Association of Chlorophyll Fluorescence with Heat and Drought Tolerance Among Accessions in the USDA Cotton Germplasm Collection

Accessions (1762) from the USDA cotton germplasm collection (TX collection) were evaluated in a growth chamber for tolerance to heat by subjecting plants to heat and measuring chlorophyll fluorescence following heat treatment. Based on high chlorophyll fluorescence values, 44 accessions were selected with chlorophyll fluorescence values two standard deviations higher than the mean for all accessions, and evaluated in the growth chamber as whole plants for tolerance to high heat and water deprivation. Seven accessions were identified that were significantly more tolerant to heat and lack of water than Deltapine 90.