干旱胁迫对桂叶山牵牛成熟苗生理生化的影响

Effects of Drought Stress on Physiology and Biochemistry of Mature Seedlings of Thunbergia laurifolia

【目的】研究桂叶山牵牛(Thunbergia laurifolia)成熟苗对干旱的生理生化应答机制。【方法】选用桂叶山牵牛成熟苗为试验材料,采用盆栽控水法,设置正常供水(CK)、中度干旱胁迫(MD)和重度干旱胁迫(SD)3个水分处理,测定相关形态指标、光合指标和叶绿体超微结构。【结果】与正常供水对照相比,随着干旱胁迫的不断加剧,各处理桂叶山牵牛的株高、地径、叶片数、叶长、叶宽和根冠比等形态指标均逐渐下降;各处理桂叶山牵牛的净光合速率日变化均存在光合“午休”现象。与对照相比,MD、SD处理水分利用率较高,分别为0.89、0.77μmol/mmol,叶绿体超微结构均发生巨大变化。【结论】桂叶山牵牛成熟苗会通过降低光合作用、关闭气孔及提高水分利用效率等方式应对环境恶劣的干旱条件。桂叶山牵牛MD处理叶绿体结构发生了变化,SD处理叶绿体结构严重受损,但成熟苗未见有死亡,说明桂叶山牵牛成熟苗的耐旱性较强,可在园林中应用。

【Objective】The study was conducted to explore the physiological and biochemical response mechanism of Thunbergia Laurifolia mature seedlings to drought.【Method】The mature seedlings of T.Laurifolia were selected as the materials,and the pot water control method was adopted.Three water treatments were set,namely,normal water supply(CK),moderate drought stress(MD)and severe drought stress(SD).The morphological index,photosynthetic index and chloroplast ultrastructure were determined.【Result】Compared with the control,the morphological indexes such as plant height,ground diameter,number of leaves,leaf length,leaf width and root-top ratio of each treatment all decreased gradually with the aggravation of drought.The diurnal variation of net photosynthetic rate of T.Laurifolia under all treatments had the phenomenon of photosynthesis"napping".Compared with the control,the water use efficiency were higher under MD and SD treatments(0.89μmol/mmol and 0.77μmol/mmol,respectively).The chloroplast ultrastructure changed greatly under MD and SD treatments.【Conclusion】The mature seedlings of T.Laurifolia could respond to harsh environmental drought conditions by reducing photosynthesis,closing stomata and improving water use efficiency.The chloroplast structure of T.Laurifolia changed under the MD treatment.Although the chloroplast structure was seriously damaged under the SD treatment,no death was observed in the mature seedlings,indicating that the mature seedlings of T.Laurifolia had strong drought tolerance.T.Laurifolia can be applied in landscape because it is more resistant to drought.