ISSN 2736-1756
Advanced Journal of Microbiology Research Vol. 2005
Available online at http://internationalscholarsjournals.org/journal/ajmr
© 2005 International Scholars Journals
Full Length Research Paper
Effect of red and far-red light on inhibition of hypocotyl elongation in ecotypes of Betula pendula Roth
Berhanu A. Tsegay1*, Jorunn E. Olsen2, and Olavi Juntttila3
1Department of Biology, Bahir Dar University, Ethiopia.
2Dept. of Biology and Nature Conservation, Agricultural University of Norway, N-1430 Ås.
3Department of Biology, University of Tromso, Norway.
Accepted 10 August, 2004
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.