HARDENING POTENTIAL IN COTTON (GOSSYPIUM-HIRSUTUM L) AT HIGH-TEMPERATURE STRESS

Leaves of cotton cultivar S-12 were acclimated at temperatures ranging from 35 to 44 degrees C for different time periods followed by heat s tress at 45 or 46 degrees C. The heat acclimation potential was analyz ed by Chlorophyll Fluorescence technique. The recovery of F-v/F-m rati o after application of heat stress was the parameter for determination of the acclimation potential. Very small fluorescence (F-v/F-m) value s were recorded after heat stress at 46 degrees C with fairly good res ponse when acclimated leaves were heat stressed at 45 degrees C.