R. Villar et al., DARK LEAF RESPIRATION IN LIGHT AND DARKNESS OF AN EVERGREEN AND A DECIDUOUS PLANT-SPECIES, Plant physiology, 107(2), 1995, pp. 421-427
Dark respiration in light as well as in dark was estimated for attache
d leaves of an evergreen (Heteromeles arbutifolia Ait.) and a deciduou
s (Lepechinia fragans Greene) shrub species using an open gas-exchange
system. Dark respiration in light was estimated by the Laisk method.
Respiration rates in the dark were always higher than in the light, in
dicating that light inhibited respiration in both species. The rates o
f respiration in the dark were higher in the leaves of the deciduous s
pecies than in the evergreen species. However, there were no significa
nt differences in respiration rates in light between the species. Thus
, the degree of inhibition of respiration by light was greater in the
deciduous species (62%) than in the evergreen species (51%). Respirati
on in both the light and darkness decreased with increasing leaf age.
However, because respiration in the light decreased faster with leaf a
ge than respiration in darkness, the degree of inhibition of respirati
on by light increased with leaf age (from 36% in the youngest leaves t
o 81% in the mature leaves). This suggests that the rate of dark respi
ration in the light is related to the rate of biosynthetic processes.
Dark respiration in the light decreased with increasing light intensit
y. Respiration both in the light and in the dark was dependent on leaf
temperature. We concluded that respiration in light and respiration i
n darkness are tightly coupled, with variation in respiration in darkn
ess accounting for more than 60% of the variation in respiration in li
ght. Care must be taken when the relation between respiration in light
and respiration in darkness is studied, because the relation varies w
ith species, leaf age, and light intensity.