山东泰山地区湖北海棠居群间变异的研究

在对山东泰山地区湖北海棠居群进行详细调查的基础上,依据花、果性状对该地区的4个湖北海棠居群间的形态变异进行了系统研究.结果表明,湖北海棠花、果性状在所选取的4个居群间出现了一定程度的分化,但这种分化是一个连续的变异过程,居群间的分化与居群生境的异质性有很大的关系;湖北海棠花、果的整体性状在4个居群间表现出一种海拔梯度变异,即随着分布海拔的升高,萼齿长、萼筒长、花柄长、果长、果径均有逐渐变小的趋势;并对泰山湖北海棠变种区别于模式变种的形态特征进行了补充描述.     

山东泰山地区湖北海棠唐群间变异的研究

在对山东泰山地区湖北海棠居群进行详细调查的基础上，依据花、果性状对该地区的4个湖北海棠居群间的形态变异进行了系统研究．结果表明，湖北海棠花、果性状在所选取的4个居群间出现了一定程度的分化，但这种分化是一个连续的变异过程，居群间的分化与居群生境的异质性有很大的关系；湖北海棠花、果的整体性状在4个居群间表现出一种海拔梯度变异，即随着分布海拔的升高，萼齿长、萼筒长、花柄长、果长、果径均有逐渐变小的趋势；并对泰山湖北海棠变种区别于模式变种的形态特征进行了补充描述．     

Estimation of evapotranspiration and its components from an apple orchard in northwest China using sap flow and water balance methods

Field experiments were conducted to investigate the effects of leaf area index and soil moisture content on evapotranspiration and its components within an apple orchard in northwest China for 2 years. Evapotranspiration in the non‐rainfall period was estimated using two approaches: the soil water balance method based on tube‐type time‐domain reflection measurements, and sap flow plus micro‐lysimeter methods. The two methods were in good agreement, with differences usually less than 10%. The components of evapotranspiration varied with canopy development. During spring and autumn, soil evaporation was dominating as result of low leaf area index. In summer, plant transpiration became significant, with an average transpiration to evapotranspiration ratio of 0·87. The crop coefficient K_c showed a strong linear dependence on leaf area index. The water stress coefficient K_s was around 1·0 when soil moisture was above 23% and started to decrease linearly after that. This study demonstrates that prediction of evapotranspiration in apple orchards can be made using the Food and Agriculture Organization's crop coefficient method from commonly available meteorological data in the area. Copyright © 2006 John Wiley & Sons, Ltd.     

小降雨事件对土壤水分及植物水势空间差异性的影响

本文以云南省蒙自市断陷盆地高原面上典型封闭式岩溶洼地小流域为研究对象,研究小降雨事件对土壤水分及植物水势的影响。结果表明:（1）在研究区内小降雨事件一般只能补给10 cm以上的土壤,因此在旱季（强降雨事件发生前）,土壤水分随着深度的增加整体呈变小的趋势;受洼地地形影响,整个土壤剖面（0 ~ 80 cm）的土壤水分存在从坡顶到洼地底部逐渐增加,苹果树叶水势逐渐升高的现象;受地质背景的影响,土石质坡地平均土壤水分比石质坡地土壤水分高2.67%,相对应的土石质坡地苹果树受干旱胁迫的程度要低于石质坡地。（2）通过观测对比发现,8天内12次的小降雨事件可以使0~10 cm土壤水分整体上略有升高,但并未能完全改变0~10 cm土壤水分洼地底部大于两侧坡地,而土石质坡地高于石质坡地的特征。（3）小降雨事件虽然只能补给0~10 cm的土壤水分,但由于坡地地区苹果树根系分布较浅（5~30 cm）,部分浅层分布的苹果树根系已能吸收到水分,另一方面小降雨事件具有降温、增湿,减少太阳辐射的作用,可以减小苹果树蒸腾作用,从而降低苹果树叶水势,因此推测小雨事件可以明显减轻苹果树受干旱胁迫的程度