Effect of Trichoderma and Aspergillus fungi biopriming on increasing tolerance threshold of zinc uptake in wheat

In order to investigate the effect of biopriming of wheat seeds with Trichoderma and Aspergillusalong with ZnSo4 on improving germination indices and the tolerance threshold of wheat to zinc a factorial experiment was done based on a completely randomized design with three replications. Experimental treatments included six levels of zinc (0, 0.6, 6, 60, 300 and 600 mg/L) and four fungal treatments (no inoculation, inoculation with Trichoderma harzianum, Trichoderma longibrachiatum and Aspergillus niger). Nonetheless, based on the results, the coexistence of wheat seedlings with Trichoderma fungi especially Aspergillus fungi reduced the lipid peroxidation of the membrane in all application levels of zinc. Also, based on the results, the highest proline content was observed in the highest level of zinc in inoculated wheat seedlings by T. harzianum (fourfold increase as compared to the uninoculated control) and in other levels of zinc in seedlings inoculated with A. niger. However, the results showed a negative relationship between malondialdehyde (MDA) content and superoxide dismutase (SOD) activity and growth indices of wheat seedlings. There was also a negative relationship between MDAecontent with both SOD activity and growth indices of wheat seedlings. Inoculation of wheat seedlings with fungal treatments with higher production of SOD may led to higher resistance and avoidance to higher concentrations of Zn. Overall, the results showed an increase in the tolerance threshold of wheat seedlings to a concentration of 60 mg/L and therefore, more effectiveness of this micronutrient in seeds inoculated with Trichoderma and Aspergillus especially inoculated with Trichoderma longibrachiatum.