新疆两个主栽核桃品种叶片结构和光合特性的比较

Comparison of leaf structure and photosynthetic characteristics of two main walnut cultivars in Xinjiang

【目的】分析新疆地区现有优良早实核桃品种‘温185’和‘新新2号’在叶片形态结构与光合特性方面的差异情况,为新疆地区早实核桃品种的丰产和优质栽培提供理论依据。【方法】以7年生的‘温185’和‘新新2号’实生核桃大树为试材,采用常规石蜡切片技术观测新梢叶片的组织结构,使用Li-6800光合仪测定环境因子(温度、CO_(2)浓度和光合有效辐射)及叶片的光合参数(净光合速率、气孔导度、胞间CO_(2)浓度和蒸腾速率),并对所测数据分别进行单因素检验和相关性分析。【结果】测定结果表明:叶片的叶面积和上表皮、下表皮、栅栏组织的厚度及叶片组织的紧密度,‘温185’均大于‘新新2号’;‘温185’和‘新新2号’的净光合速率日变化曲线类型均为单峰型;‘温185’的净光合速率、气孔导度、胞间CO_(2)浓度、蒸腾速率及水分利用率均高于‘新新2号’的。相关性分析结果表明:2个核桃品种的净光合速率与蒸腾速率、气孔导度均呈极显著正相关,‘温185’和‘新新2号’的净光合速率与光合有效辐射均呈正相关;‘温185’和‘新新2号’的净光合速率与CO_(2)浓度、叶片厚度均呈负相关;‘新新2号’的净光合速率与其胞间CO_(2)浓度、叶片组织紧密度分别呈极显著、显著正相关,而‘温185’的净光合速率与其胞间CO_(2)浓度、叶片组织紧密度均无相关性;‘温185’的净光合速率与其叶片栅栏组织厚度、叶片组织疏松度均呈显著正相关,而‘新新2号’的净光合速率与其叶片栅栏组织厚度、叶片组织疏松度均无相关性。【结论】核桃叶片的栅栏组织、叶片厚度、蒸腾速率、气孔导度及叶片的水分利用率都能影响其光合速率;‘温185’比‘新新2号’更能适应南疆地区的气候条件。

【Objective】The differences of leaf morphological structure and photosynthetic characteristics between the existing excellent early bearing walnut varieties‘Wen185’and‘Xinxin 2’in Xinjiang were analyzed to provide a theoretical basis for the high-yield and high-quality cultivation of early bearing walnut varieties in Xinjiang.【Method】Using 7-year-old‘Wen185’and‘Xinxin 2’walnut trees as test materials,the tissue structure of new shoot leaves was observed by conventional paraffin section technology.The environmental factors(temperature,CO_(2) concentration and photosynthetic effective radiation)and photosynthetic parameters(net photosynthetic rate,stomatal conductance,intercellular CO_(2) concentration and transpiration rate)of leaves were measured by Li-6800 photosynthetic instrument,and the measured data were tested by single factor test and correlation analysis.【Result】The leaf area,the thickness of upper epidermis,lower epidermis,palisade tissue and the tightness of leaf tissue,‘Wen 185’were greater than‘Xinxin 2’;the diurnal variation curves of net photosynthetic rate of‘Wen 185’and‘Xinxin 2’were single peak;the net photosynthetic rate,stomatal conductance,intercellular CO_(2) concentration,transpiration rate and water use efficiency of‘Wen 185’were higher than those of‘Xinxin 2’.The results of correlation analysis showed that the net photosynthetic rate of the two walnut varieties was positively correlated with transpiration rate and stomatal conductance,and the net photosynthetic rate of‘Wen 185’and‘Xinxin 2’were positively correlated with photosynthetic effective radiation;the net photosynthetic rate of‘Wen 185’and‘Xinxin 2’was negatively correlated with CO_(2) concentration and leaf thickness;the net photosynthetic rate of‘Xinxin 2’had a very significant and significant positive correlation with its intercellular CO_(2) concentration and leaf tissue compactness,respectively,while the net photosynthetic rate of‘Wen185’had no correlation with its intercellular CO_(2) concentration and leaf tissue compactness;the net photosynthetic rate of‘Wen185’was significantly positively correlated with the thickness and porosity of leaf palisade tissue,while the net photosynthetic rate of‘Xinxin 2’was not correlated with the thickness and porosity of leaf palisade tissue.【Conclusion】Palisade tissue,leaf thickness,transpiration rate,stomatal conductance and water use efficiency of walnut leaves can affect their photosynthetic rate‘Wen185’is more adaptable to the climatic conditions in southern Xinjiang than‘Xinxin 2’.