Effect Of Exogenous Sodium Silicate On Lead Stress In Castanopsis Hystrix Miq.seedlings

Lead pollution in soil is very common in China.Lead pollution in soil can lead to plant growth restriction and even death.Lead is easily accumulated in plants,especially in roots.Castanopsis hystrix Miq.is a valuable and high quality native wood and green tree species in southern China.It is a good wood and landscape protection tree species,and has excellent ornamental effect and greening effect.Its root system is easy to absorb environmental pollutants,affecting plant growth.In view of this,the photosynthesis,growth,physiology and lead content of Castanopsis hystrix Miq.seedlings under lead stress were investigated,and the effect of adding exogenous sodium silicate on alleviating Castanopsis hystrix Miq.seedlings under lead stress was also investigated.In the experiment,1.5-year Castanopsis hystrix Miq.seedlings with little difference and basically the same growth condition were selected as the test trees,with each pot containing 7kg of dry soil.Lead by lead acetate?CHCOO?₂Pb·3H₂O)solution,silicon was added in the form of sodium silicate solution?Na₂Sio₃?,set up four Pb concentrations?0,250,500,750 mg/kg?,three silicon concentrations?0,1000,2000 mg/kg?,a total of 12,7 repeat each processing,by recording the Castanopsis hystrix Miq.growth,physiological and photosynthetic indexes and determination of lead content in plants and soil PH and other indicators,come to the conclusion as follows:1.Different concentrations of lead would affect the growth and development of Castanopsis hystrix Miq.seedlings.The test results showed that the application of lead concentration of 250mg/kg could promote the growth of Castanopsis hystrix Miq.seedlings,but with the increase of lead concentration,the relative plant height,ground diameter growth,biomass and root development of Castanopsis hystrix Miq.seedlings decreased.2.Low concentration of Na₂Sio₃?1000mg/kg?can alleviate the toxic effect of lead stress on Castanopsis hystrix Miq.and promote the growth of Castanopsis hystrix Miq.seedlings.Under the same concentration of lead,low concentration of lead increased the plant height,ground diameter,biomass and other indicators of Castanopsis hystrix Miq.seedlings,while high concentration of Na₂Sio₃?2000mg/kg?can inhibit or even damage the growth and development of Castanopsis hystrix Miq.seedlings.3.When the lead concentration is 250mg/kg,it can promote the physiology of Castanopsis hystrix Miq.seedlings,while when the lead concentration is 500mg/kg and 750mg/kg,it can inhibit the physiology of Castanopsis hystrix Miq.seedlings.application of1000mg/kg Na₂Sio₃ can improve POD,CAT activity,photosynthetic pigment,soluble sugar,soluble protein and other indicators in Castanopsis hystrix Miq.seedlings,and reduce SOD activity,MDA content,conductivity and lead content in various organs of plants.4.High concentration of Na₂Sio₃?2000 mg/kg?can poison and inhibit the physiology of Castanopsis hystrix Miq.seedlings,reduce POD and CAT activity,increase the permeability of plant cell membrane,destroy the photosynthetic system of seedling leaves,increase the content of lead in all organs of Castanopsis hystrix Miq.seedlings,and improve the soil PH.