超高产水稻材料的需氮特征、氮素环境效应及机制研究

it will be a key step to expand planting area of super high yielding rice on limited cultivated land in China in order to ensure food safety. However, a series of questions of scientific fertilization related to planting super high yielding rice, especially for newly cultivated rice materials are urgently waiting to be solved. The questions of scientific fertilization include what optical fertilizer nitrogen (N) application rate and strategies are for super high yielding rice, how about N losses in paddy to environment after planting super high yielding rice, how to balance the relationship between high yield and environmental pollution. This project choose Taihui Lake region, which is a major region of rice production in China as study area. Firstly, hydroponic experiments will be carried out to screen out rice materials with strong ability of N uptake at early growth stage and high N use efficiency at late growth stage, and to reveal relative physiological mechanisms. Secondly, super high yielding rice materials chose through hydroponic experiments will be used as study materials in three-year field experiments set up in Yixing city of Jiangsu Province and Jiaxing city of Zhejiang Province. Two consecutive years of field experiments will clear response of super high yielding rice to different fertilizer N application rate and characteristics of N uptake and accumulation in rice, as well as N losses in paddy to environment, which will help to confirm optical N application rate for super high yielding rice in Taihu Lake region. The effect of different fertilizer nitrogen (N) application strategies on grain yield of super high yielding rice and N losses to environment will be further studied by field experiment to propose the optical. The works of this project will provide scientific basis and data support for harmonizing conflict between high yield and environmental pollution, and proposing principle of water and fertilizer management for super high yielding rice.

推广种植超高产水稻是我国有限耕地面积上提高水稻单产，保障粮食产量的关键。然而，围绕超高产水稻品种，特别是新育超高产水稻材料的一系列科学施肥问题却迫切需要解答。超高产水稻材料的最佳施氮量和氮肥运筹是什么？它的种植对氮素的环境效应怎样？如何协调好高产和环境效应之间的关系？本项目以水稻主产区—太湖地区为研究区域，以超高产水稻材料为研究对象，先通过室内实验筛选生育前期氮素吸收能力强，后期氮素利用效率高的超高产水稻材料，并揭示相关生理机制；在此基础上开展筛选所得超高产材料在江苏宜兴和浙江嘉兴两地进行多年田间试验，明确超高产水稻对氮肥的响应特征、氮素吸收累积特性及氮素环境效应，确定最佳氮肥施用量；并进一步研究不同氮肥运筹方式对水稻产量及氮素环境效应的影响，提出适宜超高产水稻种植栽培的氮肥运筹。项目研究成果可为协调高产和环境污染之间的矛盾，提出超高产水稻推广种植的水肥管理原则提供科学依据和数据支撑。

本项研究以超高产水稻材料为研究对象，以水稻主产区-太湖地区为研究区域，探明超高产水稻材料的需氮特征、耐铵特性及机制，明确田间条件下超高产水稻材料对氮肥的响应特征、最佳施氮量及运筹方式，揭示种植超高产水稻材料对稻田氨挥发、径流和淋溶以及氧化亚氮排放等氮素环境效应的影响效应及其机制。研究结果表明，超高产水稻材料根系有别于常规水稻材料，其根系更发达、根系更长、根尖数更多、通气组织更发达；在低氮条件下，NH4+吸收速率更高，吸收能力更强；在高铵环境中，对铵耐受能力更强，对NH4+毒的耐受阈值更高。在田间种植体系下，超高产水稻表现出显著的高产特征，田间施氮量以200~300kg/ha为宜，兼顾产量和氮环境效应时，以N334（基肥、分蘖肥和穗肥氮肥施用比分别为30%、30% 和40%）为最优氮运筹处理。超高产水稻氮素排放随着施氮量的增加而增加，尤其是氨挥发量和氧化亚氮排放量；在生育后期（成熟期）和低施氮量N200情况下，其氮素损失要明显小于常规水稻品种，表现为较低的氮素环境代价。超高产水稻单位产量的氮素损失量均显著低于常规品种，但有增加温室气体氧化亚氮的排放的风险，主要与其根系泌氧能力明显增强、根际硝化作用升高、根系分泌氮源和碳源增多有关。本项目研究成果可为协调高产和环境污染之间的矛盾、超高产水稻推广种植的水肥管理提供科学依据和数据支撑。