Effect of potassium doses fertirrigated in the nutritional contents of tomato fruit and leaves in their early development

Tomato is the most commonly consumed and marketed vegetables in the world and one of the plants that respond more to fertilization, and particularly in demanding potassium, which is responsible for stomata opening, sugar translocation, protein synthesis and enzymatic activation. Analysis of nutrients contents made available to the plant and its relationship with what is present in plant tissue is a great alternative for the correct handling of mineral nutrient solutions. The objectives of this study are to evaluate the influence of increased K doses on the growth of tomato and its relationship with other nutrients. For the study, two experiments of fertirigated tomatoes in pots were preformed with sand as substrate, and five different doses of potassium, grown in a greenhouse. Nutritional content in the fruit in early development and leaf immediately above each bunch was evaluated. Data were submitted to polynomial regression analysis to the second degree. Results showed that increased potassium levels significantly influenced K, S and N contents. Increasing potassium doses significantly affect nutritional contents of the plant tissue.   Key words: Plant tissue, nitric, nitric-perchloric perchloric digestion, Lycopersicon esculentum Mill.