Author:
Higgins Stewart S.,Black R. Alan,Radamaker Gary K.,Bidlake William R.
Abstract
Photosynthetic, transpirational, and stomatal responses to light, temperature, humidity, and plant moisture stress were measured for greenhouse-grown seedlings of Larixoccidentalis Nutt. Light saturation was 550 μmol photons•m−2•s−1; light and CO2 compensation points were 26 μmol photons•m−2•s−1 and 59 μL CO2•L−1, respectively. Light-saturated photosynthetic rate was over 7 μmol CO2•m−2•s−1 with a temperature optimum between 18 and 23 °C. Photosynthesis, transpiration, and stomatal conductance to water vapor declined as xylem pressure potential decreased from −1.5 to less than −2.5 MPa; above −1.5 MPa no effect was observed. Stomatal conductance declined with increasing leaf to air vapor density difference. Stomatal conductance increased with increasing irradiance. Nighttime stomatal conductance was about 50% of the daytime maximum conductance regardless of xylem pressure potential. When plants were well watered, the ratio of xylem pressure potential to transpiration (XPP/E) decreased by 1.5 × 10−3 MPa•(μg H2O•cm−2•s−1)−1 with each mg H2O•cm−2 that had been transpired. After 7 days of drought, however, XPP/E decreased at 7.9 × 10−3 MPa•(μg H2O•cm−2•s−1)−1 per mg H2O•cm−2. These characteristics are compared with other conifers and are used to suggest differences between growth patterns of L. occidentalis and sympatric species.
Publisher
Canadian Science Publishing
Subject
Ecology,Forestry,Global and Planetary Change
Cited by
13 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献