Variation Of Some Physiological Process And Biomass Of Kandelia Candel Under Stress Of N And Cd

In view of the pollution of heavy mental in mangrove wetlands is aggravating and the assumptions of the utilization of mangrove in sewage treatment at present, Kandelia candel mangrove was regarded as the research object in the paper,cultivated in sand and treated with 10%o brine for 90 days in a greenhouse,by way of simulation test to study the accumulation and distribution of N and Cd and the effects on growth and physiology of the Kandelia candel under different concentrations of N and Cd treatments.There were 4 treatments of Cd including control(0 mg/L),low Cd(0.5 mg/L),medium middle Cd(lmg/L),high Cd(2mg/L);the 4 N treatments comprises control(0 mg/L),low N(0.5 mg/L),middle N(1 mg/L),high N(2mg/L).The influence of different concentrations of Cd and N treatments on Kandelia candel including Cd content and N content of different parts,chlorophyll content,antioxidase membrane protection system and the biomass of Kandelia candel were observed after 90 days' stress of different concentrations of N and Cd treatments.The results were as follows:1.The experiment showed that the Cd content of roots was higher than that of stems and leaves,and roots of Kandelia candel were the main organ of cadmium absorption and accumulation.The Cd content of different parts showed a climb under different Cd treatment series when the N concentration increased;meanwhile,the Cd content of different parts were also promoted when the Cd concentration increased under different N treatments.The Cd accumulation coefficient of different parts of Kandelia candel was increased with the increase of N concentration under the same Cd treatment,while the Cd accumulation coefficient of different parts of KandeIia candel dropped when the Cd concentration increased under the same N treatment.2.The N content of the roots,stems and leaves varied with the Cd and N concentrations in the experiment;the N content of leaves was higher than that of stems and roots.Under the same N concentration,the increase of Cd stress concentration led to the reduction of N content of the different parts of Kandelia candel,while the N content of different parts climbed when the N treatment concentration increased.3.The contents of chlorophyll a and chlorophyll b of Kandelia candel were enhanced when the N concentration level increased under the same Cd treatment;while under the same N treatment,the variation of the chlorophyll contents were inconsistency: the content of chlorophyll a increased with the increase of Cd stress concentration and reached the max at the low Cd(0.5mg/L)treatment,then declined with the increase of Cd stress concentration;while the content of chlorophyll b were enhanced gradually with increasing Cd concentration.4.The experiment showed that SOD activity in leaves raised gradually with increasing of N treatment concentration under different Cd treatment series,and SOD activity had significant difference between different N treatments;under different N treatment series,SOD activity also raised with increasing of Cd treatment,SOD activity of Kandelia candel when treated under middle Cd(1 mg/L)and high Cd(2 mg/L)had significant difference contrasted with that of control(Cd 0 mg/L).5.The experiment showed that POD activity in leaves raised gradually with increasing of Cd treatment concentration under different N treatment series,and the POD activity of Kandelia candel when treated under high Cd(2 mg/L),middle Cd(1 mg/L)and low Cd(0.5 mg/L)had significant difference contrasted with that of control (Cd 0 rag/L).Under different Cd treatment series,POD activity in leaves declined with increasing of N treatment concentration,the POD activity of Kandelia candel when treated with higher N(≥40 mg/L)had significant difference contrasted with that of control(N 0 mg/L).6.Under different N treatment series,the MDA content of Kandelia candel leaves increased with increasing of Cd treatment concentration;there was significant difference between the MDA content of leaves treated by high Cd(2 mg/L),middle Cd(1 mg/L) and the control(0 mg/L)groups.Under different Cd treatments,the MDA content of leaves reduced when N concentration increased;there was significant difference between treatments of high N(60 mg/L),middle N(40 mg/L)and the control(0 mg/L) groups.7.The biomass of the roots,stems and leaves of Kandelia candel varied with the Cd concentrations in the same N group;in most of the treatments,the biomass reduced when the Cd concentration increased.While the biomass of roots,stems and leaves were significantly promoted when the N concentration increased under the same Cd treatment.This paper can provide theoretical basis for the cultivation of Kandelia candel under stress of Cd and the utilization of Kandelia candel mangrove in sewage treatment.