Impact of Salinity Stress on the Seedling Vigor of Green Gram (Vigna radiata L.) CO 9 Variety

Abstract

Soil salinity is a critical abiotic stress that significantly limits seed germination, seedling establishment, and productivity in legumes. This study evaluated the effects of six sodium chloride (NaCl) concentrations (0%, 0.1%, 0.5%, 1.0%, 2.0%, and 3.0%) on the germination and early seedling growth of the green gram (Vigna radiata L.) cultivar CO 9. The research was conducted under controlled laboratory conditions at the PGP College of Agricultural Sciences, Namakkal (11.2335oN, 78.1664oE). The experiment followed a Completely Randomized Design (CRD) with three replications per treatment. Data collected for germination and seedling growth were analyzed using a one-way Analysis of Variance (ANOVA), and mean separations were performed using Duncan’s Multiple Range Test (DMRT) at P < 0.05 to establish statistical significance between the varying salinity levels. Key parameters recorded included germination percentage (GP), shoot length (SL), root length (RL), and seedling vigour index (SVI). Results indicated that the germination percentage remained optimal at 0% and 0.1% NaCl (100%), followed by a non-significant decline at 0.5% (93.3%). However, a sharp reduction was observed at concentrations of 1.0% (80%), 2.0% (60%), and 3.0% (40%). Morphological parameters followed a similar dose-dependent inhibitory pattern; average shoot length decreased from 17.4 cm in the control to 0.54 cm at 3.0% NaCl, while root length declined from 13.0 cm to 0.8 cm. Consequently, the seedling vigour index decreased markedly from 3040 in the control to 54 at the highest salinity level. The findings suggest that while the CO 9 variety maintains physiological resilience under mild salinity (0.5 %), it is highly sensitive to moderate-to-high salinity stress, identifying 1.0% NaCl as the critical threshold for seedling establishment. Green gram (Vigna radiata L.) is a vital source of high-quality protein and essential minerals for the vegetarian population in India. However, its production is increasingly threatened by soil salinization, which affects approximately 6.73 million hectares of land in India, with significant tracts in the semi-arid regions of Tamil Nadu. Since seedling establishment is the most vulnerable stage in the pulse life cycle, identifying the specific salinity tolerance thresholds for popular cultivars like CO 9 is essential for local crop planning. This research addresses the gap in understanding how high-density salt concentrations specifically disrupt the morphological vigor of CO 9, providing a baseline for farmers and researchers in the Namakkal region to mitigate yield losses in salt-affected soils.