African Journal of Biotechnology
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African Journal of Biotechnology Vol. 4 (1), pp. 50-56, January 2005 ISSN 1684–5315 © 2004 Academic Journals
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 Ĺs. 3Department of Biology, University of
Tromso, Norway. *Corresponding author. E-Mail:
berhanutsegay@yahoo.com. Accepted 10 August, 2004 |
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| Abstract | |||||
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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.
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