General Aspects of Mycorrhiza

摘要: The mycorrhizal association appears to have evolved as survival mechanism for both the fungi and higher plants, allowing each survive in existing environments of low temperatures, soil fertility, periodic drought, diseases, extereme temperatures other natural stresses. Mycorrhiza be first line biological defense against stress, trees. following benefits can derived from this relationship: (i) Increased nutrient water absorption through improved absorbance area (Boyd, 1987) (ii) Increased mobilization weathering (iii) Increase feeder root longevity by provision deterrent infection soil-borne pathogens (Duchesne et al., 1989; Marx, 1973) (iv) Accumulation elements such nitrogen, phosphorus, potassium, calcium zinc their translocation host tissue. (v) Ectomycorrhizal hyphae completely permeate F H horizons forest floor thus minerals mobilized these zone absorbed before they reach subsoil system (vi) Some EM degrade complex organic substances make essential available plant (vii) Mycorrhizal afford protection delicate tissue attack pathogenic strategies use surplus carbohydrates, a physical barrier secretion antibiotics Garrido 1982; Tsantrizos 1991) (viii) Provide plant with growth hormones like auxins, cytokinins, gibberellins regulators B vitamins (Gopinathan Raman, 1992; Ho, 1987; Kraigher 1991) (ix) Important contributions matter turnover cycling ecosystems fungal biomass account much 15% net primary production majority it enter pool annually (x) Increase tolerance adverse conditions including pH temperature heavy metal toxin stress (Dixon 1994; Gardner Malajczuk. 1988; Marx Artman, 1979; Osonuki 1991; Peiffer Bloss, 1988)