Efeito do glifosato aplicado no florescimento da soja em parâmetros morfofisiológicos e no desempenho da cultura

Abstract

The use of herbicides for weed control has been established as one of the most effective methods. However, these products can induce stress in soybean plants, even those that are resistant, depending on weather conditions during spraying and the plant's developmental stage. This study aimed to evaluate the effect of glyphosate application at soybean flowering on morphophysiological traits and crop productivity. The experiment was conducted at the Universidade Tecnológica Federal do Paraná, Dois Vizinhos Campus, during the 2021/22 growing season. The treatments consisted of different glyphosate rates (0, 1.5, 3.0, and 4.5 liters per hectare of the commercial product) applied at two developmental stages (R1 and R2). The variables analyzed included chlorophyll A, B, and total content at 7, 14, 21, and 28 days after each application; leaf area index and photosynthetically active radiation at R1, R2, and R5.2; morphological and yield components; and grain yield. A randomized block design was used. Data were subjected to analysis of variance and compared using Tukey’s test. Pearson’s correlation analysis was also performed among the variables. Increasing glyphosate rates during the soybean flowering stage did not affect most yield components or overall crop productivity. In general, chlorophyll content decreased with increasing glyphosate rates, especially when applied at the R1 reproductive stage. Grain yield was generally positively correlated with chlorophyll content, particularly when measured shortly after glyphosate application.