Curva de crescimento e marcha de absorção de nutrientes da pitaia (Hylocereus undatus)

Abstract

Fruticulture is an extremely important activity for income generation and agricultural development in Brazil. Due to its continental dimensions and variations in climate, soil and temperature, the country is able to produce a wide variety of fruits, whether native or exotic. The commercial exploitation of exotic fruits has grown in the last years and the pitaia (Hylocereus undatus) it has excelled. This culture has aroused great interest due to the growing demand for their fruits, which are characterized by their exotic appearance and expressive prices in the internal and external market. However, studies on the development and nutrition of this fruit are incipient. The knowledge about the growth and mineral nutrition of the pitaia is fundamental for the correct management of the crop, since they provide information on the nutritional needs of the plants, indicating most favorable epoch for the application of fertilizers. Thus, the objective of this work was to evaluate the growth and absorption of macro and micronutrients by the pitaia. The experiment was carried out at the Federal University of Ceará (UFC), in the city of Fortaleza - CE, conducted in vase at vegetation house, using seedlings from the matrizeiro kept in the agriculture sector. The pots were filled with substrate prepared with the soil mixture and coconut fiber in a ratio of 3: 1. The experiment was set up in randomized blocks with six treatments and six replications. The treatments consisted of sampling times (45, 75, 105, 135, 165 and 195 days after planting). In each sampling period, the length and diameter of the cladodes were measured; after each measurement, the material was fragmented and sent to the laboratory for allocation in a forced air circulation oven (65°C) for 72 hours. The dry mass of the aerial part and the accumulation of macro and micronutrients were then determined. The data were submitted to analysis of variance at 5% probability, and when significant, polynomial regression was applied. It was concluded that the pitaia presented slow initial growth, intensifying from the 135 days after the planting. The total dry biomass accumulated by the plants at the end of the six-month period was 57.5 g of plant-1. The macronutrients were absorbed in greater quantity in the following order: K> N> Ca> Mg> P> S. The micronutrients were absorbed in greater quantity in the following order: Fe> Mn> Zn> B> Cu. The highest nutrient demand occurred at 195 days after planting.