172 



FUNDAMENTALS OF FRUIT PRODUCTION 



the same picture is presented except an increase from December to April, 

 accounting for which is difficult. The minimum in May is apparent, but 

 the maximum in September does not appear, as samples were not collected 

 at that time. 



In all the data presented, the roots have shown a higher percentage 

 and a greater fluctuation in carbohydrate than the shoots. However, 

 this does not indicate a greater absolute carbohydrate content. Esti- 

 mates by Curtis^^ indicating the probable relationships at the time of bud 

 swelling (April) are shown in Table 61. According to these figures the 



Table 61.- 



-EsTiMATED Number of Pounds of Carbohydrate in Tops and Roots 

 OF A 7-year Old Apple Tree^'' 



1 year twigs 1 



Older branches 5 



Trunk 5 



10 



25 



Large roots 5.71 



Small roots 2 . 43 



Total 13.24 



Total . 



14 



portions of a tree above ground contain half again as much as the roots. 

 The conditions found in apple spurs are shown in Table 62. These 

 figures evidently are comparable to the data of I^e Clerc du Sablon on the 

 pear and chestnut. 



Table 62. 



-Total Carbohydrate (not Including Crude Fiber) of Apple Spurs' 

 (In percentages of dry weight) 



Bearing (average 

 of three trees) 



Non-bearing 



(average of two 



trees) 



March . . 

 May 13. 

 June 25. 

 Sept. 2. 

 Nov. 19 

 Jan. 24. 



25.1 

 24.0 

 25.2 

 30.1 



24.5 

 23.9 



The increase in carbohydrate from May to September is explained by 

 the assimilatory activity of the leaves. The decrease from September 

 to May must be attributed to several factors. The major part is due to 

 the use of carbohydrates for the formation of other substances — probably 

 of nitrogenous compounds which increase in September and of fatty 

 substances, which are discussed presently. The decrease in carbo- 

 hydrate is also in part the result of consumption in respiration, which 

 proceeds from September to May, but most actively after growth has 

 begun and in part the result of translocation into the newly developing 

 leaves, flowers and eventually fruits. Hence the lower minimum in the 



