Response Of Rice Rhizosphere Bacteria To Ozone Dose Effects

The concentration of ozone has been increasing in recent years,posing a threat to the farmland ecosystem.At present,research on the environmental effects of elevated ozone concentration is mainly focused on the above-ground parts of plants,but there are few reports on plant rhizosphere microorganisms(including rhizosphere soil and root microorganisms).Studies have shown that rhizosphere soil microorganisms play an important role in promoting plant nutrient absorption and alleviating environmental stress.In this study,the common rice varieties Nanjing 5055,Huaidao 5,and Wuyunjing 27 in Jiangsu Province were used as experimental plants.The open-top air cell(OTC)was used to perform 5 ozone(O₃)concentrations(CF,NF,NF20)on rice.,NF40,NF60)fumigation samples were taken during the filling period.By analyzing the bacterial biodiversity and community structure of the rhizosphere soil and the roots under different ozone concentrations,combined with the soil physical and chemical properties and plant biomass analysis,the effect of rice rhizosphere bacteria on ozone was analyzed.The response law of dose effect and its driving factors.The results showed that:(1)With the increase of ozone concentration,the p H,nitrate nitrogen and ammonium nitrogen content of the rhizosphere soil of the three types of rice decreased significantly,compared with the NF treatment,they decreased by 20-22%,1.4-13.2%,respectively.8.3-11.7%;compared with CF treatment,the phosphorus content of three rice rhizosphere soils under NF60 treatment significantly increased by 11.3-17.8%.(2)Compared with CF treatment,the biomass of Wuyunjing 27 and Huaidao 5 roots under NF60 treatment decreased significantly by 2.2-7.4%;compared with NF treatment,the biomass of Nanjing 5055 stems and leaves decreased significantly under NF20 treatment Under the treatment of NF40 and NF60,the 5 panicle biomass of Huaidao significantly decreased by 2.8-8.0%.(3)Based on the 16S r RNA gene Miseq sequencing analysis,it was found that there was no significant difference in the microbial diversity between the rhizosphere soil and the root of rice.The PCo A and NMDS analysis results showed that there were significant differences in the bacterial community structure in the rhizosphere soil and the root.(4)Proteobacteria,Bacteroidetes,Actinobacteria and Acidobacteria are the predominant phylums of rhizosphere microorganisms,accounting for 47-52%,11-14%,5-7%,and 5-6%respectively;at the level of rhizosphere soil phylum,it is similar to NF treatment.Compared with NF20,NF40,and NF60 treatments,the relative abundance of Actinobacteria in Wuyunjing 27 was significantly increased by 0.1%-0.4%;at the root level,compared with NF treatment,NF20,NF40,NF60 treatments under Nanjing 5055Bacteroidetes The relative abundance of the phylum significantly decreased by 0.2-0.3%;analysis of ozone,varieties and their interactions showed that the increase in ozone concentration had an effect on the relative abundance of the non-dominant phyla Chloroflexi,Elusimicrobia,Latescibacteria and the dominant intra-root phyla Bacteroidetes and Proteobacteria.Ozone and variety have a significant effect on the relative abundance of Bacteroidetes in rhizosphere soil.(5)Geobacter and Novosphingobium are the dominant genera in the rhizosphere(>1%);at the root level,compared with NF treatment,the relative abundance of Novosphingobium in Huaidao 5 under NF20,NF40,and NF60 treatments increased significantly by 1.3-5.7%.This experiment analyzes and studies the response law of rice rhizosphere bacterial biodiversity and population structure to the ozone dose effect,which is helpful for the country to accurately grasp the influence of the increasing ozone concentration on the underground soil microorganisms and can provide in-depth understanding The ecosystem's response and feedback to climate change provide a theoretical basis.