Genetic Erosion in the Tropics.

摘要: Vanishing of genetic resources within a cultivated plant species, erosion, has been recognized as serious problem in the field agronomy. To estimate rate erosion wild rice, biomass (product total area population X rice cover percent) 21 populations northern and northeastern Thailand was measured 1983 1991 (or 1992). The nine annual reduced to 13 percent during this decade, suggesting that they will vanish by end century. twelve perennial 73 percent. In populations, weedy type caused introduction genome neighbouring cultivars is increasing. Pure now being replaced type. Genetic occurs also. Number native varieties grown approximately 50 decade. diversity also high-yielding varieties. prevent progress gene banks were established for preservation major i.e., wheat, corn, barley, beans. case built at International Rice Research Institute (lRRI). National ones various countries. Gene have playing important roles preventing vanishing resources. However, do not play effectively maintain agroecosystems. situ conservation resources, new way agroecosystem, preferred. From viewpoint agronomy, low input sustainable agriculture(LISA) should be encouraged keep agroecosystem sustainable.