The Role of Trichoderma and Enterobacter Inoculation on Improving Wheat Yield in Different Levels of Phosphorus Fertilizer

  Regarding to the high cost and environmental pollution due to the overuse of chemical fertilizers, an adoptable option for farmers are biofertilizers to increase crop productivity per unit area. Bio-fertilizers are essential components of organic farming that play a vital role in maintaining long-term fertility and sustainability of the soil by their ability to provide micro- and macro-nutrients and also to convert insoluble phosphorus (P) into available forms to plants. Phosphorus as an essential nutrient is often fixed by most soils and is unavailable to the plants. Therefore, application of the plant growth promoting rhizobacteria (PGPR) such as phosphate solubilizing bacteria (PSB) can be proposed as an efficient solution to provide P for plants. These microorganisms by staying on the plant roots surface through production of organic acids, vitamins and other growth promoting materials could increase grain yield (GY) in many crops. In addition, Trichoderma spp. fungus species symbiosis with plant roots and root growth stimulation could control plant pathogens by production of antibiotics, induced systemic resistance and improve plant health that are known as other plant growth promoting microorganisms. It has been reported that Trichoderma species have an ability to solubilizing soil insoluble phosphate which resulted in improving the soil fertility and plant growth as well. Wheat (Triticum aestivumL.) is an important source of human foods which its production is highly depending on the application of chemical fertilizers. Therefore, to reduce the economic and environmental problems, this study aimed to investigate the effect of Trichodermahamatum fungi along with Enterobacter sp. as a PSB on yield and yield components of wheat (cv. ‘Milan’) in different levels of phosphorus fertilizer (TSP). A field experiment was conducted in Mazandaran province (Sari city, located at 36°38' N, 53°32' E and 13.5 m asl) in 2014-15. The experiment was carried out in a factorial split plot arrangement based on a randomized complete blocks design with three replications.Three levels of triple super phosphate (TSP; zero, 50 and 100 kg ha-1) were used as the main plot and both fungal (inoculation with Trichodermahamatum and uninoculated control) and phosphate solubilizing bacteria (PSB) inoculations (inoculation with Enterobacter sp. and uninoculated control), were served as the sub-plots. In this experiment, the traits related to yield and yield components including number of spikes per square meter, grain number and grain weight per spike, straw yield and biological yield, grain yield (t.ha-1), harvest index and 1000-grain weight (g) were measured. Finally, data analysis was performed using SAS 9.1 and means were compared by the least significant difference (LSD) test at a 5% level of probability. The results indicated that the effect of both Trichodermahamatum and Enterobacter sp. were statistically significant on yield and yield components of wheat. GY increased from 2.66 to 3.45 (29.69%), 3.19 to 3.79 (18.80%) and 3.34 to 4.39 t.ha-1 (31.43%) for 0, 50 and 100 kg.ha-1 of TSP, respectively, when Trichodermahamatumwas used separately. In contrast, single PSB inoculation increased GY from 2.66 to 3.37 (21.06%), 3.19 to 3.46 (8.46%) and 3.34 to 5.10 t.ha-1 (52.69%) when applied 0, 50 and 100 kg.ha-1 of TSP, respectively. Simultaneous application of these microorganisms significantly increased GY from 2.66 to 3.78 (42.10%), from 3.19 to 3.85 (20.68%) and from 3.34 to 4.48 t.ha-1 (34.13%) for 0, 50 and 100 kg.ha-1 of TSP, respectively. The result of this study clearly indicate that presence of both Trichodermahamatum and Enterobacter sp. along with different levels of TSP can increase yield and yield components of wheat as compared to the application of TSP alone (without Trichodermahamatum and Enterobacter sp.).
Acknowledgements
This study was supported by a grant from the Genetics and Agricultural Biotechnology Institute of Tabarestan and Sari Agricultural Sciences and Natural Resources University, Iran. The authors thank Mr. FarzinGoran for his assistance in the field experiment.