Fig. 2

Exogenous ABA priming upregulated antioxidative defense capability in rice grains under heat stress. The rice plants were sprayed with distilled water, 50 μM ABA or 10 μM fluridone (FLU) 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 antioxidant enzyme activities. The accumulation of O₂^– (A) and H₂O₂ (B) and the activity levels of SOD (C), POD (D), CAT (E), APX (F), in rice grains, were measured at the indicated treatment days. 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