248 



Journal of Agricultural Research 



Vol. VI, No. 6 



CORRELATION BETWEEN THE PERCENTAGE OF STERILE SPIKELETS AND 

 THE AVERAGE WEIGHT OF KERNEL 



To get the average weight of kernel per plant the total weight of ker- 

 nels per plant was divided by the number of kernels and the result 

 expressed in milligrams. The coefficient of correlation is —0.421 ±0.032 

 (see Table XI). This indicates a decided tendency for the heavier kernels 

 to be associated with a low percentage of sterile spikelets. This is in 

 accord with the relations found to exist between the length of culm and 

 spike and the percentage of sterile spikelets. The more vigorous plants, 

 as indicated iDy an increased length of culm and spike , generally bear kernels 

 of a larger size. Hence, the correlation between the percentage of 

 sterile spikelets and the weight of kernel — in other words, the quality of 

 the grain — is in the same direction and approximates the other coefficients 

 very closely . 



Table XI. — Correlation between the percentage of sterile spikelets per plant and the average 

 weight of the kernel in wheat ^ 



' r = — o.4209±o.0320. 



CORRELATION BETWEEN THE PERCENTAGE OF STERILE SPIKELETS PER 

 PLANT AND THE AVERAGE NUMBER OF SPIKELETS PER SPIKE PER PLANT 



A relationship is shown below between the percentage of sterile spikelets 

 per plant and the total number of spikelets per plant. The coefficient of 

 correlation is low, —0.152 ±0.037 (see Table XII). There is only a 

 slight tendency for plants with a low percentage of sterile spikelets to 

 be associated with a large number of spikelets per plant. As the number 

 of spikelets determines to a large extent the length of the spike, it would 

 be supposed that a greater correlation would exist between the number 

 of spikelets and the percentage of sterile spikelets. This may be ex- 

 plained by the fact that the total number of spikelets includes both fertile 

 and sterile spikelets. Also, there may be more or less variation in the 

 condensation of the spikelets which go to make up the spike. 



