Investigating the effects of silver nano particles on fungi flora of seeds of Chamran wheat cultivar

This study was carried out in order to investigate the possibility of controlling seed-born disease of wheat Chamran cultivar by nano silver seed coating and indicate relevant concentration of nano silver on fungal seed-born of wheat at Khouzestan-Ramin Agricultural and Natural Resources University. Experiment was conducted in the form of completely randomized design with four replications and six treatments. Treatments included one level of disinfection by 2.5% sodium hypochlorite and five levels of seed coating by different concentration of silver nano particle (S1 = 1.30, S2 = 4, S3 = 6.70, S4 = 9.3 and S5 = 2666 mg of silver nitrate solution). Results showed that there was a significant difference among disinfection levels (P≤0.01) for disease index. In comparison with sodium hypochlorite, the Disease Index was declined about 50% by S1 treatment. The most favorable effect on decreasing Disease Index was observed with S5 treatment where it dropped up to 75%. According to results the mean of mortal concentration of nano silver on dominant species (Aspergillus sp., fusarium graminiarum, Penicilium sp. , Torula sp., Alternaria alternaria) was calculated using Fini method in order to approach the finest concentration. The maximum LC50 was obtained for Torula sp. 1875.6 ml/lit and the minimum 0.02 ml/lit was for Aspergillus sp. and Alternaria alternaria. Regarding to this point that fungal seed-borne are active on seed bed in the form of a band, for approach to efficient disinfection it is essential to use the maximum needed concentration.