Aptitude of Brazilian oat cultivars for reduced fungicide use while maintaining satisfactory productivity
The aggressiveness of fungal diseases in oats compromises grain yield. Although fungicides are effective for control, there is a need for productivity with food and environmental safety. Thus, we seek cultivars responsive to more sustainable management. The objective of this study was to identify oat cultivars that are more responsive to reduced fungicide use and a longer application-to-harvest interval with satisfactory yields, and to identify relevant variables in the simulation of grain yield by multiple linear regression. The study was carried out in 2019 and 2020 in Augusto Pestana, RS, a prominent region for oat cultivation in Brazil. The experimental design was randomized blocks, with three replications in a 22 x 4 factorial scheme, for 22 oat cultivars, recommended and no longer suitable for cultivation and four conditions of sequential use of fungicide (no application; one application 60 days after emergence; two applications, 60 and 75 days after emergence; and three applications, 60, 75 and 90 days after emergence). The fungicide used was FOLICUR® CE, at a dosage of 0.75 liters ha-1. The variables analyzed were necrotic leaf area and grain yield. The Stepwise technique was used to identify potential variables for the multiple linear regression model. The cultivars FAEM 4 Carlasul, URS Altiva, URS Charrua and URS Guará show superiority in grain yield in the absence of fungicide. In a single application, 60 days after emergence, FAEM 4 Carlasul and URS Charrua showed productivity above 3000 kg ha-1 with a long interval (around 60 days) from application to harvest. The variables minimum average temperature, necrotic leaf area and number of fungicide applications were found to be suitable for the composition of a multiple linear regression model to simulate grain yield.