Multivariate diagnosis of nutritional status of a crop and recommendation of elementary contributions to perform for optimizing the nutritional status, comprises removing dry material of aerial parts and determining their n elementary histological grades (X) in macronutrients and/or nutritional trace elements, establishing normal histological grades (x n) for each n considered nutrient elements, calculating nutritional indices (Ix n), with respect to n normal values (x n), to each n nutrient elements, and establishing basic histological grades for each nutrients. Multivariate diagnosis of nutritional status of a crop and recommendation of elementary contributions to perform for optimizing the nutritional status, comprises removing dry material of aerial parts and determining their n elementary histological grades (X) in macronutrients consisting of nitrogen, phosphorous, potassium, calcium, magnesium, sulfur and/or sodium and/or in nutritional trace elements consisting of iron, manganese, zinc, copper, boron, molybdenum, calcium, silicon and/or cobalt, establishing normal histological grades (x n) for each n considered nutrient elements, calculating nutritional indices (Ix n), with respect to n normal values (x n), to each n nutrient elements by multiple comparisons of nutrient ratios based on the calculation of arithmetic averages (diagnosis and recommendation integrated system), the calculation of geometric averages (compositional nutrient diagnosis) or any other multivariate method taking into account of the interactions of the nutrients, age and/or production of dry material of the crop at a given stage, establishing basic histological grades to be achieved for each nutrients according to the nutritional indices, and advocating basic contributions to make, to the crop, to optimize nutritional status in terms of absence of deficiencies and/or nutritional imbalance based on the basic histological grades to reach for each elements, where n normal values (x n) are d
