[Responses of different Vicia faba varieties' photosynthetic characteristics to Pb pollution]

In a field experiment of simulated Pb pollution (40 and 250 mg x kg(-1)), this paper investigated the net photosynthetic rate, stomal conductance, transpiration rate, intercellular CO2 concentration, water use efficiency, and chlorophyll content of three Vicia faba varieties K0883, K0502 and K0697. The results showed that under Pb pollution, there was no significant variation in the transpiration rate and stomal conductance of the three varieties, but their chlorophyll content increased in different extents. When the Pb concentration was 250 mg x kg(-1), the net photosynthetic rate and water use efficiency of K0883 were increased by 121.80% and 193.70%, respectively, while its intercellular CO2 concentration was decreased by 42.76%. According to the Perturbation test based on the responses of test photosynthetic characteristics, the Pb-resistance of the three varieties was in the sequence of K0883 > K0697 > K0502. It was concluded that the responses of different photosynthetic indexes and different Vicia faba varieties to small dosage Pb pollution were differed, and the intraspecific difference could only be detected by the integration of all photosynthetic indices.