Comportamento vegetativo, produtivo e fisiológico da abobrinha em resposta à aplicação de biofertilizante e diferentes fontes nitrogenadas

Abstract

Zucchini (Cucurbita pepo L.) is among the ten vegetables with the highest economic value, especially in central and southern Brazil. The commercial product is an immature fruit, rich in nutrients, like vitamins A, B2, C and E, amino acids, carbohydrates and fiber, it has been consumed baked, fried or stuffed and with potential for being used in the pharmaceutical industry due to its medicinal properties. Despite of its relative economic and nutritional importance, few studies have been made regarding the fertilization of this vegetable, especially the nitrogen and organic fertilizer. Therefore, this study aimed to evaluate the growth, yield and physiological features of the zucchini fertilized with bovine biofertilizer and sources of nitrogen. This study was carried out from June to September 2013, in an experimental design with randomized blocks, with treatments distributed into a factorial scheme 5 x 3 + 1, corresponding to five concentrations of bovine biofertilizer (0, 10, 20, 30 and 40%) and three nitrogen sources (calcium nitrate, ammonium sulfate and urea) and an additional treatment without nitrogen, in three replications. At the beginning of the blossom (45 DAS) were determined the concentration of chlorophyll a, b and total, the evaluations of gas exchange and the analysis of the leaf content of N. At 60 DAS were evaluated stem diameter, number of leaves per plant, leaf area, fresh and dry matter yield per plant, and at the end of harvest, It was determined the average fruit weight, fruit number and fruit yield per plant and the plant productivity. The biofertilizer in a concentration of 30% has provided the largest diameter of the stem of the plants. The combination of ammonium sulfate and biofertilizers have provided the maximum values xii for the number of leaves per plant, leaf area, fresh and dry matter production and per plant, average fruit weight, number and fruit production per plant, productivity, leaf content of N, chlorophyll a, total chlorophyll, net photosynthesis, transpiration, internal carbon concentration, stomatal conductance and instantaneous carboxylation efficiency. The ammonium sulfate and the urea singly have resulted in the highest chlorophyll b values and instantaneous efficiency in water use. The biofertilizer without nitrogen was not efficient upon growth, yield and physiological characteristics of the zucchini.