Location: Coastal Plain Soil, Water and Plant Conservation Research
2019 Annual Report
Objectives
Objective 1. Determine the ability of cotton germplasm to withstand soil water deficits, identify and characterize drought tolerance genes, and develop innovative management practices for optimizing use of the improved genotypes in production systems.
Sub-objective 1A. Identify genotypes with fiber length stability when subject to water deficit stress during fiber elongation.
Sub-objective 1B. Identify cotton genotypes that withstand soil water deficits.
Sub-objective 1C. Evaluate variable rate irrigation using crop feedback for site-specific irrigation management of cotton in the Southeastern U.S. Coastal Plain.
Objective 2. Develop and evaluate new cotton germplasm with increased genetic diversity, improved fiber quality, and lint yield stability traits.
Approach
New technologies and new genetic resources are needed to help the nation’s cotton producers face increasing economic and environmental challenges. The proposed research will contribute to the industry’s ability to meet the nation’s fiber needs and become more competitive in world markets. Since water deficit stress is a serious limitation to cotton production, much of this research will be aimed at finding solutions to lessen the impact of this environmental stress. The research has two objectives: (1) determine the ability of cotton germplasm to withstand soil water deficits, identify and characterize genetic variation for drought tolerance, and develop innovative management practices; and (2) develop new cotton genetic resources with increased genetic diversity, improved fiber quality, and lint yield stability. In this research, we will conduct genetic studies on the effect of water deficit stress on fiber length and yield, determine how best to use proximal sensing data collected from high throughput phenotyping platforms, design innovative double crop cotton production systems, and develop new cotton genetic resources. Research methods include field experiments and statistical analyses using modern analytical equipment and innovative analytics. Research products include new knowledge of genetic variation for fiber length stability under water deficit stress, protocols for using proximal sensing data collected from high throughput phenotyping platforms as a water deficit stress breeding selection tool, new water efficient cotton cropping systems, and high quality cotton germplasm containing exotic introgression. All segments of the cotton industry and southern rural economies will benefit from the findings of this research.
Progress Report
Water deficit stress research. The second year of two 2-year field studies was initiated in 2019. The first field study is designed to determine the impact of water deficit stress on fiber length development. Bolls will be intensively sampled among a group of diverse genotypes in well watered and water deficit stress field plots every five days through the first 35 days of fiber development. Fiber lengths will be measured across the time series to develop fiber length growth curves for each genotype. This research should provide new insights into genetic diversity for fiber length under water deficit stress. The second field study is designed to determine if canopy temperature can be used to determine genotypic differences in drought tolerance. Research was initiated in 2017 and continued in 2019 to develop methods to improve the efficiency of collecting canopy temperature data with high throughput phenotyping equipment. Using a drought susceptible genotype and a drought-tolerant genotype with a known drought-tolerance mechanism, intense canopy temperature data collection was initiated to determine soil water levels, crop growth stage, and local weather conditions which provide the best opportunity to differentiate genotypes differing in drought tolerance. This research should provide new insights into optimizing high throughput phenotyping data collection and analysis.
Cotton germplasm development research. The second year of a multi-location (Florence, South Carolina, Maricopa, Arizona, and College Station, Texas) field trial was conducted to evaluate advanced breeding lines containing exotic landrace variation. Agronomic and fiber quality performance data will be used to support germplasm line release decisions to provide industry with new genetic diversity. Also, a project to develop exotic introgression populations containing different levels of exotic introgression is ongoing. Exotic lineages of 25%, 50%, and 75% are being advanced. The introgression populations developed by the end of this project plan will provide a rich genetic resource to further study exotic landrace introgression in cotton. Together, the germplasm lines and introgression populations will also provide the cotton industry new breeding stock containing previously untapped and valuable genetic diversity.
Accomplishments
1. Using exotic landrace germplasm in cotton breeding. New genetic variation is needed to broaden the genetic base while also improving the economic competitiveness of U.S. cotton. ARS scientists in Florence, South Carolina, and College Station, Texas, evaluated the potential of using a number of exotic upland landrace accessions in cotton breeding. These exotic accessions are day-neutral (do not require a short daylength to flower) and represent an untapped, rich diversity for cotton breeding programs. The research showed that using exotic accessions generated offspring with broadened genetic diversity and good fiber quality. However, offspring also suffer from a negative relationship between yield potential and fiber quality. These results provide guidance that public and private breeding programs can use when considering using exotic landrace accessions as new sources of genetic diversity.
2. Using extra long staple germplasm in cotton breeding. Efforts to transfer improved fiber quality alleles from extra long staple or Gossypium barbadense accessions into upland cotton offers an attractive way to improve the economic competitiveness of U.S. upland cotton. In partnership with University of Georgia, ARS scientists in Florence, South Carolina, developed upland cotton populations containing small segments of extra long staple DNA. The populations were evaluated in the field to determine the effect(s) of these transferred segments on fiber quality performance. The research showed that a number of extra long staple segments of DNA contained alleles for improved fiber quality. The effect of the beneficial alleles stably expressed across environments and years. These results provide guidance that public and private breeding programs can use when considering using extra long staple accessions as new sources of fiber quality.
Review Publications
Campbell, B.T., Hugie, K.L., Hinze, L.L., Wu, J., Jones, D.C. 2019. Assessing the breeding potential of thirteen day-neutral landrace accessions in an upland cotton breeding program. Crop Science. 59:1469-1478.
Kumar, P., Singh, R., Lubbers, E., Shen, X., Paterson, A.H., Campbell, B.T., Jones, D., Chee, P. 2019. Genetic evaluation of exotic chromatins from two obsolete interspecific introgression lines of Upland cotton (Gossypium hirsutum L.) for fiber quality improvement. Crop Science. 59:1073-1084.
