The Effects of Carboxin-thiram on Associative Relationships between Azospirillum Species and Wheat (Chamran Cultivar)

Introduction: Biofertilizers have been identified as alternative to chemical fertilizers to increase soil fertility and crop production in sustainable farming systems. One of the most useful kind of biofertilizers include plant growth promoting rhizobacteria (PGPR). Azospirillum is an associative rhizobacteria which can be very useful for plants such as wheat. It can help plant by fixing nitrogen through biological way, causing root development, plant strength improvement in primary phases, causing germination percent increment, improving plant tolerance in stress situations (drought, salinity, soil compaction and pathogens), secreting plant promoting hormones like cytokinin, Oxin and finally yield increment will be observable. Modern agriculture largely relies on the extensive application of agrochemicals, including inorganic fertilizers and pesticides. Although pesticides are important, their effects on nontarget organisms are of great concern because this poses a risk to the entire ecological system. The fungicides may also adversely affect the soil microflora, especially the types of microorganisms that can applied to seeds as bacterial inoculants. Considering useful effects of plant growth promoting rhizobacteria especially Azospirillum on Wheat, this study was done in order to survey interaction effects between fungicide and available biofertilizers in Iran market. Materials and Methods: Effect of carboxin tiram in 2 levels (applied, non-applied) as fungicide, on efficacy of wheat plant (Chamran Cultivar) and final crop yields under association conditions with 5 Azospirillum species (A.brasilense, A.lipoferum, A.halopraeferense, A.irakense, A.sp) using powdery and liquid formulation were studied in a greenhouse test for four months in Soil and Water Research Institute.At first some properties of used soil, including soil texture, pH, EC,organic carbon and available soil K, P, Fe, Zn, Mn and Cu were measured by laboratory methods.Nutrient Broth medium were used for bacterial inoculum production with 108 bacterial cound per ml in final suspention. Using factorial experiment in a Completely Randomized Design (CRD), 2 bacterial inoculants factors (5 inoculation level and a non-inoculation level), CarboxinThiram fungicide levels (applied, non-applied) and two inoculants formulations (liquid and powdery) with four replicates per treatment and a total of 96 experimental units (pots), the most effective contribution of different species of Azospirillum bacte