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BREEDING CROP PLANTS 



These early studies illustrate the general mode of production 

 of new potato varieties. Certain methods are of value in giving 

 the seedlings a good start. In the latitude of Washington, 

 Stuart recommends sowing the seed in the greenhouse early in 

 March and transplanting the seedlings from 3-in. pots into the 

 field in May. The plants are placed in rows 3 ft. apart and 

 spaced at a distance of 2 ft. apart in the row. Results indicate 

 that seedlings producing tubers of irregular shape or those with 

 deep red or purple skin may well be discarded after the first 

 year's trial. After another year's study those strains with 

 undesirable characters such as low yielding ability, undesirable 

 shape, deep eyes, unusual susceptibility to fungous diseases and 



FIG. 56. An unpromising first-year seedling. Crop of 1910. Note 

 large number of small, irregular shaped tubers. (After Stuart.) 



the 



straggling or weak vine growth, should be discarded and the few 

 more promising types given a wide test to determine their 

 adaptability and value under different conditions. 



Clonal Selection. The subject of bud mutations in potatoes 

 is a somewhat difficult one, for there are numerous reported cases 

 of such sudden changes. Many of the experiments were not 

 performed with sufficient care to furnish acceptable evidence, 

 although numerous apparently authentic cases of color changes 

 have been reported. As an illustration of carefully controlled 

 experiments those carried on by East (1910a) may be cited. In 

 these studies each variety worked with was started from a single 

 hill. During the course of the study, five permanent changes 



