Evaluating Maize Yield and the Quality of Response to Vermicompost, in Thiobacillus and Foliar Application of Fe and Zn

Introduction Half of the world's population suffers from micronutrients malnutrition. Use of bio-fertilizers in sustainable agricultural systems is important in production and enables plants to absorb more water from soil and improves plant nutrient uptake and photosynthesis. Benefits of vermicompost application in agriculture is due to its content of organic matter, plant nutrients and plant growth promotion. Vermicompost increases the absorption and transition of nutrients from soil to roots and improves plant growth (Simsek-Ersahin, 2011). Zn and Fe application is highly important; foliar application causes faster and higher absorption rate and cures deficiencies symptoms (Ghaffari et al., 2010). Thiobacillus is a chemolithotroph bacterium, receiving energy from sulfur oxidation. This bacterium acidifies microcites in the rhizosphere, increasing the availability of nutrients to plant roots (Kaya et al., 2009). Regarding the benefits of integrated nutrient management, this experiment was conducted with the aim of testing the effects of Fe and Zn foliar spraying, Thiobacillu sthiooxidans inoculation and vermicompost application on growth, yield and bio fortification of popcorn maize.
Materials and methods This experiment was conducted in 2012 at the research field of Islamic Azad University, Tabriz branch, Iran. The experiment was conducted in factorial in the form of a randomized complete block design with three replications and four factors: vermicompost application in soil (0 and 2 t.ha-1, applied in strip form below the seeds before cultivation), inoculation with Thiobacillus thiooxidans, with a population of 108cfu.g-1. Sulfur was inoculated with T. thiooxidans prior to application. Fe chelate foliar application (without spraying and two times spraying of 0.002 concentration of 13% Fe chelate) and Zn chelate foliar application (without spraying and two times spraying of 0.002 concentration of 15% Zn chelate). Maize seeds (Zea mays L. var. popcorn KSC. 600) were planted, after being inoculated with Azospirillum, at the rate of 66,000 plants. ha-1. Then, 10 plants were harvested from the middle rows of each plot and grain yield was measured. To measure the absorption of nutrients, 5 other plants were harvested from each plot when grains were at dough stage and dried at 70°C oven for 72 hours. Then, samples were grinded and analyzed. Finally, data were tested for normal distribution and subjected to statistical analysis using SAS. Duncan's multiple range tests was used to compare means at p≤0.05.
Results and discussion Results indicated the significant effect of vermicompost on 1000 kernels weight, the number of kernels/ear, stem height, stem diameter, grain yield, biologic yield, Fe, Zn and protein contents. The effect of Thiobacillus inoculation was significant on all measured traits except for the stem height. Fe foliar application significantly affected stem height, biologic yield, grain yield an Fe content. Zn foliar application had also a significant effect on the number of kernels/ear, stem height, grain yield, Zn content and protein content. Results of this experiment generally indicated that application of vermicompost, Thiobacillus, Fe and Zn had improving effect on maize yield, yield components and grain quality.
Conclusion Nutrient management is one of the most important factors in successful crop production, so, it was tried in this experiment to take advantages from soil microorganisms to find a suitable method for sustainable crop nutrient management instead of chemical methods. In recent years, increased application of chemical inputs to agricultural fields has caused several environmental and health issues and reduced the quality of products. So, as the results of this experiment showed, integrated nutrient management with lower dependency on chemical fertilizers is a promising method to reach sustainable and healthy production and food safety.
Acknowledgement The authors highly acknowledge Islamic Azad University, Tabriz Branch- Iran, for their fields and laboratories support.