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引种台湾桤木的水分生理特性

Water Physiological Characteristics of Introduced Alnus formosana

  • 摘要: 台湾桤木(Alnus formosana)原产台湾,是台湾地区重要的先锋造林树种和林地培肥树种。水分是限制植物地理分布和决定植物引种能否成功的重要因子之一。采用Li-6400光合测定系统对引种两年生台湾桤木苗木的水分生理特性进行了研究,结果表明:(1)在整个生长期,叶片蒸腾速率日变化均表现为宽大的单峰型曲线,以13∶00~15∶00时左右蒸腾速率最高,不同部位叶片在不同生长期的峰值有所不同,属非蒸腾午休型植物。气孔导度日变化有单峰型和双峰型2种变化曲线;(2)蒸腾速率季节变化表现为单峰曲线,以7月为最高,整个生长期叶片日均蒸腾速率为3.25mmol·m-2·s-1,表现出高光合、强蒸腾的生理特点;(3)水分利用效率日变化与光合速率日变化相似,有单峰曲线和双峰曲线2种类型,与气孔导度的日变化有显著相关性。在整个生长期,以6月、7月叶片水分利用效率为最低,8月为最高;(4)在影响水分利用效率季节变化的生理生态因子中,以温度、光合有效辐射、气孔导度和相对湿度4个因子的直接作用为最大。

     

    Abstract: Alnus formosana,originated in Taiwan Province,is an important pioneer afforestation tree in Taiwan and can fertilize forestry soil.Water is one of the most important factors to restrict the geographical distribution of plant and to influence introduction of tree.The water ecological characteristics of two-years-old seedlings of introduced A.formosana were studied by using Li-6400 photosynthetic system.The main results showed as follows:(1) The diurnal change of transpiration rate(Tr) of leaves during the whole growth period showed a sort of wide and one-peak curve type,and the peak value occurred at about between 13∶00 and 15∶00,and leaves at different positions had different peak value during various seasons.A.formosana is of non midday depression of transpiration.The daily change of stomatal conductance have both one-peak type curve and two-peak type curve;(2) The seasonal change of Tr of various leaves all showed the double-peak curve, and the maximum of Tr during the whole growth period appeared in July, and the diurnal average Tr of leave is 3.25 mmol·m-2·s-1.This tree showed physiological characteristics of both high photosynthesis and strong transpiration;(3) The daily change of water use efficiency(WUE),which was similar to that of Pn, had obvious correlation with that of conductance, and had both the one-peak curve and the double-peak curve.The WUE of June and July were lowest during the whole growing season, and the WUE of August highest;(4) Both the correlative (ana-)(lysis) and the path coefficient analysis all indicated that the air temperature (Tair) or leaf temperature(Tleaf),photosynthetic active radiation (PAR),conductance (Cond) and the relative humidity (RH) are the four most important direct factors to influence the seasonal changes of WUE.

     

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