施磷对干旱胁迫下箭竹根际土壤养分及微生物群落的影响

以箭竹及其根际土壤作为研究对象，采用两因素随机区组实验，设置2种水分处理（正常浇水和干旱胁迫）和2种施磷量处理（施磷和不施磷），探究施磷对干旱胁迫下箭竹根际土壤养分及微生物群落结构和多样性的影响。结果表明：（1）干旱胁迫显著降低了箭竹根际土壤中微生物量碳、可溶性有机氮和有效磷的含量，虽对箭竹根际土壤微生物群落的多样性无显著影响，但显著降低了箭竹根际土壤中总PLFA（phospholipid fatty acid contents）的含量和真菌、细菌、革兰氏阳性菌与革兰氏阴性菌的PLFA含量以及革兰氏阳性菌/革兰氏阴性菌的PLFA比值，显著改变了箭竹根际土壤微生物群落结构，结果显著降低了箭竹的生物量。（2）施磷显著增加了受旱箭竹根际土壤中微生物量碳和有效磷的含量，虽大体上对受旱箭竹根际土壤微生物群落的多样性无显著影响，但显著增加了受旱箭竹根际土壤中总PLFA和真菌PLFA的含量，并在一定程度上增加了细菌、革兰氏阳性菌、革兰氏阴性菌和放线菌的PLFA含量以及革兰氏阳性菌/革兰氏阴性菌和真菌/细菌的PLFA比值，也在一定程度上改善了受旱箭竹根际土壤微生物群落结构，从而改善受旱箭竹的生长。（3）主成分分析表明，干旱对箭竹根际土壤微生物群落结构的影响显著，而施磷的影响不明显。（4）相关分析发现，箭竹根际土壤微生物群落结构与箭竹根际土壤微生物量碳、可溶性有机氮及箭竹生物量呈显著正相关。综上，干旱降低了箭竹根际土壤养分含量和微生物生物量，改变了箭竹根际土壤微生物群落结构，抑制了箭竹的生长；施磷能增加受旱箭竹根际土壤养分含量和微生物生物量，改善受旱箭竹根际土壤微生物群落结构，进而改善受旱箭竹的生长。

Effects of phosphorus application on soil nutrients and soil microbial community in rhizosphere of Fargesia under drought stress

To explore the effects of phosphorus application on the soil nutrients and the structure and diversity of soil microbial community in rhizosphere of Fargesia response to drought stress, Fargesia and its rhizosphere soil were used as experimental materials, and a completely randomized design with two factors of two watering (well-watered and water-stressed) and two P regimes (with and without P fertilization) was arranged. The results showed that:(1) Drought stress significantly reduced the contents of soil microbial biomass carbon, soil dissolved organic nitrogen and soil available phosphorus in rhizosphere of Fargesia, though it had no significant impact on soil microbial community diversity in rhizosphere of Fargesia, obviously decreased the total PLFA contents (phospholipid fatty acid contents), the PLFA contents of fungi, bacteria, Gram-positive bacteria and Gram-negative bacteria and it also decreased the PLFA ratios of Gram-positive bacteria/Gram-negative bacteria and fungi/bacteria, which significantly changed soil microbial community structure in rhizosphere of Fargesia and resultantly reduced the biomass of Fargesia. (2) Phosphorus application significantly increased the contents of soil microbial biomass carbon and soil available phosphorus in rhizosphere of Fargesia, it had no significant effect on soil microbial community diversity in rhizosphere of Fargesia, but significantly increased the contents of the total PLFA and fungi PLFA in rhizosphere of Fargesia. To a certain extent, it enhanced the PLFA contents of bacteria, Gram-positive bacteria, Gram-negative bacteria and actinomycetes and it also increased the PLFA ratios of Gram-positive bacteria/Gram-negative bacteria and fungi/bacteria. To some extent, it improved soil microbial community structure in the rhizosphere of Fargesia, and then improved the growth of droughty Fargesia. (3) The principal component analysis showed that drought had a significant impact on soil microbial community structure in rhizosphere of Fargesia, but phosphorus application had not. (4) Correlation analysis indicated that rhizosphere soil microbial community structure of Fargesia was significantly and positively correlated with rhizosphere soil microbial biomass carbon, rhizosphere soil dissolved organic nitrogen and biomass of Fargesia. In summary, drought reduced soil nutrients and soil microbial biomasses in rhizosphere of Fargesia, changed soil microbial community structure, and thus inhibited the growth of Fargesia; phosphorus application could enhance soil nutrients and soil microbial biomasses in rhizosphere of droughty Fargesia, improve soil microbial community structure in rhizosphere of droughty Fargesia, and then improve the growth of droughty Fargesia.