Eficiência de coberturas mortas no controle de plantas daninhas na cultura da alface (Lactuca sativa) em ambiente protegido

Abstract

Weed interference is one of the main limiting factors to the growth and productivity of lettuce cultivated in soil, especially in systems that aim to reduce herbicide use. The adoption of plant mulches has stood out as a sustainable alternative, as it contributes to weed suppression, soil moisture conservation, and improvement of edaphic conditions, in addition to enabling the use of regionally available agricultural residues. In this context, such mulches present technical and economic potential for conventional and organic cropping systems. Thus, this study aimed to evaluate the efficiency of different plant mulches in weed suppression and their effects on the growth and yield of Crisphead lettuce ‘Grand Rapids TBR’ (Lactuca sativa). The evaluated treatments were coffee husk, wood sawdust, emerald grass straw, no mulch with manual weeding, and no mulch without weeding. The experiment was conducted in a greenhouse at the Federal Institute of Education, Science and Technology of Minas Gerais – São João Evangelista Campus, using a randomized block design with five treatments and four replications. The analyzed variables were leaf chlorophyll content (LCC), head diameter (HD), number of leaves (NL), fresh shoot mass (FSM), dry shoot mass (DSM), and mulch efficiency (ME) in weed suppression. Data were subjected to analysis of variance, and means were compared using Tukey’s test (P ≤ 0.05). The treatment with manual weeding showed the highest values for all productive variables, with FSM of 531.1 g, DSM of 35.3 g, HD of 56.0 cm, and LCC of 31.1 SPAD units. The plant mulches composed of coffee husk, sawdust, and grass straw showed intermediate performance, with FSM ranging from 226.6 to 250.7 g and DSM from 18.5 to 21.2 g, in addition to high weed suppression efficiency, with ME above 85%. The treatment without mulch and without weeding showed the lowest productive values, with FSM of 64.5 g and ME of 0%. The results indicate that the use of plant mulches is efficient in reducing weed infestation and promotes satisfactory lettuce growth, representing a sustainable alternative to intensive manual weed management.