Effect of Biological and Chemical Phosphate Fertilizers on Growth Indices and Grain Yield of Maize under Deficit Irrigation Conditions in Karaj Region

In order to study the effect of biological and chemical phosphate fertilizers on growth trend, physiologic indices and biological and grain yield of maize under deficit irrigation conditions in Karaj region, an experiment was conducted as split-split plot arrangement based on randomized complete blocks design with three replications. The experiment treatments were included: irrigation (full and deficit irrigation), phosphate biological fertilizer (co-application of mycorrhizal fungi and Pseudomonas fluorescens bacteria, application of Pseudomonas fluorescens bacteria, application of mycorrhizal fungi and control) and chemical phosphate fertilizer (optimized consumption of triple superphosphate, consumption of rock phosphate and control). The results showed that the maximum leaf area index was equal to 3.9 with 1350 GDD and maximum crop growth rate was equal to 3.4 g m-2 with 1150 GDD obtained with co-application of mycorrhizal fungi and Pseudomonas fluorescens bacteria treatment under full irrigation condition. Application of mycorrhizal fungi and Pseudomonas fluorescens bacteria compared to the control treatment increased leaf area index, crop growth rate, relative growth rate and biological and grain yield of maize under both full and deficit irrigation conditions. The co- inoculation of seeds with fungi and bacteria increased 5.13 and 11.76 percent leaf area index and crop growth rate in terms of the optimized consumption of triple superphosphate than rock phosphate, respectively. Grain yield and biological yield at co-application of AM fungi and Pseudomonas fluorescens along with optimum consumption of triple superphosphate were also higher by 15% and 13.6%, respectively, than application of microbial inoculants along with consumption of rock phosphate. Overally, results of this experiment showed that application of mycorrhizal fungi and Pseudomonas fluorescens bacteria reduced negative effects of stress on investigated traits. Application of microorganisms along with balanced consumption of phosphorus chemical fertilizers also increased growth indices and grain yield and reduced consumption of phosphorus chemical fertilizers.