2007 Annual Report
1a.Objectives (from AD-416)
Evaluate tetraploid cotton germplasm for host plant resistance to reniform nematode. Begin introgression of genes for host plant resistance to reniform nematode into tetraploid upland cotton from candidate diploid A-genome germplasm. Evaluate the impact of biotic and abiotic crop production factors on reniform nematode populations in Mississippi. Assess the efficacy of cultural and chemical management options to minimize losses to reniform nematode in Mississippi.
1b.Approach (from AD-416)
Stabilize the phenotype of day-neutral Texas race stock lines with moderate levels of resistance to reniform nematode through self pollination, and characterize the heritability and action of genes involved in resistance in these tetraploid lines. Develop a phenotypic screening technique that evaluates root infection by reniform nematode and also allows the evaluated plant to survive to reproductive maturity. Determine if enough variability exists within reniform nematode populations to allow them to adapt to overcome host resistance. Improve efficiency and effectiveness of methods necessary to introgress genes from diploid A-genome Gossypium species into tetraploid G. hirsutum germplasm by choosing the most compatible lines and by developing methods to reduce endogenous contamination of in-vitro ovule cultures without inhibiting their development. Introgress reniform nematode resistance from G. arboreum accession A2-190 into G. hirsutum. Describe the influence of crop production practices such as irrigation, tillage, and planting date on reniform nematode population density. Evaluate the role of weeds as hosts for reniform nematode and determine their importance in maintaining inoculum levels of the nematode. Evaluate adapted cotton lines for tolerance to reniform nematode. Determine effectiveness of new commercial seed treatment nematicides for managing reniform nematode, compared to in-furrow nematicide applications. Determine if a combination of nematicide and rotation to corn will improve reniform nematode suppression over rotation used alone.
This new project, which officially began on 5 March 2007, replaces project 6402-22000-003-00D. Progress and accomplishments related to that project are reported separately. To date, this project is proceeding as anticipated. The initial focus has been planning and establishing field experiments, with other lab and greenhouse projects to follow as the year progresses. An unusually wet July has limited the time frame available for making crosses and also has reduced the number of bolls that the cotton plants have been able to produce. Thus, our breeding efforts and our experiments requiring yield data may be less than satisfactory when the growing season is complete.
Research directed toward incorporating useful levels of resistance or tolerance to reniform nematode into upland cotton is underway. A multi-year experiment designed to evaluate the impact of selected day-neutral Texas race stock lines on reniform nematode population levels in the soil has been established. Efforts to identify cotton varieties that are tolerant to reniform nematode are continuing in field trials, and lines reported to be tolerant to reniform nematode are being used as parents in crosses. Additionally, breeding efforts are continuing with the goal of transferring reniform nematode resistance from distant relatives of cotton into upland cotton.
Research directed toward cultural and chemical methods that can minimize losses to reniform nematode also has been initiated. Crop production practices including tillage, irrigation, early planting, crop rotation, and nematicides are being evaluated in several field trials. Several years will be required to complete these experiments.
Some of the research on this project is being done in cooperation with scientists at other institutions. Research in objective 4 is being conducted by Mississippi State University scientists under a Specific Cooperative Agreement between ARS and the Mississippi Agricultural and Forestry Experiment Station. A separate report summarizes work completed under this agreement (subordinate project 6402-22000-005-01S). Scientists at Texas A&M University are cooperating on research listed in objective 2 under a Non Funded Cooperative Agreement between ARS and Texas A&M University. A separate report summarizes work completed under this agreement (subordinate project 6402-22000-005-03N).
This is a new project, so there are no accomplishments to report to date. Accomplishments from the project it replaced (project number 6402-22000-003-00D) are reported separately.
5.Significant Activities that Support Special Target Populations
|Number of non-peer reviewed presentations and proceedings||3|
|Number of newspaper articles and other presentations for non-science audiences||2|