Screening salt-tolerant rice at the seedling and reproductive stages: An effective and reliable approach

Abstract

Screening salt-tolerant rice genotypes is important to develop salt-tolerant high-yielding cultivars. To categorize salt-tolerant genotypes, we used a comprehensive collection of morpho-physiological parameters, yield-contributing characteristics, and molecular and biochemical markers with multivariate analysis in this study. A total of 20 rice genotypes were screened at seedling stages in a hydroponic system at three different salinity levels (8, 10, and 12 dS m−1). Furthermore, at the reproductive stage, 12 genotypes were evaluated at 4 and 6 dS m−1 salinity conditions. The seedlings growth of the most rice genotypes were severely reduced by salinity stress, however, some genotypes (M-12, M-20, IR-10, IR-8, and M-19) showed the lowest growth reduction. Total salt stress response index revealed that the genotypes M-12 was the most salt-tolerant. Though the genotype M-12 acquired the highest position in seedling stage screening but unfortunately failed to show sufficient yield potential at reproductive stage, in which M-19 was qualified with highest yield response. Therefore, only seedling stage screening may provide misleading results. M-19 also showed the highest antioxidant activity with lower Na+/ K+ ratio, hydrogen peroxide, and malondialdehyde content, indicating a strong defense mechanism against salt-induced oxidative and osmotic stress. Overall, M-19 was selected as the most appropriate candidate genotypes for salinity tolerance. The accuracy and reliability of these methods were superbly assured by principal component analysis and seedling stage molecular assay. Therefore, the identified salt-tolerant genotypes could be further utilized as a source of appropriate donor parents in breeding of salt-tolerant high-yielding rice varieties.