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Journal of Agricultural Research voi. xviii, no. i 



The nitrogen-free extract is the proximate constituent most charac- 

 teristic of the sorghum plant and the constituent for which the plant 

 is grown. The curves for this extract in the various parts of the plant 

 are assembled in figure 13. There is a pronounced increase in all parts, 

 most noticeable in the tops. Although the percentage of increase of 

 nitrogen-free extract is greatest in the tops, the absolute increase is 

 almost equally great in the juice because of the accumulation of sugars. 

 This fact is brought out in figures 5, 7, and 8. 



The ash curves are given in figure 14. There is a very apparent tend- 

 ency for the mineral material to accumulate in the leaves. This is 

 shown not only on the percentage basis but also on the basis of the 

 absolute weights of ash per plant "(figs. 6, 7, and 8). Figure 15 indicates 



Fig. 7. — Development of the proximate and mineral constituents of the bagasse of sorghum. 



that this accumulation of ash in the leaves is not due to potassium or 

 phosphorus, for the percentage of these undergoes a marked decrease. 

 No doubt calcium and silicon would be found responsible for the increase 

 in mineral matter if analyses had been made for these elements. The 

 mineral matter in the other parts of the plant remains practically con- 

 stant throughout the periods of growth studied here. Figure 15 shows 

 that potassium is more abundant than phosphorus in all parts of the plant 

 except the tops, where the phosphorus towards maturity accumulates 

 in greater amount. This relation is perfectly normal; it obtains in the 

 seed of practically all plants. The prominence of nitrogen in the tops 

 and in the leaves, and of potassium in the stalks (bagasse), is also charac- 

 teristic of most plants. 



