234 



Journal of Agricultural Research 



Vol. in. No. 3 



all of the remaining varieties were about five weeks later in reaching full 

 maturity. It appears, therefore, that a degree of defoliation which but 

 slightly modified the size and oil content of the seed in those varieties 

 requiring a long period for the development of the seed brought about a 

 much more decided effect in the variety which is able to fully develop 

 rather large-sized seed in a very short period of time. Another reason 

 for the greater effect of the defoliation on the size of the bean, as well as 

 on the total yield of beans, in S. P. I. No. 21755 is that the fohage 

 normally is less abundant than that of the other varieties. 



Table IV. — Oil content of soy beans as affected by partial removal of very young seed pods 



Variety and treatment. 



S. P. I. No. 32907: 



Control 



I^arge number of pods removed 



on Aug. 19 



S. P. I. No. 21755: 



Control 



Larger portion of pods removed 



on July 15 and 22 



S. P. I. No. 30599: 



Control 



Larger portion of pods removed 



on July 1 5 and 22 



S. P. I. No. 3074s: 



Control 



Larger portion of pods removed 

 on July 15 and 20 and Aug. 19.. 

 S. P. I. No. 30593: 



Control 



More than two-thirds of pods 

 removed on July 15 and 20 

 and Aug. 12 



Aver- 

 age 



Date of weight 

 blooming. | of stalk 

 and 



July 30. . 



...do 



July 8. . . 



..do.... 



..do.... 



..do.... 



..do.... 

 ...do.... 

 ...do... 



do. 



Gm. 



36.3 



49-7 

 9-7 

 9.0 



24-5 

 36.2 

 24.5 

 38.7 



27-2 



42.1 



Oil in 



1,000 



beans. 



Gin. 



14.4 



iS. 2 

 33-9 

 32-4 

 35-8 

 40-4 

 38-1 

 43-7 

 39-8 



48.8 



It might be expected that the effects produced by removing a portion 

 of the young seed pods would be largely the reverse of those produced 

 by partial defoliation, and this is found to be true in part. Removing 

 a portion of the pods resulted in much heavier root and stalk. The 

 effect on yield of the reduction in the number of beans allowed to de- 

 velop is offset to a considerable extent by a notable increase in the size 

 of the beans- The increase in the size of the bean is not associated with 

 a corresponding decrease in the percentage of oil; hence, the actual 

 quantity of oil in the individual seed is considerably increased. Here, 

 again, the early-maturing variety, S. P. I. No. 21755, stands out as an 

 exception. Reducing the number of seed allowed to develop failed to 

 increase the weight of the vegetative parts or the size of the seed and 

 its oil content. 



Considering the two sets of experiments together, when the develop- 

 ment of the seed extends through a relatively long period, a reduction 

 of, say, 50 per cent in the normal proportion of leaves or photosynthetic 

 organs leads to a decreased weight of the other vegetative parts, as well 

 'as of the total yield of seed, but the size of the seed is only slightly re- 



