Interferência de doses de nitrogênio e aplicação de fungicida na severidade de mancha amarela e produtividade em trigo

Abstract

The presence of fungi in plant tissues, in addition to reducing productivity, can influence nitrogen absorption. The objective was to evaluate the influence of different doses of N, and the application of fungicide, on the severity of yellow spot in wheat plants. An experiment was carried out in a two-factor scheme arranged in a randomized block design, with four replications, at UFFS, Campus Erechim, 2021 crop season. The wheat cultivar TBIO Toruk, moderately susceptible to yellow spot, was used and the plants were submitted to four doses of nitrogen, being: 18.25; 36; 76; and 116 kg/ha, with and without the application of fungicides. The following were evaluated: severity of yellow spot, area under the disease progress curve, chlorophyll a, b and total, ear length, number of spikelets/ear, number of grains/ear, empty grains/ear, plant height, hectoliter weight, thousand grains weight, yield, number of tillers, number of ears, dry mass of leaves, dry mass of plants, leaf area index and electrical conductivity. The data were submitted to ANOVA, using the R software, the regression equations were generated for the nitrogen rates, and the comparison test of means for the fungicide factor. As the environment was not favorable for the development of the disease, the plants treated with fungicide did not differ from those of the control for the severity of yellow spot. The thousand grains weight was higher in plants treated with fungicides, while the productivity per area was higher in the control plants. Hectoliter weight and thousand grains weight decreased with increasing N doses. It is important to repeat the same experiment in a year with favorable environmental conditions for the development of the disease, in order to compare the results obtained in that study.