Isotope studies on plant productivity. Results of a co-ordinated research programme

In order to explore this approach, a Co-ordinated Research Programme (CRP) on the Use of Isotope Studies for Increasing and Stabilizing Plant Productivity in Low Phosphate and Semi-arid and Sub-humid Soils of the Tropics and Sub-tropics was initiated in October 1989 and complete in October 1994. Almost half of the work carried out under this programme concentrated on water use efficiency and the rest on phosphate use efficiency. Egypt, Morocco and Tunisia focused on wheat; Nigeria and Sierra Leone on cowpea; Kenya, Sudan and the United Republic of Tanzania on nitrogen fixing trees such as Prosopis, Acacia and Gliricidia; and Viet Nam on rice. Experiments conducted in the field showed that there is a wealth of genetic diversity among the genotypes/provenances of crop and tree species in their capacity for uptake and use of phosphorus and water from soils limited in resources. Several elite genotypes/provenances were identified which are highly efficient in water or phosphate use. In a few cases, the high water use efficiency (or the high phosphorus use efficiency) feature was seen in the same genotype where the grain yield was also high. Morphological parameters responsible for making some genotypes superior in their capacity to use phosphorus or water have also been investigated. It is our hope that the findings reported in this publication will help agricultural scientists in the Member States, particularly in Africa, in their quest of finding solutions to problems of food security. Refs, figs, tabs