• Pima Cotton Genetics

      Percy, R. G.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      A feasibility study of short season management in Pima cotton, using short season genotypes, was initiated in 1993. Four short season genotypes, a full season check, and a short season check were evaluated in replicated tests under short season and full season regimes. In this first preliminary year of data, no significant yield loss could be attributed to management regime or to earliness of genotypes. Three of the putative early maturing genotypes exceeded the full season Pima S-7 check in yield. Results were contrary to expectations. The short season test is planned for repeat in 1994. An investigation of a virescent mutant discovered in 1990 (CM-1-90) was conducted in 1991, 1992, and 1993. Crosses of the mutant to Pima S-6 to determine inheritance, and to various virescent mutants to determine allelism produced results which were anamolous to normal, nuclear inheritance. Reciprocal crosses to PS-6 and to various virescent mutants confirmed that the new mutant was cytoplasmicaly inherited.
    • Pima Cotton Improvement

      Percy, R. G.; Turcotte, E. L.; Ray, I. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Pima experimental strains P73, P75, P76, P77, and the cultivars Pima S-6 (PS-6) and Pima S-7 (PS-7) were grown in replicated regional tests at twelve locations across the Pima belt in 1993. Tests were machine harvested for yield determination, plant heights were measured, and lint samples were collected for fiber analysis. Considerable genotype by environment interaction for yield potential occurred across tests in 1993. Across all locations, the strain P76 ranked first in yield followed by the cultivar PS-7 and strain P75. Strains P73 and P76 produced fiber of equal or greater length, strength, and elongation than PS-7. Plant heights were greatest for the entries PS-6 and P75. Entries PS-7 and P73 were intermediate in height, while P76 and P77 were the shortest of the entries tested. Considering yield and fiber properties concurrently, P76 was the superior entry of the 1993 tests.