宁夏中部干旱带老压砂地枣树适应性生长对土壤水分响应关系研究

The actual situation of jujube growth condition affected by soil moisture control is obvious change in the Old Gravel-mulched Field on Arid area of central Ningxia. By the field in-situ test, the response relationship of jujube growth adaptability on Soil Moisture in the old gravel Mulched Field is investigated. Based on soil water dynamics, water saving irrigation technology as the theoretical basis, The soil water content threshold of the old gravel Mulched Field on jujube Growth rate is determined by the method of mathematical statistics with field and laboratory test. Measurement of moisture content by TDR method, using Micro Lysimeter Measurement to observe soil moisture evaporation, using stem flow gauge to observe jujube plant transpiration, the ways are used to prove jujube water movement process. A contrast experiment is studied on jujube root layer soil moisture distribution influence by the different mixed ratio of sand and soil. Lower limit of soil moisture is investigated to maintain the old gravel Mulched Field jujube life characteristics. Based on the relation of jujube root, jujube canopy distribution, Photosynthesis and soil moisture to be studied in the old gravel Mulched Field, it is researched the rules of water consumption and water use efficiency to maintain old gravel Mulched Field jujube life characteristics. In order to provide the support of theory and data for the old gravel Mulched Field Reconstruction and ecological environment governance, the experiment of the old gravel Mulched Field moisture storage capacity and the rules of water consumption, the changing process of ecological environment of micro area planting jujube in old gravel Mulched Field.

针对干旱缺水条件下老压砂地枣树生长状态受土壤水分制约呈明显变化的实际情况，通过现场原位试验，探讨老压砂地枣树适应性生长对土壤水分响应关系。以土壤水动力学、节水灌溉技术为理论基础，依据数理统计方法，结合田间和室内试验，寻求影响老压砂地枣树生长的土壤含水率阀值；采用TDR法测量含水率，用微型蒸渗仪和茎流计观测土壤水分蒸发量与枣树植株蒸腾量，探明枣树地水分运动过程；采用对比试验，研究不同砂土混合比对枣树根系层土壤水分分布的影响，重点探明维持老压砂地枣树生命特征的土壤水分下限；在研究老压砂地枣树根系、枣树冠层分布及光合作用与土壤水分变化关系基础上，探明维持老压砂地枣树生命特征的耗水规律和水分利用效率。结合老压砂地储墒能力和枣树耗水规律试验研究，探明种植枣树后老压砂地微观区域内生态环境的变化过程，以期为老压砂地改造及生态环境治理提供理论与数据支持。

针对干旱缺水条件下老压砂地枣树生长状态受土壤水分制约呈明显变化的实际情况，通过现场原位试验和桶栽试验，探讨了老压砂地枣树适应性生长对土壤水分响应关系。得出了如下结论：.（1）试验区田间持水率为26.65%（质量），土壤容重为1.412g/cm3。枯水年下，每10天的平均耗水量占到模拟降雨量的60.5%、26.5%和13%，也即超过一半的降雨量在第一个10天内被消耗。枯水年下，A12、A22、A32、A42和A52处理的平均含水率分别为6.40%、6.38%、4.93%、3.61%和1.93%，极差分别为9.68%、9.25%、8.81%、8.73%和9.29%；特枯水年下，A11、A21、A31、A41和A51处理的平均含水率分别为5.52%、1.76%、4.97%、2.15%和2.57%，极差分别为5.29%、5.55%、5.31%、4.88%和5.06%。总体而言，随着土层深度的增加，土壤平均含水率变大，极差变小，相对处于稳定状态；相同冠幅尺寸下，随着模拟降雨量增加、土壤平均含水率变大，相同模拟降雨量下，随着冠幅尺寸的增加，土壤平均含水率下降。.（2）茎粗、株高、新稍直径和新稍长度累积生长量分别呈现二次分布、线性分布、二次分布和对数分布关系，R2均达到0.85以上；在不同的模拟降雨条件下，水分胁迫对枣树的生长性状具有明显的抑制作用。.（3）基于主成分分析，枯水年各冠幅处理的最优排序为A42>A12>A22>A52>A32；基于因子分析，枯水年各冠幅处理的最优排序为A42>A12>A52>A22>A32。A42处理（枯水年、0.60m冠幅尺寸）为宁夏中部干旱带枣树枯水年下最优处理，即0.60m冠幅尺寸为枯水年下宁夏中部干旱带种植枣树最优冠幅。.（4）通过枣树耗水量和土壤含水率相结合的方法可以看出，当含水率低于3%时，枣树会死亡，并且不会复活，而当含水率为3%~5%时，枣树具有一定的耗水量并且枣树复水后可以复活，即压砂地幼龄枣树的土壤水分下限为3%~5%。