SELECTIOX WITHOUT ARTIFICIAL CROSSIXG. 



45 



A representative of the Office of Farm Management several 3'ears 

 ago reported that m a certam community in one of the Western 

 States farmers generally planted white and yellow corn in alternate 

 rows in their seed patches. In this Avay they were sure of getting 

 the vigor that comes from hybridization in the corn to be used for 

 the general field crop the next year. Some of the farmers simply 

 planted theu^ whole field m alternate rows of yellow and white corn, 

 and the next year used seed selected out of this field for planting. 

 The next year they would go back again and get pure yellow and 

 pure white corn from some outside source and start over again, but 

 this is a crude method which gets advantage of the hybridization 

 only every other year. A better plan would be to get two good 

 varieties of corn, both known to be adapted to the conditions, and 

 plant a seed patch somewhat more than twice as large as needed to 

 produce seed for the fields the next year, planting the two varieties 

 in alternate rows in the seed patch. In one-half of the seed patch 

 one of these varieties is detasseled and m the other half the other 

 variety is detasseled. On both sides of the seed plot the detasseled 

 stalks would bear only hybrid grains. On the other hand, the stalks 

 that were not detasseled would be fertilized by pollen from stalks 

 of the same variety, except in the middle of the patch, where there 

 would be some cross-pohination between the two varieties. At har- 

 vest time pure seed of the two varieties is selected for the next year's 

 seed plot from the extreme sides of the plot, where there has pre- 

 sumably been no cross-fertilization between the two varieties, while 

 seed for the general field crop is selected from the detasseled stalks 



established, and a few farmers are changing their practice accordingly. This is quite 

 easily done, by planting in one row one variety, and in the next another variety, 

 and removing the tassels of the one as soon as they appear. The ears forming on 

 the rows having the tassels removed will be fertilized with pollen from the other 

 rows, thus producing a direct cross between the two A'arieties. The seed should be 

 selected from the rows having the tassels removed, and the experiments indicate 

 that it will pretty certainly give a larger yield than the average of the parent varieties 

 when planted under like conditions. 



In a comparison of five crosses with the average yields of their parents the aA'erage 

 increase in yield due to having crossbred seed in the experiments above referred to 

 was 9.5 bushels. 



Again, in Bulletin 31 of the Illinois Agricultural Experiment Station the same 

 authors make this recommendation: ■"Farmers can produce crossbred seed in con- 

 siderable quantities in the following manner: Plant with one variety in one planter 

 box and another variety in the other. Remove the tassels of one variety before they 

 begin to shed pollen, and the shoots of the same will be fertilized with pollen from 

 the other variety, thus producing a direct cross. The seed should be selected from 

 the rows from which the tassels have been removed." 



In three out of four comparisons between crosses and their parents reported in the 

 bulletin last referred to the crosses outyielded the parents, the average increase being 

 2.3 bushels per acre in favor of the crosses. 

 165 



