Weed management using herbaceous legume plants intercropped with coffee culture

Abstract

Soil cover with legume plants is an alternative cropping method of integrated weed management, whose characteristics of the species intercropped with coffee plants might interfere physically, chemically and biologically in the crop and in the weeds. The objective of this work was to evaluate the potential of herbaceous legumes in the weed management in the interrows in the coffee crops. Therefore, two experiments were established in the region of Zona da Mata in the Atlantic Wood bioma and one experiment was set in Alto Paranaíba in the Cerrado bioma, both of which hold part of the coffee production in Minas Gerais. The coffee plantations in the Zona da Mata region have a marked slope, narrow spacing and limited mechanization and Alto Paranaíba region is characterized by coffee plantations with a flat relief, broad spacing and continuous mechanization. The experiment in Zona da Mata was conducted in Viçosa, MG, one in a bearing Catuaí Vermelho cultivar coffee crop, with a 3 x 1 m spacing, with more closed interrows because of the crown of the coffee plants, reducing weed infestation. The other experiment was set in a crop with newly pruned coffee plants, Catuaí Vermelho cultivar, with 3 x 1 m spacing, with openinter rows, increasing weed infestation, which was favored by increased exposition to light. It was used a random block experimental design in both experiments with four replicates, made up of eight treatments in 3 x 2 + 2 factorial scheme, which were as follows: three legume species: forage peanut (Arachis pintoi), siratro (Macroptilium atropurpureum) and lablabe (Dolichos lablab); and two planting forms with two and three rows of legumes centralized at the interrows of the coffee plants, spaced by 0.50 and 0.25 m in thebearing coffee crop and by 1.0 and 0.50 min the newly pruned coffee crop, respectively. The two additional treatments for those experiments consisted of hand weedings with a hoe and chemical control with glyphosate. The experiment in Alto Paranaíba was conducted in Patrocínio, MG, set up in a bearing coffee crop at eight years of age, cultivar catuaí IAC-99 with a spacing of 3.80 x 0.70 m. It was used arandom block experimental design with four replicates, constituted of ten treatments in a 4 x 2 + 2 factorials cheme, which were as follows: four species of perennial legumes (forage peanut (Arachis pintoi), java hybrid (Macrotyloma axillare), perennial soybean (Neonotonia wightii) and wild ground nut (Calopogonium mucunoides)) and two planting forms with two and three rows of legumes centralized in the interrows of thecoffee plants, spaced by 0.50 and 0.25 m, respectively. The two additional treatments consisted of hand weeding with a hoe and chemical control with glyphosate. It was found in the experiments in Zona da Mata that lablabe provided the greatest soil cover, the greatest predominance of the vegetation on the weeds and the smallest weed infestation at 90 and 120 days DAP. Lablabe and forage peanut presented higher biomass yields in its first and second year, respectively. Lablabe and siratro and forage peanut provided thesmallest density and biomass of the weeds, in their first and second year, respectively. Legume promoted higher soil moisture and less weed infestation in the first year in comparison to the additional treatments.There were no differences of influence on soil moisture, plant height and yield of the coffee plant among the legume species and among the additional treatments. In Alto Paranaíba, it was found that the java hybrid maintained the highest biomass yield and forage peanut expanded soil cover in the two years. Legumes promoted the least infestation density and the poorest weed biomass yield in the two years’ intercropping with the coffee crop compared to the additional treatments. Java hybrid, wild ground nut and forage peanut in the first year and the hybrid of Java and pinto soybean, followed by pinto soybean in the second year,promoted the smallest density and biomass of the weeds. The number of productive nodes and coffee yield did not differ among when legumes and additional treatments were compared. In all the experiments, the cultivation of two or three rows of legumes did not differ from each other in soil cover, in weeds and in the coffee crop. Herbaceous legumes intercropped with coffee reduce weed infestation and it is an alternative culture practice of integrated management for that population, contributing towards the decrease of herbicide application and weeding labour.