不同基因型杨树对Cd的耐受性差异研究

Selection of poplar species with greater Cd tolerance and exploiting the physiological mechanisms involved in Cd tolerance are crucial for application of these species to phyto-remediation. The aim of this study is to investigate variation in Cd tolerance among the seven poplar species. Cuttings of seven poplar species were cultivated for 10 weeks before exposure to either 0 or 200 μM CdSO4 for 20 days. Gas exchange in mature leaves was determined by a portable photosynthesis system. Cd concentrations in tissues were analyzed by a flame atomic absorbance spectrometry. Subsequently, Cd amount per plant, bio-concentration factor (BCF) and translocation factor (Tf) were calculated. Cd exposure caused decline in photosynthesis in five poplar species. Among the seven species, P. × canescens displayed the highest Cd concentrations, the largest Cd amount and the highest BCF in aerial parts, and Tf under Cd exposure. Under Cd stress, increases in total soluble sugars in bark and leaves, and increases in starch in roots and leaves of P. × canescens were found. Based on results of this pot experiment, it is concluded that P. × canescens is more tolerance to Cd and superior to other six species for Cd phyto-remediation.