Effects Of Heavy Metal Pb Treatment To Salix Babylonica Cuttings’ Photosynthesis Function

With this study, we have investigated the growth and photosynthesis effects of weeping willows under the influence of heavy metal contaminated soil. Cutting seedlings of weeping willow were germinated with soils that were processed with various heavy metal (Pb(NO3)2 concentrations i.e. (0、50、 200、 400、 8OOmg·kg-1. The result included the maximum net photosynthesis rate, unit mass nitrogen percentage, specific leaf weight and Nitrogen difference distribution due to the photosynthesis.1 Under Pb stress, the cutting seedlings of male and female weeping willow under different concentrations of nitrogen content processing unit mass (NM) have shown a decrease in the beginning and an increase towards the end, With only male weeping willow control group and female weeping willow group 50mg·kg-1 revealing statistical significances, none have been noticed significant under 200、400、800mg·kg-1 heavy metal concentrations.2 Under Pb stress, the chlorophyll concentration (Cc) of male and female weeping willow has exhibited a parabola curve where the Cc has risen up in the first half and has declined in the other half. The maximum peak has reached upon 50mg·kg-1. Nevertheless, little significances were addressed under all concentrations of male and female weeping willow in polluted soils.3 At low concentrations of heavy metal stress, the cuttings seedling of male and female weeping willow allocate more nitrogen to the leaf photosynthetic carboxylation system (PC), enhances its ability of CO2 fixation (Vcmax), and improve the photosynthetic capacity under stress (Pmax), thereby reduce the adverse effects of Pb stress.4 In high concentrations of heavy metals stress, the cuttings seedling of male and female weeping willow allocate more leaf nitrogen to biological energetics component (PB), and reduce the allocation to photosynthetic carboxylation system (PC) and light-harvesting component (PL) nitrogen, therefore, preserving the photosynthesis function in unwanted situations.5 At different concentrations of heavy metal stress, the cuttings seedling of male weeping willow’s all enlisted measurants, i.e. (maximum net photosynthetic rate Pmax, the utilization efficiency of nitrogen PNUE, leaf nitrogen distribution throughout the photosynthetic mechanism of photosynthesis PT and other relevant indicators) except for unit mass nitrogen content (NM), overweighed female cuttings, which indicated that male cuttings have possessed a stronger resistance against the environmental changes. However, stability among the male cuttings was less than that of famale cuttings, meaning the difference between individuals was rather large.