干旱胁迫及复水对黄芪幼苗生长、生理特性及次生代谢产物积累的影响

Effects of Drought Stress and Rehydration on Growth,Physiological Characteristics and Accumulation of Secondary Metabolites in Astragalus Mongholicus Seedlings

为明确黄芪幼苗对不同水分亏缺程度干旱胁迫的响应机制,以“同芪16-1”幼苗为试验材料,研究了不同干旱胁迫程度、胁迫时间及恢复浇水对黄芪幼苗生长、生理特性及次生代谢产物积累的影响。结果表明,轻度和中度干旱胁迫4、8 d处理,随胁迫程度加深及胁迫时间延长,黄芪幼苗株高、地上部生物量、叶绿素含量和净光合速率逐渐降低,根长、地下部生物量、超氧化物歧化酶(SOD)和过氧化物酶(POD)活性、丙二醛(MDA)和游离脯氨酸(Pro)含量逐渐升高,根中次生代谢产物大量积累;中度干旱胁迫12 d处理,次生代谢产物积累显著减少,其余指标变化趋势与4、8 d处理基本一致。重度干旱胁迫下,随胁迫时间延长,除MDA和Pro含量持续升高外,其余指标均逐渐下降。复水后,轻度、中度胁迫各项指标基本恢复至对照水平,重度胁迫未能完全恢复,且胁迫时间长的处理仍与对照差异显著。由此表明,“同芪16-1”幼苗具有一定的抗旱性,从幼苗生长和生理生化等指标综合分析,不影响幼苗生长发育的土壤水分相对含水量为50%~60%,胁迫时间不大于8 d。

In order to clarify the response mechanism of Astragalus seedlings to drought stress with different water deficit degree,the effects of different drought stress degree,stress duration and rewatering on the growth,physiological characteristics and secondary metabolites accumulation of Astragalus seedlings were studied using Tongqi 16-1 seedling as experimental material.The results showed that mild drought stress treatment and moderate drought stress treatment for four,eight days showed a gradually decreasing trend in the plant height,aboveground biomass,chlorophyll content,and net photosynthetic rate of Astragalus seedlings with the deepening of stress degree and prolongation of stress time.The root length,underground biomass,the activities of superoxide dismutase and peroxidase,the content of malondialdehyde(MDA)and proline(Pro)gradually increased,and a large accumulation of secondary metabolites in the roots was observed.After 12 days of moderate drought stress,the accumulation of secondary metabolites decreased significantly,and the change trend of other indexes were basically the same as that of four and eight days of moderate drought stress.Under severe drought stress,the contents of MDA and Pro in Astragalus seedlings continued to increase,while the other indexes decreased gradually.After rehydration,the indexes of mild and moderate stress were basically restored to the control level,while those under severe stress could not recover completely and there were significant differences between the seedlings and the control group after long treatment.The results showed that Tongqi 16-1 seedlings had certain drought resistance,according to the comprehensive analysis of seedling growth,physiological and biochemical indicators,the relative water content of soil water that did not affect the growth and development of seedlings was 50%-60%,and the stress duration was no more than eight days.