IOSR Journal Of Environmental Science, Toxicology And Food Technology (IOSR-JESTFT) e-ISSN: 2319-2402,p- ISSN: 2319-2399. Volume 5, Issue 1 (Jul. - Aug. 2013), PP 47-50 www.Iosrjournals.Org www.iosrjournals.org 47 | Page Influence of fungicide (Carbendazim) and herbicides (2, 4-D and Metribuzin) on non-target beneficial soil microorganisms of Rhizospheric Soil of Tomato Crop Majid Mohiuddin 1 , Mazharuddin Khan Mohammed 2 Department of Microbiology,Mumtaz Degree and P.G college, Hyderabad (A.P), India Abstract: In present study pot experiments for Tomato plant were conducted to evaluate the effect of Carbendazim (fungicide), 2,4-D and Metribuzin (herbicides) on certain beneficial microorganisms of rhizosphere. Total counts of bacteria, actinomycetes and fungi were lower in the treated soil than the untreated soil. The significant negative effect of the herbicides and fungicide on counts of Azotobacter, Azospirillum and PSB were observed. The period of retardation or stimulation in growth differed according to the type of pesticide and type of micro-organisms under study. Key words: Carbendazim, 2,4-D, Metribuzim, Non-target Microorganisms, Azotobacter, Azospirillum. I. Introduction The word pesticides encompass a heterogeneous group of chemicals developed to control a variety of pests. According to Miligi [1] et al., 2006 pesticides are generally categorized as insecticides, herbicides and fungicides according to the type of pest which they have shown efficacious action. The use of herbicides has increased in both developed and under developing countries during the last decades. Microorganisms play an important role in many soil biological processes, including nitrogen transformations, organic matter decomposition, nutrient release and their availability, as well as stabilize the soil structure and affect its fertility, investigated by Vyas [2] 1988; Edwards [3] and Bater, 1990; Khan [4] and S cullion, 2000. Soil microflora is the first biota that undergoes direct and indirect impacts of toxic substances introduced to soil. Due to its fast response to contaminants, ubiquity, size and recycling of elements soil microflora is suitable to act as a “biomarker” reflecting the negative effects of pesticides treatment and is commonly used in ecotoxicological tests to evaluate the influence of chemicals on soil system as concluded by Doelman [5] and Vonk, 1994; Edwards [6] et al., 1996; Doran [7] and Zeiss. Soil is the most important site of biological interactions. The indiscriminate use of pesticides disturbs the soil environment by affecting flora and fauna including microflora of soil, and also the physicochemical properties of soil like PH, salinity, alkalinity leading to infertility of soil. The important microflora, beneficial for the growth of plants includes nitrogen fixing bacteria and phosphate solubilizing bacteria, present in the rhizosphere of the plant. The rhizosphere is the zone of soil surrounding the root which is affected by it. The significance of the rhizosphere arises from the release of organic material from the root and the subsequent effect of increased microbial activity on nutrient cycling and plant growth. The excess application of these pesticides may adversely affect the function of these rhizospheric microorganisms. Since the fertility of the soil depends on the number and type of microorganisms present in the soil. Although, pesticides are intended to protect crops, they may affect non-target organisms and contaminate soil environment resulting in alterations the equilibrium of soil processes for shorter or longer periods. TU, CM [8] and Miles, J.R.W., 1976 studied that pesticides reaching the soil affect non target organisms and their activities. To examine these side effects, several investigations are necessary to identify possible changes in the bioactivity of soil organisms contributing to soil fertility. These organisms especially bacteria, fungi and actinomycetes decompose root residues and bring about many reactions necessary for plant growth and crop production. According to Chisholm [9] et al., 1950 pesticide residues generally will remain in the top 15 cm layer of the soil which is the region of greatest activity of soil microflora thus favoring the interaction of pesticide residues with the flora of the soil ecosystem, Alexander, M., [10] 1961. Most of studies on the effect of pesticides on soil microbial activity have been laboratory also studied by Kale [11] and S.P. Raghu, 1989; TU, C.M., [12] 1992; Zelles, L.[13] et al., 1985 with single applications of pesticides for short periods. The effect of repeated application in the field on activities of soil microbes and enzymes has so far received little attention. Margni [14] et al., 2002 concluded that the observed changes in the soil activity depend on the intensity and spectrum of activity as well as persistence of the parent chemicals or its metabolites. Pesticides might affect microorganisms by reducing their numbers, biochemical activity, diversity and changing the microbial community structure, Martinez-Toledo [15] et al., 1998; Smith [16] et al., 2000; Cycoń [17] and Kaczyńska, 2004. The toxic effect of pesticides may be toxic to many soil microorganisms because they can penetrate the cell, disturb the microbial metabolism and