This study examines the effect of supplemental UV-B radiation and allelochemical stress alone and in combination on growth and biochemical responses of cowpea (Vigna unguiculata). UV-B irradiation alone (20-40 min. exposure) suppressed the final percentage germination as well as speed of germination. Both root and shoot growth of cowpea were also retarded. The effect of allelopathy was tested using the allelochemical gallic acid which at 40-80ppm inhibited final germination percentage as well as speed of germination, but root and shoot growth were reduced at 20-40ppm concentrations.. Greater final germination percentage and speed of germination were reduced when both allelochemical and UV-B irradiation were applied together. Likewise, root and shoot growth in the combined stress were suppressed to a greater extent compared to the influence of either stress applied alone. UV-B alone or in combination with gallic acid treatment resulted in accumulation of total soluble phenols and greater accumulation was observed in the combined stress. Likewise, phenyl ammonia lyase (PAL) and tyrosine ammonia lyase (TAL) activities were remarkably increased when both the stresses were applied simultaneously compared to UV-B stress alone. The implications and mechanisms of biochemical responses to UV-B and allelopathy together are discussed.
S. Shahid Shaukat, Sahar Zaidi, Moazzam Ali Khan. (2013) COMBINED EFFECT OF UV-B RADIATION AND ALLELOPATHY ON GERMINATION, SEEDLING GROWTH AND PHYSIOLOGICAL RESPONSES OF VIGNA UNGUICULATA (L.) WALP., , Volume 10, Issue 3.
