is necessary to assess additionally other charac- 

 teristics to get the most accurate picture of the 

 difference in ripening. Soluble solids (or sugars) 

 generally increase in concentration during the 

 course of ripening as the result of the breakdown 

 in starches. Table 3 give the soluble solids 

 concentration of fruit from these trees in 1990, 

 1991, 1992, and 1993. Fruit from trees on B.9, 

 MAC.39, P.22, P.2, or P. 16 consistently were 

 among those with the highest levels of soluble 

 soUds. On the other hand, fruit from trees on 

 MAC.l, seedhng, M.4, M.7 EMLA, B.490, P.18, 

 or A.313 were consistently among the lowest. 



Starch breakdown is measured easily by 

 staining cut apples with an iodine-potassium 

 iodide solution. Iodine stains the starch blue. 



leaving a distinctive pattern. This pattern 

 changes during ripening in a regular way and 

 can be compared to a standard chart to assess 

 the progress of ripening. The index used in this 

 study ranged from one to nine, with one staining 

 densely and nine not staining at all. The index, 

 therefore, increases during the course of ripen- 

 ing. Table 4 reports starch index values from 

 this study for 1990, 1991, 1992, and 1993. Fruit 

 from trees on B.9, P.22, P.2, or P. 16 consistently 

 were among the highest for starch index; 

 whereas, fruit from trees on seedling, MAC.l, 

 M.4, A.313, or P.18 consistently were among the 

 lowest. 



As starch breaks down to sugar, osmotic 

 imbalances may occur in the flesh of apples 



Fril/t Holts, Summer, 1994 



15 



