Plant sap analysis helps in decision-making in fertigation

The search for knowledge of the nutritional status of the plant is carried out constantly in agriculture, through methods such as foliar analysis and, more recently, sap analysis. Leaf analysis is widely used, as it represents the accumulation of nutrients from leaf formation to harvest. As for sap analysis, it is a technique that indicates the nutritional status and demand for nutrients in the current state of the plant and at all stages, serving as the basis for fertigation programs, quickly and practically.

Through the use of fertigation, the producer is able to make frequent applications of nutrients. With input prices at high levels, fertilization must be carried out in the most assertive way possible, and sap analysis fits perfectly, as with the development of specific parameters for each type of variety and phenological phase, the producer can avoid losses due to lack or excess of nutrients.  

According to Cadahía et al. (2005) in the book “Fertirrigation: Horticultural, fruit and ornamental crops, in vine culture”, it was found that the sap analysis was more sensitive to variations in fertilization, especially potassium. This is reflected in everyday life in the countryside in the São Francisco valley, for example, where the technique is refined and producers are able to apply potassium fertilizers via fertigation on some grape varieties through the results of extraction, resulting in better use of inputs without lose º Brix (sweetness level), quality and productivity.

As it involves the extraction of material from conductive tissues such as the petiole and veins, the composition of the sap can vary according to the time of day, organ sampled, position on the plant, fertilization, climatic conditions and, therefore, should be used mainly , in specific nutritional assessments, using well-defined procedures regarding collection, transportation, evaluation and interpretation, which must be followed exactly, so that there is no error in interpreting the result. The producer, increasingly equipped with technical information, tends to make better decisions in the use of inputs, offering them at the time and in the quantity that the plant needs, bringing financial returns through high productivity and quality in the crop.