Caracteres morfoagronômicos e rutina no trigo-mourisco em função da saturação por bases, densidade de semeadura, épocas de plantio e colheita

Abstract

Buckwheat (Fagopyrum esculetum Moench) is an important pseudocereal in agriculture, animal production and human food. It is very nutritious as it contains proteins with high biological value and high fiber content; however, the most relevant property is the presence of rutin, which confers antioxidant activity to the plant. The objective of this study was to evaluate the production of the plant, grains, total flavonoids and rutin in F. esculentum cultivars as a function of base saturation, density, sowing and harvesting seasons. Three experiments were carried out. Experiments 1 and 2 were carried out in a greenhouse, in pots, in a completely randomized design with four and five replications, respectively. Influence of the harvest season (experiment 1): the treatments were seven harvest seasons (every 15 days from emerging) and two cultivars (‘IPR 92’ and ‘IPR 91’) in a factorial design (8 x 2). Influence of base saturation (experiment 2): the treatments were the cultivars ‘IPR 91’ and ‘IPR 92’, five saturations per base in a factorial design (2 x 5). Experiment 3 consisted of evaluating the influence of density and sowing season. It was carried out in the field in a randomized block design with three replications. The treatments were the cultivars ‘IPR 91’ and ‘IPR 92’, two sowing seasons, May (winter) and November (summer), five populations (50, 100, 150, 200 and 250 seeds m-1) in a factorial design (2 x 5) of conjoint analysis. At the end of the experiments, the agronomic attributes of the plants were evaluated. Analyzes of dry matter, total flavonoids (spectrophotometric) and rutin quantification (high-performance liquid chromatography) were performed on the samples (plant aerial part). Data were subjected to statistical analysis. The results showed that the ideal is to harvest the buckwheat 86 days after emerging (DAE) for a higher rutin production (94,02 mg planta1), 56 DAE for ‘IPR 91’ and 98 DAE for ‘IPR 92’ for greater production of total flavonoids (56, 88 and 63,15 mg plant-1, respectively) and 72 DAE for greater grain production (1,67 mg plant-1). The 'IPR 92' has the highest biomass production per plant (0,37 g), while 'IPR 91' (3.54 g) is the most premature. Soil base saturation of 9% to 97% has no effect on flavonoid content (11.59 ± 3.29 mg g-1) of buckwheat, however, it influences the production of biomass (maximum production of 5.15g at 62.00%) and of grains per plant of the 'IPR 92' (maximum production of 0.28 g at 9.00%). The productivity of total flavonoids (42,63 ± 17,87 kg ha-1) and of rutin (48,39 ± 20,71 kg ha-1) did not show statistical differences considering sowing and density times. The results of biomass productivity (2,78 – 6,28 t ha-1) were positive in all treatments and surpassed the Brazilian and world production of the species in a short period of time. Winter cultivation is better to obtain more biomass (5,50 – 6,28 t ha-1) and grain yield (2,38 – 0,87 t ha-1). This work contributes to future scientific studies, improvement and cultivation of the species, bringing important and unprecedented results that answer questions related to growing conditions, harvest and sowing seasons of buckwheat in Brazil.