Effect of Mycorrhizal Fungi (AMF), Brassinosteroids and Sodium Silicate on Vegetative Growth, Flower Production and Pb Concentration of Zinnia ( Zinnia elegans ) Plant Under Pb Stress

摘要

Background and Objective: In recent years, heavy metal pollution is increasing rapidly, resulting in many environmental problems. This study was carried out to investigate the effect of lead soil pollution on the vegetative growth, flower production and enzyme activity of zinnia plant (Zinnia elegans) in the presence of mycorrhizal fungi, brassinosteroids and silicon. Materials and Methods: The Plants were treated with lead nitrate Pb(NO3)2 as a soil addition at 100 and 200 ppm Pb kg–1 soil, in addition 2 mycorrhiza treatments by using Glomus mosseae and G. fasciculatum at the rate of 500 and 1000 spores pot–1 [7 kg soil], foliar spray of Brassinosteroids by using 24-epibrassinolide at 10–6 and 10–8 M and sodium silicate at 50 and 100 ppm, in addition to the control. The statistical analysis was done by using ANOVA analysis, Least Significant Difference (LSD) was applied p = 0.05 probability level to compare the mean of the treatments. Results: The results indicated that the Pb at 200 ppm gave the lowest values for most studied characteristics, but increased Pb concentration in all organs, a/b ratio and peroxidase activity with high Pb level. The different treatments especially 24-epi at 10–8 M, sodium silicate at 50 ppm and then followed by mycorrhiza at 1000 spores increased all characteristics under Pb conditions, except Pb concentration and peroxidase activity decreased compared the untreated control plant. Conclusion: The data provided evidence that 24-epi, sodium silicate and mycorrhiza treatments reduced the adverse effects of Pb stress on zinnia plants and might play a key role in providing stress tolerance.