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.
Highlights
One of the factors that presents high relevance for agricultural production is herbicide resistant biotypes in crop areas, which may be influenced by the interaction of ecological and biological characteristics of the species, genetic base and agronomical factors
The inflexion point (PtInf) obtained for resistant plants was at 101 days after emergence (DAE) with theoretical mean accumulation of 3.5 g per plant, and for biotype S, was at 97 DAE with theoretical mean accumulation of 2.5 g per plant
It is important to emphasize that the mean dry matter accumulation of biotype R was 40% higher than that of susceptible one
Summary
One of the factors that presents high relevance for agricultural production is herbicide resistant biotypes in crop areas, which may be influenced by the interaction of ecological and biological characteristics of the species, genetic base and agronomical factors. The D. insularis species is a perennial plant that is highlighted by the formation of rhizome and clumps, with slow initial growth and posterior exponential dry matter accumulation (Machado et al, 2008; Carvalho et al, 2013; Marques et al, 2014). Such factors is related to its aggressiveness as a weed species and may provide high competitiveness to the species for natural resources, among them, nutrients present in the soil. Competition for nutrients is one of the main ecological factors that may affect crop production
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