外源褪黑素对苏打盐碱胁迫大豆幼苗的缓解效应

Alleviating effect of exogenous melatonin on soybean seedlings under soda saline-alkali stress

褪黑素是缓解逆境胁迫对大豆损伤的有效途径之一。研究苏打盐碱胁迫下喷施褪黑素对大豆幼苗生长的调控效应,为大豆幼苗缓解苏打盐碱胁迫提供理论基础和技术支撑。以合农71为试验材料,采用砂培试验方法,设置常规+喷施清水处理(CK)、常规+喷施褪黑素处理(CKM)、苏打盐碱胁迫+喷施清水处理(S)、苏打盐碱胁迫+喷施褪黑素处理(SM)4个处理,研究大豆苗期不同生理指标对苏打盐碱胁迫的响应。结果表明,与常规处理(CK和CKM)相比,苏打盐碱胁迫下(S和SM)大豆幼苗生长均受到抑制;与S处理相比,SM处理大豆叶片PSII反应初始荧光(F_(0))与最大荧光产量(F_(m))显著增加,非光化学淬灭系数(NPQ)升高,作物光合机构过剩光能的耗散增强,PSII反应中心光保护能力提升,净光合速率(P_(n))显著增加,叶片抗氧化酶活性(SOD、POD、APX)和清除ROS能力显著增强,根系和茎秆可溶性糖和可溶性蛋白含量显著增加,叶片和根系中MDA产生速率显著下降,根系干物质积累量、总表面积、总体积和根平均直径显著增加,维持了叶片细胞内激素水平,叶片IAA、CTK、ETH和MT含量分别提高了15.9%、31.9%、8.7%和55%(P<0.05)。综上所述,喷施褪黑素能够缓解盐碱胁迫对大豆苗期相关生理指标的不利影响,提高大豆幼苗耐盐碱特性。

Spraying melatonin is one of the effective ways to alleviate the damage of soybean under stress.Clarifying the regulation effect of spraying melatonin on the growth of soybean seedlings under soda saline-alkali stress can provide theoretical basis and technical support for alleviating soda saline-alkali stress of soybean seedlings.Using a sand culture experiment method,we set up four treatments,including conventional treatment + spraying water(CK),conventional + spraying melatonin treatment(CKM),soda saline-alkali stress treatment + spraying water(S),soda saline-alkali stress + spraying melatonin treatment(SM).The response of different physiological indices in seedling stage of soybean cultivar Henong 71 to soda saline-alkali stress was investigated.The results showed that compared with conventional treatments(CK and CKM),the growth of soybean seedlings under soda saline-alkali stress(S and SM) was inhibited.Compared with S treatment,SM treatment significantly increased the initial fluorescence(F_(0)) and maximum fluorescence yield(F_(m)) of PSII reaction center,increased the non-photochemical quenching coefficient(NPQ),enhanced the excess light energy dissipation of crop photosynthetic mechanism,improved the photoprotection ability of PSII reaction center,and significantly increased net photosynthetic rate(P_(n)).The activity of antioxidant enzymes(SOD,POD,and APX) and scavenging ability of ROS in leaves,and the contents of sugars and soluble proteins in roots and stems were significantly increased.The MDA production rate in leaves and roots was significantly decreased.Root dry matter accumulation,total surface area,total volume and average root diameter were significantly increased.The intracellular hormone levels in leaves were maintained,and the contents of IAA,CTK,ETH and MT in leaves were increased by 15.9%,31.9%,8.7%,and 55%(P<0.05),respectively.In conclusion,spraying melatonin can alleviate the adverse effects of saline-alkali stress on the physiological indices of soybean seedlings and improve their saline-alkali tolerance.