174 



FUNDAMENTALS OF FRUIT PRODUCTION 



of departure for fat formation. Table 63 shows the seasonal variation 

 in ether extract in 7-year old apple trees. It is evident that the younger 

 the tissue, the more fat it contains and that the fat content is at a maxi- 

 mmn just before active growth begins and at a minimum after active 

 growth is over. 



Table 63. — Ether Extract in Percentages of Dry Weight in 7-year Old Apple 



Trees23 

 (Each figure is the average of analyses from two trees) 



In 

 bloom, 

 May 18 



Growth 



over, 

 July 12 



Leaves 

 falling, 

 Oct. 12 



New growth 



1-year branches 

 2-year branches 

 3-year branches 

 4-year branches 

 5-year branches 



Trunk 



Large roots 



Small roots 



5.00 

 3.03 

 2.39 

 1.57 

 1.14 

 0.79 

 2.02 

 4.06 



3.15 

 2.68 

 2.31 

 1.99 

 1.31 

 1.18 

 0.72 

 2.38 

 5.85 



4.11 

 3.01 

 2.92 

 2.71 

 1.07 

 0.91 

 0.70 

 1.31 

 6.55 



Characteristic differences between the starch content of bearing 

 and non-bearing spurs appear in Fig. 18. In winter the spurs with 

 fruit buds have more starch. Moreover starch accumulation commences 



2: s: 



Fig. 19. — Total sugar content of apple spurs in percentages of dry weight; bearing 

 spurs represented by continuous lines, non-bearing spurs by broken lines and barren spurs 

 by dot-dash lines. {After Hooker. ''■°'>) 



in non-bearing spurs in May and in bearing spurs in June. This differ- 

 ence is connected with carbohydrate utilization by the fruit. The 

 relation of this to fruit bud differentiation is discussed later. 



Sugars. — The seasonal variation in the sugar content of spurs is 

 shown in Fig. 19. The rapid drop in sugar during the spring is explained 



