Phosphate Solubilization: Their Mechanism Genetics And Application

摘要

The global necessity to increase agricultural production from a steadily decreasing and degrading land resource base has placed considerable strain on agro ecosystems (Tilak, 2005). Current strategy is to maintain and improve agricultural productivity exclusively via the use of chemical fertilizers. Although the use of chemical fertilizers is credited with nearly fifty percent increase in agricultural production but they are closely associated with environmental pollution and health hazards (Gaur and Gaind, 1999). Many synthetic fertilizers contain acids, such as sulfuric acid and hydrochloric acid, which tend to increase the acidity of the soil, reduce the soil's beneficial organism population and interfere with plant growth. Generally, healthy soil contains enough nitrogen-fixing bacteria to fix sufficient atmospheric nitrogen to supply the needs of growing plants. However, continued use of chemical fertilizers may destroy these nitrogen-fixing bacteria. Furthermore, chemical fertilizers may affect plant health. For example, citrus trees tend to yield fruits that are lower in vitamin C when treated with synthetic fertilizer. Lack of trace elements in soil regularly dosed with chemical fertilizers is not uncommon. This lack of vital micronutrients can generally be attributed to the use of chemical fertilizers. On the other hand Biofertilizer adds nutrients to soil.Environmentally friendly biotechnological approaches offer alternatives to chemical fertilizers (Dobbelaere et al., 2003). Given the negative environmental impacts of chemical fertilizers and their increasing costs, the use of PGPB is thus being considered as an alternative or a supplemental way of reducing the use of chemicals in agriculture (De Weger et al., 1995; Gerhardson, 2002, Postma, et al., 2003; Welbaum, 2004) Introduction The global necessity to increase agricultural production from a steadily decreasing and degrading land resource base has placed considerable strain on agro ecosystems (Tilak, 2005). Current strategy is to maintain and improve agricultural productivity exclusively via the use of chemical fertilizers. Although the use of chemical fertilizers is credited with nearly fifty percent increase in agricultural production but they are closely associated with environmental pollution and health hazards (Gaur and Gaind, 1999). Many synthetic fertilizers contain acids, such as sulfuric acid and hydrochloric acid, which tend to increase the acidity of the soil, reduce the soil's beneficial organism population and interfere with plant growth. Generally, healthy soil contains enough nitrogen-fixing bacteria to fix sufficient atmospheric nitrogen to supply the needs of growing plants. However, continued use of chemical fertilizers may destroy these nitrogen-fixing bacteria. Furthermore, chemical fertilizers may affect plant health. For example, citrus trees tend to yield fruits that are lower in vitamin C when treated with synthetic fertilizer. Lack of trace elements in soil regularly dosed with chemical fertilizers is not uncommon. This lack of vital micronutrients can generally be attributed to the use of chemical fertilizers. On the other hand Biofertilizer adds nutrients to soil.Environmentally friendly biotechnological approaches offer alternatives to chemical fertilizers (Dobbelaere et al., 2003). Given the negative environmental impacts of chemical fertilizers and their increasing costs, the use of PGPB is thus being considered as an alternative or a supplemental way of reducing the use of chemicals in agriculture (De Weger et al., 1995; Gerhardson, 2002, Postma, et al., 2003; Welbaum, 2004)It has been estimated that in some soil up to 75% of applied phosphate fertilizer may become unavailable to the plant because of mineral phase reprecipitation (Goldstein, 1986; Sundara et al., 2002). Phosphate-solubilizing bacteria (PSB) are able to convert insoluble phosphates into soluble forms (Illmer and Schinner, 1995; Hilda et al., 2000ab; Peix et al., 200