Photosynthesis in Polygonum reynoutria L. ssp. asiatica Grown at Different Altitudes

A relation between environmental conditions and photosynthetic ability was investigated with Polygonum reynoutria L. ssp. asiatica growing in various conditions. The optimum and the maximum temperatures for photosynthesis in the plants under field conditions varied seasonally with the variation of air-temperature. Both temperatures were located on much lower level with the plants grown at high elevation. In their seedlings cultured under an artificial controlled condition, the optimum temperature differed to every seed-source which was different in environmental temperature. The optimum temperature had a wide range in the plants grown natively at low elevation, and had a narrow range in those grown natively at high elevation. The width of the range was narrowed by transplantation into high elevation from low one, and was similar to that of the range in the native plants in the habitat into which the plants were transplanted. The width, however, was never changed by transplantation into low elevation from high one. The optimum and the maximum temperatures for photosynthesis may be genotypically decided, although both temperatures showed a variance with the seasonal variation of air-temperature. Such plasticity on both temperatures for photosynthesis seems to be larger in the plants grown natively at low elevation than ones grown natively at high elevation.Article信州大学理学部紀要 10(1): 27-34(1975)departmental bulletin pape