Adubação potássica e nitrogenada em solo com e sem biofertilizante na cultura do rabanete no litoral cearense

Abstract

The radish (Raphanus sativus L.) has stood out as a very appreciated vegetable, for its medicinal properties of popular knowledge and due to its short productive cycle. Due this aspect, the crop can be cultivated between the harvest period of other crops of the longer cycle, presenting itself as an alternative for farmers to increase the profitability of their areas. Based on the high nutritional requirement of the crop in a short period of time and the lack of research explaining the effects of nitrogen and potassium fertilization combined with the application of organic inputs such as bovine manure biofertilizer, the objective was to evaluate growth, gas exchange and the productivity of the cultivated radish under doses of nitrogen and potassium in the presence and absence of bovine biofertilizer. The experiment was conducted in the experimental area of the Agrometeorological Station of the Department of Agricultural Engineering of the UFC, Fortaleza-CE, under a completely randomized design in a 4x2 factorial scheme, with four replications, leading to two plants per pot. In the experiment 1 the treatments consisted of four doses of N (0, 64, 128 and 192 kg ha-1) and in experiment 2 in four doses of K (0; 78, 156 and 234 kg ha-1), these doses being, in both experiments, combined with the presence and absence of bovine biofertilizer in soil. The plants were grown in polyethylene pots of 15 L filled with local soil classified as Yellow Red Argisol with a sandy clay loam texture. Thirty days after sowing (DAS), the physiological characteristics of the plants were evaluated, determining the internal CO2 concentration, the net photosynthetic rate of 6.25 cm² of the analyzed leaf, transpiration rate, rate ratio liquid photosynthesis of 6.25 cm² and the internal concentration of CO2 and the Relative Chlorophyll Index. At thirty-one DAS the plants were harvested and the agronomic variables were evaluated (leaf number, total leaf area per plant, fresh and dry mass of aerial part per plant, length, diameter and fresh mass of the tufa; (Table 1), which showed that all the physiological variables were positively influenced by the nutrient content of the plants, and the plant material (aerial part) was identified and dried in an air circulation oven to determine the N, P, K, Ca and Mg foliar contents. increase in N levels and that K doses significantly influence the internal CO2 concentration and the net photosynthetic rate of 6.25 cm ² of the leaf analyzed, being this effect potentiated in the condition with application of biofertilizer. a large majority, responded to the increase in nitrogen fertilization, with the exception of the variable length of the tuber. The biofertilizer contributes nutritionally to the growth of the culture of the radish fertilized with N and K.