Dark Respiration Rates and Their Relationships with Photosynthesis Rates and Chemical Components in Mountain Birch (Betula pubescens Ehrh.), Elm (Ulmus glabra var. scabra Huds.), and Maple (Acer plataniodes L.) Leaves

1993

26 S.

zahlr. Lit. Ang.

Bandaufführung

82062

Measurements of net photosynthesis and dark respiration rates were carried out on exicised leaf discs by Warburg manometric technique. The sample plants had been grown for six weeks in varying temperature in continuous light. Photosynthesis rates were also measured at elevated CO2 level. The relationship between gas exchange rates and chemical components was studied by multiple regression analysis. In accordance with earlier studies a strong acclimation effect of temperature was found. Long- term low-temperature treatment caused a reduction in photosynthetic rates in all mountain birch populations, and increased respiration rates in the two broadleaf species. There was a strong reduction in the temperature coefficient of dark respiration with decreasing acclimation temperatures in mountain birch leaves from southern populations. There was also a relatively high soluble sugar content and low chlorophyll content in low-temperature treated plants. Mountain birch from 62Grad N latitude showed relatively high net photosynthetic rates compared with the populations from 60Grad N, and higher chlorophyll content per unit area.