灌溉方式对玉米根系时空分布的影响及调控机制

Due to the demand of High-efficient Water-saving in Xinjiang, drip irrigation gets more and more application, which promotes the development of economic and ecological benefits. The drip irrigation technology for maize, which is a reform to grain crops irrigation, has been promoted with expanding planting area for its significant effect of yield increase and water saving, and it becomes the key promotional project in Xinjiang. Irrigation Patterns may modify certain soil properties in root zone，such as bulk density, soil water content and soil nutrient condition. Root growth is determined both by plant genetic characters and by soil physical and chemical properties. If water supply in the upper soil profile is plentiful, rooting depth remains shallow. But drier soil conditions promote root elongation and increase the degree of branching, allowing the crop to exploit soil water more completely. Little research has focused on the influence of irrigation system on maize root growth. We describe experiments designed to measure the response of maize root by different irrigation patterns. Irrigation treatments are drip irrigation and conventional furrow irrigation, and the experiment is designed as a randomized complete block with three replications. The following parameters will be researched: 1) the rule of maize root growth and development is quantitative study. 2) the study describes quantitatively the dynamic relationships between root growth and development of maize and environments, such as soil salt transfer and nutrient distribution. 3) the study discusses the relationship between root growth and aboveground growth to provide theoretical basis for aboveground regulation. This study aims to solve the problem of targeting for integrated management of water and fertilizer and application of fertilizer in extractive quantity. This study may propose technology of water and fertilizer regulating and control for maize root with drip irrigation. Thus, this study may provide a theoretical basis for building reasonable maize root with management of water and fertilizer, solve the problem of lodging and premature senility, and promote high and stable yield of maize.

膜下滴灌技术由于其高效节水的特点而在新疆大面积推广使用，取得了很好的经济与生态效益。玉米膜下滴灌技术是在棉花滴灌基础上兴起的，是粮食作物灌溉制度的一次改革。但膜下滴灌独特的水肥供应方式使整个根区土壤环境表现出明显的差异。由于根系生长的趋水趋肥性，使用滴灌进行灌溉，玉米根系变浅，易发生倒伏和早衰； 但滴灌条件下玉米根系相关的研究严重滞后。本研究拟在田间试验基础上，以漫灌作为对照，应用双向切片法采集根系，对不同灌溉方式下玉米根系的生长发育规律与根系生理特性进行精确的量化研究；同时分析根系生长发育与土壤盐分运移、养分分布的关系；揭示根系构型变化的玉米地上部响应机制。最终结合以上结果，完善膜下滴灌玉米灌溉理论，解决滴灌玉米水肥一体化和精准施肥靶向问题，提出根系优化的水肥调控技术。研究结果将对构建更为健康的玉米根系、解决滴灌玉米早衰问题、实现滴灌玉米高产稳产和推动滴灌玉米水肥一体化应用提供理论依据。

膜下滴灌技术由于其高效节水的特点而在新疆大面积推广使用，取得了很好的经济与生态效益。玉米膜下滴灌技术是在棉花滴灌基础上兴起的，是粮食作物灌溉制度的一次改革。滴灌施肥独特的水肥供应方式使玉米根区土壤环境、水肥吸收过程和运移机制表现出明显的差异；另外，滴灌独特的水盐运移特征，使整个玉米根区水盐分布的特征表现出明显差异。本实验于2013～2017年在石河子进行，本在田间试验基础上，设膜下滴灌（D）和细流沟灌（M）两种灌溉模式，2013～2016年设置膜下滴灌（D）4水平：4200、4800、5400、6000m3/hm2；2017年设置膜下滴灌（D）3水平：2400、4800、6000m3/hm2；2015～2017年设置细流沟灌（M）2水平：4800、7200m3/hm2。通过与实际生产相一致的田间试验，采用实时监测手段和双向切片法相结合的方法研究膜下滴灌和细流沟灌玉米的根区水肥盐动态及根系生长特征和玉米地上部的响应。.整体上讲，本论文主要取得了以下研究成果：.（1）窄行（滴头）、根系和宽行三点之间的水分供应及消耗规律均有显著差异。滴灌呈现出由滴头→根系→宽行入渗的规律，而细流沟灌正好相反呈现由宽行→根系→窄行的规律。.（2）随着水分的变化，土壤盐分空间分布也随着变化。滴灌玉米耕层土壤盐分特征呈现出：先升高降低的单峰增长趋势；Ec值呈现出：窄行＜根系行＜宽行。滴灌较细流沟灌更有利于作物生长，膜下滴灌可以通过水盐调控，在以滴头为中心的根区构建一个椭球形或球形淡盐区，适量滴灌有利于根区土壤脱盐。.（3）膜下滴灌和细流沟灌水分的补充方式和补充位点不同；膜下滴灌根区的硝态氮、铵态氮和速效钾含量均高于细流沟灌，速效磷含量低于细流沟灌。.（4）滴灌玉米的根系主要分布在水平0～25cm，垂直0～20cm的椭圆形范围内，与滴灌玉米根区湿润体——淡盐区——高速效氮和速效钾分布区域基本上相互重合。.（5）滴灌量过量影响玉米产量，最佳滴灌量应该在4500～5500m3/hm2之间。