Abstract:

In order to truly appraise photosynthetic productivity of plain, the response of photosynthetic rate of Stipa grandis, Agropyron cristatum and Lutmus chinensis to light intensity and CO2 concentration was studied using Li-6400 in Inter Mongol China plain. Generally, photosynthetic rate of 3 grass species increases with light intensity (PPFD) or CO2 concentration, which can be expressed by Michaelis-Menten function. Photosynthetic parameters included apparent quantum yield, apparent carboxylation efficiency, light compensation point, light saturation point, CO2 compensation point, CO2 saturation point, dark respiration rate, photorespiration rate and maximum photosynthetic rate, which were calculated from those Michaelis-Menten functions, and were found to differ significantly among different species. Stipa grandis may possess high photosynthetic productivity as they displayed higher apparent quantum yield, maximum photosynthetic rate, CO2 saturation point and lower CO2 compensation point, compared with the other species. While, Lutmus chinensis possess high RuBPCase activity as they displayed higher apparent carboxylation efficiency.