PROGRESSO TEMPORAL DE COMPLEXOS DE DOENÇAS FOLIARES E PATOLOGIA DE SEMENTES DE HÍBRIDOS COMERCIAIS DE MILHO

Abstract

The knowledge of the evolutionary dynamics of the diseases in the field corn crop and its consequences on the microbial population of seeds, can represent important epidemiological information for control maize diseases. The objective of this work was to study the temporal progress in field of foliar disease complexes and seed pathology of commercial maize hybrids grown in the 2015/2016 harvest. The experiment was carried out with 14 commercial hybrids of maize and developed in the municipality of Ipameri-Goiás, represented by: Lg6050PRO2©, Dow2B610PW©, Dow2B633PW©, Dow2B810PW©, Dekalb310PRO2©, Dekalb290PRO3©, Syngenta Supremo Viptera© , Syngenta Status Viptera3©, Agroceres7098PRO2©, Agroceres8677PRO2©, Ms30A37PW©, Ms552PW©, Agroeste1633PRO2© and Ns90PRO©. The design consisted of 10 blocks. The experiment was conducted in two stages: Stage A - evaluated the severity per leaf through a diagrammatic scale, at 47 days after planting (DAP), 53, 59, 74, 81 and 95 DAP, being chosen at random 10 plants/hybrid, and on each leaf evaluated the type of incident disease responsible for the damage. The area parameters below the disease progress curve (AUDPC), productivity, and dependente variables were analyzed via componentes, biplot, heat maps and linear correlation. In stage B - the seeds were harvested at 95 DAP and submitted to the blotter test and the %germination (%G), % of microrganisms incidence (%IM), % of fungus genus (%GF) and calculated diversity parameters (species richness, Shannon, and Simpson index), analyzed by ANOVA. The complex of diseases observed in the hybrids were leaf blighthelmintosporiosis, common rust, macrospora leaf spot, leaf spot of cercosporiosis and white spot. The Ns90PRO® hybrid presented lower progression of the foliar diseases complex, thus it was the most resistant with consequent lower AUDPC in the plant, the hybrid Agroceres7098PRO2© also presented lower AUDPC and higher productivity. Dow2B610PW© showed greater progress in disease development. Lg6050PRO2© presented lower productivity and higher AUDPC in the plant. Hybrids showed %G above 87%, except Agroceres8677PRO2©, Dow2B810PW© and Ms552PW©. The genotypes of fungi observed in greater proportions were 100% of the seeds with Penicillium sp., 74% Fusarium sp. and 7% Botrytis sp. There was no relation between the pathogens causing foliar diseases and the pathogens identified in the seeds.