Fig. 1. Photomicrograph of Gregg 65 cotton pollen exposed to 28°C on the pollen germination medium for 180 min. The graphs show the temperature dependence of pollen germination and pollen tube elongation of PM2156, PM2326, and DP90 cotton compared with samples incubated at 28°C. The three replicate samples for each of the three cultivars were combined and the percentage germination and relative pollen tube lengths evaluated. The data show reduced pollen germination at 40°C and above (LSD = 22.89) while pollen tube length was reduced with temperatures of 34°C or above (LSD = 15.201). Error bars represent standard errors.