Variation and Correlation of Oats — Part II 



107 



At the above rate of seeding and under the other conditions of growth, 

 few plants of either of the varieties produced more than one culm per 

 plant. The frequency distributions for numbers of culms per plant are 

 as follows : 



Variety 



Number of culms per plant 



1 



2 



3 



1200 



300 

 295 

 295 



288 



5 



5 



11 





1219 . . 





1238 





1257 



1 







It is seen here that in 1200 plants, taken without selection from the rows, 

 there were but 1223 culms. 



The means (M), standard deviations (^), and coefficients of variability 

 (C) for six characters of these different varieties are given in Table 4. 



Taking up for consideration first the average yield of culm per plant, 

 it is seen that there is considerable difference in the means. The highest 

 is in series 1238, it being 8.217 ± .219 decigrams; the lowest is 3.433 ± 

 .096, in series 1219. For series 1200 the mean is 6.403 ± .149, and for 

 series 1257 it is 3.950 ± .102. The average yield per culm, which is 

 essentially yield per plant, is, then, for the varieties, in descending order 

 of yield, Welcome, Great American, Sixty Day, Early Champion. The 

 standard deviations follow exactly the same order as do the means, which 

 would indicate that the greatest variation exists in series 1238 and the 

 least in series 1219. The coefficients of variability, however, indicate 

 a different condition. For series 1219 this is 72.04 ± 2.82; for series 

 1238 it is 68.54 ± 2.62; for series 1257 it is 66.53 ± 2.51; and for series 

 1200 it is 59.75 ± 2.15. The greatest variability is thus indicated by 

 the coefficient of variability where the standard deviation indicates the 

 least. After an inspection of the frequency distributions for the different 

 series, one is inclined to consider the standard deviation as by far the 

 better index of variability in this case. 



