摘要
为评价不同生长期芸芥对混合盐碱胁迫的耐受性及相应的生理机制,采用不同浓度的混合盐碱溶液分别进行种子萌发期、苗期及成株期胁迫试验。结果表明:(1)在种子萌发期,低浓度(20和30mmol·L~(-1))混合盐碱胁迫仅延迟了芸芥种子的萌发时间,对种子活力的影响较小;40mmol·L~(-1)盐碱胁迫下,发芽势和发芽率均显著低于对照值;≥50mmol·L~(-1)盐碱处理下,种子完全丧失活力。(2)苗期叶片相对含水量与盐碱浓度和胁迫时间均呈负相关,盐碱浓度≥40mmol·L~(-1),相对含水量显著下降,而丙二醛含量显著升高;随盐碱浓度增加及胁迫时间延长,叶片可溶性糖和脯氨酸含量总体呈增加趋势,而可溶性蛋白含量却逐渐降低,说明芸芥幼苗对盐碱胁迫的适应在一定程度上主要取决于可溶性糖和脯氨酸等有机物质的积累;(3)成株期低浓度胁迫对株高和开花期影响不显著,≥40mmol·L~(-1)盐碱胁迫时,株高降低,开花期延迟,单株角果数少,部分种子干瘪或败育。60mmol·L~(-1)胁迫下植株能存活,但不能开花结实,70mmol·L~(-1)胁迫则严重抑制了营养生长和生殖生长,甚至死亡。混合盐碱胁迫对芸芥根长、鲜重、干重和含水量均有一定的抑制作用,对根重影响显著,低浓度胁迫促进根的伸长,盐碱浓度≥40mmol·L~(-1)时,根长逐渐变短,显著低于对照。总之,萌发期和成株期芸芥对Na Cl+Na2SO4+Na HCO3+Na2CO3混合盐碱胁迫的耐受性不同,苗期可溶性糖和脯氨酸作为主要的调节物质在芸芥适应较高浓度盐碱逆境中起到了重要作用。
To assess the tolerance of E.sativa to mixed salt-alkaline in different growth phase,and to reveal physiological mechanisms responding to salt-alkaline stress,the experiments were conducted using different concentration of salt-alkaline during germination,seedling stage and adult stage.Our results showed that:(1) At germination stage,initial germination was delayed but the seed vigor was not lost when stressed under low concentration of 20 mmol·L~(-1) and 30 mmol·L~(-1) mixed salt-alkaline.Under 40 mmol·L~(-1) salt-alkaline stress,the germination potentiality and germination rate were significantly lower than that of the control group.When the concentration was higher than 50 mmol·L~(-1),the seed vigor were lost completely.(2) Relative water content of leaves(RWC) had negative correlation with the level of salt-alkaline concentration and the stress time.When the salt-alkaline concentration was higher than 40 mmol · L~(-1),RWC was decreased significantly,but malondialdehyde(MDA) content was increased obviously.Both proline and soluble sugar content were significantly increased with the increasing of salt-alkaline concentration and time prolong,but the soluble protein content was reduced gradually,which indicated that the adaptation of E.sativa seedling to saline-alkali stress depended partly on the accumulation of organic material such as soluble sugar and proline etc.(3) At adult stage,effects of salt-alkaline stress on plant height and flowering period were considered,there were no significantly difference between the experimental group and control group when concentration of salt-alkaline was low(20 and 30 mmol·L~(-1)).When salt-alkaline concentration was 40 mmol·L~(-1) to 50 mmol·L~(-1),compared with CK,the experimental group presented shorter plants height,delayed flowering period and less number of efficient horns per plant.E.sativa failed to seed when the concentration of salt-alkaline was 60 mmol·L~(-1).Vegetative and reproductive growth were inhibited seriously,or even death as the concentration of salt-alkaline was 70 mmol·L~(-1).Root length,fresh weight,dry weight and water content were inhibited under salt-alkaline stress of different concentrations,especially the fresh root weight.When the concentration was less than 30 mmol·L~(-1),root length was longer than CK,while it was significantly shorter than CK when the concentration was higher than 40 mmol·L~(-1).In conclusion,salt-alkaline(Na Cl + Na2 SO4+ Na HCO3+ Na2 CO3) tolerance in E.sativa at germination stage and adult stage were different,soluble sugar and proline as the main organic substances played an important role in adapting to high salt-alkaline stress.
引文
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