Correlation between visual assessment and measurement of physiological criteria for salinity tolerance at seedling stage in japonica rice

To identify the usefulness of visual assessment for salinity tolerance at seedling stage, 16 varieties belong to japonica were evaluated. Twelve-day-old seedlings were grown in a salinized solution, initially at an EC of 6dSm⁻¹ for four days followed by an EC of 12 dSm⁻¹ for 20days. A physiological parameters : seedling height, dry shoot weight and dry root weight, were measured and samples were analyzed for Na⁺ and K⁺ concentration in the shoot. A seedling height, dry shoot weight and dry root weight were reduced lower in tolerant varieties than in susceptible varieties. These agronomic paramenters were highly correlated with visual score suggesting that visual assessment is reliable for characterizing salinity tolerance. Tissue analysis for shoot Na⁺ concentration was lower in tolerant varieties than in susceptible varieties indicating that uptake of Na⁺ in the plant is the typical mechanism of salinity tolerances in japonica rice, However, shoot K⁺ concentration had no trend among varieties either tolerant varieties or susceptible varieties.