Rationale of selection for specific nutritional characters in crop improvement withPhaseolus vulgaris L. as a case study

Genetic effects are obtainable for any aspect of transport, accumulation, and efficiency of nutrient use by plants, and for virtually any element. Some of the important characters are: tolerance to acid soils (18% of soils or 2.4 billion ha), tolerance to high pH induced Fe-chlorosis, and tolerance to salinity (about 1,000 m ha). Genotypes which made better use of N and P would be the means of saving fertilizers, especially important to developing countries. A 10% economy of fertilizer use represents a minimum world saving of US$6 billion annually.Phaseolus vulgaris is taken as a model to show that although we know quite a lot about the extent of its nutritional variation, e.g. adaptability to acid soils, and the crop's utilization of N and P, we are handicapped in exploiting this because of lack of genetic information. This in turn depends on knowledge of specific mechanisms, and investigating these must be a priority.IAEA Project BRA/5/009