In order to discuss causes of shoot wilting of walnut at fruiting period from the aspect of micro-environmental climate change,and to provide some references for suitable tree form cultivation,using ‘Zhonglin No.1’ walnut as materials,occurrence status of one-year-old shoot wilting at different parts of canopy of different tree forms was investigated,micro-environmental factors such as leaf net photosynthetic rate were determined by LI-6400 portable photosynthesis system,and relationships among tree micro-environment,shoot wilting and tree form were analyzed.The results showed that withered shoot rate of walnut trees with evacuation layered shape was lower than that of walnut tree with natural round shape.Leaf net photosynthetic rate,photosynthetically active radiation,CO2 concentration and air temperature of walnut trees with natural round shape and evacuation layered shape were the lowest in interior canopy,followed by middle canopy,and the indexes in peripheral canopy were the highest,however,the orders of air relative humidity were on the contrary.Leaf net photosynthetic rate and photosynthetically active radiation of the walnut tree with evacuation layered shape were higher than those of the walnut tree with natural round shape.The walnut tree form of evacuation layered shape could improve ventilation and light transmisson conditions of canopy,which was benefit for photosynthetic product synthesis in leaf,could promote nutrition accumulation in shoot,could enhance resistance capacity,and could reduce occurrence of shoot wilting.%为了从微环境气候变化方面探讨结果期核桃树枝条干枯发生的原因,从而为核桃适宜树形的培养提供参考依据,以‘中林1号’核桃为试验材料,对不同树形与树冠不同部位1年生枝条的枯枝发生情况进行了调查,在此基础上,采用LI-6400便携式光合仪,对其叶片净光合速率等微环境因子进行了观测,并对树体微环境、枝条干枯与树形的关系进行了分析.观测结果表明:疏散分层形核桃树其枯枝率低于自然圆头形核桃树;自然圆头形和疏散分层形核桃树的叶片净光合速率、光合有效辐射、CO2浓度、空气温度均以树冠内膛的为最低,中部次之,外围最高,而空气相对湿度的高低顺序却与之相反;疏散分层形核桃树的叶片净光合速率、光合有效辐射均高于自然圆头形核桃树.文中分析得出,核桃树的疏散分层树形,可使树冠内的通风透光条件得以改善,有利于叶片光合产物的合成,可促进枝条营养物质的积累,能增强其抗性,可减少枯枝的发生.
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