Thermotolerance in Gossypium hirsutum

Abstract

Heat and drought are major factors that affect the annual cotton yield. Cotton farmers are always looking for plants that are more thermotolerant and drought tolerant to increase the yield. These characteristics can be studied in many ways. This study focuses on measuring chlorophyll fluorescence in Gossypium hirsutum as a means to evaluate the desired characteristics of heat and drought tolerance. ‘Deltapine DP 90’ (DPL 90), a widely grown adapted cultivar was used as a control in this study. 1762 accessions of G. hirsutum were obtained from the USDA SPARS cotton germplasm collection in College Station, Texas. Four to five seeds of each accession were planted in a single pot, with three to four pots per accession. These plants were grown for at least four weeks in a greenhouse.

Leaf samples were collected from each accession. Chlorophyll fluorescence screening at increasing temperatures was performed on leaf samples of each accession. Plants that excelled in chlorophyll fluorescence were submitted to a traditional whole plant screening process under heat stress conditions. Chlorophyll fluorescence testing was determined to be an effective way to find cotton plants with increased thermotolerance and drought tolerance. However, all cotton plants that perform well in chlorophyll fluorescence testing do not necessarily exhibit the improved characteristics desired.