Link S O, Nash T H
Department of Botany and Microbiology, Arizona State University, 85287, Tempe, AZ, USA.
Oecologia. 1984 Oct;64(2):204-210. doi: 10.1007/BF00376872.
Net photosynthetic rates for the lichen Parmelia praesignis Nyl. were obtained as a function of 5 light levels, 5 temperature levels, and of water content as thalli dried from saturated conditions. Data are described as second order polynomials in the light, and as saturation curves in the dark. Rates in the light were depressed at high water contents reaching maximal rates between 110% and 180% water content and declining as thalli dried. Physiological parameters were derived from the drying curves to investigate temperature and light interactions. Dark respiration parameters are the maximal rate, the water content where the rate is half-maximal, the water content at which respiration is zero, and the maximal water efficiency. In the light, parameters are the maximal net photosynthetic rate, the water content at the maximal rate, the water compensation point, the maximal water efficiency, and the sensitivity of net photosynthesis to change in water content.Values of half-maximal rate water contents for respiration were found to increase as temperatures increased. The greatest maximal net photosynthetic rate occurred at higher temperatures as the light intensity increased. In the light, maximal water efficiency and the sensitivity to changes in water content were generally maximal at temperatures yielding the greatest maximal net photosynthetic rates.
对地衣Parmelia praesignis Nyl. 的净光合速率进行了测定，该速率是5个光照水平、5个温度水平以及地衣从饱和状态干燥时的含水量的函数。数据被描述为光照下的二阶多项式以及黑暗中的饱和曲线。在高含水量时，光照下的光合速率会降低，在含水量为110%至180%之间达到最大光合速率，并随着地衣干燥而下降。从干燥曲线中得出生理参数，以研究温度和光照的相互作用。黑暗呼吸参数包括最大呼吸速率、呼吸速率为最大呼吸速率一半时的含水量、呼吸为零时的含水量以及最大水分利用效率。在光照下，参数包括最大净光合速率、最大光合速率时的含水量、水分补偿点、最大水分利用效率以及净光合作用对含水量变化的敏感性。发现呼吸速率为最大呼吸速率一半时的含水量值会随着温度升高而增加。随着光照强度增加，最大净光合速率在较高温度下出现。在光照下，最大水分利用效率以及对含水量变化的敏感性通常在产生最大净光合速率的温度下达到最大值。
