Leaves mere sampled monthly throughout the biological cycle. Crop nutrition was studied by foliar analysis in 54 greenhouses over two years. The results showed that cations (C+) and anions (A(-)) were deficient during the initial stages of plant growth, declining the C+-A(-)balance. The use of C+-A(-) dynamics all along the biological cycle served to specify the predominant ionic family, the incidence of which on the morphological transformations in plants is yet unknown. After establishing norms for foliar analysis, and determining nutrient contents in appropriate tissues, the information thus obtained can be estimated by means of various diagnostic methods. The optimal range of C+ -A(-) balance may be used as initial diagnosis to establish the predominance of both cations and anions and thus provide information regarding the best fertilization treatment.