Park : Selection in Broom Corn 



215 



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"CENTRAL STEM" IN BROOM CORN 



Figure ll. On the left are shown three heads having the undesirable character, central 

 stem. On the right are two stemless heads. Central stem greatly reduces the value of the 

 crop because "Stemmy" heads are of small value in making brooms. The fact that seasonal 

 conditions cause the amount of central stem to vary from year to year has led growers to 

 believe that the kind of seed used made no difference. The present investigation shows that 

 this is by no means true. It is quite possible to select strains that produce only a relatively 

 small number of "stemmy" heads even in unfavorable years. As yet no strain has been 

 isolated that is entirely free from this undesirable character. 



The season of 1921 was a poor one 

 for all grain crops, because of drought. 

 The following year was slightly more 

 favorable. Apparently conditions which 

 favor long brush also produce a low 

 percentage of stem and vice versa, 

 though it is not easy to see just what 

 elements in the environment produce 

 the effect. 



An exception to the uniformity of 

 the seasonal rise and fall of the curves 



in Figure 10 occtirs in 1932 when all the 

 selections show a low per cent of stem, 

 but the two commercial varieties show 

 unusually high percentages. Also the 

 correlation of low percentage of stem 

 with long brush which prevails else- 

 where is reversed in this case. This 

 nonconformity of the 1922 crop is difB- 

 cult to interpret. Does the small 

 amount of stem indicate progress in the 

 selection towards its elimination, uni- 



