The effects of water management and foliar spraying of exogenous plant hormone ethylene (ETH) on the accumulation of rhizosphere iron membrane, cadmium (Cd) and health risk index of rice were studied. Through the potting test, two concentrations (50 μmol/L and 100 μmol/L) ethylene (ETH) were sprayed three times at the jointing stage, the flowering stage and the grouting stage, and the water management modes of continuous flooding (CF) and interval flooding (IF) were adopted. Compared with the IF water management mode, the storage morphology of Cd in the soil was changed in the CF water management mode, and the soluble Cd was reduced from 36% to 30%, and the reducing state Cd was increased from 30% to 40%. Compared with the IF water management mode, the Fe and Cd content in the rice root surface iron film were significantly increased in the CF water management mode, and the exogenous spraying of ETH also significantly increased the Fe and Cd content in the iron film under the two water management modes, up to 50.59% and 58.06%. Compared with the IF water management mode, the Cd content in rice roots, leaves, brown rice and polished rice decreased significantly under the CF water management mode. The external spraying of ETH was also conducive to reducing the cadmium content of rice under the two water management modes, among which the Cd content in polished rice under CF+50ETH treatment was the lowest, and the Cd content in polished rice decreased from 0.68 mg/kg to 0.45 mg/kg, a decrease of 33.82% compared with CF treatment. Exogenous spraying of ETH significantly reduced the transport coefficients of Cd from rhizome and stem-grain under the two water management modes, and the transport coefficients were the lowest under CF+50ETH treatment, which was reduced by 55.17% and 23.81% respectively compared with CF treatment. CF water management mode and spray ETH treatment have a good effect on reducing the health risk index of rice Cd. It can be seen that CF water management mode and exogenous spraying of ETH have certain application prospects for reducing the accumulation of Cd in rice.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |