Abstract

This study addresses the need to find preemergence herbicides for the direct sowing of forest species seeds dedicated to the establishment of energy plantations. Twelve different preemergence herbicides were evaluated on the direct sowing of two forest species with great potential for biomass production for bioenergy. One of the limiting aspects of dendroenergetic plantations is the high establishment cost by concept of plant acquisition, so a search was conducted for the best options for direct sowing of pregerminated seeds of Gmelina arborea (Melina) and Gliricidia sepium (Black Madero), and to offer an alternative in lowering costs. The experiment was carried out in a greenhouse (ITCR, Cartago), for 10 weeks, analyzing each species separately. A randomized complete block experimental design was used. The seeds were subjected to the best pre-germination treatment and sown in pots, they were immediately atomized by the different pre-emergent herbicides following the protocol described in the methodology. At the end of the experiment it was determined that pre-emergent herbicides with Linuron and Oxyfluorfen as their active ingredient can be used in the direct sowing of melina, as they did not cause damage to plant performance, in addition to obtaining most of the parameters with statistically superior results. In the case of black Madero, the pre-emergent Linuron obtained the best results, concluding that it can be useful for its use in direct sowing. The pre-emergent herbicide with Pendimethalin as its active ingredient obtained the lowest performance results in almost all of the analyzed parameters; for both species it produced the total death of weeds before week 7.

Key words: Dendroenergy; plantation establishment; herb control; agrochemicals; Costa Rica