菌根吸磷途径对新疆棉花磷吸收效率的贡献

Focusing on the problem of the low use efficiency of soil phosphorus in a intensive cotton planting system of "dwarfing, densifying, earlier mature" and mulched drip irrigation, which is a typical cotton culturing model in Xinjiang, topics will be investigated as follows: (1) screening the cotton genotypes which are high mycorrhizal dependence and high P uptake efficiency per unit root length,(2) the relationship between the regulations of plant growth and P uptake against the regulations of the growth of AM fungal mycelium and P uptake in field soil, (3) the responsiveness of the characteristics of root morphology, root exudation and the features of mycorrhizal fungi to soil P supplying strength, and the quantitative relationship between such responsiveness to the P uptake efficiency of cotton under the integrated management system of water and fertilizer supplying. The advanced methodologies will be employed in this project, such as the integrated technique of mesh-compartmented rhizobox combining with glass-bead which can trap indigenous AM fungal mycelium in both field and pot culture, the 32P tracing, the PLFA/NLFA, t-RFLP, RT-qPCR techniques. The expected objectives of this project are to understand the relationship between mycorrhizal dependence and P uptake efficiency, to quantify the contribution of mycorrhizal P uptake pathway and the root P uptake pathway to P efficiency of cotton, and finally to develop a manipulating approach for maximization of the biological potential of cotton to mobilizing and using soil phosphorus. The research outputs will fill our knowledge gaps of phosphorus utilization related rhizosphere biological processes and its manipulation approaches in cotton, and will provide a theoretical basis for the phosphate fertilizer management of cotton planting in Xinjiang.

以新疆 "矮、密、早"和膜下滴灌棉田土壤磷资源高效利用为对象，采用隔网根箱和玻璃珠诱集培养AM真菌的技术以及32P示踪、PLFA、t-RFLP、RT-qPCR等先进手段，通过田间原位研究与室内模拟试验相结合的方法，开展以下研究：（1）研究筛选适合膜下滴灌水磷供应条件、菌根依赖性高的棉花磷高效基因型；（2）棉花生长和磷吸收规律与AM真菌生长和磷吸收规律的协同性；（3）棉花根系形态构型性状、根系分泌作用的性状、AM真菌性状对不同供磷量条件的响应及其与棉花磷吸收效率的定量关系，探明菌根依赖性与根系吸磷能力与棉花磷效率的关系，揭示棉花根系直接吸磷途径和菌根吸磷途径对棉花磷营养的贡献，建立充分发挥棉花高效利用土壤磷生物学潜力的土壤调控途径，为新疆高产棉花体系中磷养分资源高效利用模式的建立提供理论依据。研究成果将丰富新疆棉田根土界面磷营养调控的理论，并为棉田磷肥推荐、测土配方施肥提供理论支撑。

为明确新疆不同年代棉花品种磷效率和菌根依赖性的差异，本研究采用田间、盆栽和水培试验，以新疆不同年代的22个棉花品种为材料，研究各棉花品种在苗期、蕾期、花铃期和吐絮期磷吸收效率、利用效率等的变化规律，并采用聚类分析方法进行综合评价。取得以下结果：.1.不同棉花品种对供磷水平的反应存在基因型差异。无论在低磷还是高磷条件下是否接种，磷高效品种的生物量和磷吸收效率明显高于磷低效品种，表明磷高效基因型品种具有较强的耐低磷能力。.2.对22个棉花品种吐絮期生物量、磷吸收效率、磷利用效率、籽棉产量、皮棉产量、经济利用效率等6项指标进行聚类分析，得出磷高效品种有13个，分别是新陆早50号、新陆早57号、军棉1号、新陆中35号、新陆早31号、新陆中40号、新陆早2号、新陆早48号、新陆201、TM-1、新陆早19号、C-4744、KK-1543；磷低效品种有9个，分别是C-3174、新陆早1号、108夫、塔什干2号、新陆中4号、农垦5号、车61-72、苏K202、新陆早13号。22个品种中磷高效品种占59.1%，磷低效品种占40.9%。.3.AM真菌促进棉花生长和磷吸收，同时AM真菌侵染缩小了不同基因型棉花品种磷效率的差距。.4.不同棉花品种的菌根依赖性存在差异。无论低磷还是高磷条件下菌根依赖性高的品种是新陆中35号和新陆早48号。 .5.吐絮期根系磷吸收效率与籽棉产量、皮棉产量呈显著正相关；不同品种生物量与磷吸收效率呈显著正相关，而与磷利用效率无明显的相关性。 . 此研究结果不仅对新疆棉花产业的持续发展、充分挖掘磷高效潜质和磷肥减施有重要意义，而且也是保障国家农业资源环境和作物生产安全协调发展的重大需求。