ABSTRACT
Fertilizers are extensively used essentially to meet the food demand of increasing population. Further, they help the plants in alleviating the deleterious effects of UV-B radiation. In this study, we explored this in spinach (Spinacia oleracea L.). S. oleracea plants were grown under ambient and elevated UV-B at different combinations and concentrations of NPK: (i) recommended level of NPK (RNPK); (ii) 1.5 times recommended level of NPK (1.5 × NPK); (iii) 1.25 times recommended level of N plus recommended PK (1.25N+PK); and (iv) 1.25 times recommended level of NPK (1.25 × NPK) to assess the amelioration potential of nutrient combination. Higher availability of NPK provided more protection to plants against oxidative stress as is obvious from reduction in MDA content under elevated UV-B which can be attributed to low oxidative stress due to higher induction of antioxidants. Protection provided to chlorophyll by nitrogen was enhanced by phosphorus and potassium in 1.5 × NPK and 1.25 × NPK compared to RNPK and 1.25 × N+ PK. Maximum increase in PAL activity in plants at 1.5 × NPK did not translate into flavonoid accumulation in same at initial age of observation. Maximum alleviation against UV-B radiation was observed at 1.5 × NPK which can be attributed to better ROS scavenging capacity, more metabolite production and maintaining photochemical efficiency.
ABSTRACT
Present study is conducted to evaluate the response of bean (Dolichos lablab cv . pusa early prolific) plants to supplemental UV-B (sUV-B: 280-315 nm: 7.2 kJ m-2 d-1) radiation. UV-B caused alteration in biomass translocation pattern with more retention of biomass in below ground parts leading to an increment in root shoot ratio. Specific leaf area (SLA) which is the measure of leaf thinness, increased in plants under sUV-B exposure by 95.7 and 82.3% after 15 and 30 days after germination. Photosynthetic machinery of bean plants was the potential target of UV-B as photosynthetic rate was decreased by 88.6 % at 30 days after germination. sUV-B lead to the formation of reactive oxygen species thus generating oxidative stress. Stimulation of antioxidant defense system (enzymatic and non-enzymatic) was observed due to sUV-B radiation. Phenolic content decreased (34.7 and 18.6%) but protein showed varied response, increased initially (34%) thereafter declined (10.2%) under sUV-B radiation.
ABSTRACT
Ultraviolet-B (UV-B) radiation generates an oxidative stress in plant cells due to excessive generation of reactive oxygen species (ROS). ROS can denature enzymes and damage important cellular components. In the present study, an important medicinal plant Acorus calamus (Sweet flag) was subjected to two doses of supplemental UV-B radiation (sUV-B): sUV1 (+1.8 kJ m-2 d-1) and sUV2 (+3.6 kJ m–2 d–1) to evaluate the relative response of antioxidant defense potential. Stimulation of activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) was observed at initial growth period while the activities of CAT and SOD decreased at later age of sampling. sUV-B induced lipid peroxidation (LPO) was observed showing alteration of membrane properties. No definite trend of change was observed for ascorbic acid (AsA), while increaments in thiol, proline, phenol and protein contents were observed due to sUV-B. Results suggested that sUV-B radiation may stimulate the enzymatic and non-enzymatic defense system of Acorus plants, showing its better adaptation at lower dose of sUV-B.
ABSTRACT
Ultraviolet radiation (UV) though harmful but is an important and unavoidable component of terrestrial ecosystem to which plants have been exposed since their migration from aquatic to land habitat. Incoming UV-B radiation and heavy metals abundance in contaminated soils are significant environmental threat affecting metabolic functions of plants through generation of reactive oxygen species. Plants have evolved mechanisms to counteract these reactive radicals and to repair the damage caused by UV-B and heavy metals. This study describes the impact of supplemental UV-B (sUV-B) and nickel (Ni) singly and in combination on photosynthetic pigments, flavonoids, enzymatic and non-enzymatic antioxidants, metabolites and lipid peroxidation of Pisum sativum L. (pea) plants. Compared to the controls, both the stresses individually and in combination led to reductions in photosynthetic pigments, ascorbic acid, protein and catalase (CAT) activity, whereas a reverse trend was observed for flavonoids, phenol, proline and thiol contents, superoxide dismutase (SOD) and peroxidase (POX) activities and lipid peroxidation (LPO). However, flavonoids increased significantly under individual exposure of sUV-B as compared to other treatments. An increase of LPO by 81% indicated the generation of reactive oxygen species under both the stress conditions. sUV-B and Ni in combination acted synergistically with stimulation of CAT activity by 51.6% , additively on SOD activity with increase of 16.4%, while other parameters showed antagonistic action of both the stresses.