PLANT PHYSIOLOGY , Vol 113, Issue 3 961-965, Copyright © 1997 by American Society of Plant Biologists
|
WHOLE PLANT, ENVIRONMENTAL, AND STRESS PHYSIOLOGY |
Leaf Respiration in Light and Darkness (A Comparison of Slow- and Fast-Growing Poa Species)
O. K. Atkin, MHM. Westbeek, M. L. Cambridge, H. Lambers and T. L. Pons
Department of Plant Ecology and Evolutionary Biology, Utrecht University, P.O. Box 800.84, 3508 TB Utrecht, The Netherlands
We investigated whether leaf dark respiration (nonphotorespiratory
mitochondrial CO2 release) is inhibited by light in several Poa species,
and whether differences in light inhibition between the species are related
to differences in the rate of leaf net photosynthesis. Four lowland (Poa
annua L., Poa compressa L., Poa pratensis L., and Poa trivialis L.), one
subalpine (Poa alpina L.), and two alpine (Poa costiniana Vick. and Poa
fawcettiae Vick.) Poa species differing in whole plant relative growth
rates were grown under identical controlled conditions. Nonphotorespiratory
mitochondrial CO2 release in the light (Rd) was estimated according to the
Laisk method. Photosynthesis was measured at ambient CO2 partial pressure
(35 Pa) and 500 [mu]mol photons m-2 s-1. The rate of photosynthesis per
unit leaf mass was positively correlated with the relative growth rate,
with the slow-growing alpine Poa species exhibiting the lowest
photosynthetic rates. Rates of both Rd and respiration in darkness were
also substantially lower in the alpine species. Nonphotorespiratory CO2
release in darkness was higher than Rd in all species. However, despite
some variation between the species in the level of light inhibition of
respiration, no relationship was observed between the level of inhibition
and the rate of photosynthesis. Similarly, the level of inhibition was not
correlated with the relative growth rate. Our results support the
suggestion that rates of leaf respiration in the light are closely
associated with rates in darkness.
