Agro-Climatological Studies on C3-Plants and C4-Plants
(3) Transpiration rates and leaf temperatures
1977 Volume 33 Issue 3 Pages 129-136
Details
1977 Volume 33 Issue 3 Pages 129-136
Transpiration rates, leaf temperatures and stomatal apertures in C3 plants (7 species) and C4 plants (19 species) were measured in a growth room maintained at an air temperature of about 36°C, a light intensity of 0.48ly/min, a windspeed of about 4m/sec, and a relative humidity of 80% (wet) or 40% (dry). The results obtained are as follows:
1) Transpiration rate
Under the dry condition, transpiration rates of C3 plants (5.17-3.09gH2O/100cm2/hr) were higher than those of C4 plants (2.83-0.94gH2O/100cm2/hr). Under the wet condition, transpiration rates of C3 plants (3.08-2.09gH2O/100cm2/hr) were also higher than those of C4 plants (2.21-0.64gH2O/100cm2/hr).
Under both dry and wet conditions, the mean transpiration rates of C4 plants were about half of those of C3 plants.
2) Leaf temperature
Under both dry and wet conditions, leaf temperatures of C3 plants were lower than those of C4 plants.
The temperature difference between leaf and air was correlated negatively with the transpiration rate.
3) Stomatal aperture
There was no difference in stomatal aperture between C3 plants and C4 plants. For both the plants the stomatal aperture under wet condition was larger than that under dry condition, except in the adaxial surface of goosegrass.
On the basis of the above results, a discussion is given on the difference in water requirements and geographical distributions between C3 plants and C4 plants.
