【作者】 陈曦；

【导师】 任树梅；

【作者基本信息】 中国农业大学 ， 农业水土工程， 2004， 硕士

【摘要】 本文通过室内试验、室外试验和理论分析，对北京地区降雨过程随机模型作了初步的研究，对京郊地区苜蓿需水规律与苜蓿植物学特性进行了有益的研究，得到以下主要结论：(1)建立了面向实用的P—Ⅲ型分布的AR(1)模型，经降雨过程统计特性检验，表明模型对北京地区降雨特性能较好地模拟。(2)2002年苜蓿生育期内试验区的降雨总量为399.4mm，人工灌溉水量为80mm，各层土壤的储水量没有出现剧烈变化，苜蓿能够正常生长发育，说明这样降雨年型的降雨量配合一定的灌溉水量可以满足苜蓿生长对水分的需要。(3)苜蓿草地土壤水分周年变化可分为4个时期：春季失墒期、夏季增失墒交替期、伏秋增墒期、土壤水分凝积期；春季失墒期时草地下层土壤对上层土壤水分及伏秋降水对冬前土壤水分均有明显补偿作用。(4)通过试验可以得出，中苜一号和根选苜蓿品种表现最优秀，获得的产量较高，值得在京郊地区大力推广种植；青睐苜蓿和陇东苜蓿的产量远远低于其他品种，不适于在京郊地区推广。影响苜蓿单株产草量相关性状的通径分析表明株高、叶片数、叶宽对产量贡献作用大，分枝数、叶长成为限制产量的主要因子。苜蓿根长和根重密度随深度呈指数递减规律，由试验结果导出的垂直分布规律拟合公式对建立根系吸水函数具有参考价值。更多还原

【Abstract】 On the basis of analysis and in laboratory and field, the random model of rainfall process, the principle of water requirement and botany characteristic of alfalfa in the suburb of Beijing were studied elementarily in the thesis. The main conclusions were: (1) The AR(1) model with P-III distribution was built to face practical application, and the statistical test of the rainfall process showed that the simulated results of the model matched very well with that of the measured. (2) During the experiment, the total quantity of rainfall in 2002 was 399.4 mm, the gross quantity of irrigation 80 mm, and the alfalfa grow well. The water requirement of the alfalfa, therefore, could be satisfied by irrigation measures under the similar year as typical year in this district. (3) The seasonal change of soil water for alfalfa was divided into the four stages: soil water losing stage of spring, soil water alternating stage between adding and losing of summer, soil water adds stage of autumn, soil water agglutinating stage. Lower soil water could distinctly compensate for the top soil in the first stage and the rainfall did so in the third stage. (4) The results of the experiments showed that the two kinds of alfalfa (Medicago sativa L."Zhong mu NO1" and Medicago sativa L."Gen xuan") were of higher yield and better characteristic, therefore ,should be popularized in the suburb of Beijing. The other two kinds of alfalfa (Medicago sativa L."Qing lai" and Medicago sativa L."Long dong") should not be plant in the suburb of Beijing because of the lower yield. Moreover, the results indicate that the influences of crop height, leaf length and leaf width on the yield of single trunk of alfalfa are relatively bigger and the divarication amount and leaf length were the main obstractive factors of the yield. The fitting function and need form experiments could provide consulting valuation for building the water-uptake-by-root function.更多还原