不同基因型甜菜根际土壤有机氮矿化特征及影响机理

Organic N account for 90% of soil total N, during the whole growth period, more than 50% N absorbed by plant is coming from soil organic N. The supplying ability of soil nitrogen includes the mineral N at the planting time and the mineralized N during the whole growth period, of which the former represent the supplying intensity and the later represent the supplying potential. In the chain of soil N circulation, the process of organic N mineralization is the key link. Rhizosphere is not only the most important reaction area for biological activities and changes in physical chemistry in soil body, but also the exchanging hub for material and energy between soil and plant. It is the key point to settle down the problems in plant nitrogen regulation by understanding the law and mechanisms of organic N exchanged in the Rhizosphere. Therefore, it is very necessary to conduct the studies on ①the characteristics of soil organic N mineralization in the rhizosphere of different sugar beet genotype; ②the properties of root exudation and its effects on organic N mineralization in the rhizosphere of different sugar beet genotype;③The factors of affecting soil organic N mineralization and its biological and bio-chemistry mechanisms. The presented studies will firstly enrich us theoretical knowledge in sugar beet nitrogen nutrition, open up a new way in plant N regulation; secondly, enriched theory of bio-diversity and provide a theoretic base for using biological heredity to increase the uptake ability of soil organic N in the field of crop directed breeding; thirdly, give us important practical parameters in making N regulation recommendation for high sugar beet yield and technical quality; fourthly, establish a firm foundation in regulating soil organic N by plant rhizosphere ecology.

土壤有机氮占全氮90%以上，作物吸收的氮50%以上源于生长期间土壤矿化的有机氮，土壤供氮能力包括起始矿质氮和生长季矿化的氮，起始氮反映供氮强度，矿化氮反映供氮潜势，有机氮在土壤中的矿化过程是土壤氮循环过程的关键环节。根际是土壤中生命活动、物化学反应最强的区域，是土壤与作物间能量、物质转换的枢纽，掌握根际有机氮的转化规律和效应机理是解决作物氮素营养调控问题的关键。因此进行不同基因型甜菜根际有机氮矿化特征；不同基因型甜菜根系分泌物特征；影响有机氮矿化的生物、生化因素和作用机理研究的意义：首先，在理论上可丰富甜菜氮素营养理论，为氮素营养调控途径开辟新思路；第二，丰富了生物多样性理论，为利用生物自身的遗传特点，提高土壤固有氮的吸收利用率的定向育种提供理论依据；第三，在实践上可为制定甜菜优质高糖安全N 营养调控技术提供重要参数；第四，可为通过根际生态调控途径调节土壤有机氮的矿化量奠定坚实理论基础。

土壤有机氮占全氮90%以上，作物吸收的氮50%以上源于生长期间土壤矿化的有机氮。目前我国甜菜生产上氮肥施用为欧美等国家的1.5倍左右，贯彻农业生产“一控、两减”国策，利用品种自身遗传潜力提高养分利用效率，减少投入是当前生产和科研急需解决的问题。因此进行了①不同基因型甜菜根际有机氮矿化特征；②不同基因型甜菜根系分泌物特征；③影响有机氮矿化的生物、生化因素和作用机理的研究。. 从亲缘关系较远的100个种质材料中筛选出了对土壤有机氮吸收能力强和弱的种质材料各6个。. 有机氮利用效率高的品种根际土壤有机氮矿化高于低效品种，主要表现在氨态氮和氨基酸态氮。. 小分子氨基酸，葡萄糖和有机酸（草酸和甲酸）为甜菜根系分泌物主要成分，随甜菜生长，根际三类物质含量逐渐增加；有机氮高效率品种根际上述物质分泌能力均高于低效。. 根际分泌物的差异直接影响土壤团粒组成，有机氮高效品种根际土壤的0.01-0.005mm颗粒组分在全生育期均显著高于低效品种，而0.05-1mm颗粒在前三个生长阶段均较低。. 从苗期到收获期，根际细菌高于真菌并显著递减，有机氮高效品种在各生育期根际的细菌和真菌数量均显著高于低效，谷氨酸、精氨酸、草酸、甲酸、葡萄糖含量与土壤中细菌量显著相关。有机氮高效品种根际细菌中的变形菌门的溶杆菌属、放线菌门的细菌及真菌中的接合菌门和担子菌门均高于低效的品种。. 有机氮高效甜菜根系分泌物中还原的峰电位高于低效品种，根系分泌物中溶解态活性物质以还原性物质为主。在甜菜根系分泌物和根际革兰式阳性菌的共同作用下， 有机氮高效品种产电性能略高于低效品种。. 发表论文12篇，获得专利4项，培养硕士2名、博士1名。. 本研究为氮素营养调控途径开辟新思路，给制定甜菜优质高效安全氮营养调控技术提供重要参数；丰富了生物多样性理论，为利用生物自身的遗传特点，提高土壤固有氮的吸收利用率的定向育种提供理论依据；可为制定甜菜优质高效安全氮营养调控技术提供重要参数。