Abstract
Certain experimental results obtained in Indonesia, with no water deficit, show that leaf potassium contents well below the critical levels normally accepted enable excellent yield to be obtained that that correction of this apparent deficiency remains without any significant effect on overall production. In Benin, reponse to potassium is strong under high water deficit conditions and weak when irrigation is given. For an identical potassium concentration level in the leaf, the response which can be expected from KC1 applications depends on the water supply. This hypothesis would seem to provide back-confirmation of the extent to the role played by potassium nutrtion in drought resistance phenomena. The potassium critical level also depends on the type of soil, particularly clay minerals, the absorbing complex and the exchangeable cation balance. The examples used in this study concern a great number of situtations in Africa, America an Asia. They confirm the need for specific experiments in situ to determine potassium critical levels for each of the ecologies considered.Incluye 11 referencias bibliográficas.Certain experimental results obtained in Indonesia, with no water deficit, show that leaf potassium contents well below the critical levels normally accepted enable excellent yield to be obtained that that correction of this apparent deficiency remains without any significant effect on overall production. In Benin, reponse to potassium is strong under high water deficit conditions and weak when irrigation is given. For an identical potassium concentration level in the leaf, the response which can be expected from KC1 applications depends on the water supply. This hypothesis would seem to provide back-confirmation of the extent to the role played by potassium nutrtion in drought resistance phenomena. The potassium critical level also depends on the type of soil, particularly clay minerals, the absorbing complex and the exchangeable cation balance. The examples used in this study concern a great number of situtations in Africa, America an Asia. They confirm the need for specific experiments in situ to determine potassium critical levels for each of the ecologies considered.