Salinity sensitivity in mungbean: tissue ion accumulation in relation to growth and yield in contrasting genotypes

Abstract

Background and aims

Salinity poses a significant challenge to agricultural production, and mungbean (Vigna radiata L.) is among the more salt-sensitive food legumes. This study evaluated salinity tolerance in four contrasting mungbean genotypes by analysing their morpho-physiological responses at the vegetative stage and at maturity.

Methods

Plants were grown in soil-filled pots subjected to five salinity treatments (0, 25, 50, 75 and 125 mM NaCl) in a temperature-controlled glasshouse. Salinity was imposed 15 days after sowing (DAS) and plants were harvested at 38 DAS and 56 DAS.

Results

Genotypes varied in their sensitivity to salinity measured as various morpho-physiological traits including foliar injury, SPAD, nodulation, growth, yield and yield components. Growth reduction was similar across genotypes at the vegetative stage but was more pronounced in sensitive than tolerant genotypes at maturity. High seed yield in salt tolerant genotypes was associated with large seeds, more flowers and pods, and number of seeds per plant in saline soil. Salinity stress decresead leaf osmotic potential while increasing leaf water content in all genotypes. Salinity stress increased leaf Na⁺, Cl^– and also leaf K⁺ in all genotypes for maintaining the charge balance as Na⁺ was only about 14% of Cl^– in leaf tissues. Tolerant genotypes accumulated less leaf Na⁺ and Cl^– and maintained higher leaf K⁺/Na⁺ than sensitive genotypes, however, Cl^– concentrations were increased to 260–395 mM in all genotypes.

Conclusions

Salinity sensitivity results from toxic concentrations of Na⁺ and Cl^– in leaves, leading to reduced chlorophyll content, growth and yield. These findings demonstrate that the ability of controlling Na⁺ and Cl^– accumulation in leaves, tissue tolerance to high Cl^– and maintaining high leaf K⁺/Na⁺ ratio may contribute to salinity tolerance in mungbean.