模拟干旱胁迫下构树和桑树的生理特征比较

Comparison of the physiological characteristics of paper mulberry(Broussonetia papyrifera)and mulberry(Morus alba)under simulated drought stress

Key words:  paper mulberry(Broussonetia papyrifera)  mulberry(Morus alba)  polyethylene glycol(PEG 6000)  carbonic anhydrase  chlorophyll fluorescence  karst

摘要:

在不同浓度聚乙二醇(PEG 6000)的处理下,测定构树和桑树的碳酸酐酶活性、光响应曲线、二氧化碳响应曲线和叶绿素荧光等指标,比较它们的抗干旱能力。结果表明:(1)构树的碳酸酐酶活力变化不显著,而桑树的碳酸酐酶活力不同的PEG 6000浓度间差异较大。(2)构树的净光合速率受PEG 6000的影响较小,而桑树受到抑制较大。(3)构树的PSⅡ原初光能转化效率(Fv/Fm)和PSⅡ实际光合效率ΦPSⅡ受到PEG影响不显著,而桑树则明显受到PEG的抑制。构树的PSⅡ原初光能转化效率(Fv/Fm)和PSⅡ实际光合效率ΦPSⅡ要比桑树高,光化学淬灭系数(qP)和电子传递速率(ETR)也明显高于桑树。稳定的碳酸酐酶、较强的光合能力是构树适应岩溶干旱环境的重要机制。

Abstract:

Under the treatment of different concentrations of polyethylene glycol(PEG 6000),the carbonic anhydrase activity,photosynthetic responses to light and CO₂,and chlorophyll fluorescence characteristics in leaves of two woody plant species,paper mulberry(Broussonetia papyrifera)and mulberry(Morus alba),were determined. The drought resistance of the two species plants was compared. The results indicated that the activity of carbonic anhydrase in paper mulberry did not vary significantly. There are significant differences of the activity of carbonic anhydrase in mulberry among treatments with different concentration of PEG 6000. PEG 6000 had little influence on net photosynthetic rate of paper mulberry,but caused significant inhibition on mulberry. No significant variation of maximum quantum yield of photosystem II(Fv/Fm)and actual photosynthetic efficiency of PS II(ΦPSⅡ)of paper mulberry among the treatments of PEG was observed,but those of mulberry were significantly inhibited by PEG. Fv/Fm and ΦPSⅡ of paper mulberry was also higher than those of mulberry. The photochemical quenching coefficient(qP)and electron transport rate(ETR)of paper mulberry was significantly higher than those of mulberry. The stable carbonic anhydrase and the strong photosynthetic capacity is an important mechanism for paper mulberry to adapt to karst-arid environment.