STOMATAL-RESISTANCE AND THE RATIO OF INTERCELLULAR TO AMBIENT CARBON-DIOXIDE IN CONTAINER-GROWN YELLOW-POPLAR SEEDLINGS EXPOSED TO CHRONIC OZONE FUMIGATION AND WATER-STRESS
Wn. Cannon et Br. Roberts, STOMATAL-RESISTANCE AND THE RATIO OF INTERCELLULAR TO AMBIENT CARBON-DIOXIDE IN CONTAINER-GROWN YELLOW-POPLAR SEEDLINGS EXPOSED TO CHRONIC OZONE FUMIGATION AND WATER-STRESS, Environmental and experimental botany, 35(2), 1995, pp. 161-165
One-year old container-grown seedlings of yellow-poplar (Liriodendron
tulipifera L.) were exposed to 0.15 ppm ozone (O3) fumigation and wate
r stress (two 1-week drying cycles) in continuously stirred tank react
ors prior to measuring stomatal resistance (R(s)), intercellular carbo
n dioxide [CO2 (C(i))], and the ratio of C(i) and ambient CO2 (C(a)) a
fter 20 and 36 days. Water stress increased R(s) by more than 250% and
reduced C(i) and the C(i)/C(a) ratio by just over 20%. There were no
significant effects of 0.15 ppm O3 on C(i) and the C(i)/C(a) ratio but
R(s) was significantly increased by the interaction of water stress a
nd O3 fumigation. For water-stressed seedlings fumigated with charcoal
-filtered air, C(i) and the C(i)/C(a) ratio were significantly lower t
han those of the other treatments. The data show that interactions inv
olving low levels of ozone and short periods of water stress may have
a substantial influence on stomatal physiology.