Modification in spinach response to UV-B radiation by nutrient management: Pigments, antioxidants and metabolites

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 (<em>Spinacia oleracea</em> L.). <em>S. oleracea</em> 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.