Leaf stomatal response to blue light and CO2 concentration in six fern species
Date Issued
2015
Date
2015
Author(s)
Huang, Yi-Ching
Abstract
Stomata, pores for gas exchange between leaves and atmosphere, are surrounded by a pair of guard cells. The evolution of stomata is an important adaptation for plants to live on land. It is well known that environmental factors, such as light and CO2 concentration ([CO2]), can affect stomatal openness in angiosperms. Recently, stomata of ferns were found less sensitive to the environmental factors. However, previous studies showed that stomatal response in Marsilea crenata (a fern species) is similar to that in angiosperms. To know whether stomata of other ferns also react the same or not, I measured some leaf characteristics, stomatal distribution and stomatal response of Cibotium taiwanense, Cyathea lepifera, Adiantum capillus-veneris, Vittaria anguste-elongata, Woodwardia prolifera, Asplenium australasicum, six fern species belonging to different clades and distributed in habitats with diffent light regimes. I transplanted field growing plants and grew them in a greenhouse. After they have established, I measured stomatal morphology and leaf characteristics of these plants and stomatal conductance (gs, a measurement of stomatal openness) when leaves were under the condition of 50 μmol m-2 s-1 blue light superimposed onto the red light and under different [CO2] (100, 400, 600 ppm). I also compared gs of the same species grown under different light intensity. The six ferns have stomata only on abaxial surface. Stomatal density (11.7 ~ 259.9 mm-2) of leaves follows: C. lepifera = C. taiwanense > W. prolifera > A. capillus-veneris = V. anguste-elongata = A. australasicum. Stable carbon isotope analysis revealed that these six ferns are C3 plants, and A. australasicum has the highest water use efficiency while V. anguste-elongata the lowest among the six ferns. Stomata of these six ferns didn’t response further under the condition of superimposed blue light onto the red light indicating no blue-light specific response. In comparison to gs at 400 ppm of [CO2], gs of the six species showed three different degrees of change in response, which indicates that their stomata have different sensitity to changes in [CO2]. Stomatal conductance of same species grown under two light intensity have greater difference in low [CO2] (100 ppm). In conclusion, the stomata of the six fern species showed different degree of response in three [CO2] which did not follow their evolutionary order. The light intensity of their habitats may have an effect on their stomatal response.
Subjects
Fern, stomatal response, blue-light specific response, CO2 concentration, gas exchange
Type
thesis
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