466 Plant-Breeding 



large a field can be planted if the yield has been at the rate of 

 200 bushels per acre ? 



Fourth and Subsequent Years. Continue this same scheme, 

 constantly discarding the poor units and selecting the best for 

 breeding. 



Estimate how large your breeding plot should be in order to 

 supply a 5-acre field with seed in the third year, supposing the 

 yield from your selected units to be the same as the average 

 yield given by the 25 best selected units in your former report, 

 i.e. about 370 bu. per acre. 



Scheme for Corn Breeding Plots 



All corn breeding and increase plots should be at least 1200 

 feet from any other corn. Why? 



First Year. Select front the field 100 ears. From these 

 choose the best 50 for planting a breeding plot the next year. 



Second Year. From these 50 ears, plant a breeding plot 

 by the ear- to-row method. Rows should be 4 feet apart, hills 

 3 feet apart in the row, each row to contain 100 hills. Surround 

 the breeding plot with 2 or more border rows planted with seed 

 from the unused select ears. Why? Detassel alternate halves 

 of adjacent rows. Why? Select from the best 10 or 12 rows 

 50 to 100 of the best ears, choosing the best 50 for the next 

 year's breeding plot. Save the seed from the other best-yielding 

 rows for an increase plot, or the general field. 



Third Year. Plant your breeding plot as before, with the 

 best selected 50 ears. With the other selected ears plant an 

 increase plot or general field. Select as before the best 50 ears 

 from the breeding plot for the next year's breeding plot, saving 

 the remainder for a new increase plot. Save ears from this 

 year's increase plot for planting next year's field. 



Fourth and Subsequent Years. As before, plant your breed- 

 ing plot, increase plot, and field, using a continuous and pro- 

 gressive scheme of selection. 



