玉米根系响应土壤耕层调控的生态机制研究

The root growth and yield of maize are restricted severely by the poor soil quality. As two important technological measures in agriculture production, soil tillage and straw returning are vital ways to improve soil quality, increase fertility and crop production. However, few studies focus on the effects of topsoil regulation on maize root, the same with the effects of soil regulation on the undisturbed soil texture and soil biological characters. Moreover, the ecological mechanisms of responses of maize root to topsoil regulation are also needed to be studied. The study has based on six-year fixed-site soil tillage. This research intend to study the effects of different soil tillage (rotary tillage, deep mouldboard ploughing and chisel ploughing) and straw returning (crop residue retained and crop residue removed) on maize three-dimensional root growth and physiological function, analyze the effects of soil regulation on undisturbed soil texture, soil fertility, soil biological characters, and then explain the ecological mechanism how maize root responds to the soil regulation. The results will provide a theoretical guide for technology establishment to improve the compacted soil and yield-increasing of maize.

土壤耕层质量差严重限制了玉米根系的生长和产量形成。土壤耕作和秸秆还田作为农业生产中两项土壤耕层调控的重要技术措施，是改善土壤耕层质量、培肥地力、促进作物生产持续增加的重要途径。但目前关于土壤耕层调控对玉米根系影响的研究较少，而关于土壤耕层调控对原位土壤结构、以及对玉米根际土壤生物性状的影响更是鲜有研究，且没有系统深入研究玉米根系对土壤耕层调控响应的生态机制。本项目以长达六年的土壤耕作定位试验为基础，主要研究不同耕作方式（旋耕、深耕、深松）和秸秆还田（秸秆还田、秸秆不还田）下玉米根系三维生长模型和生理功能，探讨耕层调控对原位土壤结构、土壤肥力和土壤生物性状的改良效应，分析玉米根系对土壤耕层调控响应的生态机制，为研发缓解玉米田土壤紧实的调控技术、进一步提升玉米增产潜力提供理论依据。

为明确玉米根系响应土壤耕层调控的生态机制，以长达六年的耕作定位试验为基础，研究土壤耕层调控措施（耕作方式和秸秆还田）对玉米根系生长分布和生理功能的影响，探讨土壤耕层调控对原位土壤结构和根际土壤微生物环境功能的改良效应，揭示玉米根系响应土壤耕层调控的生态机制。研究结果表明，土壤耕层调控措施深耕结合秸秆还田可以促进玉米根系生长，增加玉米产量。深耕可以使玉米产量提高7.3%，秸秆还田使玉米产量提高2.8%，深耕结合秸秆还田可以使玉米籽粒产量提高10.3%。土壤耕层调控可以改善土壤结构，缓解土壤紧实状况。与旋耕+秸秆不还田相比，深耕结合秸秆还田可以使土壤紧实度降低23.5%，土壤孔隙体积和孔隙面积分别增加41.1%和27.8%，土壤有机质和全氮含量分别增加14.3%和6.4%，土壤呼吸速率提高47.2%，土壤土壤脲酶、蔗糖酶、蛋白酶和碱性磷酸酶活性分别提高8.3%、15.8%、14.2%和39.4%。此外，土壤耕层调控促进玉米根系生长分布和地上部物质积累。深耕结合秸秆还田可以使玉米根系长度、根系体积和根系干重分别提高35.2%、35.1%和27.1%，植株干物质积累量增加3.8%，植株氮、磷、钾积累量分别提高16.2%、15.0%和17.5%。土壤耕层调控不仅可以丰富土壤细菌多样性，OTUs比旋耕+秸秆不还田增加13.1%，独有细菌种群数量增加150.7%，还增加有益菌门的水平丰度，对土壤微生物生态环境具有良好的调控效果。因此，土壤耕层调控创造了更有利于玉米根系生长的土壤结构和微生物环境。