Estabilidade e adaptabilidade fenotípica de linhagens de melancia em várzea tropical e épocas de plantio de cultivares de cebola na região centro sul do Estado do Tocantins

Abstract

The study aimed at evaluate the stability and adaptability of fruit yield of watermelon genotypes in tropical lowland condition, and evaluate the effect of sowing dates on the agronomic and post-harvest characteristics of onion cultivars in South Central region of Tocantins state. To evaluate the stability of watermelon genotypes, four experiments were implanted in lowland, in Formoso do Araguaia municipality. The experimental design was a randomized block design with three replications. To study the stability and adaptability, the characteristics were average weight and fruit yield. In the year 2012 it was also evaluated the fruit format and Brix. To evaluate the adaptability and stability, we used the methods of Annicchiarico (1992) and extended Centroid by Nascimento (2009). To meet the second objective, three experiments were conducted, the first seeded on May 26, the second on 26 June and the third on 26 July 2015. We used the following onion cultivars: NUN 1205, Dulciana and Cimarron, all early-cycle type. The experimental design was randomized complete block with four replications and the evaluated agronomic traits were commercial bulb yield, plant height, average weight of commercial bulbs, bulb length, bulb and pseudostem diameter, bulb size and number of leaves. The characteristics analyzed in post-harvest were pungency, total acidity, pH, format and classification of bulbs. As a result, it became clear that the watermelon lines MCST # 01, MCST # 04, MCST # 09 and MCST # 12 were classified as general adaptability in lowland environments. The lines MCST # 01, MCST # 03, MCST # 04, MCST # 05, MCST # 06 and MCST# 12 as well as high yield, have ºBrix between 9 and 10, not differing from standard commercial Top Gun. The lines MCST # 01, MCST # 04, and MCST # 12 are promising for commercial cultivation or for the development of lowland-suitable hybrids. The sowing time affects yield, average bulb weight, plant height, length and diameter of the bulbs of onion cultivars. The highest yields were observed in June. The format and classification of the harvested bulbs meet the market demands, in several sowing dates, for the three cultivars. The pungency of the cultivars NUN 1205 and Dulciana was classified as middle and as high for Cimarron cultivar, regardless the evaluation time.