Richey: Use of Greenhouse in Corn Breeding 



395 



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GREENHOUSE-GROWN CORN 



These fifty-four ears were produced by the plants shown in Fig. 4. The flowers were pol- 

 linated by hand; although the ears are small, the seeds are well-developed, "the average weight 

 of 100 from each ear being 28 . 5 grams in comparison with an average of 28 . 9 grams per 100 seeds 

 of the parents." These ears were harvested 153 days after the emergence of the plants. (Fig. 5.) 



Emergence was complete on October 

 19, 7 days after planting. The tem- 

 perature was maintained at from 70° 

 to 90° F. during the day and at from 

 68° to 70° F. at night. Under these 

 temperatures and with the unusually 

 bright weather that obtained during 

 the winter, the plants developed rap- 

 idly, and were 32 to 40 inches high on 

 November 26, 38 days after emergence. 

 The plants silked between January 7 

 and 21, or in from 80 to 94 days after 

 emergence. In contrast, the parent 

 strains silked in from 65 to 79 days 

 after planting, when grown under field 

 conditions in Arkansas in 1920. The 

 plants grown in the greenhouse were 

 vigorous and attained a good size. 

 This is shown in Fig. 4, which gives a 

 general view of the house on January 

 31. The cross braces in this illustra- 

 tion are six feet high. 



The 54 hand-pollinated ears shown 

 in Fig. 5 were harvested on March 21, 

 153 days after the plants emerged. 

 Thirty-eight of these ears were self- 

 fertilized, and although small, there 

 were enough seeds to answer the pur- 

 pose. The seeds were well developed, 

 the average weight of 100 from each 

 ear being 28.5 grams, in comparison 

 with an average of 28.9 grams per 100 

 seeds of the parents. Kernels from 

 these selfed ears have been planted, 



have given as good a stand as field 

 grown seed, and will be used as the 

 basis for a second cycle of selection 

 within self-fertilized lines. The use of 

 the greenhouse, therefore, has saved a 

 full year in the accomplishment of the 

 breeding program. 



DISCUSSION 



The greenhouse does not seem to 

 offer much usefulness in the earlier 

 years of selection from a commercial 

 variety of corn. The percentage of 

 culls is so large during these years that 

 field conditions seem essential to pro- 

 vide enough material for selection. 

 However, in later years there are many 

 phases of the corn breeding problem that 

 suggest themselves as being adapted 

 to greenhouse manipulation, and it 

 seems that if breeding operations were 

 on any considerable scale, the main- 

 tenance of greenhouse facilities for 

 annual use in connection with them 

 would be entirely warranted. 



The height of the corn plant, its 

 need for abundant room, and the 

 necessity for maintaining relatively 

 high temperatures, require the pro- 

 vision of special facilities planned for 

 this particular crop. The best type of 

 house is one that has no side benches 

 and has as low a solid wall as possible. 

 The light requirement seems of the 



