黄腐酸对干旱胁迫下燕麦叶片类囊体膜脂肪酸组分及膜功能的影响OA

To investigate the effects of fulvic acid(FA)on fatty acid composition and thylakoid membranes function in oat leaves under drought stress,two cultivars,'Yanke 2'(drought-resistant)and'Bayou 9'(drought-sensitive),were used as experimental materials.A pot experiment was conducted using randomized block design.Three water gradients were set up:Normal water supply(75％of field capacity,D0),mild drought stress(60％of field capacity,D1),and severe drought stress(45％of field capacity,D2).Under each water gradient,two treatments were applied at the jointing,heading,and grain-filling stages:Foliar spraying of 600 mg/L(FA)and spraying of an equal amount of water(CK).A total of 12 treatments were set up.The following parameters of flag leaves were measured:Thylakoid membrane fatty acid composition,thylakoid lamellar structure,Hill reaction activity,H+-ATPase activity,photosynthetic pigment content,net photosynthetic rate(Pn),grain yield and its components.Additionally,correlation analysis was also performed.The results showed that:1)Spraying FA significantly increased the proportion of unsaturated fatty acids and unsaturated fatty acid index(IUFA)in oat thylakoid membrane under drought stress,stabilized the structure of the membrane,and enhanced the Hill reaction activity and H+-ATPase activity.Compared with CK,the proportions of unsaturated fatty acids(linolenic acid and linoleic acid)and IUFA in thylakoid membranes of both cultivars were significantly increased under FA treatment.The thylakoid lamellar structure became more compact,while Hill reaction activity and H+-ATPase activity were also significantly increased.Under D1,for'Yanke 2'and'Bayou 9',linolenic acid increased by 7.89％and 6.08％,linoleic acid increased by 17.98％and 22.06％,IUFA increased by 17.15％and 20.64％,Hill reaction activity increased by 10.02％and 14.05％,and H+-ATPase activity increased by 12.92％and 17.01％,respectively.Under D2,the corresponding increases were 14.80％and 15.82％,19.96％and 27.77％,19.59％and 26.95％,13.27％and 18.13％,and 14.48％and 24.00％.2)FA significantly increased photosynthetic pigment content,net photosynthetic rate(Pn),spikelet number per spike,1 000-grain weight and grain yield of both cultivars under drought stress.3)Correlation analysis showed that IUFA was significantly positively correlated with Hill reaction activity,H+-ATPase activity,photosynthetic pigment content,Pn and grain yield.In conclusion,fulvic acid alleviated the inhibition of photosynthesis and increased grain yield in oat under drought stress by increasing the proportion of unsaturated fatty acids in thylakoid membranes,maintaining lamellar structural integrity,and increasing Hill reaction activity and H+-ATPase activity.Its mitigation effect on severe drought was better than that under mild drought,and its effect on drought-sensitive variety'Bayou 9'was better than that on drought-resistant variety'Yanke 2'.