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be free from breakdown during storage, whereas at 3 mg/100 g fresh 

 weight the fruit is very likely to develop breakdown early in stor- 

 age. In Canada, Lidster, et al . determined that nearly this same 

 Ca level (4.5 mg/100 g) was required for maximum protection of 

 •Spartan* apples from breakdown in storage. Spraying and dipping 

 apples with Ca solutions before storage have frequently been effec- 

 tive in reducing internal breakdown. One spray program raised the 

 Ca level of the fruit from 3.7 to 5.4 mg Ca/100 g of fruit flesh, 

 and correspondingly reduced the occurrence of breakdown in storage 

 from 16% in the controls to 0% in the treated fruits. In Massachu- 

 setts, we have consistently found in recent years that in a given 

 situation, greatest incidence of internal breakdown occurs in the 

 apples with the lowest Ca content. 



There is, therefore, strong reason for a fruit grower who is 

 having difficulty maintaining fruit quality during storage, to be 

 concerned about Ca nutrition of the fruit. Unfortunately, it is 

 not easy to substantially increase Ca levels of apples. Ca is one 

 of the most abundant minerals in most soils, yet fruit frequently 

 contain inadequate amounts of this mineral. Apple tree roots do 

 not readily take up Ca from the soil, and what they can take up is 

 influenced by numerous soil conditions. Thus, lime and Ca fertil- 

 izers do not quickly or markedly increase Ca levels in apples. 



Leaves seldom show Ca deficiency symptoms even though fruit 

 may be severely deficient. What Ca is absorbed from the soil is 

 transported very slowly within the tree, and what is transported 

 is apparently directly by water use in the tree. Movement is 

 largely within the xylem (the water transporting system) . Early 

 in the season, small apples are using large amounts of water, and 

 relatively large amounts of Ca move to the fruit with this water. 

 By mid-season, however, apples are using much less water and are 

 also serving as a large depository for sugars and other organic 

 nutrients coming from the leaves. These nutrients are moving 

 through the phloem (the food transporting system) , in which Ca is 

 relatively immobile. Therefore, little Ca is transported to the 

 fruit late in the season, since the fruit are being supplied large- 

 ly by the phloem system. As a result, 901 of the apple's Ca may 

 move in during the first 6 weeks after full bloom. When water 

 stress occurs in the apple tree, water may be drawn from the fruit 

 to the leaves, and simultaneously Ca may be withdrawn from the 

 fruit. In this way, water stress may create or intensify Ca defi- 

 ciency in the fruit. 



The average Ca level in the fruit is considerably lower than 

 that in the rest of the tree. Within the apple fruit itself there 

 are large differences in the concentration of Ca. In the cortex 

 (outer flesh) of mature apples, Ca concentration declines steadily 

 from the stem end to the calyx (blossom) end, which is probably 

 why bitter pit and internal breakdown usually begin to develop (and 

 develop most intensively) at the calyx end of the apple. The apple 



