Effects Of Lead Nitrate On Growth And Physiology Charactors Of Podocarpus Nagi Seeding

In this study,pot experiment using Podocarpus nagi 2-year-old seedlings,different concentrations of heavy metals lead nitrate solution Podocarpus nagi seedling growth characteristics under stress,physiological characteristics and lead accumulation in different organs Podocarpus nagi seedlings.The results showed that:1.At low concentrations(?300mg/kg)lead nitrate solution stress,lead nitrate solution have a great role in promoting the growth potential of Podocarpus nagi seedlings,as the concentration increases.The height and diameter increment of Podocarpus nagi seedlings showed a rising trend.When the concentrations exceeding 400mg/kg,the lead nitrate solution stress on plant growth and play an inhibitory effect,height increment Podocarpus nagi seedlings decline diameter increment appears.Comprehensive comparison,was born of growing strength:T3>T2>T1>CK>T4>T5>T6>T7>T8.The results of length and number of roots statistical analysis told us that as the lead nitrate concentration increases,the length and number of roots downward trend,heavy metals lead nitrate solution on the plant roots causing injury.The results of seedling quality index showed that in the concentration range of 0 to 300mg/kg had no significant difference between them.When the concentration exceeds 300mg/kg,Pb resulted nhibition effect on the seedling growth,and Pb significantly reduced the seedling quality of Podocarpus Nagi seedlings.2.Under Pb stress the seedling show significantly positive correlation between cell membrane permeability,MDA and lead nitrate concentration.Lead caused the damage in leaves cell membrane of Podocarpus nagi,so that the cell membrane permeability increased,MDA as a plant cell membrane lipid peroxidation product,but also with lead nitrate solution concentration increases.Soluble protein in plant cells as a major osmotic adjustment,as the concentration increases,the soluble protein content seedlings display increased at first and then decreased.When in 300mg/kg concentrations,the soluble protein showed the highest content.When concentrations exceed 400mg/kg,the soluble proteins showed a downward trend.3.Under different concentrations of lead nitrate solution stress Podocarpus nagi Leaves of SOD,CAT and POD activity of three enzymes were treated with increasing at first and then decreased.The peak of SOD,CAT activity appears in the 300mg/kg concentration,and the peak of POD activity peak appears at 500mg/kg concentrations.In low concentration of stress,antioxidant enzyme systems have ability to clean the cell body of reactive oxygen species has been improved.At high concentrations,Pb on Podocarpus nagi membrane lipid peroxidation enhanced blade,which results in a large amount of active oxygen free radicals and damages cell structure,and it will affect the growth and development of plants.4.Low concentrations of lead nitrate solution stress can promote chlorophyll content of Podocarpus nagi seedlings.When the concentration exceeds 300mg/kg,the synthesis of chlorophyll has been hampered.Photosynthetic parameters between different treatment plants was measured,including photosynthetic rate,stomatal conductance,intercellular C02,transpiration rate,which have similar trend of chlorophyll content.5.By researching the lead content of each part of the organ Podocarpus nagi seedlings under different concentrations of lead nitrate solution,the order as follow:root>stem>leaf.The result tell us that root absorption of lead ions remain in most of the roots,then transport to the supreme less stem and leaf portions,thus low concentrations of lead nitrate solution,the amount of lead ions in the stem portion of the accumulation is insufficient on stem cell damage,the plant can still be normal photosynthesis and metabolism.When lead ions in the roots accumulated to a certain amount,more than patience root,root damage will also influence the upward transport of nutrients,and thus harm the plant.6.The height and diameter increment,root length,root number,seedling quality index,cell membrane permeability,MDA content and antioxidant enzyme activity content and soluble protein content and other physiological and biochemical indexes,can be considered in the lead content of 300mg/kg Podocarpus nagi soil or less able to grow well.Therefore,Podocarpus nagi can be used as green trees in industrial zones,and it also can effectively repair the polution soil.