【作者】 于金凤；

【导师】 刘文兆；

【作者基本信息】 西北农林科技大学 ， 生态学， 2010， 硕士

【摘要】 苹果园蒸散由果树蒸腾与株间土壤蒸发组成,蒸腾作用既是植物生命节奏中的重要环节,又是土壤—植物—大气系统( SPAC)水循环与水平衡的重要组分。本论文利用TDP茎流计实时监测苹果树蒸腾速率变化过程。并藉由中子仪测定果园土壤水分含量,分析其蒸散变化特征,获得的主要研究结果如下:(1)平均单株苹果树(平均边材厚度为3.71cm,边材面积为95.73 cm2)蒸腾速率的日变化表现为单峰曲线特征,白天差异显著,每日蒸腾速率变化幅度为300 g/h–1000 g/h,夜间差异不大,蒸腾速率接近于0 g/h;苹果树蒸腾速率晴天的日变化表现为骤升骤降型,下午15:00时左右,蒸腾速率达到最大值;雨天蒸腾速率的变化为单峰曲线,蒸腾开始时间较晴天迟一小时左右,下午15:30,蒸腾速率达到峰值,蒸腾速率明显低于晴天蒸腾速率;阴天呈不规则的多峰曲线变化特征,蒸腾速率的变化过程与天气情况太阳辐射强度、气温、风速的变化过程接近。(2)在苹果树的主要生长期,果树各月蒸腾量的变化为:7、8月较高,分别为62.8 mm和54.9 mm,其次是6月份37.4 mm,9月31.7 mm,10月蒸腾量最低,为26.7 mm;果园各月蒸散量的变化为:7、8月蒸散量最高,其次是6月、5月、9月,10月蒸散量最低。5-10月各月蒸腾总量分别占蒸散总量的比例为70.3%、57.9%、75.3%、75.8%、62.7%、67.6%。(3)苹果树的蒸腾速率与太阳辐射强度、气温、风速、土壤含水量呈正相关,相关系数分别为0.967、0.911、0.796、0.895,蒸腾速率与相对湿度呈负相关,相关系数为- 0.843。太阳辐射强度、气温、风速、空气相对湿度和土壤含水量是影响果树蒸腾速率的重要因子。(4)苹果树生长后期7月-10月0-800 cm剖面土壤含水量的变化为:土壤重量含水量在0-30 cm不稳定,变化幅度大,在30-220 cm范围内,土壤含水量随土壤深度的增加而降低,土壤含水量在13%-17%之间波动,在220-800 cm范围内,土壤含水量随土层深度的增加变幅较为平缓,土壤含水量在15%左右,表现出较为稳定的变化过程。更多还原

【Abstract】 The evapotranspiration of an apple orchard includes evaporation and transpiration. Transpiration is an important tache in plants’living rhythm. This experiment was conducted to study the change characteristics of water transpiration rate of apple trees by TDP and analyze the evapotranspiration of orchards by neutron?probe on the Loess Plateau. The main results and conclusions are as followed:(1) The diurnal change in transpiration rate for the average tree (the average sapwood thickness was 3.71 cm and the average sapwood acreage, 95.73 cm2) was in a form of single-peak curve. The difference was evident in the daytime, but little at night, with transpiration rate being nearly 0 mm/h. In clear days, transpiration rate was characterized by a rapid rise and drawdown change and reached the maximum at about 15:00. However, in rainy days, transpiration rate was by an irregular multi-peak curve change. The beginning time for transpiration in rainy days was about one hour later than that in clear days. Transpiration rate in rainy days reached the maximum at about 15: 30 and was lower than that in sunny days. In cloudy days, the changing process of transpiration was consistent with the changing processes of solar radiation, atmospheric temperature, and wind velocity. Transpiration rate in cloudy days was lower than that in clear days.(2) The monthly evapotranspiration was different in the main growing months of apple trees. In July and August, the monthly evapotranspiration was higher than other months and was 62.8 and 54.9 cm, respectively. In June, it was 37.4 cm and in September, 31.7 cm. In October, it was the lowest and only 26.7 cm. The result indicates that the monthly evapotranspiration was higher in June, July, and August and lower in May, September, and October. The percentages of the monthly evapotranspiration over the total evapotranspiration were 70.3%, 57.9%, 75.3%, 75.8%, 62.7%, and 67.6 %, respectively.(3) Transpiration rate was positively correlated with solar radiation, atmospheric temperature, wind velocity, and soil water and the relative coefficients were 0.967, 0.911, 0.796, and 0.895, respectively. There was a negative correlation between transpiration rate and relative humidity and the relative coefficient was -0.843. Solar radiation, air temperature, wind velocity, and soil water are the important factors to transpiration rate. (4) During the late growing months of apple trees, the changes of soil water content in 0-800 cm layers were different. Soil water content in the 0-30 cm layer was unstable and the change amplitude was evident. In the layer of 30-220 cm, soil water content was increased with soil depth and fluctuated from 13% to 17%. In the layer of 220-800 cm, soil water had little change with soil depth and soil water content was about 15%, indicating a stable change process in the layer.更多还原