Oct. 1, 1919 Notes on the Composition of the Sorghum Plant 27 



better than most crop plants, it can not develop normally, as is shown 

 by the low content of solids in these samples and by the high purity of 

 of the juice during the early periods. As regards the latter, it should be 

 kept in mind that the "purity" means the relative proportion of total 

 sugars in total solids. In an immature cane the purity is low, as is shown 

 by the curve for the Virginia samples. The relatively high purity of the 

 Minnesota samples is another example of the oft-observed fact that 

 during periods of unfavorable growth conditions a plant attempts to 

 reach maturity as quickly as possible. Usually this is evidenced in the 

 reproductive parts alone ; in the sorghum it is apparent also in the com- 

 position of the juice. 



The curve representing the percentage of nitrogen in the juice remains 

 practically level. This signifies that the absolute amount of nitrogen 

 must increase clear to maturity. The nitrogen compounds comprise a 

 prominent portion of the nonsugar solids, and the flatness of the nitro- 

 gen curve is in harmony with that of the purity curve. 



VI.— EFFECT OF REMOVING THE SEED HEADS 



There are many references in the literature on sugar-producing plants 

 relating to the effect on the composition of the juice of removing the 

 fruiting parts of the plant. Collier {p. 138-140) found that removing 

 the seed heads at immature stages hastened the maximum production 

 of sugar in the juice, but that this maximum was the same as that in 

 unheaded stalks, although in the latter it was reached a week or 10 days 

 later. Thus the effect of heading the cane was to hasten the maturity 

 of the juice but not to increase its potential sugar content. Wiley {ig) 

 reports analyses which show very slight differences in favor of topping. 

 Heckel (9) reports an increase in sucrose in both corn and sorghum due 

 to removal of the floral parts. It is not clear from the latter data, 

 however, whether only the sucrose is increased or the total sugars as 

 well. Other work shows similar inconclusive data on this question. 



For two seasons heading experiments were conducted at this station. 

 The results are presented in Tables II and III. It will be seen that in 

 general the data corroborate Collier's conclusions that heading merely 

 hastens the maturity of the juice but does not affect its final composi- 

 tion. There is some evidence that the amount of starch produced is 

 increased, but the differences are too small and the number of analyses 

 too limited to warrant any definite conclusions. From the standpoint 

 of sirup manufacture, the removal of the seed heads should be practiced 

 in order to bring about an earlier maturing of a portion of the crop, 

 although by so doing the value of the seed would be lost. 



