ROLE OF UV RADIATION IN SEED PHYSIOLOGY, DORMANCY AND SEEDLING VIGOUR IN LEGUME CROPS

Abstract

Legume crops (Fabaceae) are fundamental to global food security and soil sustainability, yet their productivity is frequently constrained by seed dormancy, poor germination uniformity and suboptimal early seedling establishment. Ultraviolet (UV) radiation encompassing UV-A (315–400 nm), UV-B (280–315 nm) and UV-C (100–280 nm) is an important environmental and technological factor that significantly modulates seed physiology and early growth. This review synthesizes current knowledge on the role of UV radiation in legume seed biology, encompassing seed coat structural responses, water imbibition, membrane stability, reserve mobilization, antioxidant defense and dormancy regulation. Evidence from major legume crops including soybean (Glycine max), mung bean (Vigna radiata), black gram (Vigna mungo), Bengal gram (Cicer arietinum), horse gram (Macrotyloma uniflorum) and groundnut (Arachis hypogaea) indicates that moderate, controlled UV exposure can break physical dormancy by inducing micro-structural modifications in the seed coat, enhance germination rate and speed, stimulate hydrolytic enzyme activity and promote early seedling vigor. At the molecular level, UV radiation activates the UVR8–HY5 signalling pathway, triggers DNA repair mechanisms, upregulates phenylpropanoid and flavonoid biosynthesis and modulates the abscisic acid–gibberellic acid hormonal balance. These responses are strongly dose-dependent and species or genotype-specific; while low to moderate UV doses elicit adaptive, growth-promoting effects, excessive exposure generates oxidative stress, membrane damage and growth inhibition.. Overall, UV radiation presents a promising, non-chemical, eco friendly approach for seed invigoration and dormancy management in legume-based cropping systems, with significant potential for sustainable agricultural application.