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EFFECTS OF MINERAL NUTRITION ON KEEPING QUALITY 

 OF MASSACHUSETTS McINTOSH: RESULTS OF A FOUR-YEAR SURVEY 



W.J. Bramlage, M. Drake, S,A. Weis, and C.A. Marmo 

 Department of Plant and Soil Sciences 



During the past 4 years we have been sampling commercial Mc- 

 intosh orchards in Massachusetts and comparing the mineral con- 

 centrations in fruit at harvest with their keeping quality after 

 storage. Full details of the procedures and of the results with 

 apples from regular air storage have been published in the Proceed- 

 ings of the 1983 Massachusetts Fruit Growers' Association, Inc. 

 Annual Meeting; only the thrust of those findings will be presented 

 here . 



Between 1979 and 1982, a total of 172 orchard blocks of Mc- 

 intosh were sampled. Samples came from 6 counties in Massachusetts. 

 Fruit samples for analyses were taken 2 weeks before harvest, and at 

 the start of commercial harvest 2 bushels of fruit were taken from 

 each block. These 2 bushels were stored at the Horticultural Research 

 Center in Belchertown, 1 bushel at 32°F in air storage, and 1 bushel 

 in CA storage. Only results for air storage are reported here. 



The air-stored fruit were removed in late January or early Feb- 

 ruary and placed at 70-80 F. After 1 day they were tested for firm- 

 ness and after 1 week they were examined for the occurrences of break- 

 down, scald, rot and bitter pit. Bitter pit was so infrequent that 

 data for it have been omitted. The average Ca and Mg concentrations 

 were quite uniform across the 4 years, and the concentrations of K 

 and P were only slightly more variable (Table 1). The concentrations 

 of N changed dramatically, however, falling by nearly 50% between 

 1979 and 1981. The cause of this decline is not known, but no com- 

 parable reduction of leaf N has been observed during this period. 



The ranges of mineral concentrations among orchards are also 

 shown in Table 1. For Ca , in each year there were very broad ranges, 

 with some samples containing twice as much Ca as other samples. Many 

 of these orchards used calcium chloride foliar sprays during this 

 period, which likely contributed to this wide range. For K, P and 

 N there were approximately 50% ranges, i.e., some samples contained 

 50% more of the element than other samples. For Mg , less than 

 a 50% range existed in all years but 1980. Thus, Ca was the most 

 variable element in fruit from these orchards. 



