不同外源物质对盐、碱及干旱胁迫下草木樨种子萌发、幼苗生长及生理的影响

Effects of different exogenous substances on the seed germination,seedling growth,and physiology of Melilotus suaveolens under salt,alkali,and drought stress

为筛选出促进盐、碱及干旱胁迫下草木樨种子萌发和幼苗生长的最佳外源物质及其处理浓度,采用培养皿滤纸发芽法,研究不同浓度赤霉素(GA)和褪黑素(MT)浸种6 h对盐、碱及干旱胁迫下草木樨种子萌发及幼苗生长的影响。结果表明,盐胁迫下,200 mg·L^(-1)的GA是促进种子萌发的最佳处理,50μmol·L^(-1)的MT是提高幼苗超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性的最佳处理。在碱胁迫下,200μmol·L^(-1)的MT则使幼苗胚轴长出现最大值。在干旱胁迫下,100 mg·L^(-1)的GA使草木樨种子发芽率和胚根长出现最大值。隶属函数综合评价得出,缓解盐胁迫的最佳外源物质是GA,最佳处理浓度是200 mg·L^(-1),缓解碱和干旱胁迫的最佳外源物质是MT,最佳处理浓度分别是50和100μmol·L^(-1)。综上所述,MT和GA浸种能够在盐、碱及干旱胁迫下促进草木樨种子萌发和幼苗生长,研究结果可为提高草木樨对盐、碱及干旱胁迫的耐受能力提供参考。

The aim of this study was to determine the best exogenous substance,and its optimal concentration,to promote the seed germination and seedling growth of Melilotus suaveolens under salt,alkali,and drought stress.Seeds of M.suaveolens were germinated in Petri dishes on filter paper with gibberellin(GA)and melatonin(MT)at various concentrations.The effects of these substances on the seed germination and seedling growth of M.suaveolens,as well its responses to 6-h salt,alkali,and drought stress treatments,were evaluated.The results showed that 200 mg·L^(-1) GA was the best treatment to promote seed germination,and 50μmol·L^(-1) MT was the best treatment to improve the activities of superoxide dismutase(SOD),peroxidase(POD),and catalase(CAT)in seedlings under salt stress.Under alkali stress,the maximum hypocotyl length of seedlings was in the 200μmol·L^(-1) MT treatment.Under drought stress,the maximum germination rate and radicle length were in the 100 mg·L^(-1) GA treatment.According to a multivariate evaluation using a membership function method,the best exogenous substance for alleviating salt stress was GA,and the optimal concentration was 200 mg·L^(-1).The best exogenous substance for alleviating alkali stress and drought stress was MT,and the optimal concentration was 50 and 100μmol·L^(-1),respectively.In conclusion,MT and GA can promote the seed germination and seedling growth of M.suaveolens under salt,alkali,and drought stress.These findings provide reference data for improving the tolerance of M.suaveolens to salt,alkali,and drought stress.