Evaluation Of The Fecundity Of Cyperus Rotundus L.and Its Effect On Maize Rhizosphere Soil Bacteria

Cyperus rotundus L.,with strong reproductive and competing ability,is currently counted among the ten most malignant weeds in the world.It is easy to develop into“a single weed community”in crop fields and caused large-scale damage,causing serious damage to crop ecosystems.In this research,we clarified the effect of fecundity of the tuber of C.rotundus in different factors conditions by analyzing the biological characteristics of tuber of C.rotundus to different burial depths,adaptability of tubers to low temperature,and ability of tuber regeneration.And interference effects of C.rotundus on soil bcateria,soil enzyme activity,soil physicochemical properties and maize crop growth,which elucidate the community effect of C.rotundus on maize rhizosphere soil bacteria.This aim of study was to provide basic data for the prevention and control management of C.rotundus.The main contents and results are as follows:1.The tuber propagation of C.rotundus has a wide range of soil niche adaptability,at different burial depths from 0 to 40 cm,the tuber number were significantly less in only 40cm,and the soil depths about 20cm was the most suitable propagation of C.rotundus tuber via comprehensive evaluation analysis.In addition,C.rotundus tuber has super strong regeneration ability.There was no significant difference in the newly proliferated tuber number between the damaged tubers and the initial tubers.The C.rotundus tuber also has strong low temperature adaptability,whose still grow and reproduce normally after 180 d of storage at 4℃and not significantly different from the control.2.More plant rhizosphere beneficial microorganisms(PGPR)and nitrogen-fixing microorganisms(NFMs)were selectively enriched into the rhizosphere soil of C.rotundus.At the phylum level,the relative abundance of Proteobacteria,Actinobacteriota,Bacteroidetes and Patescibacteria of C.rotundus rhizosphere in high density of C.rotundus(HMC)were 0.7%,3.5%,1.4%,1.4%higher than those in maize rhizosphere soil,respectively,while the Cyanobacteria were uniquely enriched in C.rotundus rhizosphere soil.At the order level,the more PGPR of Rhizobiales,Sphingomonadales,Micromonosporales,Streptomycetales were enriched in the rhizosphere soil of C.rotundus,which the relative abundance were 1.5%,2.1%,2.2%,1.3%higher than those of maize rhizosphere soil in HMC.At the genus level,the relative abundances of NFMs such as Azospirillum,Mycobacterium,Burkholderia and Rhizobium in the rhizosphere soil of C.rotundus were all higher than that of maize rhizosphere soil.The PICRUSt function prediction,soil enzyme activity and soil physicochemical properties analysis showed that the relative abundance of nitrogen cycle process-related genes in the rhizosphere soil of C.rotundus was higher.The relative abundance of nitrification process genes nar B and hao,the denitrification process genes nas A,nar G,nor B,nor C,nos Z,and the nitrogen assimilation reduction and dissimilatory reduction genes nir A,nir B,nrf A,nrf H were all higher than those in maize rhizosphere soil.The sucrase(S＿SC)and urease(S＿SU)activities in C.rotundus rhizosphere were 4.82-fold,9.06-fold,2.63-fold,5.07-fold and 2.97-fold,1.68-fold,1.81-fold higher than those in maize rhizosphere soil,respectively.The vector fitting revealed that the change of bacteria structure of C.rotundus were correlated with the activity of the enzymes S＿SC(R~2=0.8233,P=0.001)and S＿SU(R~2=0.8188,P=0.001).The soil organic carbon,organic matter,total nitrogen,total potassium,total phosphorus and available phosphorus contents were significantly decreased by54.9%,54.8%,32.8%,15.6%,18.4%and 86.2%in HMC.These results further proves that C.rotundus could enrich more NFMs in its rhizosphere by changing soil enzyme activities,nitrogen cycle,and soil physicochemical properties.3.As the density of C.rotundus increase,the plant height,biomass accumulation of aerial and underground,spikelet height,and root-shoot ratio of maize were significantly reduced by 14.9%,31.9%,47.9%,21.2%,and 32.5%,respectively.Leading to affect in growth and quality of maize in the end.