In order to determine the resistance of leading rice varieties to rice blast in Guangxi, three natural induction rice blast nurseries were established in Cenxi, Sanjiang and Yongfu. The resistance of the 45 leading ri...In order to determine the resistance of leading rice varieties to rice blast in Guangxi, three natural induction rice blast nurseries were established in Cenxi, Sanjiang and Yongfu. The resistance of the 45 leading rice varieties in Guangxi to rice blast was determined under conditions of spray inoculation and natural induction at seedling stage. The results showed that resistance frequencies of the 45 leading rice varieties ranged from 8.33% to 94.44%. Among the 45 tested varieties, there were 8 varieties of which the resistance frequencies were all higher than 80%, accounting for 17.78%; there were 11 varieties of which the resistance frequencies ranged from 50% to 80%, accounting for 24.44%; the resistance frequencies of the remaining varieties were all lower than 50%, accounting for 57.78% of the total tested varieties. The twoconsecutive-year determination results showed none of the 45 leading rice varieties showed resistance to rice blast. In 2010, there were 26, 12 and 7 varieties that were moderately sensitive, sensitive and greatly sensitive to rice blast respectively, accounting for 57.78%, 26.67% and 15.56% of the total tested varieties. In 2011, there were 16, 23 and 12 varieties that were moderately sensitive, sensitive and greatly sensitive to rice blast respectively, accounting for 35.56%, 51.11% and 13.33%. The overall resistance of the 45 leading rice varieties trended to be decreased year by year. So in rice production, they should be selected properly.展开更多
Eight strains of nervous necrosis virus （NNV） isolated in Vietnam were used to detect the pathogenicity and immune response in sea bass （SB）. All strains induced cytopathic effect in SB cell line, complete destruc...Eight strains of nervous necrosis virus （NNV） isolated in Vietnam were used to detect the pathogenicity and immune response in sea bass （SB）. All strains induced cytopathic effect in SB cell line, complete destruction of monolayer of cells appeared after seven days post infection （dpi）. Virus titer was different for each strain, TCIDso ranged from 102.7 to 1069, and LDs0 from 1015 to 1075. Five NNV strains named QN 02, QN 05, QN 07, ND 11 and KH 05 had higher virulence than the other three, the first causing 100% mortality in experimental fish 3-5 dpi. NNV KH 05 had the highest antigenic similarity, and it was inactivated completely by 0.2% formalin, 0.002 mol/L binary ethylenimine （BEI） and 0.1% beta-propiolactone. The neutralization antibody titer obtained in fish of groups immunized by BEI 0.002 M and beta-propiolactone 0.1% inactivated virus was four to eight times higher than that of the group treated with the formalin inactivated virus. The antibody titer in fish immunized with beta-propiolactone inactivated virus was more persistent. The efficacy of vaccines developed from beta-propiolactone inactivated virus and aluminium hydroxide （AH） or aluminum phosphate （AP） was observed by intramuscularly immunizing Epinephelusfuscoguttatus size 1.5 cm. Neutralizing antibodies appeared in vaccinated fish on 10th day post-immunization （dpi） at a dilution of 1：16; 1：32 and highest levels were reached on 30-45 dpi, at dilutions of 1：256 and 1：512, after treatment with AH and AP vaccine, respectively. The relative percent of survival （RPS） of vaccine at 30 dpi was highest with challenge doses 0.2-1 × 10^6.8 TCIDs0, the RPS varied from 80%-83.3% in both groups of AH and AP immunization. This result provides the basis for developing a vaccine against NNA disease.展开更多
In order to establish a fast and effective high-throughput method for identifying maize resistance to Aspergillus flavus infection in the field,5 conidial concentrations and 3 inoculation methods were compared and opt...In order to establish a fast and effective high-throughput method for identifying maize resistance to Aspergillus flavus infection in the field,5 conidial concentrations and 3 inoculation methods were compared and optimized. A correlation model between disease levels and aflatoxin B1 accumulation was established. The results showed that inoculating maize inbred lines with the optimal conidial concentration of 1.0×10^6 c/mL could accurately show the different resistance levels of maize to A.flavus infection,and the spiral quantitative inoculation technique could effectively avoid the defect of calculation error caused by commonly used methods. The positive correlation model of resistance level and aflatoxin B1 accumulation could effectively predict the capability of maize being resistant to A.flavus. 8 resistant and 9 medium resistant maize inbred lines of the RIL population were identified.The spiral quantitative identification method realized the high-throughput identification of maize inbred lines resistant to A.flavus infection in the field,and the results have shown high accuracy,stability and repeatability.展开更多
Stem rust race Ug99, also designated TTKSK （Puccinia graminis f. sp. tritici） cause stem or black rust, which is a serious disease of wheat worldwide. Field experiments were conducted at two sites during 2008 and 20...Stem rust race Ug99, also designated TTKSK （Puccinia graminis f. sp. tritici） cause stem or black rust, which is a serious disease of wheat worldwide. Field experiments were conducted at two sites during 2008 and 2009 growing seasons to evaluate the effectiveness of two new foliar fungicides： viz. Nativo 300 SC （trifloxystrobin 100 g L^-1 ＋ tebuconazole 200 g L^-1） and Prosaro 250 EC （prothioconazole 125 g L^-1 ＋ tebuconazole 125 g L^-1）, in controlling stem rust on susceptible wheat cultivar Duma. AmistarXtra 280 SC （azoxystrobin 200 g L^-1 ＋ cyproconazole 80 g L^-1） and Folicur 250 EC （tebuconazole） were used as checks. The treatment at each site and year included non-treated control and two spray applications of the fungicides at growth stages （GS） 55 （heading） and 65 （flowering）. Stem rust severities were scored using the modified Cobb scale at 14-day intervals after application. The data were used to calculate mean rust severity （MRS）. Stem rust epidemics were severe at KARI-Njoro in 2008 and the treatment effects on stem rust severities, grain yield and 1,000 kernel weights were significant at both KARI-Njoro and Mau-Narok sites. The fungicide treatments, significantly （P _〈 0.05） reduced stem rust severity, increased grain yield and 1,000 kernel weight of the susceptible wheat cultivar Duma compared to the non-treated control. Both fungicides： Nativo 300 SC and Prosaro 250 EC applied at the rate of 1.0 L hat were recommended for commercial use.展开更多
This study was conducted to assess the incidence of seed-borne fungi on rice seeds sourced from the major rice growing areas of South-Eastern Nigeria. The rice seeds were collected during the dry seasons between 2009 ...This study was conducted to assess the incidence of seed-borne fungi on rice seeds sourced from the major rice growing areas of South-Eastern Nigeria. The rice seeds were collected during the dry seasons between 2009 and 2010. Four hundred rice seeds randomly collected and surface sterilized by washing in 3% sodium hypochlorite and rinsed two times with sterile distilled water were placed in three circular rings inside the Petri dishes. The incubation was done one after the other for each variety from all the locations. Ten fungi species from eight genera were isolated from the rice seeds in all the rice growing areas of South-Eastern Nigeria. The fungi pathogens vary from one locality to another, as well as the frequency of occurrence. The pathogens isolated include： Fusarium moniliforme, F. solani, F. oxysporium, Aspergillus spp., Botridiploidia spp., Helminthosporium spp., Penicillium spp., Trichoconis padwickii, Curvularia oryzae and Phoma oryzae. Though, there was the presence of some seed-borne fungi in the rice seeds from the areas studied, most of the cultivars experienced up to 90% germination. But some cultivars had very low germination. IR 1416 from Arochukwu and GB90 from Arondiuzogu had less than 1% germination. This study shows that seed-borne organisms are major constraint in rice production in the South-Eastern states of Nigeria as a result of low seed germination stemmed from infestation of fungi organisms in the seeds.展开更多
文摘In order to determine the resistance of leading rice varieties to rice blast in Guangxi, three natural induction rice blast nurseries were established in Cenxi, Sanjiang and Yongfu. The resistance of the 45 leading rice varieties in Guangxi to rice blast was determined under conditions of spray inoculation and natural induction at seedling stage. The results showed that resistance frequencies of the 45 leading rice varieties ranged from 8.33% to 94.44%. Among the 45 tested varieties, there were 8 varieties of which the resistance frequencies were all higher than 80%, accounting for 17.78%; there were 11 varieties of which the resistance frequencies ranged from 50% to 80%, accounting for 24.44%; the resistance frequencies of the remaining varieties were all lower than 50%, accounting for 57.78% of the total tested varieties. The twoconsecutive-year determination results showed none of the 45 leading rice varieties showed resistance to rice blast. In 2010, there were 26, 12 and 7 varieties that were moderately sensitive, sensitive and greatly sensitive to rice blast respectively, accounting for 57.78%, 26.67% and 15.56% of the total tested varieties. In 2011, there were 16, 23 and 12 varieties that were moderately sensitive, sensitive and greatly sensitive to rice blast respectively, accounting for 35.56%, 51.11% and 13.33%. The overall resistance of the 45 leading rice varieties trended to be decreased year by year. So in rice production, they should be selected properly.
文摘Eight strains of nervous necrosis virus （NNV） isolated in Vietnam were used to detect the pathogenicity and immune response in sea bass （SB）. All strains induced cytopathic effect in SB cell line, complete destruction of monolayer of cells appeared after seven days post infection （dpi）. Virus titer was different for each strain, TCIDso ranged from 102.7 to 1069, and LDs0 from 1015 to 1075. Five NNV strains named QN 02, QN 05, QN 07, ND 11 and KH 05 had higher virulence than the other three, the first causing 100% mortality in experimental fish 3-5 dpi. NNV KH 05 had the highest antigenic similarity, and it was inactivated completely by 0.2% formalin, 0.002 mol/L binary ethylenimine （BEI） and 0.1% beta-propiolactone. The neutralization antibody titer obtained in fish of groups immunized by BEI 0.002 M and beta-propiolactone 0.1% inactivated virus was four to eight times higher than that of the group treated with the formalin inactivated virus. The antibody titer in fish immunized with beta-propiolactone inactivated virus was more persistent. The efficacy of vaccines developed from beta-propiolactone inactivated virus and aluminium hydroxide （AH） or aluminum phosphate （AP） was observed by intramuscularly immunizing Epinephelusfuscoguttatus size 1.5 cm. Neutralizing antibodies appeared in vaccinated fish on 10th day post-immunization （dpi） at a dilution of 1：16; 1：32 and highest levels were reached on 30-45 dpi, at dilutions of 1：256 and 1：512, after treatment with AH and AP vaccine, respectively. The relative percent of survival （RPS） of vaccine at 30 dpi was highest with challenge doses 0.2-1 × 10^6.8 TCIDs0, the RPS varied from 80%-83.3% in both groups of AH and AP immunization. This result provides the basis for developing a vaccine against NNA disease.
文摘In order to establish a fast and effective high-throughput method for identifying maize resistance to Aspergillus flavus infection in the field,5 conidial concentrations and 3 inoculation methods were compared and optimized. A correlation model between disease levels and aflatoxin B1 accumulation was established. The results showed that inoculating maize inbred lines with the optimal conidial concentration of 1.0×10^6 c/mL could accurately show the different resistance levels of maize to A.flavus infection,and the spiral quantitative inoculation technique could effectively avoid the defect of calculation error caused by commonly used methods. The positive correlation model of resistance level and aflatoxin B1 accumulation could effectively predict the capability of maize being resistant to A.flavus. 8 resistant and 9 medium resistant maize inbred lines of the RIL population were identified.The spiral quantitative identification method realized the high-throughput identification of maize inbred lines resistant to A.flavus infection in the field,and the results have shown high accuracy,stability and repeatability.
文摘Stem rust race Ug99, also designated TTKSK （Puccinia graminis f. sp. tritici） cause stem or black rust, which is a serious disease of wheat worldwide. Field experiments were conducted at two sites during 2008 and 2009 growing seasons to evaluate the effectiveness of two new foliar fungicides： viz. Nativo 300 SC （trifloxystrobin 100 g L^-1 ＋ tebuconazole 200 g L^-1） and Prosaro 250 EC （prothioconazole 125 g L^-1 ＋ tebuconazole 125 g L^-1）, in controlling stem rust on susceptible wheat cultivar Duma. AmistarXtra 280 SC （azoxystrobin 200 g L^-1 ＋ cyproconazole 80 g L^-1） and Folicur 250 EC （tebuconazole） were used as checks. The treatment at each site and year included non-treated control and two spray applications of the fungicides at growth stages （GS） 55 （heading） and 65 （flowering）. Stem rust severities were scored using the modified Cobb scale at 14-day intervals after application. The data were used to calculate mean rust severity （MRS）. Stem rust epidemics were severe at KARI-Njoro in 2008 and the treatment effects on stem rust severities, grain yield and 1,000 kernel weights were significant at both KARI-Njoro and Mau-Narok sites. The fungicide treatments, significantly （P _〈 0.05） reduced stem rust severity, increased grain yield and 1,000 kernel weight of the susceptible wheat cultivar Duma compared to the non-treated control. Both fungicides： Nativo 300 SC and Prosaro 250 EC applied at the rate of 1.0 L hat were recommended for commercial use.
文摘This study was conducted to assess the incidence of seed-borne fungi on rice seeds sourced from the major rice growing areas of South-Eastern Nigeria. The rice seeds were collected during the dry seasons between 2009 and 2010. Four hundred rice seeds randomly collected and surface sterilized by washing in 3% sodium hypochlorite and rinsed two times with sterile distilled water were placed in three circular rings inside the Petri dishes. The incubation was done one after the other for each variety from all the locations. Ten fungi species from eight genera were isolated from the rice seeds in all the rice growing areas of South-Eastern Nigeria. The fungi pathogens vary from one locality to another, as well as the frequency of occurrence. The pathogens isolated include： Fusarium moniliforme, F. solani, F. oxysporium, Aspergillus spp., Botridiploidia spp., Helminthosporium spp., Penicillium spp., Trichoconis padwickii, Curvularia oryzae and Phoma oryzae. Though, there was the presence of some seed-borne fungi in the rice seeds from the areas studied, most of the cultivars experienced up to 90% germination. But some cultivars had very low germination. IR 1416 from Arochukwu and GB90 from Arondiuzogu had less than 1% germination. This study shows that seed-borne organisms are major constraint in rice production in the South-Eastern states of Nigeria as a result of low seed germination stemmed from infestation of fungi organisms in the seeds.
