PHYSIOLOGICAL RESPONSES OF FIELD GROWN ZEA MAYS L. PLANTS TO ENHANCED UV-B RADIATION

Field grown corn (Zea mays L. cv VC_2) plants were treated at an enhanced level of ultraviolet-B radiation (predicted at 20% ozone depletion) from sowing to plant maturity. Photosynthesis rate was always lower in UV-B treated plants. Photosynthesis rate did not correspond to stomatal response. Total chlorophyll and carotenoid concentrations were higher in UV-B treated plants except at preflowering stage. Chlorophyll a:b ratio was lower in plants grown at enhanced level of UV-B till preflowering stage thereafter increased compared to the control. Anthocyanin concentration was higher initially but later reduced in UV-B treated plants. Absorbance profile of flavonoids showed higher values in plants treated at enhanced UV-B. Total plant biomass was higher for UV-B treated plants at all stages of growth compared to untreated control. Net primary productivity also showed a pattern similar to biomass accumulation. The study clearly indicates that corn is resistant to enhanced UV-B levels predicted at 20% ozone depletion under field conditions