Salinity Effect at Seedling and Flowering Stages of Some Rice Lines and Varieties(Oryza sativa L.)

This study used 10 rice lines and varieties,including the salt tolerant variety(Pokkali)and salt susceptible variety(IR29)as control.Experiment for screening rice salinity tolerance at seedling stage was conducted in hydroponic system using five different salinity concentrations(0,4,6,8 and 10 dS/m).Flowering stage was evaluated at the salinity level of 8 dS/m.The experiment was designed in randomized completely block(RCBD)with three replications for each line/variety under non-saline and saline condition.The results showed that the growth of rice lines/varieties was retarded severely with increasing salinity levels,and almost all of leaves were drying and dead completely(score 7 and 9).Plants of IR29 and OM7347 were dead at the electrical conductivity(EC)=10 dS/m,whereas Pokkali(the tolerant variety)and IR93350 were evaluated at score 5.Salinity stress caused the reduction of overall vigor of rice lines/varieties especially in the pollen germination,fertilization and grain yield.Rice lines/varieties were classified to salinity tolerance levels as following:IR5040,IR93350,IR86385-8D-1-2-B and Pokkali(tolerant);OM8104,IR93340 and IR93343(moderate susceptible);OM7347,IR87832-303-1-B and IR29(susceptible).

Evaluation of Agronomic Characteristics,Drought Tolerance and Yield of Some Rice Varieties in Central Vietnam

The aim of the study was to evaluate the drought tolerance,agro-morphological characteristics and yield of 10 rice varieties collected from different locations.In experiment one,drought tolerance of rice varieties under artificial drought condition in the greenhouse was assessed through root and leaf characteristics.In experiment two,the growth and yield of rice varieties in the rainfed rice field was estimated.The results showed that drought has affected the root characteristics,leaf rolling and leaf drying of these varieties.In rainfed rice field of Thua Thien Hue and Quang Nam province,summer-autumn 2016 and winter-spring 2016-2017 crop season,these rice varieties grew and developed well.The growth time was 90-119 d in summer-autumn crop season,while in winter-spring crop season was 107-131 d.The yield of these rice varieties ranged from 37.02 quintals/ha to 56.33 quintals/ha and from 42.33 quintals/ha to 66.60 quintals/ha,respectively.Some rice varieties with high yields in both two crop seasons were OM4900,GSR38,IR93340 and OM7347.It is sugessted to conduct production experiment on a large area in rainfed field for these four varieties to evaluate them objectively and early put them into structure of rice varieties in Central Vietnam.