Competition of maize hybrids with alexandergrass (Urochloa plantaginea)

Abstract

Maize is one of the world's major cereals, and alexandergrass is the most damaging weed in the crop. The objective of this work was to evaluate the relative competitive ability of maize hybrids in the presence of alexandergrass through replacement series experiments. The experiments were set up in a complete randomized block design, with four replications. Firstly, for the maize hybrids as well as for the alexandergrass, the plant population was determined in which the final production becomes constant. were composed of plastic pots with a capacity of 8 dm3, and in each experimental unit was placed in the proportion corresponding to each treatment (100: 00, 75:25, 50:50, 25:75 and 0: 100) in each experimental unit, the species competing or not between them. For each hybrid, a separate experiment was considered with the objective of evaluating intra and interspecific competition. The analysis of the competitiveness of the species was carried out through diagrams applied to the replacement experiments and by the relative competitiveness indexes. At 50 days after the emergence of the maize the leaf area (LA) and the dry mass of the aerial part (DM) of the plants were checked. The relative competition was occured among the weed and each maize hybrid, being negatively affected for both of species, independently of the proportion of weed causing reductions in LA and DM of the maize. Interspecific competition causes less damage to LA and DM of species than intraspecific competition. There is basically competition for the same environment resources (water, CO2, sun light and nutrients) between maize and alexandergrass, being the crop more competitive than the weed.