1a. Objectives (from AD-416):
1. Identify the range of diversity for drought tolerance and disease resistance on selected entries within the USDA-ARS Cotton Germplasm Collection. 2. Identify and/or develop lines with stacked drought tolerance and disease resistance traits for release to public and private cotton breeding programs.
1b. Approach (from AD-416):
Drought responses of progeny, breeding lines, germplasm, and cultivars will be conducted for Upland, Acala, Pima, and intra- and interspecific progeny. Field evaluation of water stress responses will be through the use of an assay first described by Burke (2007), and later modified for faster screening (Burke, 2010). A series of laboratory and greenhouse experiments will be conducted to identify environmental factors such as temperature, inoculum level, and exposure of time (days after inoculation) that influence pathogenicity and virulence during plant infection.
3. Progress Report:
-Progeny, breeding lines, germplasm, and cultivars for Upland, Acala, Pima, and intra and interspecific progeny were planted in May 2013. On June 5th, 1800 plots were destroyed by hail. Selected breeding lines, germplasm, and commercial cotton lines were replanted based upon available seed supplies. We are evaluating water stress responses through the use of an assay first described by Burke (2007), and later modified for faster screening (Burke, 2010). This assay permits a high throughput analysis of cotton responses to drought. We are currently imposing differential irrigation, and lines will be initially identified for drought avoidance and/or tolerance. Lines shown to exhibit enhanced drought tolerance will then be evaluated for disease resistance. Lines with insufficient seed number will be increased in the winter nursery.