PEG模拟干旱胁迫对栓皮栎种子萌发及生长生理的影响

为了阐明栓皮栎种子萌发期对水分胁迫的耐受性,以当年采集的栓皮栎种子为材料,采用培养皿滤纸萌发的方法研究了不同浓度（0%、5%、10%、20%、30%）PEG-6000溶液对其种子萌发、生长、保护酶活性和有机渗透调节物质的影响,并对种子萌发率、胚根生长速率等与PEG浓度进行了回归分析。结果表明:（1）随着干旱胁迫程度的加剧,栓皮栎种子的发芽率、发芽指数、胚根长度、胚根生长速率和活力指数均呈先升高后下降趋势,说明低浓度（5%、10%）PEG胁迫可以促进栓皮栎种子萌发及生长,而高浓度（20%、30%）则具有抑制作用。（2）建立水分胁迫条件下种子萌发率、胚根生长速率等与PEG浓度的回归方程发现,栓皮栎种子在PEG胁迫下的萌发临界值和极限值分别为32.01%和36.99%,胚根生长速率的临界值和极限值分别为30.1%和33.35%。（3）随着PEG浓度的升高,栓皮栎种子中3种保护酶（SOD、POD、CAT）活性和3种有机渗透调节物质（可溶性蛋白、脯氨酸、可溶性糖）含量呈现不同的变化,但均有不同程度升高趋势。由此可见,栓皮栎种子可通过增加保护酶活性和体内渗透调节物质来适应水分胁迫环境,使自身萌发和生长受抑制程度降到最低。

Effects of PEG Simulated Drought Stress on Seed Germination and Growth Physiology of Quercus variabilis

In order to study the water tolerance of Quercus variabilis in seed germination stage,the effects of different concentrations (0%,5%,10%,20%,30%) of PEG stress on seed germination,growth,protective enzyme activities and the organic osmoregulation substances were measured with choosing fresh cork oak seeds and using Petri dish and filter paper germination method.The correlation analyses were done between seed germination,radicle growth rate and PEG stress.The results showed that:(1)With the increasing of drought stress,seed germination rate,vigor index,germination index and radicle length of cork oak were all increased then decreased,showing that low concentration PEG stress (5%,10%) can promote the cork oak seed germination and growth,whereas high concentrations (20%,30%) had inhibition effects.(2)The regression equation between seed germination,radicle growth rate and PEG stress showed that the critical and the maximum value of the seed germination of Q.variabilis were 32.01% and 36.99%,while the corresponding radicle growth rates were 30.1% and 33.35% under the PEG stress.(3)With the increase of PEG concentration,three protective enzyme (SOD,POD and CAT) activities and contents of three kinds of organic osmoregulation substances were presented different responses,but had a same rising trend.Thus it can be seen that cork oak seeds increased protective enzyme activities and contents of osmotic regulation substances in vivo to adapt to the water stress,making the inhibition degree of germination and growth to the minimum.