作 者 ：回振龙1,2，李自龙1,2，刘文瑜1，李朝周1,2*，张 鑫1，徐 毅1，张晓芳1，王 栋1
期 刊 ：西北植物学报 2013年 8期 页码：1621~1629
Keywords:fulvic acid, Medicago sativa, PEG, drought stress, germination, resistance,
摘 要 ：以紫花苜蓿（Medicago sativa L.）为研究对象，采用不同PEG模拟干旱处理（CK、10% PEG、0.03% FA+10% PEG和0.05% FA+10% PEG）方法，探讨黄腐酸（FA）浸种对紫花苜蓿种子萌发、幼苗生长及抗逆性生理生化指标的影响。结果显示：（1）在PEG模拟干旱胁迫下，紫花苜蓿种子的发芽率、发芽势、发芽指数、活力指数、以及幼苗叶绿素含量、膜稳定指数（MSI）和根系活力较对照均呈下降趋势，株高和生物量的增长速率均显著低于对照；而幼苗叶片丙二醛（MDA）、过氧化氢（H2O2）、脯氨酸、可溶性糖含量均随处理时间呈上升趋势，过氧化氢酶（CAT）和谷胱甘肽还原酶（GR）活性则呈下降-升高-下降的趋势，超氧化物歧化酶（SOD）、过氧化物酶（POD）活性及超氧阴离子（O-·2）产生速率则均呈先升高后降低的趋势。（2）经黄腐酸浸种处理后，模拟干旱胁迫下紫花苜蓿种子的发芽率、发芽势、发芽指数、活力指数和幼苗株高、生物量、脯氨酸和可溶性糖含量均显著升高，并显著减小了模拟干旱胁迫引起的叶绿素含量、根系活力和MSI下降的幅度，相对提高了SOD、POD、CAT、GR活性，降低了MDA、H2O2含量和活性氧水平。研究表明，10% PEG模拟的干旱胁迫使紫花苜蓿的种子萌发及幼苗生长发育受到显著抑制，而黄腐酸浸种处理可通过提高渗透调节物质含量和保护酶活性来有效缓解干旱胁迫对紫花苜蓿幼苗造成的氧化伤害，增强植株的整体抗旱性，维持其正常生长发育，并以0.05% 黄腐酸浸种对干旱胁迫下紫花苜蓿种子萌发及幼苗生长的保护效应较为显著。
Abstract:The seed germination,seedling growth and physiological and biochemical indexes of stress resistance of Medicago sativa were discussed in this paper as the different treatments (CK,10% PEG,0.03% FA+10% PEG and 0.05% FA+10% PEG) were carried out in the experiments.The results showed that:(1)M.sativa seed germination rate,germinating energy,germination index,vigor index and seedling chlorophyll content,membrane stability indexcatalase (MSI) and root activity were downward trend.The growth rate of stem length and biomass were decreased,but the contents of malondialdehyde (MDA),hydrogen peroxide (H2O2),proline and soluble sugar of seedling leaves increased with the increasing of treatment duration.The activities of catalase (CAT) and glutathione reductase (GR) decreased firstly and secondly increased and finally decreased.The activities of superoxide dismutase (SOD) and peroxidase (POD) and superoxide anion (O-·2) increased firstly and then decreased under the simulated drought stress.The growth and development of M.sativa were inhibited significantly under the simulated drought stress and the seedling suffered from drought stress.(2)As being treated with the fulvic acid,the M.sativa seed germination rate,germinating energy,germination index,vigor index,and seedling’ stem length,biomass,proline and soluble sugar contents were increased significantly.The treatment of fulvic acid also significantly alleviated the decline in the content of chlorophyll,root activity and MSI,promoted the activities of SOD POD,CAT and GR relatively,and even reduced the contents of MDA,H2O2 and the level of reactive oxygen species.It is thus clear that the seed germination and seedling growth and development of M.sativa were significantly inhibited under 10% PEG solution simulated drought stress.In soaking seeds with fulvic acid,the content of osmotic adjustment substances was increased and enzyme activities were protected to effectively reduce oxidative damages caused by drought stress to the seedling of M.sativa,enhanced overall drought resistance of plants and maintained their normal growth.Besides,relatively significant effects were achieved by 0.05% FA in maintaining the seed germination and seedling growth of M.sativa under drought stress.