槟榔间作香露兜对土壤细菌群落结构和多样性的影响

Effects of Areca catechu L.intercropping Pandanus amaryllifolius Roxb.on soil bacterial flora and diversity

【目的】研究槟榔间作香露兜对土壤细菌群落结构和多样性的影响,明确间作模式影响土壤细菌群落的关键环境因子,为优化槟榔间作香露兜模式及热带农田经济的发展提供理论依据。【方法】通过大田试验的方法,在海南省兴隆热带植物园内建立包括槟榔单作、香露兜单作和槟榔间作香露兜种植模式的试验样地,测定土壤理化性质、养分含量、土壤细菌丰度与多样性等指标,以槟榔和香露兜单作为对照,探究槟榔间作香露兜模式对土壤细菌群落结构和多样性的影响。【结果】槟榔间作香露兜模式下土壤养分含量降低,土壤逐渐趋于酸性且盐离子浓度提高;土壤细菌群落的ACE指数、Chao1指数和Shannon指数显著降低(P<0.05,下同),pH、电导率、全磷、容重是影响土壤细菌群落变化的主要环境因子。在3种种植模式下细菌优势菌门均为变形菌门(Proteobacteria)、放线菌门(Acidobacteriota)、酸杆菌门(Actinobacteriota)和绿弯菌门(Chloroflexi),间作后变形菌门、放线菌门和酸杆菌门的相对丰度均出现降低,绿弯菌门相对丰度则提高。其中,放线菌门相对丰度与土壤容重呈显著正相关;绿弯菌门相对丰度与电导率和有机质呈极显著正相关(P<0.01,下同),与全磷呈极显著负相关,与全钾呈显著负相关。【结论】槟榔林下间作香露兜不影响细菌OTU总数,但通过降低pH及提高电导率而显著降低土壤细菌群落多样性指数;间作模式通过提高土壤容重降低全磷、全钾及有机质含量,而降低变形菌门、放线菌门和酸杆菌门的丰度,却提高了绿弯菌门的丰度。可见,尽管槟榔间作香露兜体系显著降低土壤养分含量,但能改善槟榔林原位土壤细菌区系的丰度及多样性,对维持槟榔林土壤健康及促进槟榔与香露兜相关产业发展具有积极意义。

【Objective】The present paper aimed to study the effects of Pandanus amaryllifolius Roxb. intercropping with Areca catechu L.on the structure and diversity of soil bacterial communities, to clarify the key environmental factors affecting soil bacterial community in the intercropping mode, so as to provide a theoretical basis for optimizing the betel nut intercropping mode and the development of tropical farmland economy. 【Method】Through the method of field experiment, the experimental plots including A. catechu monocropping(control), P. amaryllifolius monocropping(control) and P. amaryllifolius intercropping with A. catechu were established in Xinglong area to measure soil physical and chemical properties, nutrient content, soil bacterial abundance, and diversity to explore the effect of intercropping model on soil bacterial community structure and diversity.【Result】The results showed that the ACE index, Chao1 index and Shannon index of the bacterial community under the A. catechu intercropping P. amaryllifolius model were significantly reduced than control(P<0.05,the same as below). In intercropping mode, pH, electrical conductivity, total phosphorus, and bulk density were the main environmental factors that affected the changes of soil bacterial communities. In the three planting modes, the dominant bacteria phyla of bacteria were Proteobacteria, Actinobacteriota, Actinobacteriota, and Chloroflexi. The relative abundance of Proteobacteria, Acidobacteriota and Acidobacteria was decreased, and the relative abundance of Chloroflexi was increased. Among them, Acidobacteriota was significantly positively correlated with soil bulk density;Chloroflexi was extremely significantly positively correlated with conductivity and organic matter(P<0.01,the same as below), extremely significantly negatively correlated with total phosphorus, and significantly negatively correlated with total potassium. 【Conclusion】P. amaryllifolius intercropping with A. catechu does not affect the total number of bacterial OTU, but significantly reduces the diversity index of soil bacterial community by reducing pH and increasing electrical conductivity. Intercropping mode reduces the contents of total phosphorus, total potassium and organic matter by increasing soil bulk density, while reducing the abundance of Proteobacteria, Actinomycetes and Acidobacteria, but increasing the abundance of Chloroflexi. It can be seen that although the betel nut intercropping system significantly reduces the content of soil nutrients, it can improve the abundance and diversity of in-situ soil bacterial flora of betel nut forest, which is of positive significance to maintain the soil health of betel nut forest and promote the development of related industries of betel nut and betel nut.