C. Castell et J. Terradas, WATER RELATIONS, GAS-EXCHANGE AND GROWTH OF DOMINANT AND SUPPRESSED SHOOTS OF ARBUTUS-UNEDO L, Tree physiology, 15(6), 1995, pp. 405-409
Basal shoots produced by Arbutus unedo L. after cutting at ground leve
l vary in size and growth rate, and are classified accordingly as domi
nant 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 rela
tions over the year, suggesting that water status is not responsible f
or the lack of flushing in suppressed shoots. Although suppressed shoo
ts did not flush under low light, they showed many characteristics of
shade-tolerant plants. Leaves of suppressed shoots had lower leaf cond
uctance and light-saturated photosynthetic rate, and higher specific l
eaf area than leaves of dominant shoots. We conclude that light was th
e main resource determining competition among shoots and the death of
suppressed shoots.