Rice cropping method is primarily decided by soil moisture regime.System of rice intensification(SRI)and direct-seeded aerobic rice are two primary modifications of traditional wetland rice.Understanding rice rhizosph...Rice cropping method is primarily decided by soil moisture regime.System of rice intensification(SRI)and direct-seeded aerobic rice are two primary modifications of traditional wetland rice.Understanding rice rhizosphere microbiome and functioning as influenced by these cropping methods is essential for sustaining rice productivity.The objective of this study was to assess the impact of three different rice cropping methods(wetland rice,SRI,and aerobic rice)on the biochemical properties and bacterial communities within the rice rhizosphere across three key rice growth stages:tillering,flowering,and maturity.Soil organic carbon(SOC),microbial biomass carbon(MBC),dehydrogenase activity,substrate-induced respiration(SIR),and metabolic quotient(MQ)were assessed along with high-throughput 16S rRNA sequencing of rice rhizosphere soils.The rice rhizosphere soil registered the highest SOC,MBC,and dehydrogenase activity in SRI followed by wetland rice and then aerobic rice.Cropping method had a minimal impact on SIR and MQ.Along with cropping method,growth stage also significantly altered these biological attributes of rice rhizosphere.The trends of the highest SOC content and dehydrogenase activity at the flowering stage and the highest MBC content and SIR at the tillering stage of rice were observed in all three rice cropping methods.The analysis of bacterial communities,based on 16S rRNA gene sequencing,revealed that both cropping method and growth stage significantly impacted the composition of rhizosphere microbiomes.However,the influence of cropping method was less pronounced compared to growth stage.Cropping method caused notable shifts in the abundances of Proteobacteria,Bacteroidetes,and Chloroflexi,while growth stage affected the abundances of Proteobacteria,Actinobacteria,Cyanobacteria,Firmicutes,Chloroflexi,and Bacteroidetes.Based on these results,the SRI method led to higher diversification to the rhizosphere bacteriobiota,as well as greater incorporation of carbon into the soil and increased dehydrogenase activity compared to wetland rice and aerobic rice.This study deepens our understanding of how different cropping methods influence plant-microbe interaction and the implications for overall rice productivity and soil health.展开更多
Bemisia tabaci is a polyphagous herbivore that feeds on a wide range of horticultural and ornamental crops cultivated under diverse ecological zones. In Sierra Leone, B. tabaci is found to infest a wide range of veget...Bemisia tabaci is a polyphagous herbivore that feeds on a wide range of horticultural and ornamental crops cultivated under diverse ecological zones. In Sierra Leone, B. tabaci is found to infest a wide range of vegetable crops by directly feeding on phloem sap thereby inducing physiological disorders, and also serve as a vector to gemini viruses. Invariably the destructive feeding of B. tabaci affects the productivity and aesthetic values of vegetables and other horticultural crops and hence is considered a serious economic pest. A bioassay experiment was carried out by rearing B. tabaci populations on four vegetable crops under controlled laboratory conditions to determine its life table and demographic parameters. Results showed that the intrinsic rate of growth which measures the population size and growth pattern was highest for populations reared on tomato crops with the following values: rm 0.145 female female−1 day−1, the gross reproduction rate (Ro), and finite growth rate λ were highest for population reared on tomato, correspondingly the development period from egg-adult emergence was shortest with a value of 26 d. Conversely, the computed demographical parameters rm, λ and Ro for the population reared on sweet pepper were 0.106 female female−1 day−1 respectively, with a corresponding development period egg-adult emergence as 36d. The computed biological parameters for okra and garden egg varied with intermediary values between tomato and pepper host materials. The survivorship rates were quite significant for the smaller instars (Instars 1-III) with over 80% surviving to pre-pupa and pupa stage for the populations reared for all the test materials. High mortality was noticed for the pre-pupa and pupa stages as their survival rates were significantly low compared to the high survival rates of the smaller instars. Less than 50% of pupae failed to emerge to adults except for populations reared on tomato test materials where 52% emerged to adults. The study indicated tomato as the most suitable host among the four vegetable crops. Although life table and demographic parameters are invaluable information for forecasting pest populations and help in designing pest management efforts, further investigations such as the economic threshold and economic injury levels of B. tabaci population are requisite decision tools for sound pest management decisions of B. tabaci on these vegetable crops. The information obtained from this investigation would be quite relevant for extension service and pest management practitioners where mixed vegetable farming is a common practice.展开更多
基金support from the Indian Council of Agricultural Research through the All India Network Project(AINP)on Soil Biodiversity and Biofertilizers to conduct this study is acknowledged。
文摘Rice cropping method is primarily decided by soil moisture regime.System of rice intensification(SRI)and direct-seeded aerobic rice are two primary modifications of traditional wetland rice.Understanding rice rhizosphere microbiome and functioning as influenced by these cropping methods is essential for sustaining rice productivity.The objective of this study was to assess the impact of three different rice cropping methods(wetland rice,SRI,and aerobic rice)on the biochemical properties and bacterial communities within the rice rhizosphere across three key rice growth stages:tillering,flowering,and maturity.Soil organic carbon(SOC),microbial biomass carbon(MBC),dehydrogenase activity,substrate-induced respiration(SIR),and metabolic quotient(MQ)were assessed along with high-throughput 16S rRNA sequencing of rice rhizosphere soils.The rice rhizosphere soil registered the highest SOC,MBC,and dehydrogenase activity in SRI followed by wetland rice and then aerobic rice.Cropping method had a minimal impact on SIR and MQ.Along with cropping method,growth stage also significantly altered these biological attributes of rice rhizosphere.The trends of the highest SOC content and dehydrogenase activity at the flowering stage and the highest MBC content and SIR at the tillering stage of rice were observed in all three rice cropping methods.The analysis of bacterial communities,based on 16S rRNA gene sequencing,revealed that both cropping method and growth stage significantly impacted the composition of rhizosphere microbiomes.However,the influence of cropping method was less pronounced compared to growth stage.Cropping method caused notable shifts in the abundances of Proteobacteria,Bacteroidetes,and Chloroflexi,while growth stage affected the abundances of Proteobacteria,Actinobacteria,Cyanobacteria,Firmicutes,Chloroflexi,and Bacteroidetes.Based on these results,the SRI method led to higher diversification to the rhizosphere bacteriobiota,as well as greater incorporation of carbon into the soil and increased dehydrogenase activity compared to wetland rice and aerobic rice.This study deepens our understanding of how different cropping methods influence plant-microbe interaction and the implications for overall rice productivity and soil health.
文摘Bemisia tabaci is a polyphagous herbivore that feeds on a wide range of horticultural and ornamental crops cultivated under diverse ecological zones. In Sierra Leone, B. tabaci is found to infest a wide range of vegetable crops by directly feeding on phloem sap thereby inducing physiological disorders, and also serve as a vector to gemini viruses. Invariably the destructive feeding of B. tabaci affects the productivity and aesthetic values of vegetables and other horticultural crops and hence is considered a serious economic pest. A bioassay experiment was carried out by rearing B. tabaci populations on four vegetable crops under controlled laboratory conditions to determine its life table and demographic parameters. Results showed that the intrinsic rate of growth which measures the population size and growth pattern was highest for populations reared on tomato crops with the following values: rm 0.145 female female−1 day−1, the gross reproduction rate (Ro), and finite growth rate λ were highest for population reared on tomato, correspondingly the development period from egg-adult emergence was shortest with a value of 26 d. Conversely, the computed demographical parameters rm, λ and Ro for the population reared on sweet pepper were 0.106 female female−1 day−1 respectively, with a corresponding development period egg-adult emergence as 36d. The computed biological parameters for okra and garden egg varied with intermediary values between tomato and pepper host materials. The survivorship rates were quite significant for the smaller instars (Instars 1-III) with over 80% surviving to pre-pupa and pupa stage for the populations reared for all the test materials. High mortality was noticed for the pre-pupa and pupa stages as their survival rates were significantly low compared to the high survival rates of the smaller instars. Less than 50% of pupae failed to emerge to adults except for populations reared on tomato test materials where 52% emerged to adults. The study indicated tomato as the most suitable host among the four vegetable crops. Although life table and demographic parameters are invaluable information for forecasting pest populations and help in designing pest management efforts, further investigations such as the economic threshold and economic injury levels of B. tabaci population are requisite decision tools for sound pest management decisions of B. tabaci on these vegetable crops. The information obtained from this investigation would be quite relevant for extension service and pest management practitioners where mixed vegetable farming is a common practice.
