Ecological weed control in rice and maize using Orbygnia phalerata with focus on the weed seedbank in the soil
The aim of this study was to evaluate the effect of mulching with dry leaves of babassu palm (Orbygnia phalerata Mart.) on germination of weed seed bank on rice tiller number and on grain yield of rice and maize in Maranhão state, northeastern Brazil. In the field the experimental design was a split plot in a randomized complete block with 15 replications. Rice, maize and rice intercropped with maize were allocated to the main plots and mulching treatments with unprocessed whole dried palm leaves (0 and 23 t ha-1) to the subplots. Germination of the weed seed bank was assessed after crop harvest in the greenhouse by means of a collection of three soil samples per subplot (n = 270) with an open metal device of 25 cm in length x 16 cm in width x 3 cm in height as sampling unit. Soil samples were placed in aluminum trays in the greenhouse and irrigated daily. The germinated weed species were identified and counted every fifteen days. The results showed that mulching can reduce germination in the weed seed bank up to 55% and promoted a significant increase in rice tiller number from 63 to 95 m-2, grain yield of rice from 1,077 to 2,251 kg ha-1 and grain yield of maize from 1,137 to 2,293 kg ha-1. Therefore, mulching can be recommended for weed control in smallholder farming of rice and maize crops.