FIGURE 2.

Effect of heat stress on the spikelets fertility of superior and inferior spikelets of rice at anthesis. These rice plants were subjected to heat stress of 40°C for 5, 10, and15 days, respectively, from anthesis, and determined at maturity. (A) The pictures of panicles with superior and inferior spikelets in both genotypes under control condition and heat stress condition. (B) The mean data of fertility of superior and inferior spikelets in both genotypes under control and heat stress. SS and IS were indicated as superior spikelets and inferior spikelets, respectively. 0 day was indicated as control that rice plants without heat stress imposed. Six panicles (SP) were controlled in each rice plants except for the treatments of FP and TP. SP, FP, and TP present each rice plant possessing six panicles, four panicles, and two panicles, respectively. Vertical bars denote standard deviations (n = 3). Different letters indicate significant differences between the superior spikelet and inferior spikelets in the same cultivar (P < 0.05).