Effect of Organic and Biological Fertilizers on Growth and Yield of Tomatoes (Lycopersicon esculentum Mill.) and Bacterial Colonization

Introduction: In recent decades, excessive use of chemical fertilizers causes environmental problems such as water resource pollution and decrease in soil fertility. Organic matters are excellent sources of plant-available nutrients and their addition to soil could maintain high microbial populations and activities. In crop studies, Prabha et al. (2007) reported that there was excellent plant growth as well as yield in garlic plants that received vermicompost as nutrient in the field (28). Recent studies confirmed that, a number of bacterial species mostly associated with the plant rhizosphere, are found to be beneficial for plant growth, yield and crop quality. Therefore, the objective of this study is to investigate the growth promoting effects of organic and bio-fertilizers on tomato growth and yield. Materials and Methods: A factorial experiment in randomized complete block design with three replications was conducted at the College of Agricultural, University of Shahrood in 2011. Geographically, the site is located in Bastam (36° 25’E, 54° 58’N, 1349 m a.s.l.).The climate of this region is semi-arid. Treatments included three levels of organic fertilizers: vermicompost (1300 kgha-1), cow manure (3350 kgha-1), and control, biological fertilizer in four levels (Pseudomonas putyda, Pseudomonas fluorescens, Azotobacter chrococcum and control). The bacterial suspension for each species was applied at a rate of 3 liters per hectare. Metribuzin herbicide (wettable 80% powder) was used at a rate of 1000 gr. ha-1. Petopride No. 2' variety of tomato (Lycopersicon esculentum Mill.) was used in the present experiment. At the time of harvesting, the plant characteristics namely lengths and diameter of stem, number and weight of fruit, weight of stem and leaf were also registered. Statistical analyses of data were performed with statistical software Mstatc. Significant differences between means refer to the probability level of 0.05 by LSD test. Results and Discussion: There sults showed that main interaction effects of bio and organic fertilizers were significant (P