白梭梭同化枝对干旱胁迫的生理生态响应

Physio-Ecological Response of Haloxylon persicum Photosynthetic Shoots to Drought Stress

对白梭梭同化枝自然水分胁迫下的季节抗旱特征进行研究。结果表明:自然干旱胁迫条件下,不同生长发育时期同化枝的主导抗旱生理因子不同。5月31日至6月29日盛花期间,同化枝内源ABA含量甚微,气孔导度值与光合强度处于生长发育过程的最高水平,可溶性糖含量呈现下降趋势,而脯氨酸含量略有增加,植物通过渗透调节作用适应此阶段轻度干旱胁迫;6月29日至7月26日盛夏期间,ABA迅速积累,气孔导度值降为生长发育过程的最低值,叶绿素分解,可溶性糖与脯氨酸均呈现快速积累趋势,且可溶性糖积累强度大于脯氨酸;8月9日至8月22日同化枝生长发育后期,ABA急剧积累为生长发育过程的最高浓度,气孔导度值有所增大,脯氨酸和可溶性糖保持在高水平平稳变化。此阶段高浓度ABA调节植物生理过程适应干旱的效应受CTK、IAA两种内源激素的抑制,进而抑制脯氨酸和可溶性糖的继续积累。

This paper studied the seasonal characteristics to resist the drought stress of Haloxylon persicum photosynthetic shoots at habitat. The results showed that the predominant drought resistance factors were varied at the different stage from growth to development. In the blooming season （from 31 May to 29 June） , endogenous ABA contents were rare; stomatal conductance and photosynthesis intensity were the highest at the whole stage from growth to development; soluble sugar contents had a decreasing trend and proline contents increased a little that made proline become the predominant factor to resist the drought under this light water stress. In the hot summer （ from 29 June to 26 July）, ABA contents accumulated rapidly ; stomatal conductance dropped to the lowest level of the growth and development ; chlorophyll was also decomposed; both soluble sugar and proline contents showed the trend of quickly accumulating, but the former was faster than the latter. It was due to stomatal limition and osmotic organic molecules accumulation that would affect the photosynthetic shoots to resist severe drought stress. At the late period of the development （from 9 Aug. to 22 Aug. ）, ABA rapidly accumulated, its contents got to the highest level of whole life-span; stomatal conductance increased a little; proline and soluble sugar contents changed little at high level; while the ratios of ABA to CTK content and ABA to IAA content got up obviously, the effect to resist drought stress on high content ABA was inhibited by endogenous hormone CTK and IAA, then the continuing accumulation of proline and soluble sugar would be prevented. Osmosis of organic molecules was the most important factor to adjust leaves to severe water stress at this period.