[Effect of root-zone CO2 enrichment on tomato photosynthetic physiology]

The root system of tomato plant (Lycopersicon esculentum L. cv. Liaoyuanduoli) was treated with CO2 enrichment by aeroponical culture for 60 days. The experiment showed that the chlorophyll content and leaf area of tomato plant were significantly lower under 2500 µL . L-1 or above CO2 condition of root zones than under 370 µL . L-1 CO2 condition. At the same time the Ca2+-ATPase, Mg2+ -ATPase and phosphoenolpyruvate carboxylase (PEPC) of plant leaf were significantly reduced while the PEPC of root increased significantly, which resulted in the significant decreases of net photosynthetic rate, stomatal conductance and intercellular CO2 concentration of plant leaves. The results indicated that under a long-term root-zone CO2 enrichment condition, the decline of photosynthetic physiological parameters of tomato leaf maybe mainly result from the increased PEPC of root, and the decreased CO2 fixation, Mg2+-ATPase and Ca2+-ATPase of leaves.