Effects of Low Phosphorus Stress on Root Growth and Rhizosphere Bacteria of Different Root Types Alfalfa
A pot experiment was conducted to investigate the response of root growth and rhizosphere soil bacterial community structure to low phosphorus stress in three types of root type alfalfa,including creeping rooted Medicago varia cv.Gongnong No.4(GN),rhizomatous rooted Medicago sativa cv.Qin-gshui(QS),and tap-rooted Medicago sativa cv.Longdong(LD)by 16S rRNA gene high-throughput sequencing technique.The results showed that under low phosphorus stress(0.01 mmol/L KH2PO4),the total root length,taproot length,root tip number,root angle and lateral root number of three root types of alfalfa increased significantly,while total root surface area,total root volume,average root diameter,spe-cific root length,and the specific root surface area decreased significantly.The total root length,tap root length,total root surface area,lateral root number,total root volume and root tip number of QS were sig-nificantly smaller than those of GN and LD.The comprehensive evaluation of membership function showed that GN had the strongest ability to tolerate low phosphorus,while QS had the worst.Under low phospho-rus stress,the Shannon-Weiner index and Chao1 index of rhizosphere soil bacteria of different root types of alfalfa increased,possibly due to the reduction of stress damage caused by alfalfa root exudates,thereby affecting the diversity of soil bacterial communities.At the level of phyla classification,the dominant phyla rhizosphere soil bacteria were Proteobacteria,Bacteroideta,Chloroflexi,Desulfobacterota and Actinobac-teria.Low phosphorus treatment increased the relative abundance of Proteobacteria and Actinobacteria,while decreased the relative abundance of Desulfobacterota and Chloroflexi.The increased relative abun-dance of dominant bacterial group may be related to the resistance of alfalfa to low phosphorus stress.At the level of family classification,Anaerolineaceae,Desulfobacteraceae,Rhizobiaceae,and Sphingomona-daceae were the dominant families in the rhizosphere soil of alfalfa.Low phosphorus stress significantly increased the number of Sphingomonadaceae and decreased the number of Desulfobacteraceae in different root types of alfalfa.
AlfalfaRoot systemLow phosphorus stressRhizosphereBacterial community abun-dance
NETL
NSTL
万方数据
