-4- 



even when the fruit all come from the same tree on the same date. Obviously, 

 there are factors that affect the movement of Ca into individual apples, since 

 apples of a given size and variety can vary considerably in the total amount of 

 Ca they contain (Perring and Jackson). 



Perhaps the most dramatic variation from this pattern is found with very small 

 apples. Perring has observed that very small apples (which should have high Ca) 

 sometimes are heavily afflicted with bitter pit. We have also observed that very 

 small Mcintosh and Delicious are sometimes severely broken down. We have also 

 noted that these small apples with breakdown often contain no, or almost no, 

 plump seeds, and in a recent study we found that in Delicious, fruit Ca concentration 

 decreased as seed number decreased, even when the fruit were all the same size. 

 We have also noted that Mcintosh with few or no seeds tend to mature earlier 

 than ones with many seeds, as as is well known, more mature fruit tend to 

 deteriorate faster than less mature fruit. Thus, seed number may be one cause 

 of the variation in Ca concentration among fruit of a given size. Poor pollination 

 may contribute to low fruit Ca. 



The absolute relationship between apple size and Ca concentration changes 

 somewhat from year to year (Perring and Jackson) and also varies considerably 

 from variety to variety (Perring), even when bulk samples are analyzed. For 

 example, Perring found that for a given size of fruit, Mutsu contained a higher 

 Ca concentration than did Cox, although in both varieties the general pattern 

 of Figure 1 was displayed. 



These findings demonstrate that while there is not an absolute fruit size: fruit 

 Ca relationship, there certainly is a strong and highly important general relationship. 

 When growing conditions are such that average fruit size is increased for a variety, 

 average fruit Ca can be expected to be lowered, and with this lowering of fruit 

 Ca concentration there is increased potential for fruit disorders during and after 

 storage. 



This situation creates a paradox for apple growers. Production of larger fruit 

 can increase yield substantially, thereby increasing potential income substantially. 

 However, this greater fruit size creates a greater Ca problem, and needs to be 

 accompanied by remedial actions to prevent reduced storage life of the fruit that 

 have been produced. Production of larger fruit increases then need for foliar 

 applications of Ca and/or for postharvest Ca treatments to the fruit. 



It is the opinion of many investigators that the "calcium problem" of apples 

 that exists world-wide today is one that has been created by intensive production 

 methods that have increased average fruit size and yield. It is unlikely that the 

 need for high productivity will diminish with time, and so it is also unlikely that 

 the need for Ca treatments will diminish with time. 



Literature Cited 



1. Perring, M.A. 1979. The effects of environment and cultural practices on cal- 



cium concentration in the apple fruit. Commun. Soil Science and Plant 

 Anal. 10:279-29 3. 



2. Perring, M.A. and C.H. Jackson. 19 75. The mineral composition of apples. 



Calcium concentration and bitter pit in relation to mean mass per apple. 

 J. Sci. Food Agric. 26:149 3-1502. 



