Variation and Correlation of Oats — Part II 111 



Considerable difference is shown in average yield of culm per plant by 

 the means determined. This may be due to the difference in stand, 

 caused by the large size of kernels in certain varieties. The means of 

 height of plant seem to denote some varietal differences. The larger 

 yields from certain varieties are not due to a larger number of kernels 

 per culm, or to a larger number of spikelets per culm, as the means for 

 these characters are nearly the same for each variety. The yield per culm 

 seems directly proportional to the average weight of kernels per plant. 

 The average number of kernels per spikelet is largest in the Sixty Day 

 variety and smallest in Early Champion. The proportion of straw to 

 grain differs in the different varieties. As the average yield of culm per 

 plant increases, the proportion of straw to grain decreases — not entirely 

 regularly, however, for the different varieties. 



The standard deviation is probably the better index of variability, 

 when the same character of different varieties is being compared and when 

 the same unit of measure has been used. Basing conclusions on this 

 constant, then, it is seen that the greatest variability occurs in the Welcome 

 variety for all characters considered, except average weight of kernels. 

 In this character the variability of this variety is exceeded only 

 by that of the Great American. The least variability occurs in Great 

 American for height, number of kernels, and number of spikelets, 

 in Early Champion for yield and for weight of straw, and in 

 Sixty Day for average weight of kernels. Sixty Day is next to the 

 lowest in variability in all characters considered, except average weight 

 of kernels. The order of value of the standard deviations is the 

 same as that of the means, for yield, number of kernels, and weight of 

 straw; that is, the greatest variability in these characters is found where 

 the means are largest, and decrease in variability takes place in the same 

 order as decrease in means. In the number of spikelets the standard 

 deviation is highest when the mean is next highest, and next highest when 

 the mean is highest. The same condition exists for the lowest and the 

 next lowest standard deviations. Exactly the same conditions hold for 

 average weight of kernels as hold for number of spikelets. For height 

 there is more complication, the lowest standard deviation being associated 

 with the second highest mean, the second lowest standard deviation with 

 the lowest mean, and the second highest standard deviation with the 

 second lowest mean. 



