Desempenho agronômico e reação de linhagens e cultivares de soja ao oídio (Eysiphe diffusa) em casa de vegetação

Abstract

The fungal diseases that attack the soy are represented by a scale of pathogens that reduce the productivity of the grains causing a higher damage to the agriculture. Among them we can highlit powdery mildew that develops itself in the leaf surface in form of spores reducing the photosynthetic rate of the plant. The genetical enhancement use for the diseases resistance is important to identifying the resistant’s genotypes beyond the prediction of a possible crossing that improve force and a better production for the desirable caracteristics. The work’s objective was evaluating cultivars for agronomic characters and evaluate the reaction to powdery mildew and determine the genetic divergence for the selection of parents. The experiment was performed in the vegetation’s house of Fazenda Capim Branco that is part from the Federal University of Uberlândia. They were evaluated eight genotypes in total, being four cultivars (UFUS 7415, UFUS 8310, UFUS 6901 e UFUS 7910) and two lineages (UFUS LTK e UFUS 7801) developed by the Genetic Improvement Program of Soy of UFU and two witnesses (BR MG 46 Conquista) and (BRS Jiripoca). It was verified the existence of genetic variability for all the agronomic traits NDF, NDM, APF, APM, NNM, AIPV, VG2, VG3, NTV, NSV, AACPD, PROD besides the level of infection for powdery mildew (POWDERY MILDEW). The characters OIDIO, NDM e AACPD showed H² higher than 89%. The genotypes UFUS 7910, UFUS 8310, UFUS L78 e BR MG 46 Conquista obtained the highest grain yields. The genotypes were grouped using the Tocher no method resulting in the formation of three groups and using the UPGMA method that result in two other groups. The NDM character was the one that more contributed for the genetic diversity among the genotypes. The promising hybridizations for a set of more powdery tolerant progenies with higher production were UFUS L78 x UFUS 8310, UFUS 7801 x UFUS 7910 e UFUS 7801 x BR MG 46 Conquista.