DIFFERENTIAL RESPONSES OF GROWTH AND PHOTOSYNTHESIS IN CYAMOPSIS-TETRAGONOLOBA L. GROWN UNDER ULTRAVIOLET-B AND SUPPLEMENTAL LONG-WAVELENGTH RADIATIONS

Cyamopsis tetragonoloba L. seedlings were subjected to continuous ultr aviolet (UV)-B radiation for 18 h and post-irradiated with ''white lig ht'' (WL) and UV-A enhanced fluorescent radiations. W-B treatment alon e reduced plant growth, pigment content, and photosynthetic activities . Supplementation of UV-A promoted the overall seedling growth and enh anced the synthesis of chlorophyll and carotenoids with a relatively h igh photosystem 1 activity. Post UV-B irradiation under WL failed to p hotoreactivate the UV-B damage whereas a positive photoregulatory effe ct of UV-A was noticed in electron transport rates and low temperature fluorescence emission spectra.