磷硒配施对冬小麦硒吸收及根际土壤微生物群落的影响

Effects of combined application of phosphorus and selenium on selenium absorption of winter wheat and microbial community in rhizosphere soil

探讨磷硒配施对冬小麦产量及根际土壤微生物群落结构与多样性的影响,明确土壤微生物群落与磷硒有效性的关系。采用盆栽试验,设置3个磷水平(0、0.2和0.4 g·kg^(-1))和2个硒水平(0和0.5 mg·kg^(-1)),完全交互设计,共6个处理(Se_(0)P_(0)、Se_(0)P_(0.2)、Se_(0)P_(0.4)、Se_(0.5)P_(0)、Se_(0.5)P_(0.2)、Se_(0.5)P_(0.4)),分析冬小麦籽粒产量、磷硒浓度、土壤有效磷含量、硒形态转化及微生物群落结构等的变化。施磷显著增加Se_(0)和Se_(0.5)水平下冬小麦籽粒产量、各器官磷浓度及累积量,但显著降低Se_(0.5)水平下根系、茎叶及籽粒硒浓度,且籽粒、颖壳及茎叶硒累积量随施磷量的增加呈先增加后降低的趋势,均在Se_(0.5)P_(0.2)处理下达到最大值。施硒显著增加了冬小麦各部位硒浓度和累积量,降低了P_(0.4)水平下籽粒产量和P_(0.2)和P_(0.4)水平下冬小麦各器官磷浓度及累积量,但对P_(0.2)水平下籽粒产量无显著影响。施磷显著增加了Se_(0.5)水平下土壤有效磷含量、可溶态硒含量及所占比例,施硒显著增加了P_(0.4)水平下土壤有效磷含量。在Se_(0.5)水平下,P_(0.2)和P_(0.4)处理分别显著增加了放线菌门(Actinobacteria)和芽单胞菌门(Gemmatimonadetes)的相对丰度,但均显著降低了拟杆菌门(Bacteroidetes)的相对丰度。施硒显著增加了P_(0.2)水平下放线菌门的相对丰度和P_(0.4)水平下酸杆菌门(Acidobacteria)的相对丰度。在Se_(0.5)水平下,与P0相比,P_(0.2)显著提高了Shannon指数;在P_(0.2)水平下,施硒显著提高Simpson指数。适宜的磷硒配施改变土壤微生物群落结构、促进土壤中磷硒的释放并提高其有效态含量,进而增强磷对冬小麦籽粒产量的促进作用和籽粒硒的累积,以Se_(0.5)P_(0.2)处理为宜。

The effects of combined application of phosphorus and selenium on the grain yield and microbial community structure and diversity in rhizosphere soil of winter wheat were studied to investigate the relationship between the microbial community and the effectiveness of phosphorus and selenium of winter wheat rhizosphere soil.A pot experiment with three phosphate levels(0,0.2 and 0.4 g·kg^(-1),respectively)and two selenium levels(0 and 0.5 mg·kg^(-1),respectively).A total of 6 treatments(termed as Se_(0)P_(0),Se_(0)P_(0.2),Se_(0)P_(0.4),Se_(0.5)P_(0),Se_(0.5)P_(0.2) and Se_(0.5)P_(0.4),respectively)were used to analyze their effects on the grain yield,phosphate and selenite concentration of winter wheat,soil available phosphate content,the transformation of chemical forms of selenite and microbial community structure.At Se_(0) and Se_(0.5),phosphate application significantly increased the grain yield of winter wheat,phosphate concentration and accumulation in each tissue,but significantly decreased selenite concentration in root,straw/leave and grain in Se_(0.5).While at Se_(0.5),the grain,glume and straw/leave selenite accumulation were firstly increased and then decreased with the increasing phosphate application,where the highest value appeared under the Se_(0.5)P_(0.2) treatment.Selenite application significantly increased selenite concentration and accumulation in each tissue,decreased grain yield at P_(0.4) and phosphate concentration and accumulation in each tissue at P_(0.2) and P_(0.4),but had no significant effect on grain yield at P_(0.2).At Se_(0.5),phosphate application significantly increased available phosphorus concentration and the selenium concentration and proportion of soluble selenite in soil,and selenium application significantly increased available phosphorus concentration at P_(0.4).At Se_(0.5),P_(0.2) and P_(0.4) treatments significantly increased the relative abundance of Actinobacteria and Gemmatimonadetes,respectively,but significantly decreased the relative abundance of Bacteroides.Selenite application significantly increased the relative abundance of Actinobacteria at P_(0.2) and the relative abundance of Acidobacteria at P_(0.4).At Se_(0.5),compared with P0,P_(0.2) treatment significantly increased Shannon index.At P_(0.2),selenium application significantly increased Simpson index.Appropriate combined application of phosphate with selenium altered the microbial community structure,promoted the release of phosphate and selenite in soil and increased soil available phosphate and selenite content,enhanced the promoting effecting of phosphate on grain yield of winter wheat and the selenite accumulation of grain,the overall performance of at Se_(0.5)P_(0.2) treatment was better than others.