Ov. Dymova et Tk. Golovko, LIGHT ADAPTATION OF PHOTOSYNTHETIC APPARATUS IN AJUGA-REPTANS L., A SHADE-TOLERANT PLANT AS AN EXAMPLE, Russian journal of plant physiology, 45(4), 1998, pp. 440-446
Characteristics of the photosynthetic apparatus of Ajuga reptans L, pl
ants grown under a forest canopy and in an open plot were examined. Sh
aded plants had leaves with lower weight per unit leaf area (2.5-fold
reduction) and 1.3 times higher chlorophyll content. The chlorophyll a
: b ratio varied within the limits of 2.2-2.8 and 2.5-3.2, with light
-harvesting complexes comprising 57-69 and 53-62% of the total chlorop
hyll, respectively. Leaves did not markedly differ in their maximum ph
otosynthetic rates (3-5 mg CO2/(dm(2) h)) and photosynthetic rates at
the intensity of radiation of adaptation (IRA) (1.8 mg CO2/(dm(2)/h)).
The IRA (5-10 W/m(2)) and light compensation point (1-3 W/m(2)) were
significantly lower in shaded plants. On the whole, morphological and
physiological characteristics of the photosynthetic apparatus varied w
ithin a rather narrow range, which characterizes Ajuga reptans as a sh
ade-tolerant plant. It is concluded that shade tolerance is a heredita
ry trait, and that plant viability under shade conditions slightly cor
relates with its ability to achieve high photosynthetic rates in light
.