Fig. 8
Effect of exogenous paraquat and antioxidant (proanthocyanidins, PCs) on ROS content, starch synthetase activities, yield component and starch content in rice under heat stress conditions. The rice plants were sprayed with distilled water, 10 μM paraquat or 1% PCs at the 5th d after initial heading stage (AIH) or 12th d after initial heading stage, and then subjected to unstressed or heat stress conditions at 8–14 days after initial heading (AIH) stage or 15–21 days after initial heading stage, respectively. Rice grains at the indicated treatment times of 0 d, 3 d, 5 d and 7 d were sampled in liquid nitrogen which were used to measure the ROS contents and starch synthetase activities. The levels of O2– (A) and H2O2 (B) and the activity levels of AGPase (C) and SSS (D) in rice grains were measured at the indicated treatment days. (E) Percentage of filled spikelets (PFS, %), (F) 1000-grain weight (TGW, g), (G) grain yield per plant (GY, g) and (H) starch content were measured at the mature stage. Values are means ± SDs, n = 3. Different letters on the column represent significant differences (P < 0.05) between different treatments at the same treatment day based on Duncan’s test