长期种植大豆对黑土磷素化学行为及其有效性的影响

The study about high efficient utilization of phosphorus by crops has been attracted more and more attention under the background that phosphorus does not meet the demand of crops in most of arable land all over the world. Recently, the study of high efficient utilization of phosphorus by crops has been paid more attention to the consideration of the phosphorus efficient gene type and the response of root architecture and physiological and biochemical indexes of crop under low phosphorus stress.It has been known that leguminous crop has more effective utilization of soil phosphorus and fertile field function comparing with cereal crops. In terms of fertile field function of soybean, the mechanism of the change in phosphorus chemical characteristics resulting from soybean root activities and efficient utilization of phosphorus for next season cereal crops are very important for the high efficient utilization of soil phosphorus. Based on long-term soybean continuous system field experiment and laboratory simulation experiment combining with isotopictracer and molecular biotechnology, the following research contents are considered: (1) the evolution of soil phosphorus chemical characteristics after long-term planting soybean, (2) the mechanism of the change in soil phosphorus status directly driving by soybean root metabolite, (3) The effect of organic acids resulting from the decompostion of soybean litter and residues on soil microbial community structure,(4) maize is planted to test if above change could improve the utilization of soil phosphorus by next season cereal crops. Above findings have very important theoretical and practical significant in enriching soybean fertility field function and designing rotation system with the core of soybean and high efficient utilization of soil phosphorus.

全球大部分土壤处于缺磷状态，所以作物高效利用土壤磷的研究变得越来越重要。目前这方面研究主要集中在低磷协迫下作物生理生化、根构型和磷高效基因型等方面。豆科作物与禾本科作物相比能更有效地利用土壤磷素并具有肥田功能。在肥田功能中，明确大豆根系活动对土壤磷素化学行为和下茬禾本科作物吸收磷的影响，在提高土壤磷素利用方面具有重要作用。本项目利用长期大豆连作田间试验和模拟试验、同位素示踪技术和分子生物学技术，在我国东北的黑土耕地上系统研究：（1）长期种植大豆后土壤磷素化学行为演变规律，（2）大豆根系代谢产物（有机酸、酶类）对土壤磷素形态变化的内在驱动机制，（3）大豆凋落物和残茬腐解过程中的有机酸对土壤微生物群落结构尤其是解磷微生物类群变化的影响；（4）用玉米验证这些变化是否使下茬禾本科作物能更有效地利用土壤磷。这项研究将在大豆肥田理论和土壤磷素高效利用以及合理设计以大豆为核心的轮作制度等方面具有重要意。

豆科作物与禾本科作物相比能更有效地利用土壤磷素并具有肥田功能,研究大豆根系活动对土壤磷素化学行为和对下茬禾本科作物吸收磷的影响，对提高土壤磷素利用效率方面具有重要作用。本项目利用长期大豆连作田间试验和模拟试验及分子生物学技术，取得了如下研究结果：（1）明确了长期种植大豆后的土壤磷素化学特征。长期种植大豆，土壤磷素平衡率达到了145.7%，全磷含量增加了17.6%，速效磷含量增加了74.3%，无机磷含量增加了12.7%，各无机形态磷均发生了显著变化。（2）大豆根系代谢的有机酸对土壤磷素形态转化具有驱动作用，其中钙和铝络合态磷素含量增加显著，有利于作物吸收。（3）长期种植大豆对土壤微生物群落结构尤其是解磷微生物数量及群落变化具有显著的影响。大豆长期连作较草地、裸地和长期玉米、小麦种植处理对土壤微生物的影响小。长期种植大豆降低了解无机磷微生物的数量，对解无机磷微生物的影响大于解有机磷微生物。植被类型影响解磷微生物和溶磷微生物的群落结构，进而分离得到的不同解磷和溶磷能力的菌株，植被对解磷菌和溶磷菌具有选择性，这主要与不同作物根系分泌物有关，而种植大豆更利于高效解磷菌和溶磷菌生长和繁殖。