Effects of NaHS pretreatment on the content of endogenous H
S (A) under normal culture conditions and survival percentage (B) under heat stress at 47°C. Seedlings of maize were irrigated with 100 ml of 0 (control), 0.3, 0.6, 0.9 and 1.2 mM NaHS for 6 h, respectively, and then determined the content of endogenous H2S in coleoptiles of maize seeds. Afterwards, treated seedlings were subjected to heat stress at 47°C for 15 h and survival percentage of seedlings was counted. Error bars represent standard error and each data in figure represents the mean ± SE of three experiments, and asterisk and double asterisks indicate significant difference (P < 0.05) and very significant difference (P < 0.01) from the control without NaHS treatment, respectively.