Potencial agronômico e em pós-colheita de genótipos de cebola em condição de clima tropical de baixa altitude

Abstract

The Tocantins is a state in the northern region of Brazil that does not produce onion commercially. Its main characteristic is to have a low altitude tropical climate. The objective of this work was to select onion hybrids with potential for cultivation in the Center South region of the state of Tocantins based on agronomic and postharvest characters in two years of evaluation. Two experiments were carried out in different years in the geographical coordinates 11º 44’42 ”south latitude, longitude 49º 03’05” W Gr. And 276 m altitude in a dystrophic red-yellow latosol. The experiments were developed in the experimental area of the Federal University of Tocantins, campus of Gurupi / TO. Twelve genotypes were evaluated, ten of yellowish bulbs: Cimarron, Don Victor, Dulciana, NUN 1205, Serengeti, Serena, Optima F1, Rebecca, NUN 1504, NUN 1502 and two with purple bulbs: Mata Hari and NUN 3010 In the two years of cultivation, the experimental design used was randomized blocks, with three replications. The agronomic characteristics of the cycle (days), diameter (mm), length (mm), shape (mm), average mass of the bulbs (grams) and productivity (t ha-1) were evaluated. The characteristics evaluated in post-harvest were: pyruvic acid content (Pungency), total soluble solids (ºBrix), pH, titratable total acidity and loss of fresh weight (%). Tocantins has the potential to cultivate early-cycle onion with a range from 78.00 to 130.66 days. Most of the evaluated genotypes have bulbs with a standard commercial cross- sectional diameter corresponding to class 3 (greater than 50 to 60 mm) and 3 full (60 to 70 mm), only the genotypes Optima F1, Rebecca, Serena and Cimarron were classified in class 2 (35 to 50 mm). The genotypes with the highest average bulb mass were the most productive: NUN 1504 (67.56 t ha-1), NUN 1205 (51.75 t ha-1), NUN 3010 (61.25 t ha-1), Don Victor (64.11 t ha-1) and Serengeti (70.00 t ha-1). There was a significant influence on the postharvest characteristics evaluated. All bulbs of the evaluated genotypes showed good post- harvest quality, with NUN 1205, Optima, Cimarron, Dulciana, NUN 1504, Don Victor, Serena and NUN 1502 of medium pungency, and the genotypes NUN 3010, Mata Hari, Rebecca and Serengeti considered of high pungency in the growing conditions of the south center of the State of Tocantins. The total soluble solids content was 6.83 to 8.16 ° Brix in the first year, with no difference between the evaluated genotypes, in the second Mata Hari, Cimarron, Rebecca and NUN 1504, with values of 7.93, 7.63 , 7.50 and 7.50 (ºBrix) respectively, were superior to the other genotypes. For ATT (% of pyruvic acid), only the Optima F1 genotype showed an increase in the second year of cultivation. The Cimarron genotype had a lower pH (5.04) and in the second year a reduction in the pH of the Rebecca genotype was observed. Greater weight loss (%) was observed in the NUN 3010 genotype, being more pronounced in the second year (9.55%), similar to the Serengeti genotype in the second year (9.80%).