【作者】 李召宝；

【导师】 吕国安； 刘钰；

【作者基本信息】 华中农业大学 ， 土壤学， 2010， 硕士

【摘要】 气孔阻力和冠层阻力均是研究作物蒸发蒸腾的重要参数,两者既有区别又有联系,气孔阻力是水汽进出植物气孔的阻力,是研究植株尺度蒸腾量的依据；而冠层阻力是研究农田尺度蒸发蒸腾的基本参数,其基本出发点是将作物冠层概化为一张“大叶”,依据“大叶理论”,冠层阻力是各叶片气孔阻力和土壤阻力的综合。气孔阻力和冠层阻力的变化规律是否相同,能否通过建立二者之间的关系进行不同尺度间的转换,是目前国内外广泛关注的研究热点和难点。本论文以大量田间实测数据为基础,分析了冬小麦和夏玉米气孔阻力的日内及生育期内变化过程,研究了环境因子对气孔阻力的影响,对比了利用Penman-Monteith公式反推作物冠层阻力和利用气孔阻力计算冠层阻力的方法,得出以下研究结果：1.不同作物气孔阻力的日变化不尽相同。冬小麦气孔阻力的日变化表现为“W”型,气孔阻力在早、中、晚时刻高,只有在土壤水分供应充足或生育早期温度较低时中午的峰值较小或无峰,日变化呈“U”型；夏玉米气孔阻力的日变化基本呈“U”型变化的,以早晚最高。2.冬小麦的气孔阻力在整个生育期的变化是多峰型的。在生育前期较高(以返青后为起点),转入旺盛生长期后阻力值有所减小,在抽穗灌浆期常会出现一个阻力升高点,而后又减小,随着作物的衰老,叶片功能的衰退气孔阻力又逐渐增大,总体上是呈多峰型变化的；夏玉米的气孔阻力在整个生育期内的变化基本上是平缓增加的。3.影响气孔阻力大小变化的环境因子不同的作物不尽相同。冬小麦最重要的影响因子依次为相对湿度、温度、蒸腾和冠气温差,而影响夏玉米气孔阻力重要的环境因子是净辐射、温度和相对湿度。4.冠层阻力可以通过不同的方法推算,但不同的方法对不同作物的吻合程度不相同。气孔阻力结合叶面积指数计算出的冠层阻力在日内的变化趋势同所测的气孔阻力基本一样,只是数值上要小些。在植株及小区尺度上这种方法算的冠层阻力是比较准确的；利用PM公式反推的中等尺度上的冠层阻力,由于是中等尺度,反推出的日变化趋势比较简单。冬小麦反推出冠层阻力同利用气孔阻力计算出的数值差别普遍较大。夏玉米两种方法计算的冠层阻力相关性则较好,在数值大小和趋势上均吻合较好。更多还原

【Abstract】 Stomatal resistance and canopy resistance are important parameters of crop evapotranspiration study. They are different and related. Stomatal resistance is the resistance of water vapor in and out of plant stomata, which is the basis for the evapotranspiration on the plant scale. Canopy resistance is the basic parameter of evaporation and transpiration on the field scale, the basic starting point is generalized crop canopy into a "big leaf".According to the "big leaf theory" canopy resistance is the integrated of leaf stomatal resistance and soil resistance. Whether there is the same variation between stomatal resistance and canopy resistance, or through the establishment of the relationship between them to do conversion between different scales is a widespread concern topic at home and abroad. In this thesis, based on the large number of field measured data, we analyzed the changing process of stomatal resistance of winter wheat and summer maize growth on days and growth season, studied the effects of environmental factors on stomatal resistance, and compared the method of using Penman-Monteith equation inversed crop canopy resistance and using stomatal resistance calculated canopy resistance, the main results as follows:1.The diurnal variations of stomatal resistance of different crops are various. Diurnal variation of stomatal resistance of winter wheat is on the performance of "W-type". Stomatal resistance is higher in the early, middle and late time in daytime, the peak would be less or disappearance and likes as the "U-type"if the supply of soil moisture is adequate, or the temperature is low on the early growth stage. The diurnal variations of stomatal resistance of summer maize like as "U-type" in all measurement days with the higher values in the morning and evening time.2.Stomatal resistance of winter wheat change as multiple peaks curve throughout the growth period. It is higher (to start after turning green period) at the early growth stage then tune to less with plant vigorous growth, and a resistance increase point often is seen on heading and filling stage, then decreases again, stomatal resistance increases gradually with the crop aging and declining of leaf functional. On the whole the stomatal resistance of winter wheat in the whole growth season shows as a multiple peaks curve. While the stomatal resistance of summer maize are basically gentle rise in the whole growth period.3.Factors determine stomatal resistances on different crops are not the same. The most important factors affecting stomatal resistance on winter wheat are in the order of relative humidity, temperature, transpiration and canopy-air temperature difference.The most important environmental factors on summer maize are net radiation, temperature and relative humidity.4.Canopy resistance can be calculated in different ways, but different methods for different crops are in different degree of agreement. Using stomatal resistance combined of leaf area index to calculated canopy resistance has the same trends in the days with the measured stomatal resistance, but the value is less.Calculated canopy resistance in plant and cell scale in this method is more accurate. The diurnal variation of canopy resistance shows a simple trend by using PM formula promoted on the medium scale.Canopy stomatal resistance values calculated with the two methods are larger different. Correlation of summer maize canopy resistance calculated by those two methods is good, both are in good agreement in numerical size and trends.更多还原