Comparison Of Photosynthetic Characteristics For C₃,C₄ Plants And PEPC Transgenic Rice

In this research, we compared data of photosynthesis and characteristics of chlorophyll fluorescence between some C₃ and C₄ plants, and in different rice developmental stage, we also reviewed the data of photosynthesis, characteristics of chlorophyll fluorescence and the drought resistance of rice plant transformed PEPC gene. And the main result is list here:1. The photosynthetic ability and the efficiency of water application of C₄ plants is obviously better than that of C₃ plants, it is mainly due to the difference of their CO₂ assimilative capacity, and the increasing of stomatal conductance also positive to the increasing of photosynthetic ability.2. Under low light intensity, there is no difference of photosynthetic rate and efficiency of photons between C₃ and C₄ plants. When we increased the light intensity C₄ plants exhibited its superiority. Besides, the stoma of C₃ plant is more sensitive to the low light intensity than that of C₄ plants. We can conclude that C₃ and C₄ plants are different in adaptability of photo-ecology.3. The PS II photochemical efficiency of C₄ plants was obviously lower than that of C₃ plants. In all-day long, the Fv/Fm, ΦPSH and ETR of C₃ plants were higher than that of C₄ plants notably, it was based on the high PS II activity and high efficiency of energy conversion and energy transmission. The photochemical quenching value of C₃ and C₄ plants differs little, while the none photochemical quenching of C₄ plant was 36%⁶7% higher than that of C₃ plant, it has a good heat dissipation.4. The photosynthetic rate of the rice plant transformed with maize PEPC gene was 24.6% higher than that of wild type during the whole filling stage, it indicated PEPC gene was positive to elongate the photosynthetic function duration and delay the senescence of leaves. The WUE value of rice with PEPC gene was higher than control at any phase, especially the plants with a integrity PEPC gene, its WUE value of florescence was higher than wild type during all the day. While under xeric condition, the WUE value of certain individual plants was obviously higher than control. It represented that PEPC gene had latency effect to improve the drought resistance of C₄ plants.5. The photosynthetic rate of rice reached the maximum at tillering stage, and the decline of photosynthetic rate during florescence mainly due to the obviously descend of stomatal conductance. The physiological asthenia of photosynthetic organ, the decline of CO₂ assimilative capacity and the decline of stomatal conductance together weakened the photosynthetic rate.