Pima cotton breeding and genetics.
The primary focus of my research is to develop new Pima cotton cultivars.
American Pima cotton (Gossypium barbadense L.) yields a long, strong, and fine fiber that is used primarily for the manufacture of sewing thread, luxury fabrics, shirting, combed sheets, and fine knit goods. Pima cotton is grown on about 200,000 acres in California, Arizona, New Mexico, and Texas, and supplies about 2% of the total production of cotton in the United States.
Pima cotton is a full-season crop that is adapted for production under irrigation in arid regions. When compared to the more widely grown upland cotton (G. hirsutum L.), Pima is lower yielding, less heat tolerant, and later maturing. The lack of heat tolerance can result in erratic yields from year to year in some regions. The extended growing season required for Pima cotton production requires greater input costs to the grower and increases the risk of experiencing late season insect pressure and inclement weather. Thus, the basic breeding objective of this program is to produce new cultivars of Pima cotton that combine high lint-yield, greater heat tolerance, and earlier maturity, yet also retain or improve the superior fiber quality of the present cultivars.
We conduct an aggressive program of cultivar development. Our approach is to make many crosses each year, evaluate the resulting populations in early-generation tests, and select only the best populations for further inbreeding, selection, and line development. We test 80 to 120 new experimental lines each year in extensive field trials conducted at five locations across the Pima belt. We then evaluate the most promising candidates in large scale tests on grower farms under grower management as a final measure of their performance. The University of Arizona will seek a patent on new cultivars developed by this program, and then grant an exclusive license to Delta and Pine Land Company to market those varieties. Delta and Pine Land Company funds a large part of this project.
Insects, such as the Sweetpotato whitefly (Bemesia tabaci Genn.), lygus (Lygus hesperus Knight), and pink bollworm (Pectinophora gossypiella Saunders), pose a major threat to Pima cotton. We have initiated a program to develop resistance to these important insect pest of Pima cotton.
We are continually testing and evaluating different breeding techniques that will allow us to evaluate more material in a shorter amount of time. Development of more efficient breeding strategies requires a thorough understanding of the inheritance of the important agronomic characteristics of Pima cotton.
Finally, we are conducting studies, in collaboration with other scientists, to identify heat tolerance mechanism(s) in recently released cultivars of Pima cotton that have resulted in higher lint yields under low desert production. These studies are intended to identify desirable physiological traits that can be incorporated into our breeding program, and improve our ability to select for greater heat tolerance in Pima cotton.