Genetics, Biofuels and Local Farming Systems
Sustainable agriculture is a rapidly growing field aiming at producing food and energy in a sustainable way for humans and their children. Sustainable agriculture is a discipline that addresses current issues such as climate change, increasing food and fu
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Abstract The new challenges that will be faced by agriculture in the twenty-first century impose the adoption of strategies able to increase food production without further increase the area of arable land and with low environmental impact. Soil microorganisms are a major component of the natural fertility of soils. They can promote plant growth, increase crop productivity and contribute significantly to the mineral nutrition of crop plants. This review examines the up-to-date knowledge about the potential and existing uses of beneficial microbes as biofertilizers and gives an outline of their modes of action. Plant growth promoting microorganisms (PGPM) influence plant nutrition and growth through various mechanisms including nitrogen fixation, breakdown of organic matter, solubilization of sparingly soluble minerals, release of chelating compounds and biologically active substances such as phytohormones, vitamins and enzymes, and increase of the root system efficiency in nutrient uptake. Non symbiotic soil- or endophytic bacteria belonging to the genera Azospirillum, Azotobacter, Acetobacter, Gluconacetobacter, Azoarcus, Bacillus, Paenibacillus, Burkholderia, Herbaspirillum, Clostridium, Klebsiella, Enterobacter, Citrobacter, and Pseudomonas are able to fix atmospheric N2 and have been found to be responsible for supply of biologically fixed nitrogen to crop plants. They may also improve plant growth through production of bioactive metabolites and indirect mechanisms, such as suppression of phytopathogens or induction of resistance to pathogens in plants.
C. Altomare () Institute of Sciences of Food Production, National Research Council, Via Giovanni Amendola 122/O, 70126 Bari, Italy e-mail: [email protected] I. Tringovska Maritsa Vegetable Crops Research Institute, 32 Brezovsko shosse Street, Plovdiv 4003, Bulgaria e-mail: [email protected] E. Lichtfouse (ed.), Genetics, Biofuels and Local Farming Systems, Sustainable Agriculture Reviews 7, DOI 10.1007/978-94-007-1521-9 6, © Springer Science+Business Media B.V. 2011
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Numerous species of soil and rhizosphere microorganisms may solubilize insoluble mineral phosphates, mainly through acidification and production of organic acids, and thus mobilize the enormous reserves of phosphorus (P) that are stored in most soils and are otherwise unavailable to plants. Generally, fungi exhibit greater P-solubilizing ability than bacteria. Members of the genera Aspergillus, Penicillium, and Trichoderma are particularly efficient P-solubilizers. Among bacteria, good results have been obtained with Bacillus spp. and Pseudomonas spp., especially in combination with P-solubilizing fungi and arbuscular mycorrhizal fungi (AMF). Under field conditions, the combined use of P-solubilizing microorganisms with mineral fertilizers such as rock-phosphate has often given successful results. Also, the biological activities of microorganisms in the rhizosphere can mediate the solubility, and hence the availability at root surface of micro-nutrien
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