© 1995 Heron Publishing—Victoria, Canada
Water relations, gas exchange and growth of dominant and suppressed shoots of Arbutus unedo L.
Carles Castell and Jaume Terradas
Centre de Recerca Ecològica i Aplicacions Forestals, Facultat de Ciències, Universitat Autònoma de Barcelona, 08193 Bellaterra,
Spain / Received October 19, 1993
Summary
Basal shoots produced by Arbutus unedo L. after cutting at ground level vary in size and growth rate, and are classified accordingly as dominant or suppressed.
The suppressed shoots eventually cease growth and die. In this study, we investigated the role of light and water in the competition
among shoots of A. unedo.
Dominant and suppressed shoots of A. unedo showed similar leaf water potentials and tissue water relations over the year, suggesting that water status is not responsible
for the lack of flushing in suppressed shoots. Although suppressed shoots did not flush under low light, they showed many
characteristics of shade-tolerant plants. Leaves of suppressed shoots had lower leaf conductance and light-saturated photosynthetic
rate, and higher specific leaf area than leaves of dominant shoots. We conclude that light was the main resource determining
competition among shoots and the death of suppressed shoots.
Keywords:
competition, growth rate, irradiance, leaf conductance, leaf water potential.
