Growth of peas Pisum sativum L. in the presence of diesel and bacteria consortia in peat and sandy soil Laila Dubova 1 , Olga Muter 2 , Alina Mihailova 2 , Ina Alsina 1 , Vilhelmine Steinberga 1 , Baiba Limane 2 , Dzidra Zarina 2 1 Latvia University of Agriculture, 2 Liela Str., Jelgava LV -3001, Latvia 2 Institute of Microbiology & Biotechnology, University of Latvia, 4 Kronvalda boulvd., Riga LV-1586, Latvia, Abstract: Remediation of contaminated soils, using plant-based systems, is known as a very perspective and rapidly developing area of biotechnology. In this respect toxicity of diesel for plants is of great importance. In this work, the results of the greenhouse experiments with soils artificially contaminated by diesel are presented. The seeds of peas were sown into peat and sandy soil mended with 1% and 3% of diesel, as well as inoculum of bacteria consortia, which was previously isolated from oil-contaminated sites. After 85 days, when peas were entering the bloom stage in the control samples, plant biomass was harvested. The presence of 1% diesel in sandy soil totally inhibited the growth of peas, although in peat soil an inhibition effect was about 50 %. Harvested biomass was also tested for moist and dry weight, height, content of chlorophyll a and b. Fermentative activity of soils, i.e. FDA (fluoresceine diacetate hydrolysis), dehydrogenase, urease, as well as respiration were measured. The total microbial number in rhizosphere was 10-100 times higher that in average soil sample. The number of colony forming units on the selective medium with diesel was higher in the samples inoculated with bacteria consortia. The results provided additional information on plant response to diesel contamination in the context of toxicity study and perspectives for phytoremediation. Keywords: peas, diesel, bacteria consortia, soil fermentative activity, respiration, chlorophyll Abbreviation: FDA - Fluorescein Diacetate (3',6'-diacetylfluorescein); DHA – Dehydrogenase Activity; TGA Tryptone Glucose Yeast Extract Agar. 1 Introduction The concept of using plants to remediate contaminated soil has recently become an area of intense scientific study. Plants have been shown to encourage organic contaminant degradation principally by providing an optimal environment for microbial proliferation in the rhizosphere [1-2]. These degradative processes are influenced not only by the rhizosphere microorganisms but also by unique properties of the host plant [3]. Diesel oil is a complex mixture of petroleum hydrocarbons containing everything from volatile, low molecular weight alkanes which are potentially phytotoxic, to naphthalenes which may interfere with normal plant development [4]. If plants can be successfully established on polluted soil, then the plant–microbial interaction in the rhizosphere may provide enhanced breakdown of diesel fuel in vegetated soils as opposed to non vegetated soils. It is apparent that more plants that grow well in contaminated soils need to be identified and screened for use in phytoremediation technologies [5]. Many researchers have studied the phytoremediation of different organic contaminants by using plant species in Europe, North America, Japan. Italian ryegrass, sorghum, maize, alfalfa, rice, Bermuda grass, rice, kudzu, beggar ticks are recognized as phytoremediators [6-10]. Sunflower, southern crabgrass and red clover are recognized as hydrocarbon-tolerant plants [4, 11]. These studies suggested that grass species and Leguminosae could be suitable for phytoremediation of petroleum hydrocarbon-contaminated soil. The aim of this study was to investigate an ability of peas P. sativum L. to grow in peat and sandy soil in the presence of diesel. 2 Materials and methods The greenhouse vegetation experiment was performed with P. sativum L. sown in peat and sandy soil contaminated by diesel fuel. The scheme of the MATHEMATICAL METHODS, COMPUTATIONAL TECHNIQUES, NON-LINEAR SYSTEMS, INTELLIGENT SYSTEMS ISSN: 1790-2769 403 ISBN: 978-960-474-012-3