Reação de genótipos de trigo (Triticum aestivum L.) a doenças ocasionais em área de transição agroecológica

Abstract

Wheat (Triticum aestivum) is one of the most important cereals in the world, but its productivity can be impacted by diseases. Genetic improvement is an effective strategy for controlling these diseases. This study evaluated the area under the disease progress curve (AUDPC) and damage caused by diseases in wheat, as well as agronomic traits, during the crop cycles from May to October 2023 and June to October 2024, in 100 wheat genotypes. Evaluations were carried out weekly using diagrammatic scales for foliar diseases and calculating the AUDPC. Spike diseases were analyzed based on the proportion of infected spikelets. At the end of the crop cycle, plant height, number of tillers, stem thickness, number of spikes per plant, number of spikelets per spike, number of grains per plant, and plot grain mass were measured. In the AUDPC assessment for leaf rust, three groupings were identified, with 98 genotypes showing greater resistance. Regarding disease severity, in 2023, 23 genotypes had an average severity of 4%, and in 2024, 85 genotypes had an average severity of 0.3%. For yellow spot AUDPC, three resistance groups were observed, with 93 genotypes in the most resistant group. There was no significant difference in severity for this disease. For brown spot, there was no significant difference in AUDPC or severity in 2023. For blast, the 2023 AUDPC analysis identified four groups, with the resistant group containing 51 genotypes. In terms of severity, 64 genotypes had an average severity of 4% that year. For Fusarium head blight (FHB), in 2023, the AUDPC results divided the genotypes into three groups, with the most resistant group comprising 93 genotypes; regarding severity, 95 genotypes showed an average severity of 1%. For glume blotch in 2023, the AUDPC analysis identified four groups, with the resistant group including 80 genotypes. The group with the lowest severity had 79 genotypes, with an average severity of 2%. In 2024, brown spot, blast, Fusarium head blight, and glume blotch were not observed. Regarding agronomic traits, plant height showed significant differences. In 2023, eight groups were identified, with the best-performing group comprising a single genotype with a height of 81 cm. In 2024, only two groups were identified, with the best-performing group consisting of 87 genotypes and a mean height of 55 cm. No significant differences were observed for number of tillers per plant, main stem thickness, or number of spikes per plant. For the number of spikelets per spike, three groups were identified, with the best group including 95 genotypes and an average of 14 spikelets per spike. For the number of grains per plant, the topperforming group included 72 genotypes, with a mean of 43 grains per plant. As for grain mass per plant, the best-performing group included 55 genotypes, with an average mass of 14 g. This study enabled the identification of disease resistance in wheat accessions under the evaluated conditions.