obtained in 1062 are given in Table 4, The average minimum night temperature for the five week period after petal fall was 4.1 F above normal for the East Lansing area, The percentage of possible sunshine received during this period was 75%, which was 9% above normal for the area, The average daily maximum temperature for this period was 80 F which was 6.8 F above normal, Soil moisture was adequate for growth during this period. The nutritional conditions of the trees were adequate and the nitrogen and potassium levels were in the normal range (Kenworthy, 1961) as shown in the Appendix, B. Vegetative growth As in 1961, high night temperature accelerated shoot TABLE 4. Average weekly temperature (“F) regimes obtained for five weeks following petal fall in 1962 at the M,S.U. Horticulture farm, East Lansing, Treatment Avg. Avg, Controli/ 75rF21 Daily Daily Week (night) (night) maximum minimum 1 66 78 84 59 2 60 75 77 50 3 63 75 78 55 4 64 76 78 56 5 65 77 83 56 3/ Average of hourly night temperatures between 9 p.m. and 6 a.m. 45 elongation in 1962, see Figure 7. The low light intensity treatment resulted in longer and more slender shoot growth than was observed in the control. Low light intensity com- bined with a 75‘F night temperature resulted in the greatest shoot growth of all the treatments. The short day treatment was similar to the control while the long day treatment re— sulted in the lowest shoot growth of all treatments. However, the tree which received the long day treatment was stunted in growth the previous year from wind damage and hence, did not yield a satisfactory test. Trees which received low light intensity and short day treatments underwent a second— ary finish of terminal growth, The influence of the various environmental treatments on leaf expansion is shown in Figure 8. Leaf expansion paralleled shoot elongation, Shoot elongation and leaf expansion ceased on the same date for all except the low light intensity plus 75'F night temperature treatment, C, Fruit growth High night temperature accelerated fruit growth as was observed in 1961 and is shown in Figure 9. Low light intensity suppressed fruit growth but this was overcome when combined with a high night temperature. Day length did not seem to have any marked effect on fruit growth, Although considerable differences in fruit size among treatments were evident 30 days after full bloom, there was little difference in fruit size at harvest time, This suggests .m«:mEuwouu on» mo open camum5:mucoommo mowmomocm soua< .moofi em mammcmq poem as :oMummeodo «oozw cucucmoz co camcoa awn new >ummnou=m unmma tmouauoquEou «emu: mo mucosaucH h munmwm >60 0:3 Hafiz Ollie >60 :95 ages. Illi- zecu cm,» an: 7114 _o:coo HERO} .Ill. 26:25 :35 30.. fl .3: To £225 26: 33 33295. one U Hos. T4 .928 u .82 olo mm? 1 l0 l 1 In 0 N N (wo) W5U97 #0098 IOV .wucoEumouw on» mo pump acmuuanmacoowmo woumomocw 30nu< .mooH cm mcmwceq «mam we :uSOum Moog swepcmoz no camcoa use new >umwcoucm «cmm~ .ounwouomEmw «swan mo conundmcm w ouswmm 260 t E __ m m N82. on Z X $162 . _ _ _ _ _ _ _ _ _ \ >8 9.3 H362 6.116 >8 :96 5322 T11- EBE a? as: 4.114 6.28 EH62 oil. 4 IIIII \ £225 29.. 23 m Hos. I races :3: 26.. was 29: 09. H .32 a q _otcoo UH .HQS. OIIO mm? L (LUO) q45u97 ,1097 O. .mucoEvoouw on» mo ouoo cameancwucoommc mowuomocm zouu< .mooH cm mcmwcnq «mom «a nuSOom «menu nwoucHuz :0 camcoa >mo new rumwcoucm unmma «ousumuoaao» unmm: mo mocoafimcm o ou=MMm m. .334 _ . MN ..oo 95.. UHHos. 9.110 .8 :65 Ed: T11- 295. one an: fln< 3:80 EH62 0.11. 3.2.2:. ...o... 23 .H .35. To 3.22:. so... 36.. 3.3.3.1.... .2 .H .32 T4 3.5.00 HH .HQS. OIIO Nwm_ (um) 191.9me 1.1an 49 that ultimate fruit size is essentially independent of early season night temperatures, The influence of high night temperatures on fruit growth during the remainder of the growing season was not investigated. D. whrssseflejiegmsiuiyfiier The influence of the various environmental treatments on starch accumulation in 1962 is given ilhTable 5. High night temperatures shortened the interval from full bloom to starch accumulation by two days. The greatest effect on starch accumulation occurred in the low light intensity treat- mc nt where a delay of nine days was observed, High night temperature combined with low light intensity partially overe came the delaying effect of low light intensity on starch accumulation. A relationship was found between cessation of cell division, cessation of shoot elongation, June drop and starch accumulation in the McIntosh fruits (Table 6). All these events occurred at about the same time, which was about 30 days after full bloom, Although the different environments altered the dates of cessation of cell division and starch accumulation, the association between the two was not Changed, 15. Fruit maturity The course of the respiratory climacteric of fruits from the various environmental treatments is shown in Figure 10, Essentially no differences are discernible among th . . . . e rE‘spiratory curves of fruits from trees which received .mamo cemueasesoon nouauw ecu noume zoo: 0:0 I cosnwvcoommo one: one Eoofin uaam uwumm w>mo anew nouunum one; mucosawmuu manuauanoH \e ama mm om axe wa\o ca\¢ acxuz .mcwch «ammo zoo awn an em w\o ma\o o~\m HH\uz acmmcmcec ucqu son + unmaz ions omH so on w\o o~\o He\n Hh\u2 AucuflnEav acupeoo and cod mm om\o m~\c HH\w HH>\oz awe «cocm 0 5 emu oo mm e~\o s\o o~\m HH>\uz anmaz m we mm“ mod on caxo oe\o _~\n HH>\oz Aucmmnsac souucoo Anaeov Awaan Anamov \M «coacoumacm oauoaoasmfio .uuasmao .uuaemao mean wean even 0» 0w 0“ omuou .E:oo< Eoon sooam afism .< .m .m .i nuaemao euumum Haze mammcdq comm «a anuCHoz mo cemumusems on» :o mucoecoumbco .NcoH cm oommfiooe mo mocmzflwcw .w mqmme Hfiwu fl . mo cemumemo nueomnsemmno douueoo sauna zoo .esee came: moms source; ec;e “noem moms Hw\uz HH>\w2 u:oEc0umacw .mcod am mawmcmq poem «a mucm5:0um>:o oommmooe o» ooaoownsm woouu scum cucunHuz mo mumsum em comumH=E:oum gunman one gene wash rcempmmeofio poonw mo coauwmwmu .mumsum cm scammbmo dame mo comummmoo on“ «0 open on» consume amnw:0mua~ou 02H .0 mumcm owmmmooe Eoum wuwauw aneucHoz mo owumaomEmau aneumuwammm OH musmmm gold} 0 Egzuonh :>\02 :5 :26 :30: O O\OIOJOIOIOO\ola/O/o .8200 =>\02 Nwm_ 1'4/ 6’1/209 6w 26¢ .35 v~ 8 9 N_ m e > _ _ u _ _ _ _ _ _ _ _ _ _ _ _ A _ q I— _ _ _ _ < A A m o o -T I 0 low races in: 33 + r 292 93 3o h. .mn E Us. :8 W o k A o w. 1d. I \6 18 _I o 18 I 0 £22.: ES 33 :\ u: I O O c RV AV ' 1 0\p10/O I o o I o. l m N _ JON I o 3:50 : \oz .569 I _ _ ~ ~ _ _ _ _ _ r _ _|_L....p L.|P'h on Ju/ 61/ 303 Gal post-bloom environment of low light intensity, low light intensity plus 75 F night temperature, short day length or the ambient environment. The 75°F night temperature treat- ment appeared to have hastened maturity slightly. Fruits from trees grown on EM II rootstocks reached the preclimac— teric minimum about a week earlier than those from trees on EM VII r-'I * :ks. This was a2~e observed in 1961, No differences were readily apparent in the physical characteristics of the fruit at any of the three harvests regardless of the postnbloom environment received, III. Natural Environment Study, 1062. A, Ihg_environment The various locations selected to evaluate natural environmental variations during the post-bloom period exhi- bited a range in full bloom date from May 4 to May 10, Trees at seven of the ten locations reached full b100m within three days of one another as a result of widespread unseasonably high mid-may temperatures, The heat units (base 40 F) accumulated at the various locations during the post-bloom period are given in Tables 7 and 8, The cumulative values for the 30 day period ranged from a low of 726 to a high of 832, The maximum difference between the various locations was only 106 units, and eight of the ten locations fell Within 66 units, The accumulation of heat units from the same localities for the same 30-day period in 1963 varied {ION a low of 494 to a high of 695, The values for the .wumca can: uumfisofino an new: no: meow mo ousumuomeou owns < \M .eooHc Hasm enema w>wm \M Ham on an mnm mm we mom mm ow mam mm mm emu an m mom an om mom en we can on me Hon me we mmfi on H mom mm we omm mm as saw an me com em as ems om : mom mm we omm mm as cam an ms com em as HNH om o osm mm as enm en es on am he emm Ho mm mma an a mam mm Hm cam mm mm Mam se me New en ow mma mm m osm mm as smm em as cam am as emm no mm mma mm a M wen en we now an em emm an me ”am He mm ema mm o I n I oem mm we oem an as mom wm Hm awn om m cam on as amm mm ms mmm no cm was av 00 ema am < mean: .:L 1--., mafia: x x .. mums: M x mafia: x.: x I.Awwnov nm>mav d0mu \muaom son an”: \Iumm: son and: \a luau: son new: \mumw: so; ewe: .smao scream Iauon ow Ow \m mean ceyam \M wade OMIam \m mama omIHH \M mama oHIo .m.i .m.m .Nooa :m neodchOa cop scum mpwsum cucucmoz now asamcme omuvuoeawfiooum use one cemunasssoun zuueuw o» EooHc Haam scum Hu>umuem ommamao on» one mouspnuonEou EooAnnumoQ cmozuon Qm5m=0mvaom .5 mqm5 «mm mm on wwe mm on “ma om O beau mm mu won mm on bmw cm on NMfi an m mooH mm Hm nwb N am man an ow NNH wN m vooa mm 55 can mm on hmm on on mmfl mm Q vofiu mm on omw ow we nmw on FF ema mm 0 t I I 00% em on wen mm or bNH om m ooo~ vn wb emu mm on non em wb amg am < .c: J: x x .c: J: x x. .c: .u: x x 33.5 3:5 5383 NWWE=Uu< 3mg Awe: \M.ano< 3mg nmmz \m.Esoo< 3mg nmmm .omWWHU :0Mmum \M m>eo ov \M mane 0m \M sea om .m.m .m.m .Ncofi em m:0maeooH :ou scum mumzum amoveHoz now Enamcme omuouanMfloocm may one comumasesoue coueuw o» EOOan fiasm Eouw He>uou=m commeao on» new mouaumuwmeou eooanuuwon :oo3uon awcmc0mua~om .m mumma \M mom sq as omm an we amm on es cma mm mood mum an an cam on ms omm on as has on mcoa - - . mug we no mam mm ms maa mm goo" memo: gem mm as ewm mm on cad ow eo nma am mesa new an as «am on ms Hon no we mma om mood . - . mom on es cod me we mma om flood maaa> a -umxamz «mm em mm ama fie we won oe so oma mm moOH mnm mm as new mm om sum mm mm “ma am Noon man an co sou ow so mna ”a no nma Hm acoa mcamuad “mam mama: M w wumca m W mama: M W Am>mov Amkeav umw> newumuoq luau: god a a: lame: so; 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Av Av LV .2 . £411? 1 u o r 10“ 1 .ON - v o s o n v n ~ _- n. o n c n N .-on r .8 2 >333. - 838. - ......._........_.......>r ........................_ m/Drl/Zoo 9'" .mHm>uoacm web m we muwobumn co>mm Eouu cmxmw who; mpfinum .NcoH :« wxuonu00u 2m cobmw 85 co esopm meduN noducHoz mo cow>mcon auoumumnwoz «H muzmmm __X\ 0! __>\o! 8 N. 0 Q o O n N . > xv! ~00. .....P»bp...... A ‘0 9 )r (1 m/ 01/100 0-" .8 u - ,m n o N _ JON W l 9 . . . . :50 W- N. a new — _ _ _ _ 4 a < — _ — _ _ > K .O. o \ \d .8 - >3: .8 N V V n O ION 0 O r \ .8 1 :3: 13 H N no. r A H .2 f o s o ... n 1 w 8 (a! Non. - — — _ — — — _ — — — p r h — NI Huh/zoo 6'“ commenced September 15 for EM 1, II, V and VII. McIntosh 0 from trees on EM rootstocks IV, X11 and XIII showed a slightly earlier onset of the respiratory climacteric. The reason for this earlier climacteric in these three rootstocks is not known, These rootstocks did not have a different ‘ elapsed period from full bloom to starch accumulation in comparison to the other rootstocks. with the exception of rootstock EM XII, all rootstocks commenced a climacteric rise within three calendar days of one another. 3, Storage quality Fruits from each of seven harvests from trees on seven EM rootstocks grown in one location under the same environments were evaluated following air storage for five months, or CA storage for eight months, The values obtained for ground color are given in Table 27, Ground color values at harvest are also included, Little difference was observed in ground color values at harvest over the course of a three week period within or between rootstocks, The average change for all rootstocks was onlv 0.2 units over the har— vesting period. During air storage, fruits from later har- vests from most rootstocks registered a considerable change in ground color from that observed at harvest, The ground color of very immature fruits remained essentially the same during the storage period, The ground color change in storage generally increased with maturity of the fruit at harvest, This is readily apparent from the average values for all rootstocks, The same general results were obtained 87 «zmmo now ommuouw <0 no usages opmw Noe umo cm uoNONN one: woman; on? .NooH em wxuouwuooe 2. eo>ow no women seem Npmo>uac :m>ow scum :wo«=Hoz mo mcmueu NoHoo ecsoum No scaumsHN>o omeucuwoowoo can «wo>u woman» a: .eN ideas .NOHOo unson onHo> who am umnnhu.N :N mo_nowc=N shown NoHOo seesaw :N unmouooc d N.m o.m h., N " e.e , N ;.N m.~ r ....m m... Q.m w. M." .u .. N. H. ..N c.e N.N :.m a w :.w a 1 e a a.» N Hon m.o c.m c e a.m I n w w c.m n m.w c.H. e.e H n.. n m. n N +., a n.o c.H N.e ..1 . i. n . e m e e , e.w s.¢ N.e u a :.q a N. a," a H Mn N NM...“ m 1,. N.N N.q N.4 a a -.N e . a.H N”. r H.w N.¢ w.« M e 9.: m w p q q H : N.q x.e r.1 N e o.m i N N m c h N N.w O.N O.N x , e.i : s e N p w w N.¢ O.N e.N x q N.¢ «.a n 1 L e e N.e O.N o.w O N w.e i a r 1 _ a a N.e O.N O.N a e 9.1 N e N.¢ : N H o.¢ O.w b.x c a m.¢ o m e.w m.r N N.w O.N a.N e m e.e w e o.e m v N n . O.N 3.N c e m.¢ h a r e N a N N.v O.N e.N x _ N.a n e N.a a.» e e.e O.N ..u r a c.w H q 9.1 c.e N w.". o.—" .a ... ....» r ._ his 3.. ,N N.e a." r a a.» a w a.q m s H wwm>uwz om~uo>< "Ham 23 ”Ha an H~> 2: > an >H 2: HH 2; H 2m “No>ua: quvW#OCx .WLHCOE for fruits following CA storage. The ground color change from that at harvest was greater after CA storage for eight months than after air storage for five months. Flesh firmness values of fruits from the seven EM rootstocks are given in Table 28, marked differences were observed at harvest within, but not between, rootstocks over the three week harvesting period. These differences were not readily apparent upon removal from air or CA storage, The average difference in firmness of fruits from all root- stocks between the first and the seventh harvest was 5,0 lbs. at harvest and only 0,9 lbs. and 0.6 lbs. after air and CA storage respectivelv, Flesh firmness values following storage were essentiallv the same within rootstocks for all harvests. Soluble solids values of fruits from the EM rootstceks are given in Table 29, A gradual increase was observed over the three week harvesting period. In general, the differ- ences observed at harvest were retained during air storage or CA storage. Ratings for appearance and eating quality following storage of the fruits from the seven EM rootstocks are sum, marized in Tables 30 and 31. Both appeérance and eating quality were found to increase with the maturity at harvest_ ln general. the fifth and sixth harvests were Judged the most desirable in appearance and eating quality and generally coincided with the harvest judged to be the closest to the preclimacteric minimum as was shown in Table 33. n.s~ o.m e.aa a.Ca c.cs e.as m.ci r.si n m.da n.s_ s.su n.c~ s._s s._i w.fls s.s~ c e.~a a.ms m.~s m.ss 9.:s m.;s s.~s a.ss m c..# w.ss a.ms o.cs w.sm m.~s m.ss ..ms e e.- c.ss s.~n r.es w.fin m... e.is c.wa m m.a~ :.- :.na @.~“ 0.1“ c.w~ x.- 3.,“ a w.~a m.w~ ..ms m.fls o.c~ a.m. ..NH s.np ” wwwucpv .n 1.s~ H.u~ a.si w.ss «.ca u._a m.ss m.:m u m.as e.sa _.s~ c.sr e.ss w.i“ a.s_ :.H_ ; n._s c.aw p.ws a.fir c.~s s.sm w.ss a.sa m c.ss a.ma r.~n :.m t.~s m.ss :.»s ;.,s e m.~_ m.ms m.ms ~.ns c.~s :.rs w.~i ~.~M « m.- h.~s e.pa ,.ms a.mfl c.w~ w.~n a.ma u a.ms m.qs s.m~ a.ms :._s s.pl o.~w :.pm a Amimu~.pn uJAm 9 8 m.ns s.oH s.ms n.es m.ms n.r~ n.wfl t.ms s m.wH e.os a. a (.ms «.ms a.m_ e.e~ r.ms o p.c~ m. ; ..rm n.hs e.ns ”.en a.ma :.:u m o.o~ e.ns a.-s c.1s r.cs ,.nu m.ca e.:s v b.0s o.ns «.ma m.ms n.5a p.ns m.m~ H.»s m a.ms m.ms a.ms r.:s m.xa a.mw m.w“ «.ms m m.cm m.ea x.sm e.t. .cn o.cs e.c~ 2.:n a umm>um: ammum>< HHHX 2m HH< 2m “Hp :m » 2s >H 2s as :3 H :i pmw>eaz ..... Uh. u m use .0. m .wxu20E uzmwm new mmau0um mm no“ new cm venoud ewe: mafi:um 0:9 .moca :m wx90umaoou 2m cm>mm :0 ween» Edna wwwm>umz cmbww Edam mumsem :wc»c_u2 mo a.mouv www25umu meam no cofium5~m>e mmequwnuwog cue uwm>uez .-. .4 Average —v ...... - .. .4 .... XIII All EM 131 for five months or CA storage VII EM in air _‘ .. -—-s n... - .—v -n-'- .n“-__..—. stored otstock seven harvests from trees on seven EM rootstocks fruits were ht months. .. -m.—.—.—.--_ «fl--. . r -....r- - -. - ...—“mu..- -...__._.... fl L h fruits from T ’3 c... or 313 1”6 t f 5 Harvest and post-storage evaluation of flesh firmness (lbs,) of in Hclntosh ...“... 25, llar are? TlBLE Harvest dimclrtln-er‘ Q C O O C D O cook—hence :‘3—4'4 Ftp-0H ...-1.4.4.4...4...‘ Hmr’dr—ynnof- mrveJcInCuq .0 O. 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