To assist with rapid screening for rice blast resistance as a precursor in a breeding program, the susceptibility to rice blast of 13 rice genotypes from Australia was evaluated in May to June 2013 using three distinc...To assist with rapid screening for rice blast resistance as a precursor in a breeding program, the susceptibility to rice blast of 13 rice genotypes from Australia was evaluated in May to June 2013 using three distinct inoculation methods（spot, filter paper and standard methods） at seedling, vegetative and reproductive stages. The results revealed that the spot and filter paper inoculation methods were successful in discerning susceptibility to the rice blast disease（P ≤ 0.05）. Disease susceptibility declined significantly from the vegetative to reproductive stages. The standard method was conducted at three different stages for pot plants grown inside the mist house. However, low temperatures did not produce disease symptoms except in a few genotypes. Among the 13 rice genotypes screened, AAT9 expressed a highly resistant response, and AAT4, AAT6, AAT10, AAT11, AAT13, AAT17 and AAT18 expressed resistance at various stages. The results will be useful for selecting elite genotypes for disease tolerance where rice blast is prevalent. In addition, the resistant genotypes can serve as a gene pool used in breeding programmes to develop new resistant genotypes.展开更多
Current watershed-scale,nonpoint source pollution models do not represent the processes and impacts of agricultural best management practices on water quality with sufficient detail.A Water Erosion Pre-diction Project...Current watershed-scale,nonpoint source pollution models do not represent the processes and impacts of agricultural best management practices on water quality with sufficient detail.A Water Erosion Pre-diction Project-Water Quality(WEPP-WQ)model was recently developed which is capable of simulating nonpoint source pollutant transport in nonuniform hillslope conditions such as those with BMPs.However,WEPP-WQ has not been validated for these conditions,and prior validation work only eval-uated calibrated performance rather than uncalibrated performance,with the latter being most relevant to model applications.This study evaluated uncalibrated and calibrated model performance in two plot-scale,artificial rainfall studies.179 observations were compared to corresponding WEPP-WQ simulations of runoff,sediment yield,and soluble and particulate nutrient forms for both nitrogen and phosphorus.Uncalibrated validation results were mixed for the different field conditions,model configurations,and prediction variables.Nash-Sutcliffe Efficiencies for uncalibrated simulations of uniform conditions were generally greater than 0.6 except for soluble nitrogen predictions which were poor.Simulations of nonuniform conditions were generally'unsatisfactory'except for runoff predictions which were quite good(NSE=0.78).Performance was improved substantially for almost all endpoints with calibration.Some exceptions to this occurred because the objective function for calibration was based on log-space differences so as to more equally-weight calibration of unsaturated conditions that tend to produce lesser runoff volumes and sediment yields.Calibrated results for both uniform and nonuniform condi-tions were generally'satisfactory'or'good'according to widely accepted model performance criteria.展开更多
Strategies are sought to reduce the impact of nonpoint sources of pollution,including fecal bacteria,and meet TMDL criteria.Vegetative filter strips(VFSs)are one such strategy,though the data of VFS function under fie...Strategies are sought to reduce the impact of nonpoint sources of pollution,including fecal bacteria,and meet TMDL criteria.Vegetative filter strips(VFSs)are one such strategy,though the data of VFS function under field conditions,particularly for fecal bacteria,are limited.The objective of this study was to evaluate the efficiencies in removing fecal bacteria,N,and P from VFSs installed to treat contaminated runoff from a working feedlot.VFSs were found to be effective in removing a broad range of constituents from beef feedlot runoff pretreated by a settling basin.The first 30 m provided most or all of the reductions found within the 150 m VFSs studied:reductions average 85%of inflow water,85%of sediment,77%of N,and 84%of P.Fecal bacteria removal by the VFSs was about one order of magnitude:reductions at 30 m ranged from 83.5%for FC and FS to 91%for E.coli.On the site being studied,this provided an important level of protection and reduced surface-flow concentrations of fecal coliforms to below the 200 CFU/100 mL(coliform-forming units,CFU)water-quality standard for Kansas.展开更多
文摘To assist with rapid screening for rice blast resistance as a precursor in a breeding program, the susceptibility to rice blast of 13 rice genotypes from Australia was evaluated in May to June 2013 using three distinct inoculation methods（spot, filter paper and standard methods） at seedling, vegetative and reproductive stages. The results revealed that the spot and filter paper inoculation methods were successful in discerning susceptibility to the rice blast disease（P ≤ 0.05）. Disease susceptibility declined significantly from the vegetative to reproductive stages. The standard method was conducted at three different stages for pot plants grown inside the mist house. However, low temperatures did not produce disease symptoms except in a few genotypes. Among the 13 rice genotypes screened, AAT9 expressed a highly resistant response, and AAT4, AAT6, AAT10, AAT11, AAT13, AAT17 and AAT18 expressed resistance at various stages. The results will be useful for selecting elite genotypes for disease tolerance where rice blast is prevalent. In addition, the resistant genotypes can serve as a gene pool used in breeding programmes to develop new resistant genotypes.
文摘Current watershed-scale,nonpoint source pollution models do not represent the processes and impacts of agricultural best management practices on water quality with sufficient detail.A Water Erosion Pre-diction Project-Water Quality(WEPP-WQ)model was recently developed which is capable of simulating nonpoint source pollutant transport in nonuniform hillslope conditions such as those with BMPs.However,WEPP-WQ has not been validated for these conditions,and prior validation work only eval-uated calibrated performance rather than uncalibrated performance,with the latter being most relevant to model applications.This study evaluated uncalibrated and calibrated model performance in two plot-scale,artificial rainfall studies.179 observations were compared to corresponding WEPP-WQ simulations of runoff,sediment yield,and soluble and particulate nutrient forms for both nitrogen and phosphorus.Uncalibrated validation results were mixed for the different field conditions,model configurations,and prediction variables.Nash-Sutcliffe Efficiencies for uncalibrated simulations of uniform conditions were generally greater than 0.6 except for soluble nitrogen predictions which were poor.Simulations of nonuniform conditions were generally'unsatisfactory'except for runoff predictions which were quite good(NSE=0.78).Performance was improved substantially for almost all endpoints with calibration.Some exceptions to this occurred because the objective function for calibration was based on log-space differences so as to more equally-weight calibration of unsaturated conditions that tend to produce lesser runoff volumes and sediment yields.Calibrated results for both uniform and nonuniform condi-tions were generally'satisfactory'or'good'according to widely accepted model performance criteria.
基金Contribution No.11-046-J Kansas Agricultural Experiment Station.Financial support for this project was provided,in part,by the Kansas EPA EPSCoR program.
文摘Strategies are sought to reduce the impact of nonpoint sources of pollution,including fecal bacteria,and meet TMDL criteria.Vegetative filter strips(VFSs)are one such strategy,though the data of VFS function under field conditions,particularly for fecal bacteria,are limited.The objective of this study was to evaluate the efficiencies in removing fecal bacteria,N,and P from VFSs installed to treat contaminated runoff from a working feedlot.VFSs were found to be effective in removing a broad range of constituents from beef feedlot runoff pretreated by a settling basin.The first 30 m provided most or all of the reductions found within the 150 m VFSs studied:reductions average 85%of inflow water,85%of sediment,77%of N,and 84%of P.Fecal bacteria removal by the VFSs was about one order of magnitude:reductions at 30 m ranged from 83.5%for FC and FS to 91%for E.coli.On the site being studied,this provided an important level of protection and reduced surface-flow concentrations of fecal coliforms to below the 200 CFU/100 mL(coliform-forming units,CFU)water-quality standard for Kansas.
