控制灌溉条件下烟田水分分布规律及灌溉指标选择

Regularity of Water Distribution and Selection of Irrigation Indexes in Tobacco Fields under Water-controlling Irrigation

设计不同节水灌溉下限处理,对不同处理下烟田水分的去向、分布和平衡特征进行了分析;引入投影寻踪分类模型,以烤烟品质为评价标准,选择最优灌溉指标。结果表明:棵间蒸发量在烤烟全生育期内呈现"先增大,后减少,再增大"的趋势,棵间蒸发量占腾发量的比率与烤烟叶面积指数呈y=1.137exp(-0.375x)的指数函数关系;深层渗漏、地表径流、棵间蒸发、植物蒸腾和土壤水分变化分别占总耗水量的1.81%、21.17%、17.46%、58.47%、1.09%,各部分耗水量与灌溉量相关性显著,灌溉量大的处理,深层渗漏和地表径流占总耗水量的比例也更大;深层渗漏量、径流量(y)与灌溉量(x)呈二次函数关系,所建立模型相关系数分别为0.8806与0.9910;实际生产实践中,推荐60%-80%-70%的节水灌溉下限指标。

Different water-saving irrigation treatments were designed to analyze the whereabout, distribution and balance char- acteristics of water in tobacco fields. The projection pursuit classification modei Was applied to select the optimal irrigation indexes based on the quality of flue-cured tobacco leaves. The soil evaporation revealed a tendency of ＂increase at first, then decline, and increase again＂ in the whole growth period of flue-cured tobacco. An exponential relationship [ y= 1.137exp（-0.375x） ] was detec- ted between the leaf area index （x） and the ratio of soil evaporation to total evaporation （y）. The deep seepage, surface runoff, soil evaporation, plant transpiration, and soil water variation accounted for 1.81%, 21.17%, 17.46%, 58.47% and 1.09% of total water consumption, respectively. Each part of water consumption was significantly correlated with the irrigation amount. The ratio of deep seepage or surface runoff to total water consumption was greater in the treatment of large irrigation amount. There was a quadratic function relationship between the amount of deep seepage or surface runoff （y） and the irrigation amount （x）, and the correlation coefficient of the built two models reached 0.8806 and 0.9910, respectively. The water-saving irrigation low limit of 60%-80%- 70% in the production practice was recommended.