Glyphosate resistant ryegrass competitive ability

Abstract

Herbicide resistant plants may present changes in their physiology and aggressiveness. In order to evaluate the competitive differences of glyphosate resistant ryegrass, in a first experiment, resistant and susceptible biotypes grew in intra and interbiotypic competition in different environmental conditions (check, irradiance and water deficit). In a second experiment, these biotypes grew together in different proportions in the presence of wheat. The development of plants was evaluated in the first experiment by analyzing the number of leaves, height and dry biomass accumulated until flowering. In the second, the culture (tiller, nutrients and estimated productivity) and the ryegrass plants (quantitative and qualitative analysis) were analyzed through graphs and indices of grouping and competitiveness. Resistant ryegrass plants developed better in both conditions and experiments. In wheat, the presence of the potassium, sulfur and zinc nutrients and the final yield of plants in the coexistence with greater proportions of resistant plants were higher reduced. By the substitutive analysis, resistant ryegrass presented higher clustering coefficient and greater competitiveness than the susceptible biotype.