The Saline-tolerant Mechanism of the Bangladeshi Soybean Variety AGS313

Abstract

The saline-tolerant Bangladeshi soybean, AGS313, and the saline-sensitive Japanese soybean, Fukuyutaka, were cultivated under saline conditions to better understand the saline-tolerant mechanism. Plants in the vegetative stage were subjected to a 50 mM saline treatment for 3 weeks. Physiological responses, including photosynthetic and transpiration reactions, were measured in both soybean varieties. The accumulation of Na⁺, Cl^-, K⁺, Ca²⁺, and Mg²⁺ was also measured in upper and lower leaves, upper and lower stems, and in the roots. The physiological responses of AGS313 were little affected by saline treatment, but those of Fukuyutaka were markedly decreased. The two varieties accumulated Na⁺ in their lower stems to a similar extent, and both controlled Na⁺ accumulation in the leaves. Soybean reportedly accumulates Na⁺ in its roots, but we found that lower stems had the largest Na⁺ accumulations. The similar Na⁺ accumulation patterns of the two varieties suggest that saline tolerance in AGS313 was not related to its pattern of Na⁺ distribution. However, while the saline-sensitive Fukuyutaka accumulated Cl^- in its leaves under saline stress, AGS313 did not. These results suggest that AGS313 achieves saline tolerance by reducing Cl^- accumulation in its leaves.