EFFECT OF SUPPLEMENTAL UV-B RADIATION ON GERMINATION, SEEDLING GROWTH, AND BIOCHEMICAL RESPONSES OF SUNFLOWER (HELIANTHUS ANNUUS L.)
This investigation attempts to examine the effect of UV-B radiation on germination, seedling growth, chlorophyll a and b content, soluble phenol, anthocyanin and flavonoid contents of sunflower (Helianthus annuus L.). Final germination percentage was significantly reduced but germination velocity was enhanced. Chlorophylls a and b and total Chlophyll a+b content declined significantly in response to UV-B exposure. However, chlorophyll a/b ratio was substantially increased. Marked accumulation of soluble phenol was observed as a result of UV-stress. Anthocyanin and flavonoids were increased in response to UV-B radiation as they provide a protective mechanism to UV-radiations. These results are discussed in the light of the mode of action of UV-B radiation.