Seleção de progênies de soja visando à resistência ao nematoide de cisto

Abstract

Soybean is an oilseed considered one of the most important species in the economic world environment and has greatly contributed to the Brazilian crops’ economic and technological revolution. Soybean breeding has increasingly focus on studies to diseases resistant, and in Brazil about 35 pathogens affect soybean crop, and soybean cyst nematodes (Heterodera glycines) is one of the most yield limiting to this crop. The increase of resistance alleles has been the focus of soybean breeding programs since the use of resistant cultivars to the soybean cyst nematode is still one of the most efficient method of control. In this context, the goal of this study was to select resistant soybean progenies to the soybean cyst nematode with the use of molecular markers associated to sources PI 88788 and Peking resistance. The experiments were carried out in two distinct periods: 2019 winter season, at Formoso do Araguaia city, Tocantins State; and in 2019/2020 summer season at Jaciara, Rondonópolis and Santo Antônio do Leste cities, all located in Mato Grosso State. Eight biparental populations obtained by crossings were used. In 2019 winter season, the plot consisted of one line with 3.0 meters length, spaced 0.5 meters apart. In 2019/2020 summer season, the experimental design used was randomized blocks with two replications. Any plot consisted of two lines with 5.0 meters length and 0.5 meters rows spaced. Assessment of the following agronomic traits was done: resistance to cyst nematode determined by molecular markers associated to resistance alleles Rhg1 and Rhg4 and grain yield, determined by the conversion of plot yield weight to bags.ha-1, at 13% standardized moisture. Data analysis was performed through R Statistical software analysis program and selection of the best progenies was done. From 96 progenies analyzed by molecular markers, 14 were selected with resistance to Soybean cyst nematode resistant, and two of them, 17BC560328_7 and 17BC560328_5, the most promising in terms of yield grain, yielding the highest averages in the three tested environments, in addition, both carrying the Rhg1 gene associated with the resistance source PI88788, which carry tolerance to race 3, and moderate tolerance to races 6, 9, 10 and 14 of the soybean cyst nematode.