[Effects of Exogenous Spermidine on Seed Germination and As Uptake and Accumulation of Rice Under As⁵⁺ Stress]

As pollution in farmland has a toxic effect on the growth of crops, which reduces their yield and quality. The effects of exogenous spermidine (Spd) on rice seed germination and seedling growth under As⁵⁺ stress were studied. The results showed that exogenous Spd could promote the germination of rice seeds under As⁵⁺ stress, improve the germination potential and germination rate of seeds, and promote the growth of seedling roots. The addition of Spd could increase the activity of catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) of rice seedlings and roots under As⁵⁺ stress, and reduce the content of malondialdehyde (MDA) in rice buds and roots. When As⁵⁺ concentration was 25 μmol·L^-1, adding 500 μmol·L^-1 and 1000 μmol·L^-1 Spd, MDA content in rice roots was decreased by 12.3% and 31.3% and CAT activity of rice shoots was increased by 105.1% and 101.4%, and CAT activity of rice roots was increased by 29.9% and 57.1%, respectively. The addition of Spd also affected the uptake and accumulation of As in rice. When the concentration of As⁵⁺ was 25 μmol·L^-1, adding 500 μmol·L^-1 and 1000 μmol·L^-1 Spd, the concentration of As in rice shoots decreased by 69.4% and 75.1%, and As concentration in rice roots decreased by 7.6% and 24.4%, respectively. Spd could therefore effectively alleviate the toxic effect of As⁵⁺ on rice.