有机水稻氮高效基因型的筛选及机理研究

As an environment-friendly agricultural system, organic agriculture has attracted more public attentions than before. Consequently, because of its healthy and safe characteristics, organic rice production develops rapidly with huge market potential in China. In this project, mechanism of nitrogen absorption of organic rice is studied as follows. Firstly, by applying different amounts of organic fertilizer, organic rice genotypes of high nitrogen use efficiency (NUE) would be selected from sixty typical japonica rice, with similar growth period and different NUE in the area of Lower-Middle Reaches of the Yangtze River. Secondly, under organic farming and inorganic agriculture systems, four categories rice of different NUE are choosed to investigate some ecophysiology characteristics such as photosynthetic rate of leaves, senescence, the sink, source and flow,the number of tiller and nitrogen assimilation at four key stages. At the same time, combined with the dynamic balance between soil nutrients and rice, the NUE of organic rice is analyzed in more details. Thirdly, along with the activites of some key nitrogen metablism enzymes and nitrogen absorption, the expression levels of genes,which related to nitrogen metabolism, are detected by Real-time Fluorescent Quantitative PCR to indentify the NUE of organic rice thoroughly. Through this study, special germplasm resources of organic rice with high NUE will be screened. The NUE mechanism of organic rice will also provide a scientific basis for organic rice cultivation, selection of species and nutrient management.

有机农业作为环境友好型农业生产体系日益受到公众重视，有机稻米因其健康安全在中国迅猛发展且潜力巨大。本项目针对有机水稻的氮素吸收机理展开研究：①以60个长江中下游地区生育期相近、不同氮素利用效率的常规粳稻品种为供试对象，在有机稻米生产基地运用不同量有机肥处理，筛选氮高效利用的有机水稻基因型。②选取有机与常规栽培条件下氮素利用效率协同与转变的四类水稻品种，在关键生育期通过叶片光合、衰老、茎蘖动态、源库流和氮素物质生产等生理生态指标，结合土壤供氮动态变化阐明水稻在有机栽培条件下氮素利用效率发生协同与转变的机理。③运用实时荧光定量PCR实验检测氮吸收转运系统相关基因的表达量，结合氮代谢关键酶活性、氮素物质生产与利用效率的差异，从基因水平深入剖析有机水稻氮素吸收机理。通过本研究，筛选氮高效利用的有机水稻专用种质资源，探讨有机水稻氮高效利用的机理，为有机水稻种植、品种选择及养分管理提供科学依据。

近年来，有机稻米因其健康安全在中国迅猛发展且潜力巨大，但有机栽培下关键营养元素氮素吸收利用的研究尚缺乏系统性。本研究设置了对照、低中高量有机肥4个有机栽培模式和1个常规栽培模式，以长江中下游地区生育期相近、不同氮素利用效率的常规粳稻品种为材料，研究了有机与常规栽培体系下水稻产量、氮素利用效率协同转变及其机理，为有机水稻生产品种选择及养分管理提供科学依据。主要研究结果如下：.1. 随着有机肥施用量增加，水稻基因型间的产量差异有减小的趋势。各水稻品种获得最高生产力所对应的施氮量主要集中在中量和高量有机肥水平。有机栽培群体最高生产力变幅为5.31-8.45 t•hm-2，品种间变异系数达10.96%。有机水稻氮素利用效率变幅为12.12%-35.36%，随着有机肥施用量的增加呈现先上升后下降的趋势，在中量有机肥处理下最高。.2. 常规栽培模式下各水稻基因型氮素利用效率变幅为31.44%-45.83%。比较有机和常规两种栽培体系氮素吸收利用效率，将水稻品种分成4种类型：有机与常规栽培均高效（高效协同型，A类）；有机栽培高效而常规栽培低效（高-低转变型，B类）；有机栽培低效而常规栽培高效（低-高转变型，C类）；有机栽培与常规栽培均低效（低效协同型，D类）。.3.在水稻孕穗期－成熟期，测定了4类水稻在有机与常规模式下剑叶氮素、生理活性指标。B类基因型在有机栽培下剑叶含氮率较高，SPAD值和含氮率下降较慢；C、D两种类型剑叶含氮量下降幅度均大于常规栽培。有机栽培下A、B两类剑叶GS、GPT、GOT活性下降幅度小于常规栽培，而C、D两类相应活性均大于常规栽培。表明有机栽培模式能减缓高产氮高效品种（A、B）氮代谢酶活性的下降速率，维持水稻生育后期相对较高的氮素吸收利用能力。同时，有机栽培方式较常规栽培能减缓A、B类品种生育后期SOD活性的下降速率和MDA含量上升速率，加快了C、D类品种叶片衰老速度。.4. 以优质杂交粳稻和常规粳稻作比较, 探索有机栽培条件下杂交粳稻实现稳产优质的可能性。实验表明有机栽培下杂交粳稻产量优势明显且有较好的品质性状，在有机稻米产业发展中具有独特的应用价值。.5. 研究了有机栽培优质食味水稻品种产量、品质和氮素利用协同性，结果表明有机栽培肥料处理以中量有机肥较优，品种以南粳46产量、品质和氮素利用效率协同性较好，更适合有机水稻生产。