Effect of Trichoderma and biochar application on some morpho-physiological traits of sainfoin seedlings grown in soils containing heavy metals

Amending biochar alone or with microbial inoculation, as a soil amendment, helps to reduce the toxicity of heavy metals in contaminated agricultural soils. On the other hand, the interaction of inoculation with microorganisms and the application of biochar on the absorption of lead and zinc and the growth and yield of plants are somewhat unclear. The objective of this greenhouse experiment was to explore the influences of the application of biochars (obtained from peanut shells and carrot pulps) and conidial suspension of Trichoderma fungi (Trichoderma harzianum Rifai-T22) on seedling growth and some physiological characteristics of sainfoin grown in the soil polluted with heavy metals Pb and Zn. The application of biochars and inoculation with Trichoderma fungus improved the growth parameters of sainfoin seedlings such as root length, plant height, fresh and dry leaf weight. Also, the synergy of these treatments caused an increase in the total protein content, the soluble sugars, the total flavonoids in roots and leaves, catalase and peroxidase activity and also the rate of seedling germination compared to the control treatment (no use of biochar and conidial suspension). Overall, the application of biochar and Trichoderma in soils contaminated with heavy metals caused enhanced growth of sainfoin seedlings by improving some physiological parameters in the leaves, increasing root growth, alleviating the oxidative stress-induced damage and thus possible improvement in water and nutrient uptake.