两种桑科植物叶片光合及光呼吸对模拟干旱的响应

采用150 g/L的聚乙二醇(Polyethylene glycol,PEG)模拟干旱胁迫,研究两种桑科植物(构树和桑树)的叶片光合及光呼吸特征对干旱胁迫的响应。对植物培养液的相关化学参数以及叶片的光合参数进行测定,结果表明:干旱对构树根系吸水能力的影响小于桑树的;构树以中光合-低蒸腾-高水分利用率的模式适应干旱环境,桑树以低光合-低蒸腾-高水分利用率的模式来应对干旱环境;在模拟干旱环境下,构树以稳定的羧化效率-高光呼吸速率-高光呼吸利用份额来适应外界胁迫,而桑树以低羧化效率-低光呼吸速率-低光呼吸利用份额来应对外界胁迫。构树表现出对外界干旱胁迫更好的适应性,这种适应机制可能与其较强的光呼吸作用及其碳酸氢根离子利用能力有关。这种"以碳换水"的机制可能是喀斯特适生植物适应岩溶干旱的又一个重要机制。

The Responses of Leaf Photosynthesis and Photorespiration to the Simulated Drought by Two Moraceae Plants

The responses of photosynthetic and photorespiration characteristics of two plants of Moraceae (Broussonetia papyrifera and Morus alba.) to the drought stress were studied by applying 150 g/L polyethylene glycol (PEG) to simulate the arid environment. The relevant chemical parameters of the culture medium and the photosynthetic parameters of leaves were measured. The arid environment was found to have less effect on the water absorption capacity of Broussonetia papyrifera than that of Morus alba. The Broussonetia papyrifera adapted to the arid environment by moderate photosynthesis, low transpiration and high water use efficiency, while the Morus alba by low photosynthetic, low transpiration and high water use efficiency. In the simulated drought environment, the Broussonetia papyrifera adapted to external stress by stable carboxylation efficiency, high photosynthetic capacity, high photosynthetic capacity utilization share, while the Morus alba by low carboxylation efficiency, low light respiration rate and low light respiration utilization share. The mulberry tree showed a higher adaptive capacity to the external drought stress than Morus alba. This adaptive mechanism of Broussonetia papyrifera may be related to its higher photorespiration rate and the ability of utilizing bicarbonate ions. The "consuming carbon for water" mechanism may be an important mechanism for plants to adapt for the karst drought.