Abstract

VARIATION IN LEAF MORPHOLOGY, WATER STATUS AND BIOCHEMICAL TRAITS DURING EARLY DEVELOPMENT OF RICINUS COMMUNIS UNDER UV-B STRESS

*Priyanka Uniyal and L. R. Dangwal

ABSTRACT

The present study investigates the impact of ultraviolet-B (UV-B) radiation (280-315 nm) on the early growth stage of Ricinus communis L., focusing on morphological, physiological, and biochemical traits. Seedlings were subjected to three different UV-B exposure regimes: ambient UV-B (control), enhanced UV-B, and UV-B exclusion, and evaluated after eight weeks of plant germination. Key parameters such as number of leaves, petiole length, leaf area, mid-vein length, number of veins, relative water content, chlorophyll a and b, carotenoid levels, and total soluble protein were measured. Significant variation was observed across treatments in several traits. UV-B exclusion led to a marked increase in leaf number, mid-vein length, chlorophyll content, and protein levels, suggesting a favourable influence on plant development under reduced UV-B stress. In contrast, enhanced UV-B exposure significantly reduced relative water content and total soluble protein, while elevating carotenoid levels, indicating a physiologicalstress response. Traits such as petiole length, leaf area, and number of veins did not differ significantly across treatments. These findings reveal that UV-B radiation modulates both growth and metabolic profiles of castor oil plant during early development, with UV-B exclusion promoting optimal physiological conditions, and enhanced UV-B acting as a stressor. These results suggest that managing UV-B exposure could help improve the growth and productivity of castor oil plant, especially in areas facing high UV radiation due to climate change. This research provides useful insights for developing UV-resilient crops and optimizing protective cultivation practices.

Keywords: Oxidative Stress; UV-B radiation; UV-B exclusion; Stress physiology; Oxidative damage; Castor oil plant.