外源褪黑素缓解干旱胁迫对春大豆苗期影响的生理调控效应

The Physiological Regulation Effect of Exogenous Melatonin Relieving Drought Stress at Seedling Stage of Spring Soybean

为研究外源褪黑素对干旱胁迫下春大豆的缓解作用,以绥农26为试验材料,采用盆栽试验方法,以PEG6000引起的水分渗透势模拟干旱胁迫,研究干旱胁迫下叶面喷施和根施褪黑素对苗期春大豆的生理调控效应。结果表明:干旱胁迫降低了大豆叶片光合色素含量(叶绿素a、b、总叶绿素含量)和光合作用强度(净光合速率、蒸腾速率、气孔导度和胞间CO2浓度),提高了相对电导率、超氧阴离子(O-2)、过氧化氢(H2O2)和丙二醛(MDA)含量,增加了渗透调节物质(可溶性糖含量、可溶性蛋白含量和游离脯氨酸)含量,增强了抗氧化剂活性(超氧化物歧化酶、过氧化物酶、过氧化氢酶和抗坏血酸过氧化物酶)。干旱胁迫条件下施用褪黑素,与干旱处理相比,大豆光合色素含量、干物质积累量、光合速率、抗氧化剂活性、可溶性糖、可溶性蛋白和脯氨酸含量均显著增加,而O-2、H2O2、MDA含量和相对电导率则显著降低。结果表明外源褪黑素能够缓解干旱胁迫对大豆苗期相关生理指标的不利影响,提高大豆幼苗耐旱性,其中根施褪黑素处理好于叶面喷施处理。

In order to study the relieving effect of exogenous melatonin on soybean under drought stress. This study investigated the effects of exogenous melatonin on soybean physiological regulation effect of osmotic stress under water deficit stress induced by PEG6000. We conducted a potting experiment using the soybean(Glycine max L. Merrill) cultivar Suinong 26 to study the effects of the application of exogenous melatonin by leaf spray and root application on relieving the physiological regulation effect of osmotic stress at seedling stage of spring soybean. The results showed that the drought stress treatment reduced photosynthetic pigments(Chla, Chlb and total Chl) and photosynthesis(Pn, Tr, Gs and Ci) in soybean leaves, increased electrolyte leakage, O-2, H2O2 and MDA, enhanced osmotic antioxidant activity(SOD, POD, CAT, APX, GSH and AsA) and adjustment substances content(soluble protein content, soluble sugar content and proline content). The application of exogenous melatonin under drought stress significantly relieved the inhibitory effects of PEG6000 stress on seedling growth, compared with drought stress, photosynthetic pigment content, dry matter accumulation, photosynthesis of soybean leaves, antioxidant activity, the soluble sugar, soluble protein and proline content were significantly higher, while O-2, H2O2, MDA content and electrolyte leakage were significantly decreased. Overall, the results showed that application of exogenous melatonin at the seedling stage of soybean was effective in alleviating the adverse effects of drought stress on physiological indexes and improving the drought tolerance of soybean seedlings. In addition, the results showed that application of exogenous melatonin by root is superior to foliar spraying.