SELECTION TO INCREASE PROTEIDS IN KERNEL. 



79 



Table 17. — Analyses of spikes of wheat, showing difference in froteid nitrogen. 



These results show that there may be large differences between 

 the proteid nitrogen content of spikes on the same plant. They do 

 not, however, indicate that the determination of the average com- 

 position of the kernels on a plant is not a safe guide for selecting 

 breeding stock. If the plant is the unit in reproduction, whether the 

 plant reproduces itself from one seed or another does not affect its 

 hereditary qualities in very marked degree. 



It is evident, from a comparison of the variations that occur in the 

 composition of the spikes from a single plant, and of the kernels on a 

 single spike, that it is impossible to do more than obtain a reasonably 

 close estimate of the composition of the kernels either on a part or on 

 the whole of a plant. It therefore becomes desirable to obtain as 

 closely as possible the average composition of the unit of reproduction. 

 If the plant as a whole, and not any particular part, is this unit, the 

 average composition of all of the kernels on the plant is a much, safer 

 guide as a basis for selection than is the average composition of the 

 kernels of any part of it. One row of spikelets from each spike 

 should therefore give the best sample for analysis. 



In Table 18 is given a statement of the percentage of proteid 

 nitrogen in the dry matter of the kernels on a row of spikelets of 800 

 spikes of wheat of the Turkish Red variety. These spikes were taken 

 from a field of wheat, and were selected with reference to length of 

 head, plumpness of kernel, uprightness of straw, freedom from rust, 

 etc. They are therefore not spikes in which high nitrogen content is 

 likely to be due to immaturity or arrested development." Variations 

 in the nitrogen content of different plants may in some degree be due 

 to a larger or smaller supply of available nitrogen, although all were 

 taken from the same field. Variations due to climate are, of course, 

 precluded, as all grew during the same season. 



« In practice undeveloped kernels are discarded. 



