Browsing Cotton Report 1990 by Subjects
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Pima Cotton GeneticsIn an investigation of the genetic diversity and structure of Gossvpium barbadense L. it was determined that northwestern South America was the species' center of variability and probably the species' center of origin. Cultivars of the species were found to possess as much genetic variability as the center of variability. Cultivar variability was due in large part to introgression with G. hirsutum. Studies of interspecific hybrid performance revealed that development of G. barbadense parents could significantly affect the plant height, earliness, and yield of the resulting hybrids. Environment significantly affected hybrid performance and could enhance or obscure any beneficial effects of hybrid parent selection. A conversion program to convert photoperiodic short-day flowering tropical accessions to day neutrality continues. Preliminary results from inheritance and linkage studies of a male sterility factor and a foliar mutant indicate that both are single gene, recessive traits. No linkages between the male sterility factor and 21 marker traits were found.
Pima Cotton ImprovementFive experimental strains, P67, P69, P71, P72, P73, and Pima S -6 were grown in Regional tests at eight locations in 1989. P69 averaged highest in mean yield across locations followed by P73, Pima S-6, P71, P67 and P72. The difference in mean yield between P69, the highest yielding entry, and Pima S-6 was 35 pounds of lint per acre. Pima S-6 was the latest maturing and tallest entry in the Regional test at Maricopa. Pima S-6 also showed less tolerance to heat stress than the experimental strains. The experimental strains had longer, stronger, finer, and more whitish fiber than Pima S-6.