RESULTS OF SELECTION WITH SELF-FERTILIZED CROPS 125 



TABLE XXV. THE RELATION OF WEIGHT OF GRAIN TO YIELD IN OATS 

 Four- Year Average Results 



A current popular belief is that plants from large or heavy seeds 

 yield more than plants from light or small seeds. The data col- 

 lected by various investigators do not substantiate this view. 

 As a matter of fact, from a practical viewpoint it would be 

 difficult to demonstrate any increase in yield as the result of the 

 use of a fanning mill. The fanning mill, however, is very useful 

 in removing weed seeds or diseased light grains. 



SELECTION FOR THE PURPOSE OF ISOLATING PURE LINES 



The determination of the better selections requires at least five 

 years. Accordingly, there have been consistent attempts to 

 find some character or characters which were so closely associated 

 with yield or other economic qualities that they were of actual 

 selection value. If such could be found it would be possible to 

 use them as checks on the yield results. Manifestly they would 

 be of especial value in the early period of head selection, for the 

 results from short rows planted from individual heads are not 

 very accurate indications by which to discard selections. 



In this connection DeVries (1907) states that " correlation 

 between botanical marks and breeding qualities are to be con- 

 sidered as reliable guides in the work of selection." As an illus- 

 tration of such correlations, the belief that there is an association 

 between two-grained spikelets of oats and yield may be mentioned. 

 Some of the early data collected at Svalof indicated that such 

 was the case. After fifteen years further study, five or six of 

 the best yielding oat varieties were examined. Some were three- 

 grained types and others were two-grained types. Newman (1912) 

 in summarizing these results concludes that "there seems, there- 

 fore, to be no definite relationship between the yield of a given 

 strain and the number of kernels per spikelet by which it is char- 

 acterized." The relationship between other characters was 



