Effects Of Growth And Photosynthesis Physiology And Water Metabolism Of Platycladus Orientalis And Amorpha Fruticosa Under Drought And Pb Stress

In order to reveal effect of drought stress, Pb stress and interaction sterss between thetwo on chlorophyll content, net photosynthetic rate, cell membrane permeability, leaf waterpotential and growth index of Platycladus orientalis and Amorpha fruticosa. The experimentselected one-year-old seedlings of Platycladus orientalis and Amorpha fruticosa, through thepot water control experiment determine under different water condition (the soil relative watercontent with40%,60%,80%and100%) and Pb stress (Pb content with0,1000,2000,4000,6000mg/kg) on chlorophyll content, net photosynthetic rate, cell membrane permeability, leafwater potential and growth index of Platycladus orientalis and Amorpha fruticosa. To studythe two trees on the adaptability of drought resistance and lead pollution and the resistantmechanism of growth status of plants under stress and plant under stress, To providetheoretical basis for vegetation restoration in arid and semiarid regions of heavy metal miningwaste. The main results as follow:1. The chlorophyll content of Amorpha fruticosa had no obvious regularity with waterstress, but the chlorophyll content of Platycladus orientalis decreased with the increasing ofwater stress. The chlorophyll content of Amorpha fruticosa firstly decreases and thenincreases trend with Pb stress increase, the chlorophyll content of Amorpha fruticosa achieveminimum value which is the control treatment72.23%under the soil relative water contentwith60%and soil lead content with4000mg/kg. The variation tendency of chlorophyllcontent of Platycladus orientalis has the same rule with the variation tendency of chlorophyllcontent of Amorpha fruticosa with Pb stress increase under the control treatment (the soilrelative water content with100%) and slight water stress treatment (the soil relative watercontent with80%), the chlorophyll content of Platycladus orientalis achieve minimum valuewhich is the control treatment17.21%under the soil relative water content with100%andsoil lead content with4000mg/kg, but the chlorophyll content of Platycladus orientalisdecreased with Pb stress increase under milt water stress treatment (the soil relative watercontent with60%) and severe water stress treatment (the soil relative water content with40%).2. The net photosynthetic rate of Amorpha fruticosa decreased with water stress, the net photosynthetic rate of Platycladus orientalis firstly increases and then decreases trend withwater stress increase. The net photosynthetic rate of Amorpha fruticosa firstly increases andthen decreases trend with Pb stress increase. The net photosynthetic rate of Amorpha fruticosaachieve maximum value which is control treatment117%under the soil relative water contentwith100%and soil lead content with2000mg/kg, and net photosynthetic rate of Amorphafruticosa achieve minimum value which is control treatment15%under the soil relative watercontent with40%and soil lead content with4000mg/kg. Different water stress condition ofnet photosynthetic rate of Platycladus orientalis had no obvious regularity with Pb stress.3. The water use efficiency of Amorpha fruticosa and Platycladus orientalis increasedwith the increasing of water stress. The water use efficiency of Amorpha fruticosa under thethree water stress had significant differences with the control treatment, and the water useefficiency of Amorpha fruticosa achieve maximum value which is control treatment202%under the soil relative water content with40%and soil lead content with4000mg/kg, thewater use efficiency of Platycladus orientalis only under the severe water stress treatment hadsignificant differences with the control treatment, the water use efficiency of Platycladusorientalis achieve maximum value which is control treatment293%under the soil relativewater content with40%and soil lead content with1000mg/kg. Different water stresscondition of water use efficiency of Amorpha fruticosa increased with the increasing of waterstress, and the water use efficiency of Platycladus orientalis had no obvious regularity withthe increasing of water stress.4. The electrical conductivity of Amorpha fruticosa and Platycladus orientalis increasedwith the increasing of water stress. Different water stress of electrical conductivity of Amorphafruticosa and Platycladus orientalis firstly decreases and then increases trend with Pb stressincrease, the electrical conductivity of Amorpha fruticosa achieve minimum value which iscontrol treatment88%under the soil relative water content with100%and soil lead contentwith4000mg/kg and the electrical conductivity of Platycladus orientalis achieve minimumvalue which is control treatment77%under the soil relative water content with100%and soillead content with1000mg/kg. the electrical conductivity of Amorpha fruticosa achievemaximum value which is control treatment171%under the soil relative water content with40%and soil lead content with0mg/kg, the electrical conductivity of Platycladus orientalisachieve minimum value which is control treatment175%under the soil relative water contentwith40%and soil lead content with6000mg/kg.5. The leaf water potential of Amorpha fruticosa and Platycladus orientalis decreasedwith the increasing of water stress. Different water stress of leaf water potential of Amorphafruticosa had no obvious regularity with Pb stress, the leaf water potential of Amorpha fruticosa achieve maximum value which compared with control treatment45.27%under thesoil relative water content with80%and soil lead content with2000mg/kg, the leaf waterpotential of Amorpha fruticosa achieve minimum value which compared with controltreatment855.22%under the soil relative water content with40%and soil lead content with6000mg/kg, the leaf water potential of Platycladus orientalis decreased with Pb stress, theleaf water potential of Platycladus orientalis achieve minimum value which compared withcontrol treatment424.78%under the soil relative water content with40%and soil leadcontent with6000mg/kg.6. Under the same conditions of soil Pb, the electrical conductivity of Amorpha fruticosaas the growth phase increased first and then decreased, the leaf water potential of Amorphafruticosa as the growth phase increased first and then decreased. Under the same conditions ofsoil Pb, the electrical conductivity and the leaf water potential of Platycladus orientalis as thegrowth phase increased.