毛竹鞭根和蔸根磷吸收及其根际效应对施磷响应的分异机制：精准施肥诠释

Phyllostachys edulis is one of the most important economic plants in the southern mountainous area of China. Bamboo industry is known as "sunrise industry". Under the new situation is one of the important ways of alleviation of poverty method. At present, efficiently cultivation of Ph. edulis resources mainly faces the problem of shortage of nutrients, soil fertility decline, labor shortages, and so on. Precision fertilization is an effective measure to solve such problem, but the lack of relevant theories and mechanisms leads to limiting its technology innovation and application. The different characteristics of structure and function in Ph. edulis stump root and rhizome root systems can be used as explain precision fertilization theory interpretation research. This study selected typical hilly mountain Ph. edulis forest as the object, with P supply and absorption as the breakthrough point. Through the broadcast P long-term experiment and stump root and rhizome root application of P short-term experiments respectively two field platforms, focus on the research about stump root and rhizome root fine root structure traits, nutrient uptake by plant root system, phosphorus in rhizosphere transformation and effective, rhizosphere soil P-solubilizing microorganism and related enzyme activity, new Ph. edulis shoots and Ph. edulis nutrient content respond to phosphate fertilizer. Analyze the differences of Ph. edulis stump root and rhizome root phosphorus in rhizosphere transformation and effectiveness respond to phosphate fertilizer. Reveal the P-solubilizing microorganism driving effect the process of phosphorus in rhizosphere transformation. Clarifies the differences of stump root and rhizome root nutrient absorption and utilization. Provide theoretical explanation for Ph. edulis precise fertilization.

毛竹是我国南方山区最重要的经济林木之一，竹产业被誉为“朝阳产业”，是新形势下林区扶贫脱贫的重要出路之一。目前，毛竹资源高效培育主要面临养分不足、地力衰退、劳动力短缺等问题，精准施肥是解决此类问题的有效措施，但相关的理论及机制解释缺乏，限制其技术创新与应用。毛竹根系系统蔸根和鞭根结构和功能的分异特征可作为精准施肥理论诠释研究的突破口。本研究选取丘陵山区典型毛竹林为对象，以红壤区养分限制最强的磷素供应与吸收为切入点，通过撒施磷肥长期实验和鞭根、蔸根分施短期试验两个野外平台，重点研究毛竹鞭根和蔸根细根结构性状、根系养分吸收、根际磷转化及有效性、根际溶磷微生物及相关酶活性、新笋及新竹养分含量对磷肥的响应；剖析毛竹蔸根、鞭根磷素吸收及根际效应对磷肥响应的异同，揭示溶磷微生物在毛竹根际磷素转化过程中的驱动效应，阐明毛竹鞭根、蔸根养分吸收与利用对施肥响应的分异机制，为竹林精准施肥提供理论诠译。

毛竹是竹类植物中最重要的经济林种，针对毛竹林分布于缺磷的南方丘陵红壤区，竹资源培育面临养分不足、地力衰退、劳动力短缺等问题，而目前精准施肥虽然是解决此类问题的有效措施，但相关的理论及机制解释缺乏，限制其技术创新与应用。本课题从毛竹根系系统蔸根和鞭根结构和功能的分异特征入手开展创新研究，以期为竹林精准施肥提供理论诠释。主要研究成果如下：1）明确了毛竹鞭根细根系在对土壤磷素的吸收利用要显著高于毛竹蔸根细根系，鞭根是毛竹磷吸收的主要途径，阐明了毛竹鞭根和蔸根对磷肥具有不同的响应机制，结果显示在今后毛竹林施肥中应采取鞭根施肥和蔸根施肥相结合的技术来提升竹林生产力，而不应是单一的施肥方式培育竹林；2）从毛竹鞭根和蔸根土壤分离出解磷细菌和真菌，建立了竹林土壤解磷微生物种质资源库，并分析解磷微生物在毛竹鞭根和蔸根土壤中的分布特征，明确了毛竹鞭根和蔸根土壤中与磷素转化的相关解磷微生物种类及多样性；3）从竹林土壤中筛选出1株高效解磷细菌和2株高效解磷真菌，探讨了这3株高效解磷菌株的解磷特性和最适解磷条件；4）通过盆栽试验研究了这3株高效解磷菌株对毛竹的促生效应及其光合和养分代谢机制，分析了不同施菌处理对毛竹根际土壤微生物群落多样性的影响，阐明了高效解磷菌株对毛竹根际土壤磷有效性、磷组分和微生物功能群落的变化规律及其相互关系，揭示了解磷微生物调控毛竹根际土壤磷素活化的微生物学机制。总之，这些发现深入地揭示了毛竹蔸根和鞭根对磷素吸收利用的异同，揭示了解磷微生物在毛竹根际土壤磷素转化过程中的驱动效应，阐明了毛竹鞭根、蔸根养分吸收与利用对施肥响应的分异机制，本研究结果可为我国南方毛竹林可持续经营和管理提供科学支撑。