VIEW ARTICLE

Ecology and Epidemiology

Influence of Seed and Root Exudates on Fluorescent Pseudomonads and Fungi in Solarized Soil. A. Gamliel, Department of Plant Pathology and Microbiology, The Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot 76100, Israel; J. Katan, Department of Plant Pathology and Microbiology, The Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot 76100, Israel. Phytopathology 82:320-327. Accepted for publication 15 July 1991. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/Phyto-82-320.

We investigated the effect of soil solarization on seed and root exudates of tomato plants and the role of these exudates in the establishment of fluorescent pseudomonads in soil. Seed and root exudates of tomato grown in solarized soil contained lower amounts of sugars and higher amounts of amino acids and amino compounds and were less favorable for growth of bacteria and fungi in culture compared with seed and root exudates of tomato grown in nonsolarized soil. Addition of exudates from germinating seeds into solarized soil, however, increased populations of fluorescent pseudomonads and decreased populations of fungi compared with nonsolarized soil. A similar effect was obtained with volatile exudates from germinating seeds. Addition of antimicrobial agents to nonsolarized soil supplemented with exudates reduced populations of soil microorganisms and increased populations of fluorescent pseudomonads. We suggest that the rapid establishment of fluorescent pseudomonads in the rhizosphere of plants in solarized soils is due to an improved capacity of these bacteria to compete for exudates.