局部灌水施氮条件下作物水氮高效利用的生理机制及模式

In the face of agricultural resources waste and the environments pollution due to low efficient use of fertilizer and water in worldwide, how to explore the adaptive potential of crop-self to nutrients, water and so on environmental factor for realizing high yield and high quality as well as high water and nutrients use efficiency through jointly regulate effect of water and nutrient has roused intensive attentions. Partial root zone irrigation (PRI) is considered as water-saving irrigation method and has been intensively practiced. However, little information is available on nutrients supply method under PRI, In this project, the pot culture experiment on maize will be carried out to study the effect of different supply methods of water and nitrogen fertilizer on characteristics of plant’s physiological properties based on the differences of photosynthesis, activities of nitrate reductase and root, osmotic adjustment ability and oxidation resistance system between the different environments. Dynamic changes of plant’s physiological properties (photosynthetic, soluble sugar and proline content, root, nitrate reductase and protective enzyme activities) will be investigated. Explore relationships between dynamic characteristics of plant’s physiological properties and use and uptake of water and nitrogen fertilizer. Responding mechanism of the physiological properties to different supply methods of water and nitrogen fertilizer will be revealed. Moreover, using field experiment, based on yield formation and uptake and use of water and nitrogen fertilizer, combination of supply methods and rates of water and nitrogen fertilizer will be evaluated to search for the optimal management measures of irrigation water and nitrogen fertilizer for getting high use efficiency of both water and nitrogen resources, then to find an more effective approach for high use efficiency of both irrigation and fertilization.

面对世界范围内普遍存在的水、肥利用率低造成的资源浪费与环境污染问题，如何通过水肥联合调控充分挖掘作物自身对水分、养分等环境因子的适应潜力，实现作物优质高产、水肥利用效率提高成为大家关注的焦点问题。局部灌溉技术自提出以来获得了良好的节水效益，但局部灌溉下施肥方式的研究受到较少关注。项目以玉米为研究对象，通过盆栽生物试验，在不同水、氮供应方式下，从处在不同环境光合作用、硝酸还原酶活性、根系活力、渗透调节能力和抗氧化体系的差异，揭示作物生理特性的动态变化规律；探索作物水、氮吸收利用与生理特性的动态变化间的关系；揭示作物生理特性对水、氮局部供应的响应机制。同时，通过田间生物试验，将水、氮供应方式与供应水平结合起来，从作物产量形成和水氮吸收利用方面，探索最大提高资源利用效率的水肥调控措施，为水肥综合高效利用寻求更为有效的途径。

分根区交替灌溉技术自提出以来获得了良好的节水效益，但该技术条件下水氮高效耦合的生理机制及其模式尚不清楚。通过避雨测坑试验，研究发现同一水氮供应水平下，不同灌水施氮方式显著影响玉米的生理特性，主要体现在光合作用、硝酸还原酶活性、根系活力、渗透调节能力和抗氧化体系的差异，造成了水氮利用效率的不同。与常规灌水均匀施氮相比，交替灌水均匀施氮和交替灌水交替施氮水氮协同供应利于提高玉米根系活力、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)和硝酸还原酶活性、可溶性蛋白含量和净光合速率，降低丙二醛（MDA）、可溶性糖和脯氨酸含量，改善了活性氧产生与清除之间的关系，从而提高了玉米产量和水氮利用效率。进一步地，研究交替灌水均匀施氮下不同灌水下限与施氮水平对玉米的根系生长、干物质积累分配、产量和水肥吸收利用的影响，发现采用60%～65%田间持水量（FC）配合中氮量（200 kg N/hm2）或75%～80%FC配合高氮量（300 kg N/hm2）可以实现协同提升玉米产量和水分利用效率的目的。特别地，与75%～80%FC配合高氮水平相比，60%～65%FC配合中氮水平（200 kg N/hm2）的收获指数、根长、根干质量、根表面积和根体积增加，根冠比减少，在保持玉米产量基本稳定的前提下使灌水量减少14.3%～15.9%，施氮量减少33.3%，因此获得最高的水、氮利用效率。项目研究成果对丰富和发展节水灌溉理论具有重要意义。