控释尿素水氮耦合对夏玉米产量形成的生理机制及氮高效机理研究

As a new type of high-efficiency fertiliser, how can the controlled release urea coordinate with soil moisture in summer maize fields and obtain high yield? It is a bottleneck restraining the controlled release urea development and application. The mechanism of coupling between moisture and nitrogen will be studied to clear effects of controlled release urea on yield of summer maize. Controlled release urea (resin coated, nitrogen content is 42%, nitrogen release period for 90 d) as the experimental material is produced by Shandong Kingenta Ecological Engineering Co., LTD. which is developed by shandong agricultural university itself. Combining the soil column and field experiment,using advanced technology and method including 15N isotope tracer, efficient gas chromatography, system simulation in this project, root distribution and spatiotemporal distribution of the root vibrant will be studied to contain characteristics of regulation mechanism for coupling of controlled release urea and irrigation. Meanwhile, the photosynthetic characteristic and kernel growth process will be studied to make sure the regulation way for the coupling controlled release urea and moisture to root source, Leaf source, kernel source and kernel quality. Dynamic regulation of transportation of controlled release urea-N in summer maize farmland system will be studied to prove the mechanism and correlation between moisture and nitrogen. The aim of this project is to provide scientific evidences for extensive application of controlled release fertilisers and summer maize simplified cultivation through seeking physiological and biochemical mechanism of the influence for coupling between the controlled release urea and water with summer maize yield, clear their best coupling plan and formulation technical specification for effective utilization of controlled release fertiliser and irrigation.

控释尿素作为新型高效肥料，在玉米生产上能否与水分合理运筹实现高产？成为制约其发展和大面积推广的瓶颈。为明确控释尿素对夏玉米产量影响的生理机制，探讨其水氮耦合机理，本项目以山东农业大学自主研发、山东金正大公司生产的控释尿素为试验材料，大田与土柱试验相结合，利用15N同位素示踪、高效气相色谱、系统模拟等先进技术和方法，系统研究控释尿素水氮耦合条件下黄淮海夏玉米根系分布、活力的时空变化动态，光合特性、籽粒发育进程，明确控释尿素水氮耦合对夏玉米根源、叶源与籽粒库的调控机理。研究控释尿素水氮耦合条件下夏玉米农田系统氮素运移规律，探明水氮的影响机制及相互关联；探讨控释尿素水氮耦合对夏玉米产量和品质形成影响的生理生化机制及氮高效利用机理，优化控释尿素水氮运筹方案，为控释肥大面积高效应用，玉米轻简化栽培提供科学依据。

本项目以郑单958为试验材料，采用土柱栽培与大田试验相结合，15N示踪技术，设置3个水分处理（W1：水分含量为田间持水量的35%±5%；W2：水分含量为田间持水量的55%±5%；W3：水分含量为田间持水量的75%±5%），4个控释尿素施氮处理（N0：不施氮肥、低氮N1：施纯氮150 kg hm-2、中氮N2 ：施纯氮225 kg hm-2、高氮N3：施纯氮300 kg hm-2），系统研究了控释尿素水氮耦合对产量、氮素积累与分配、光合特性及根系分布、活力的时空变化动态，明确了控释尿素水氮耦合对夏玉米产量形成影响的生理生化机制及氮高效利用机理。研究表明，控释尿素水氮耦合存在显著的互作效应。相同水分条件下，夏玉米的产量随着施氮量的增加而增加，其中W1条件下增产13.2%-21.0%，W2条件下增产13.9%-32.5%，W3条件下增产14.4%-21.8%。相同施氮水平，各处理产量也呈现随着水分的增加而增加，其中W2N3、W3N2和W3N3的产量在所有处理中最高。主要由于控释尿素水氮耦合能有效提高夏玉米花后穗位叶净光合速率，保证籽粒对营养物质的需求；开花及花后各时期，0-60cm土层中根系的总量、根系活跃面积保持较高，为后期的养分吸收提供足够的源供应，从而提高夏玉米的产量，产量构成因素中增加千粒重和穗粒数的优势较大。控释尿素和水分含量对夏玉米花后干物质量和氮吸收、运转、分配具显著影响及互作效应。各处理的氮素利用率也存在显著的水氮互作效应，趋势与产量一致，其中，W2N3的氮肥农学效率、氮肥利用率及氮肥生理效率都显著高于W2N2和W3N3，W3条件下，N2比N3处理氮肥农学效率高54.2%，氮肥利用效率高34.9%，氮肥生理效率高14.4%，而产量差异不显著，表明N2优于N3。W2N3和W3N2处理能保持氮素的高效释放，有利于高产群体的建成，从而提高夏玉米植株氮素积累、协调氮素分配。综合产量、光合特性与氮素高效利用，W2N3和W3N2为本试验最佳处理。结合本项目研究结果提出控释尿素与田间水分运筹方案：在水分含量为田间持水量的75%±5%的土壤条件下，控释尿素施氮量以纯氮210 kg hm-2为最佳；在水分含量为田间持水量的55%±5%的土壤条件下，控释尿素施氮量以纯氮315 kg hm-2为宜。