Analysis of UV radiation-induced changes: effects on morpho-physiological, and biochemical traits of Portulaca...

Ultraviolet (UV) radiation is a significant environmental stressor for plant growth, stress responses and secondary metabolites. UV-B (280-315 nm) and UV-C (100-280 nm) wavelengths are particularly known to induce oxidative stress among the UV wavelenghts. The physiological and biochemical reactions of Portulaca oleracea with differing intensity of UV radiation are still uncertain. P. oleracea plants were exposed to UV-B and UV-C with measurements at 0, 200, 400 and 600 J.m⁻². Both UV-B and UV-C treatments reduced plant height, biomass, and leaf water potentially the largest reductions were under UV-C treatments in fact at 600 J.m⁻². Photosynthetic pigments such as chlorophyll a, chlorophyll b and carotenoids decreased with rising intensities of ultraviolet (UV). However, proline, malondialdehyde (MDA), phenols and flavonoids increased indicating more oxidative stress. Activities of the antioxidant enzymes catalase and peroxidase increased under increasing UV-C doses; the antioxidants increased with intense UV-C. Although UV-B and UV-C radiation produces physiological and biochemical effects that are dose-dependent in the greenhouse weed, P. oleracea, the exposure of plants to UV-C caused growth inhibition and decrease in pigments, but induced the defense mechanism against oxidative stress. Overall findings shed light on plant resilience to natural stress together mitigation measures for sustainable agro-ecosystem management amidst an increasing UV environment.