Field emergence of Marandu palisadegrass infl uenced by specifi c seed weight and sowing depth1

Abstract

Several species of harmful grass weeds were voluntarily brought in by man, mainly with the specifi c purpose of produce forage. These species compete with crops for physical area and environmental resources, can host pests and diseases, and interfere on harvesting. This work aimed to evaluate in fi eld conditions, the eff ects of diff erent specifi c seed weight and sowing depths on the emergence of the species Urochloa brizantha cv. marand & uacute;. It was adopted a randomized blocks design with four replications and the treatments arranged in a 6 x 3 factorial scheme, with six sowing depths (1.0, 2.0, 4.0, 8.0, 12.0 and 16.0 cm) and three specifi c seed weight (low, medium, and high). The treatment eff ects were evaluated by seedling emergence in fi eld. The marandu-grass seedlings emerged until 12 cm depth, regardless of specifi c seed weight and year. Sowing depths between 1.0 and 4.0 cm depth have promoted the greater percentage of emergence, and the lowest average time and speed index for emergence of seedlings on fi eld, regardless of the specifi c seed weight. High-specifi c weight seeds resulted in greater percentage of emergence on fi eld, speed and synchronicity index of emergence of marand & uacute;-grass seedlings. Sowing depths higher than 1.0 cm induces a delay on marand & uacute;-grass propagation.