施用棉秆炭对新疆连作棉花根际土壤微生物群落结构和功能的影响

Effects of cotton stalk biochar on microbial community structure and function of continuous cropping cotton rhizosphere soil in Xinjiang,China

以棉秆移除(NPK)和棉秆还田(NPKS)为对照,采用平板计数、Biolog和DGGE等3种方法,研究了棉秆移除基础上施用常量棉秆炭(22.50 t·hm^(-2),NPKB_1)和增量棉秆炭.(45.00 t·hm^(-2),NPKB_2)对新疆连作棉花根际土壤微生物数量、群落功能和结构多样性的影响.结果表明:与NPK和NPKS处理相比,棉秆炭施用显著增加了连作棉田根际土壤中细菌和放线菌数量;NPKB_1处理真菌数量显著高于NPK处理,但增量棉秆炭NPKB_2处理与NPK处理差异不显著;2个棉秆炭处理的真菌数量均低于NPKS处理.棉秆炭处理AWCD值较高显著提高了微生物丰富度指数,可促进利用糖类、氨基酸类和羧酸类碳源的微生物生长,尤其是利用与根系分泌物相关的酚酸类碳源的微生物.DGGE电泳结果表明,施用棉秆炭(尤其是增量棉秆炭)后,土壤细菌DGGE图谱条带数增多,增加了土壤中芽单胞菌门、酸杆菌门、变形菌门和放线菌门中一些菌群的丰度.UPGMC聚类分析表明,NPKB_2处理明显区别于其他处理,而NPKS、NPK和NPKB_1处理细菌群落结构相似.表明高量施用棉秆炭可显著提高棉花根际土壤微生物多样性,并明显改变土壤细菌群落结构,对连作棉田生态系统健康有改善作用.

In this study,field trials were conducted to examine the effects of cotton stalk biochar on microbial population,function and structural diversity of microorganisms in rhizosphere soil of continuous cotton cropping field in Xinjiang by plate count,Biolog and DGGE methods.The experiment was a factorial design with four treatments：1） normal fertilization with cotton stalk removed（NPK）;2） normal fertilization with cotton stalk powdered and returned to field（NPKS）;3） normal fertilization plus cotton stalk biochar at 22.50 t·hm^-2（NPKB1）;and 4） normal fertilization plus cotton stalk biochar at 45.00t·hm^-2（NPKB2）.The results showed that cotton stalk biochar application obviously increased the numbers of bacteria and actinomycetes in the rhizospheric soil.Compared with NPK treatment,the number of fungi was significantly increased in the NPKB1 treatment,but not in the NPKB2 treatment.However,the number of fungi was generally lower in the biochar amended（NPKB1,NPKB2） than in the cotton stalk applied plots（NPKS）.Application of cotton stalk biochar increased values of AWCD,and significantly improved microbial richness index,suggesting that the microbial ability of utilizing carbohydrates,amino acids and carboxylic acids,especially phenolic acids was enhanced.The number of DGGE bands of NPKB2 treatment was the greatest,with some species of Gemmatimonadetes,Acidobacteria,Proteobacteria and Actinobacteria being enriched.UPGMC cluster analysis pointed out that bacterial communities in the rhizospheric soil of NPKB2 treatment were different from those in the NPK,NPKS and NPKB1 treatments,which belonged to the same cluster.These results indicated that application of cotton stalk biochar could significantly increase microbial diversity and change soil bacterial community structure in the cotton rhizosphere soil,thus improving the health of soil ecosystem.