Arizona republican., 1921-12-18
River valley should they once gain q foothold
 Selection and Breeding

Selection and Breeding
 Some of our growers have errone- ous ideas of selection. They forget that the practical purpose is to main- tain the type of the variety in the highest degree of uniformity, and type by preserving plants. which usu- ally are hybrids or abnormal indi- viduals. The idea that 1t is possible to secure. further improvement of cotton by selecting especially large bolls or bolls with four locks does not appear to have any basis in fact. The proposition of three lock and four-lock bolls in the Pima cotton varies with the conditions of growth, as in other varieties. The number of locks is not constant in any va riety. Bolls with five locks are an indication of crossing with upland cotton and are not a normal char acter of the Pima variety
 Superiority of Pima Cotton
 Uniformity of the fibre is essential to high quality, especially in long staple cottons. The superiority of the Pima variety is a result of the careful and continued selection that has been applied in developing the variety and maintaining the seed supplies. The present Pima variety traces back to the selection of a single superior plant from the Yuma variety previously develnn"i by se- lection from the well known ''mitaf- fir variety, imported from Egypt. The SubstitutionS of the Pima va riety for the parent Yuma stock was undertaken in 1915, but was not rec commended until exhaustive tests and comparisons had shown marked su- peroirity of the new type in several important characters. Pima was found to be of more productive habit, earlier maturity, larger bolls, longer fibre and greater abundance of lint. Tn the opinion of this committee, such tests and comparisons by disinterest- ed experts, form the only rational basis for selecting the proper variety of cotton to be grown in this district or for changing from one variety to another
 The basic strain of the Pima va riety was produced at Sacaton as a result of systematic selection and breeding work carried on by Dr. Kearney. This work is being con tinued every year. Comparisons are made each year with seed of the original stock and seed from the rogued field at Tempe and seed of the progenies resulting from more re-
 
 progeny selections trace back in an unbroken line to the original plant of the Pima variety selected in 1910.
 Maintaining the Purity of Pima
 The system of maintaining varietal purity is as follows: A carefully se- lected field near Tempe is planted each year with seed that traces back directly to the original plant of the Pima variety. This field is gone over plant by plant during the growing season by experts from the United States department of agriculture wbo pull out every plant that differs in the slightest degree from the Pima type. This field is known as the ''rogued'' field and the seed cotton from this field is ginned separately with every precaution again contami- nation. The seed from this field is known as "rogued seed"
 Each year a number of carefully selected fields in the Tempe district are planted with this rogued seed. These fields are examined at least once during the growing season to be sure that there has been no accident al contamination of the seed supply of persistence of volunteer plants of another variety or of hybrid origin These fields are known as inspect ed'' fields The seed cotton from these fields is also ginned with es- pecial care. and the resulting seed is known as inspected seed" Eacf year this inspected seed is planted or selected fields in a district known tt be free from contamination with un- selected stocks of seed. The result i ing crop of seed cotton Is ginned sep l arately, the seed delinted and sacked at the gin and stored in specia 1 warehouse. This stock of seed whicl | is then available for general planting | is certified by the Maricopa County | Farm bureau and is known as "certi. 1 fled seed.''
 By this system of handling the seeC l supply, every necessary precaution il taken to assure the cotton grower' l an adequate supply of pure seed, O