Objectives: To improve cotton germplasm with potential heat stress tolerance, better fiber quality, lint yield and pest resistance, broadening the genetic base of cotton.
Justification and Problem Statement
Over the last 3 5 years, the cotton germplasm base used in plant breeding has narrowed. This relatively narrow genetic diversity has been suggested as a contributor to an apparent plateau in breeding progress. It may also represent an impediment to efforts to sustain high yields (May and Taylor, 1998; Meredith, 1992; Ulloa, 2006). Since the re-establishment of a cotton breeding effort within the USDA-ARS, Western Integrated Cropping Systems Research Unit, we have focused on increasing genetic diversity through acquisition of novel germplasm (from multiple sources including non-commercial land races and species of wild cottons)…
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Fusarium w.ilt of cotton in California has been considered a potentially serious fungal disease caused by the organism Fusarium oxysporum vas infectum (also called ”FOV”) for many decades in several areas of the San Joaquin Valley (SJV). In the past, however, damage associated with FOV in SJV cotton has been notable only in areas with the combination of: (a) moderate to high populations of one or more specific races of FOV (usually race 1 ); (b) soils with a sandy or sandy loam texture; and (c) where root lrnot nematodes were present in high-enough populations to cause some significant root damage. Past research generally indicated that FOV damage was worst when both FOV inoculum and nematodes were present in relatively high…
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Summary:
Cotton is routinely grown in the hot, irrigated areas of the far Western U.S., and these extended periods of high temperature can reduce cotton ( Gossypium hirsutum L. and G. barbadense) lint yield, even with adequate irrigation conditions. Extended periods of extremely high temperatures are common in these areas during the critical stage of peak flowering. When temperatures in the San Joaquin Valley reach temperatures above normal during the critical stage of peak flowering, California growers suffer the consequences of reduced yield by these cotton varieties weaknesses to heat. The number of cotton commercial varieties for California with heat tolerance is not really known. However, it is known that Acala varieties Maxxa and Phytogen 72 yield poorly in the heat stress environment of…
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Summary:
Since the re-establishment of the USDA-ARS, WICS, genetic/breeding program, we have been focusing on bringing germplasm from any possible source available to us in order to increase genetic diversity. Most of the time, the genetic diversity in the cotton crop is used as an indicator to recognize potential threats to sustaining high yields. In the last couple of years, several troubling developments have recognized Fusarium oxysporum f.sp. vasirifectum (FOV) Atk. Sny & Hans as a recurring and potentially expanding threat to cotton production. The vulnerability of cotton production to this pathogen highlights the need for comprehensive research to protect the cotton industry from FOV, both from virulent populations which may be introduced and new virulent strains arising from within cotton production areas. Until recently, only race 1 and race 2 were known to occur in the United States (DeVay, 1986; Smith et al., 1981). UC scientists have recently identified race 4 ofFOV in cotton plants…
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