1700 Simple electrolyte leakage protocols to detect cold tolerance in cotton genotypes

Temperature is the dominant environmental factor affecting cotton development and yield. Chilling temperatures can significantly reduce cotton yield. The ability to screen cotton for cold tolerance can lead to the development of cultivars that can maintain yield and quality in marginal cotton growing regions where exposure to chilling stress is more common. This study tests the hypothesis that the relative electrical conductivity (REC) technique can be used in assays to detect cold tolerance in cotton. A cold water bath protocol was developed using various cold temperatures (3, 0, -2, -5°C) and a control (20°C) for 2 and 4 h. The 0°C for 2 h assay gave the best discrimination in REC between two cultivars, Namcala and DP16. A complementary whole plant assay was also developed using various night temperatures (5, 2 and -1°C) and a control at 20°C for 6 nights, with day temperatures at 30°C. The 5°C for 6 nights assay increased REC and reduced photosynthesis and chlorophyll fluorescence in DP16 compared to Namcala. DP16 plants exposed to -1°C died after 4 weeks while Namcala remained alive. Hence, both assays corroborate showing that Namcala is more cold tolerant than DP16. These newly developed protocols have the potential to be used in breeding programs to screen for cold tolerant cotton breeding lines and cultivars.