The Growth Adaptability Evaluation Of Different Group Of Salix Viminalis In Beijing Area And It’s Physiological Response To Cd²⁺ Stress

With the rapid development of economy, environment pollution problem is increasingly serious,as the priority pollutant of "pollution ecology" or "ecological environmental protection",heavy metal pollution has become an important problem that seriously restrict the sustainable development of human society. As the representative of the heavy metal pollution of cadmium because of strong mobility, high pollution, toxic characteristics especially huge damage to the environment. Depend on the control of soil heavy metal pollution of plants repair technology because of its simple, friendly to the environment without side effects and low cost advantages, such as more and more get the welcome of people.The salix viminalis has Large quantities of biomass, short rotation period, update propagation capability is strong, is the environment purification, ecological restoration, the biomass production potential of tree species.To speed up the germplasm screening and promotion of the salix viminalis in Beijing aera,the research group collected the salix viminalis clones back to Beijing from Moerdaoga、Yakeshi 、 Chifeng this three areas to field training.based on this, the good adaptability evaluation of a certain group of salix viminalis clones were subjected to Cd2+ stress.expounding salix viminalis on the physiological response of Cd2+, so as to the heavy metal pollution in Beijing area and providing a reference for the application of phytoremediation. The main results were as follows:1. Make the growth adaptability evaluation in the three populations of salix viminalis where is in south field, from eleven aspects in the growth of leaf length, leaf width, number of branches, branch length and plant height, branching angle, yellow leaf number, leaf number, and leaf scorch, branch diameter, SPAD, winter survival rate of the growth in Beijing area. Survey results show that Moerdaoga, Yakeshi clones growing poor population,the yellow leaves is in large proportion with leaving early, Chifeng populations grow faster, until midNovember, does not appear dead leaves, fallen leaves phenomenon,adapted to the phenological conditions in Beijing area.2. Choicing Chifeng group as the research object, to the heavy metals Cd2+ stress of salix viminalis clones, Treatment with Cd2+ concentration is set to 0, 50 umol/L, Cd2+ by Cd Cl2 ist 2.5H2O(pure), whole Hoagland nutrient solution preparation.In stress after 6, 12, 18, 24 d when measured in chifeng group of salix viminalis clones leaf gas exchange parameters and fluorescence parameters, Meanwhile in 6d, 12 d, 18 d, 24 d, 30 d,taking fully expanded function leaves of 12 clones of each treatmen which is measured in various physiological indices Under the condition of Cd2+ stress, leaf SOD activity, Pro activity were higher than control, CAT activity and MDA content showed a trend of decline after rising first;Processing of chifeng group of salix viminalis clones in leaf net photosynthetic rate, stomatal conductance were significantly lower than control, intercellular CO2 concentration increased after lower first;Processing of chifeng in salix viminalis clones leaf transpiration rate(Pn) in the treatment of 6, 12, 18, 24 d after compared to drop;Processing plant under the light of maximum fluorescence after 6d significantly lower than control;Biggest fluorescence in 6d, 12 d increases significantly than control, and after 18 d, 24 d decreased significantly than control;The minimum initial fluorescence at 24 d decreased significantly than control;The actual photochemical efficiency decreased significantly than control;Blade photochemical quenching coefficient in 18 d, 24 d decreased significantly than control;Non photochemical quenching coefficient rise after fall first.The content of Cd in salix viminalis bottom-up from the roots to the leaves in descending order,as root >stem > leaf; The transfer coefficient of Cd of stems is larger than that of leaves in the aboveground organs of salix viminalis;The roots,stems and leaves of Chifeng salix viminalis clones’ Cd accumulation factor is greater than 1,among them the root system of salix viminalis clones have the strongest enrichment ability of Cd.The above conclusions provide the reference basis for the screening of different populations of salix viminalis and application of heavy metal pollution phytoremediation in Beijing area.