Extração de mucilagem, qualidade fisiológica e sanitária de sementes de pitaia

Abstract

The pitaya (Hylocereus undatus) is one of the fruit that has been standing out in the market, which demands more detailed scientific information about the establishment of the culture, in order to improve its production. Thus, four experiments were carried out, and in the first one, the objective was to study the effect of different methods of extracting mucilage from pink pitaya with red pulp on seed germination and vigor. The experimental design used was completely randomized, in a 4x2 factorial scheme, with four ways of extracting the mucilage from the seeds (water, sand, fermentation and blender) and two evaluation times by the accelerated aging test (48 and 72 hours). The variables analyzed were germination, first germination count, electrical conductivity and accelerated aging. The second experiment was developed with the objective of characterizing the imbibition curve for pitaya seeds with white pulp. The experimental design used was completely randomized, using four replications of 25 seeds. The curve was determined by weighing at systematic intervals, until the primary root protrusion of at least 50% of the seeds. The third experiment was carried out with the objective of proposing a methodology for evaluating the viability of Hylocereus polyhizus seeds by the tetrazolium test. The experimental design was completely randomized with four replications composed of 100 seeds each. Initially, the quality of seeds was evaluated by germination tests and first germination count. For the adequacy of the tetrazolium test, pitaya seeds were submerged in the solutions, in the respective concentrations of 0.075%; 0.1%; 0.25% and 0.5% for 2 hours in the BOD at 40ºC, temperature. The fourth experiment was carried out with the objective of evaluating the influence of the storage period on the health of pitaya seeds with pink and white pulp. The experimental design was completely randomized, in a 2x3 factorial scheme (2 cultivars and three storage periods: 6 months, 1 year and 2 years), with twelve replications of 50 seeds in each gerbox. The test was performed using the filter paper method (Blotter-test) to quantify the percentage of seeds infested by seed pathogens. The fifth experiment was carried out to evaluate the seeding depth in the pitaya (Hylocereus polyrhizus, Hilocereus undatus) seedling emergence test. The experiment was carried out in a completely randomized design, consisting of two cultivars submitted to three treatments (1.5, 2.5 and 3.5 cm depth), and four replications of 50 seeds each treatment. In the first experiment, it was concluded that the extraction of mucilage from pitaya (Hylocereus polyrhizus) seeds can be performed using the water and sand method. In experiment two, pitaya seed shows a three-phase pattern of imbibition. Phase I was characterized by an average permanence of six hours, followed by phase II, with an average of 19 hours, and concluding the threephase pattern with the emission of the radicle, phase III, after 36 hours. In experiment three, it was concluded that the tetrazolium test conducted at a concentration of 0.075% at 40 ºC for 2 hours is efficient to evaluate the viability of the seeds of Hylocereus polyhizus, as well as to differentiate lots with different physiological qualities. In experiment four, it is concluded that the storage of Hylocereus undatus and Hylocereus polyrhizus in a cold chamber can be carried out for up to 1 year. In experiment five, pitaya (Hylocereus polyrhizus and Hilocereus undatus) sowing can be carried out in trays with sand at 1.5 and 2.5 cm depth.