外源甜菜碱对干旱胁迫下紫花苜蓿种子萌发与幼苗生长的影响

Effects of Exogenous Glycine Betaine on Seed Germination and Seedling Growth of Alfalfa Under Drought Stress

以大叶紫花苜蓿(Medicago sativa)为试材,采用培养皿发芽法及盆栽法,选择20%浓度聚乙二醇(polyethylene glycol,PEG 6000)模拟干旱胁迫,设置甜菜碱(glycine betaine,GB)浓度为0、10、20、30、40mmol·L^(-1)和50mmol·L^(-1)开展种子萌发和幼苗生长试验,幼苗期通过根注和叶施2种方式施加GB,测定萌发期及幼苗期的相关指标,研究GB对干旱胁迫下紫花苜蓿生长的影响,以及外源甜菜碱对干旱胁迫的缓解效果,以期为进一步提高紫花苜蓿的抗逆性及产量提供参考依据。结果表明:1)在甜菜碱浓度为0mmol·L^(-1),蒸馏水代替甜菜碱时种子萌发各项指标均有所下降,施加GB后得到有效缓解。当甜菜碱浓度为10mmol·L^(-1)时效果最佳,发芽率相比C0增加了30.5%;发芽势增加了46.8%;发芽指数增加了36.1%;活力指数增加了15.4%。2)幼苗期,叶施20mmol·L^(-1)时主根长最长,株高增加值最大;根注50mmol·L^(-1)时过氧化氢酶(CAT)活性最高;叶施20mmol·L^(-1)时丙二醛(MDA)含量显著降低。50mmol·L^(-1)时对组织含水量和过氧化物酶(POD)活性影响最大。

Medicago sativa was used as the test material,and 20%concentration of polyethylene glycol(PEG 6000)was selected to simulate drought stress.The seed germination and seedling growth experiments were carried out at the concentrations of 0,10,20,30,40mmol·L^(-1)and 50mmol·L^(-1).GB was applied by root injection and leaf application at seedling stage.The related indexes of germination stage and seedling stage were studied,and then the effects of GB on the growth of alfalfa under drought stress were analyzed,in order to study the alleviating effect of exogenous betaine on drought stress,and provide reference for further improving the stress resistance and yield of alfalfa.The results showed that,1)when glycine betaine concentration was 0mmol·L^(-1)and distilled water replaced betaine,all indexes of seed germination decreased,and GB was effectively relieved.When betaine concentration was 10mmol·L^(-1),the effect was the best,and the germination rate increased by 30.5%compared with C0;germination potential increased by 46.8%;the germination index increased by 36.1%;the vitality index increased by 15.4%.2)At the seedling stage,when 20mmol·L^(-1)was applied to the leaves,the main root length was the longest and the increment of plant height was the largest;CAT activity was the highest when 50mmol·L^(-1)was injected into the root;MDA content decreased significantly when 20mmol·L^(-1)was applied to leaves.50mmol·L^(-1)had the greatest effect on tissue water content and POD activity.