Dec. 15, 1914 Oil Content of Seeds and Nutrition of Plant 247 



the addition of phosphorus alone, very much the same results were 

 obtained; but with the addition of potassium alone there was only a 

 small increase in yield and practically no increase in oil content. In 

 similar tests with Spanish peanuts phosphorus gave a large increase in 

 yield and slightly increased the weight of the peas, but had no effect on 

 the oil content. Potassium had practically no effect on the yield, the 

 weight of seed, or the oil content. 



SUMMARY 



Experiments with soy beans have shown that, except for the period 

 immediately following blooming and that directly preceding final matu- 

 rity, there is a fairly uniform increase in oil content, both relative and 

 absolute, throughout the development of the seed, and no evidence was 

 found that there is a critical period of very intense oil formation at 

 any stage of seed development. Tests with cotton likewise indicate 

 that the increase in oil proceeds somewhat more rapidly than the in- 

 crease in the weight of the seed. 



As a consequence of the physiological relationship of oil to carbohy- 

 drate, it appears that maximum oil production in the plant requires 

 conditions of nutrition favorable to the accumulation of carbohydrate 

 during the vegetative period and to the transformation of carbohy- 

 drate into oil during the reproductive period. As a special phase of 

 this relationship between carbohydrate supply and oil formation in soy 

 beans, it was found that when the normal distribution of the vegeta- 

 tive and reproductive plant parts was modified by partial defoliation 

 (50 to 60 per cent) the yield of beans was decidedly reduced, but the 

 size of the beans and their oil content were only slightly affected, except 

 in the case of an early-maturing variety. On the other hand, the re- 

 moval of a portion of the blossoms or young pods caused a notable 

 increase in the size of the beans allowed to develop, but did not mate- 

 rially affect the percentage oil content. 



There is always lack of uniformity in the size of the seed from an 

 individual plant; but it was found that there was no correlation be- 

 tween the size of the seed and the percentage content of oil. 



Some varieties of soy beans show a marked tendency to shorten the 

 time required for reaching maturity when planted late in the season, 

 but no correlation was found between the date of planting and the 

 size of the seed or their oil content. These properties appear to be 

 influenced more by the character than by the length of the growing 

 period. 



Different varieties of soy beans grown imder the same conditions 

 showed marked differences in oil content and very great differences 

 in size of the seed. Although different varieties of cotton showed de- 

 cided differences in the size of the seed, there was very little difference 



