• Pima Cotton Genetics

      Percy, R. G.; Turcotte, E. L.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      Seed increase of 104 accessions and data collection on 65 accessions were obtained in 1988 to further the maintenance and evaluation of the Gossypium barbadense L. germplasm collection. In a program of conversion of tropical non flowering cottons to a day-neutral flowering habit, 63 accessions were advanced 1 generation by backcross. A systematic screening of the G. barbadense collection for bacterial blight resistance involving 200 accessions from 21 countries yielded 8 accessions resistant to races 1, 2, 7, and 18 of the pathogen. Genetic inheritance and linkage investigations of a male sterile and a foliar mutant progressed. An investigation of the geographic and taxonomic distribution of the ovate leaf trait was concluded with negative results. The frequency of the 2 mutant genes ov₁ and ov₂ proved to be too rare to yield meaningful taxonomic or geographic information about the species. Preliminary results from a performance evaluation of interspecific hybrid cottons conducted at Maricopa and Safford AZ, indicated strong environmental influences on hybrids, but generally favorable yield earliness and plant height data were obtained from the higher -elevation Safford location.
    • Pima Cotton Improvement

      Turcotte, E. L.; Percy, R. G.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      Five experimental strains, P65, P67, P64 P69, P70, and pima S-6 were grown in 9 regional tests across the pima belt in 1988. Mean yields from the 9 locations showed that P67 averaged highest in yield followed by P69, P70, P65, P68 and pima S-6 respectively. The difference in mean yield between P67, the highest yielding entry, and pima S-6 was 82 pounds of lint per acre. Pima S-6 was the latest maturing and tallest entry in the regional test at Maricopa. The 5 experimental strains had longer, finer, and whiter fiber than pima S-6.