4 BULLETIN 38, U. S. DEPARTMENT OF AGRICULTURE. 



quality of the fiber, which more nearly resembles that of the Egyp- 

 tian Jannovitch. Other promising types have since been developed 

 in Arizona by the Department of Agriculture and are being tested in 

 comparison with the Yuma variety. 



The methods used in this plant-breeding work are simple. In the 

 first planting of imported seed every individual plant was examined. 

 The productiveness, earliness, habit of growth, and size of the bolls 

 were noted, and the lint was combed out on the seed, measured, and 

 pulled to test its strength. The best individuals were then selected 

 and the seed from each was saved separately. In the following year 

 the seed from each selection was planted in a " progeny row," the 

 rows being side by side and of equal length. It now became possible 

 to compare the different selections on the basis of the uniformity and 

 desirability of their progeny and to discard rows in which the plants 

 showed much variation or were for the most part inferior. All 

 plants in the superior rows were then compared, the best individuals 

 were selected, and their seed was planted in progeny rows the follow- 

 ing spring. 



This procedure has been repeated each year. When a strikingly 

 superior progeny row, such as that from which the Yuma variety 

 originated, is discovered, an isolated field is planted with the seed 

 and the inferior and off-type plants are rogued out before they come 

 into blossom. By repeating this process of roguing several years in 

 succession a high degree of uniformity is attained. 



HOW THE FARMER MAY KEEP HIS SEED PURE. 



Thus far we have been discussing the work of the plant breeder in 

 producing new strains and varieties. No less important, however, 

 is the maintenance of a variety after it has been developed, and here 

 the cooperation of the grower is necessary. Take, for example, the 

 Yuma variety, which is now being grown in the Salt River Valley. 

 The grower should become thoroughly acquainted with the appear- 

 ance of the plants, so that he may learn to recognize the characters of 

 the leaves, bracts, and bolls which belong to typical Yuma cotton. 

 This can scarcely be done by reading a printed description, but M r hen 

 the characters have been pointed out by a person who is familiar with 

 them they are not likely to be forgotten. With this knowledge well 

 in mind, the farmer should then go over the field from which he 

 expects to save seed for next year's planting and should rogue out 

 every plant which strike^ him as not typical. The work had better be 

 done before the plants begin to blossom, so as to avoid contamina- 

 tion of the good plants with pollen from the bad ones. A second 

 roguing when the bolls begin to set is also advisable in order to re- 

 move any untypical plants that may have been overlooked the first 



