外源AsA对干旱胁迫下旱作稻AsA-GSH循环的影响OA

[Purpose]This study investigated the effect of exogenous ascorbic acid(AsA)application on the drought tolerance of rainfed rice under drought stress.[Method]The rainfed rice variety'Hengfeng You Jinsimiao'was used for the experiment de-signed with the following treatments:normal watering+foliar spraying of AsA,drought+foliar spraying of AsA,normal watering+foliar spraying of an equal volume of distilled water,and drought+spraying of an equal volume of distilled water,with the latter two as the control groups.Spraying was conducted from the day of heading for three consecutive days.On the day of harvest,flag leaves were sampled for subsequent determination of reactive oxygen species accumulation and membrane lipid peroxidation levels,the con-tent of key enzymes and substances in the AsA-GSH cycle,the content of osmoregulatory substances,and the expression levels of genes involved in AsA biosynthesis.In addition,the rice yields were measured.[Result]Under drought stress,foliar application of AsA reduced the H2O2,O2·-,and MDA content in rice leaves by 36.31％,16.08％,and 31.58％(significantly),respectively,compared with the drought treatment.In addition,foliar application of AsA enhanced the activities of APX,AO,GR,DHAR,and MDHAR by 21.32％,21.12％,10.19％,26.04％,and 23.87％and increased the content of proline,soluble protein,and soluble sugar by 20.46％,15.85％,and 22.46％,respectively.Simultaneously,foliar application of AsA significantly up-regulated the ex-pression of key genes such as VTC2/5 and GME involved in AsA synthesis and metabolism,increasing the yield by 4.47％and 14.19％in 2024 and 2025,respectively.[Conclusion]Exogenous AsA can enhance the drought tolerance of rainfed rice by activa-ting the AsA-GSH cycle,strengthening the antioxidant system,improving osmotic regulation,and upregulating the expression of key genes involved in AsA synthesis and metabolism.