Effect of carboxin-thiram fungicide on viability and effectiveness of some selected plant growth promoting Azospirillum strains in wheat seed.

In addition to that biofertilizers have positive effects on soil stable fertility; they also have some other beneficial attributes such as economical and environmental. Therefore they can be used as a suitable substitute to replace all or at least some of chemical fertilizers. Biofertilizers include Plant Growth Promoting Rhizobacteria (PGPR). One of the most important components of PGPR group is Azosprillum. These bacteria can increase plant growth through direct and indirect mechanisms. Considering wide use of Carboxin thiram to control fungus pathogens in wheat cultivation in Iran, this project was designed and performed to define the effects of this fungicide on the establishing association relation with species of Azosprillum. Performing green house test, use and non-use Carboxin thiram effects on growth indexes of wheat plant (Chamran Cultivar) association conditions with 5 Azosprillum species (A.brasilense, A.lipoferum, A.halopraeferense, A.irakense, A.sp) were studied. Also effect of Carboxin thiram on two Azosprillum species inoculant formulations (powder and liquid) on wheat seeds was surveyed in vitro condition. Bacteria counting test results showed that bacteria are different in susceptibility against Carboxin thiram . .A. irakense was resistant and A.sp was more sensitive. In A.sp, liquid form of bacterial inoculum was better than powdery form, because of higher population of bacteria on Carboxin thiram coated wheat seeds Final results showed that in bacteria and Carboxin thiram interaction, tillering, node interface, flag length, seed number and seed weight per raceme, plant wet and dry matter weight were significant. If we consider 3 indexes including tillering, seed weight per raceme and plant dry matter weight, we can propose two species of Asosprillum, A.lipoferum and A.halpraeaferense for using with and without Carboxin thiram in wheat cultivation. Keywords: Azosperillum, Carboxin thiram, wheat.