Dry Matter and Macronutrient Accumulation in Digitaria insularis Biotypes Susceptible and Resistant to Glyphosate

Abstract

Herbicide resistant is associated with morphological, physiological and metabolic alterations in weeds. These alterations may reflect changes in the nutritional status of resistant plants and their growth it can be inferred in greater adaptability and competitive ability of the resistant biotypes. Thus, the objective of this research was to determine the dry matter and macronutrient accumulation and distribution by glyphosate-resistant and susceptible plants of Digitaria insularis (sourgrass), growing under mineral nutrition standard conditions. The experimental design was completely randomized, with eleven treatments and four replicates. The treatments consisted of evaluation periods at 15, 30, 45, 60, 75, 90, 105, 120, 135, 150 and 165 days after emergence (DAE). The average time for maximum theoretical accumulation (PtMax) and for inflection points of dry mass and macronutrient were lower for susceptible (133 DAE; 99 DAE) than for resistant biotype (141 DAE; 105 DAE). However, considering the average time obtained by susceptible, dry mass (g) and macronutrients (mg) accumulation was always higher for resistant biotype. The decreasing sequence of nutrient accumulation was similar for both sourgrass biotypes: K, N, Ca, Mg, P and S.