荒漠绿洲过渡带一年生草本植物对干旱胁迫的响应

The responses of typical annual herbaceous plants to drought stress in a desert⁃oasis ecotone

选取河西走廊荒漠绿洲过渡带典型一年生草本植物雾冰藜(Bassia dasyphylla)、虎尾草(Chloris virgata)和狗尾草(Setaria viridis)为研究对象,设置5个水分梯度(正常水分(CK),轻度干旱(5d)、中度干旱(10d)、重度干旱(15d),重度干旱(15d)复水),分析了3种一年生草本植物生理和形态等性状对干旱胁迫的响应。结果表明:一年生草本植物可以通过生理反应(渗透调节)适应轻度和中度干旱胁迫,而通过个体形态来适应重度干旱胁迫。在轻度和中度干旱处理下,一年生草本植物通过调控叶片渗透调节物质脯氨酸、可溶性蛋白和可溶性糖维持叶片渗透压,提高保水能力,叶绿素含量增加,使丙二醛含量维持在较低的水平,同时,根系活力增强,有效促进了根系水分吸收;而在重度胁迫下,渗透调节物质作用降低,丙二醛含量迅速增加,导致可溶性蛋白含量下降,叶绿素分解加速,植物生长受到抑制,在有限的生物量下,一年生草本植物主要通过根系伸长、根长与茎长的比增加和减小茎长来适应重度干旱胁迫,最终导致了种子百粒重和结种数量下降。

We selected three typically annual herbaceous plants Bassia dasyphylla,Chloris virgata,and Setaria viridis as study subjects in a typical desert⁃oasis ecotone in the Hexi Corridor,and analyzed their responses under five drought gradients which included normal water supply(CK),light drought stress(5 d),moderate drought stress(10 d),severe drought stress(15 d),and re⁃watering after severe drought stress(15 d).The results showed that the annual herbaceous plants adapted to mild and moderate drought stress through physiological response(osmotic regulation),but through individual morphology for severe drought stress.Under mild and moderate drought conditions,the annual herbaceous plants maintained leaf osmotic pressure by regulating leaf osmoregulation substances proline,soluble protein and soluble sugar,and improved the water holding capacity.Meanwhile the chlorophyll content increased,so that the malondialdehyde content was maintained at a low level.Moreover,the root activity was enhanced,which effectively promoted the increase of the root water absorption.Under the severe drought condition,the function of osmoregulation substances decreased.The increase of malondialdehyde content caused the decrease of soluble protein content and the acceleration of chlorophyll decomposition.Thus,the plant growth was slow and the biomass was very limited.The annual herbaceous plants adapted to severe drought stress by elongating the root length,increased the ratio of root length and reduced the stem length.Under severe drought stress,the 100 seed weight and the seed number of the annual herbaceous plants also decreased significantly.