The Effects Of Water And Nitrogen On Jatropha Curcas L. Under Lead Stress

Soil lead(Pb)pollution is an important environmental problem,which is being widely concerned by all the countries in the world.Jatropha curcas is with great potential for development of energy crops,it has certain tolerance to heavy metals,hence it has a wide application prospect in the aspects of remediation of heavy metal contaminated soil.Reasonable irrigation is conducive to the phytoremediation of heavy metal contaminated soil and the improvement of water use efficiency.Applying nitrogen fertilizer can promote plant growth,and can change the soil pH value and the availability of heavy metals.Based on the above background,The Jatropha curcas was taken as the research object,through indoor pot experiment this paper studied water lead stress effect on the growth and physiological characteristics of Jatropha curcas L;this paper also studied on the effect of nitrogen interaction on the growth and accumulation of lead Pb of Jatropha curcas L,and effects of lead stress on water and nitrogen regulation on the growth of Jatropha curcas L.The main results obtained are as follows.1.Under the interactive stress of water-lead,Jatropha curcas biomass decreased gradually,after soil Pb concentration reached 1000mg/kg the difference was significant,Jatropha curcas leaf SOD,POD enzyme activity was first increased and then decreased,compared with single moisture stress,the lead water interaction stress increased the activity of SOD and POD.Under the interaction stress of water-lead,Jatropha curcas cell membrane permeability increased,the appropriate stress can improve the resistance of Jatropha curcas Pb stress ability and restoration efficiency.2.With the increase of nitrogen fertilizer,the inhibition effect of Pb on Jatropha curcas decreased gradually,when there is nitrogen fertilizer,the 5cm soil layer soil nitrate content is almost the same as the 10cm and 15cm soil layer,Application of N reduced Pb content in plants,and improve the effective Pb of Jatropha curcas extraction,In Pb 1000mg/kg contaminated soil,the effective Pb extraction of 300 and 600mg/kg N treatment were increased by 18.1%and 27.9%compared with the non-N treatment;In Pb 1000mg/kg contaminated soil,the application of 600mg/kg N increased the extraction rate of biomass of Jatropha curcas and Pb,which can improve the efficiency of repair.3.When Lead concentration in soil reached 1500mg/kg,Lead stress plays a leading role,No matter how the irrigation and nitrogen changes,the growth and development of Jatropha curcas was significantly inhibited;Compared with 50%irrigation level,Jatropha curcas average plant height and stem diameter under 75%irrigation level were significantly increased by 30%and 21.3%,the average effective extraction rate was significantly increased by 25.4%,and the water use efficiency increased by 24.2%;compared with the non-N treatment,300 and 600mg/kg N Jatropha curcas average plant height significantly increased by 12.5%and 24.8%,the average effective extraction was increased by 2.8%and 5.3%respectively,Moderate water stress inhibited the growth of Jatropha curcas,water use efficiency decreased.The level of lead in soil is less than 1000mg/kg,the treatment of 75%irrigation level and 600mg/kg N can increase the biomass,water use efficiency and the efficiency of phytoremediation of Jatropha curcas significantly compared with other levels.