Emergência e sobrevivência de plântulas de capim-navalha quando submersas em diferentes alturas de lâmina de água

Abstract

The razor grass (Paspalum virgatum L.) is an invasive pasture weed that has been actually reaching high importance due the difficulty of controlling by conventional methods. This trial was carried out in order to evaluate the outgrowing pattern and survival of razor grass seedlings as a function of different water depths covering the seeds. The experiment was executed on two methodologies, where the first one evaluates the outgrowing pattern, and the second evaluates the survival of razor grass seedlings. The trials were installed at green-house conditions and it was used the completely randomized design, with six replications and the treatments arranged at factorial scheme 11 x 3 performed by 11 water depths covering the seeds (0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0 e 10.0 cm) and three ecotypes (Rondonópolis, Redenção and Cacoal). The effect of water depth and ecotypes was measured in the first trial by percentage of outgrowing seedling, relative frequency of outgrowing, medium time of outgrowing, seedlings outgrowing synchronism and outgrowing velocity index obtaining in the course of 30 days after planting; and in the second trial by mortality tax and dry matter also at 30 days after planting in the second trial. The ecotype Rondonópolis has seeds with high vigor, followed by ecotypes Redenção and Cacoal. It is possible to conclude in the first trial that the high percentage, uniformity and velocity of seedling outgrowing were obtained at condition of without water (0.0 cm) and 1.0 water depth covering the seeds, independently of ecotypes. The second trial showed that water depths equal or upper to 6.0 cm reduce the survival and dry matter of P. virgatum seedlings.