Criteria for a sustainable and ecologically beneficial use of genetically engineered crop cultivars Currently it is estimated that by the year 2000 more than six billion people, and by the year 2050 more than ten billion people will live on the earth. In order to meet the food requirements of this rapidly growing world population, agricultural production must be increased first of all by improving crop yields on the currently managed land areas. The United Nations Conference on Environment and Development held in Rio de Janeiro in 1992 has defined the concept of sustainability for agriculture. Concomitant to the need to increase the global food production, the main objectives are the  reservation of natural resources and the maintenance of the environment.