Effect of red and far-red light on inhibition of hypocotyl elongation in ecotypes of Betula pendula Roth

Abstract

Plants sense the quality, quantity, and duration of light signals and use them to optimise their growth and development. These signals are perceived by special light receptors of which the phytochrome pigment system is one of the most important for photomorphogenetic responses. Using special diodes that emit monochromatic light, we studied the effect of red (R), far-red (FR) and R+FR combinations on hypocotyl elongation of latitudinal ecotypes of Betula pendula. Continuous R and FR inhibited hypocotyl elongation equally, but inhibition was higher when seedlings were irradiated by continuous R+FR. In all cases, inhibition increased with increasing irradiance, from 0.75 μmol m^-2 s^-1 to 76 μmol m^-2 s^-1. Moreover, seedlings treated by R or R+FR synthesised more anthocyanins than those exposed to FR. Accumulation of anthocynins increased with increasing irradiance up to about 19 μmol m^-2 s^-1.

Key Words: Anthocyanin, diode, ecotype, monochromatic, photomorphogenesis, photosynthetically active radiation, skotomorphogenesis.

African Journal of Biotechnology Vol.4(1) 2005: 50-56