FRUIT PRESSURE TESTERS \) 



nitrated plots were considerably softer at harvest but not after storage. 

 Aldrich (2) obtained inconsistent results in that in most instances 

 nitrogen fertilization had no effect on firmness, but in one instance it 

 resulted in softer apples and in other instances in firmer apples. 

 Degman and Weinberger (21), working with apples and peaches, 

 concluded that it was impossible to find any direct influence of nitro- 

 gen on the firmness of the fruit. Haller and Harding 4 found that 

 nitrogen fertilization considerably reduced the firmness of York 

 Imperial apples when thinned to the same leaf-to-fruit ratios and in 

 seasons of deficient rainfall. 



In a report by Degman and Weinberger (21), Weinberger concluded 

 that peaches from plots receiving potash in addition to nitrogen were 

 no firmer than those from plots receiving nitrogen alone. The same 

 conclusion was applicable to apples, except that one source of potash 

 (sulfate of potash magnesia) resulted in a definite increase in firmness. 

 Phosphate fertilizer did not affect the firmness of apples or peaches. 



Thinning and Size of Crop 



Hartman (32) determined the firmness of pears from 50 heavily 

 loaded and 50 lightly loaded trees and found the fruit from heavily 

 loaded trees to be much softer (4.5 to 5.5 pounds). He attributed the 

 lower test to the more advanced maturity of the fruit on heavily 

 loaded trees. Haller and Magness (30), studying apples grown on 

 ringed branches with different leaf-to-fruit ratios, found that Ben 

 Davis apples were softer when grown with a large leaf-to-fruit ratio 

 representing a light crop. With York Imperial, Baldwin, and 

 Jonathan apples, however, the softest apples were those grown with 

 intermediate leaf areas (medium-size crop), and those with large leaf 

 areas (light crop) were firmer. Other factors indicated that the 

 firmer apples grown with large leaf areas were also more mature. 

 With treatments applied to whole apple trees, Haller and Harding * 

 found that fruit from heavily loaded trees was firmer at harvest than 

 that from lightly loaded (thinned) trees. However, the apples from 

 the heavily loaded trees softened more rapidly in storage and became 

 softer after 6 months at 32° F. These results indicate that the size of 

 the crop may influence the firmness of fruit, but in either direction. 

 It is doubtful whether this indicated a corresponding change in 

 maturity. 



A heavy preliminary picking of pears has been reported (32) to 

 retard the softening of the fruit remaining on the trees even though it 

 continues to mature. On the other hand, Allen (6) found that a pre- 

 liminary picking had no effect on the softening of the remaining fruit. 



Fruit Size 



Murneek (52) reported that the size of the pears on a tree did not 

 influence their pressure test. However, heavy irrigation of trees 

 under deficient soil-moisture conditions has increased the size and 

 reduced the firmness of apples (26). On the other hand, when the 



! Unpublished data by M. H. Haller and P. L. Harding. 

 407589° 



