微咸水喷灌条件下盐分的分配规律及其界面调控研究

Both soil salt and sprinkler-irrigated brackish water salt affected crop growth and productivity. Salt absorption rate by plant leaf was linear functionally related with water salt concentration and irrigation duration. Generally, increasing irrigation frequency led to a greater increase in salt absorption than increasing irrigation duration. Sprinkler irrigation with fresh water following sprinkler irrigation with brackish water reduced leaf salt uptake. Crop yield was not significantly related with leaf sap ion concentration. The project will focus on the following points: (1) The mechanism of effect on the absorption of salt from canopy interception of winter wheat under sprinkler irrigation with brackish water. The main research includes the relationship between brackish water absorption of leaves and the salt content of brackish water sprinkler irrigation process, the effects of salt leaching by fresh water on the absorption of salt, the effects of dissipation process of water on leaves on the absorption of salt. (2) The mechanism of effect of straw mulching on the distribution of water and salt under sprinkler irrigation with brackish water. The main research includes the effect of straw mulch on water and salt from canopy interception under brackish water sprinkler irrigation and the distribution of the water and salt in soil profile. (3) Effect of water and salt regulation under sprinkler irrigation with brackish water on the absorption of salt and crop yields. (4) Reasearch on the comprehensive regulating model based on the salt leaching from leaves and soil. Bring out new methods of salt and water regulation providing the scientific basis and basic parameters for the application of sprinkler irrigation with brackish water.

微咸水喷灌条件下, 作物同时受到土壤盐分和喷灌水盐分的双重影响。大部分作物通过叶片吸收盐分的速率与盐分浓度和喷水历时基本上呈线性函数关系。喷灌频率的增加比喷水历时的增加更能增加作物盐分的吸收。微咸水喷灌后短时间的淡水冲洗可以减少作物叶片对盐分的吸收。微咸水喷灌作物产量和叶片汁液离子浓度没有明显的相关关系。本项目将重点研究：（1）微咸水喷灌条件下冬小麦冠层截留对叶片吸收盐分的影响机制。主要研究微咸水喷灌过程叶片吸收盐分与灌溉水盐分的关系；淡水淋洗对叶片吸收盐分的影响；叶片水分消散过程对叶片盐分吸收的影响。（2）秸秆覆盖对微咸水喷灌水盐分布的影响机制。主要研究秸秆覆盖对微咸水喷灌水盐截留的影响；秸秆覆盖对土壤水盐分布的影响。（3）微咸水喷灌水盐调控对作物盐分吸收和产量的影响。（4）基于叶片和土壤盐分淋洗的综合调控模式研究。提出水盐调控的新方法，为微咸水喷灌的应用提供科学依据和基本参数。

本项目基于微咸水喷灌条件下淡水淋洗，在土壤和作物冠层两个界面上对微咸水喷灌的水盐分配、作物响应机制和盐分的产量效应进行研究，提出喷灌利用微咸水的水盐调控方法，初步确定了调控参数。项目执行期为2013年1月-2015年12月，通过3年的研究，开展了项目申请时的研究内容，完成了项目预期目标。主要开展的工作和获得重要进展如下：.（1）研究微咸水喷灌条件下淡水淋洗调控对土壤盐分分布的影响及冬小麦的响应机制，确定喷灌利用微咸水时适宜的淡水淋洗比例：以喷灌25%灌水量（12.5 mm）的淡水淋洗效果最佳，可有效缓解微咸水喷灌对冬小麦生长造成的不利影响，能达到喷灌淡水97.9%以上的产量；.（2）研究覆盖条件下淡水淋洗调控对喷灌水盐分配及冬小麦的响应机制，明确全量秸秆覆盖条件下微咸水喷灌秸秆截留水量最大为2.00 mm，盐分截留量为2.20 kg/ha，随着淡水淋洗水量的增加，秸秆截留灌溉水的盐分逐渐减少，25%淡水（12.5 mm）淋洗加上秸秆覆盖能减少冬小麦主要根系分布层（0-40 cm）盐分的累积。 .（3）以淡水喷灌为对照，研究微咸水喷灌条件下喷灌水矿化度对土壤盐分分布的影响及冬小麦响应机制，揭示喷灌水矿化度对土壤水溶液盐分的影响机制以及灌溉水盐分与作物产量的关系：利用2.5-5.5 g/L微咸水喷灌+15%淡水淋洗时，灌溉水每增加1 g/L，0-20 cm土壤水溶液EC值增加1.248 dS/m，冬小麦产量下降263.5 kg/ha，微咸水喷灌冬小麦的灌溉水矿化度推荐在3.5 g/L以内。.（4）研究微咸水喷灌条件下秸秆覆盖量对土壤盐分分布的影响及冬小麦响应机制，阐明秸秆覆盖量对喷灌水盐分配影响的规律，确定微咸水喷灌时秸秆覆盖量对作物产量的效应：秸秆覆盖量每增加1 t/ha，秸秆截留水量增加0.201 mm，在0-1.5倍覆盖量时，随着秸秆覆盖量的增加，冬小麦产量呈增加趋势，以1.5倍秸秆覆盖量为最高。