246 



Journal of Agricultural Research 



Vol. VI. No. 6 



CORRELATION BETWEEN THE PERCENTAGE OE STERILE SPIKELETS AND THE 

 AVERAGE YIELD OE GRAIN PER SPIKE 



The average yield of grain per spike (Table VIII) was determined by 

 dividing the total weight of grain per plant by the number of spikes per 

 plant. The coeflficient of correlation between this yield and the percentage 

 of sterile spikelets is again negative, —0.589 ±0.02 5, which indicates a 

 much closer relationship between the low percentage of sterile spikelets 

 and yield of grain per spike than is shown between the same character 

 and the yield per plant. There is a rather high correlation existing be- 

 tween the percentage of sterile spikelets and the yield of grain per spike. 



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

 average yield of grain per spike in wheat ^ 



ir= — o. 5S8S±o.o2S4. 



CORRELATION BETWEEN THE PERCENTAGE OF STERILE SPIKELETS PER 

 PLANT AND THE AVERAGE LENGTH OF CULM PER PLANT 



In this case the average length of culm per plant (see Table IX) was 

 found by taking the sum of the lengths of the culms of a plant in centi- 

 meters and dividing it by the number of culms. The correlation coeffi- 

 cient is —0.448 ±0.03 1. This is a rather high degree of correlation and 

 is expressed as negative, although with reference to the relation of the 

 two characters compared it means that the longer culms tend to form a 

 lower percentage of sterile spikelets. This is what might be expected, 

 since the yield of grain per spike is generally closely associated with the 

 length of spike, and that in turn with the length of culm. 



