Determinação do período crítico de controlo de infestantes na cultura de feijão-verde - Phaseolus vulgaris L.

Abstract

Effective weed control is essential to ensure the success of agricultural production. In the green bean culture (Phaseolus vulgaris L.), weeds pose a significant threat, capable of vigorously competing for essential growth resources and the lack of knowledge of the most appropriate period for their control can result in reduced crop yield, in addition to increasing costs and time needed to control weeds. In this context, this study aimed to determine the critical weed control period in green bean cultivation. To achieve this, an experiment was conducted at the experi- mental field of the Faculty of Agronomy and Forestry Engineering (FAEF) from March to June 2023. The experimental design used was randomized complete blocks (RCBD), with eight treat- ments and four replications (blocks). Treatments were divided into two groups: one without control and the other with weed control during the first 15, 30, 45, and 60 days after emergence (DAE). The composition of the weed community, including frequency, density, weed height, species coverage, and dry biomass, was evaluated. Variables related to the crop measured were plant height, number of pods, pod length, pod diameter, yield, and respective losses due to treatments. ANOVA was performed using Fisher's test, followed by mean comparison using Tukey's test, both at a significance level of 5%, using STATA 14 software. Through the Sig- maplot 15.0 software and by fitting the yield data to the Gompertz Sigmoidal model, it was possible to determine the period before interference (PBI) and the total prevention period to interference (TPPI), thus allowing for the determination of the critical period for weed control, with a tolerance of 5% yield loss. In this study, 19 weed species were identified, distributed across 14 families. The species that stood out most within the weed community in terms of relative density were Portulaca oleracea (43.26%), Cyperus rotundus (11.51%), and Tribulus terrestris (9.99%). The highest crop yield was recorded in the treatment with weed control throughout the cycle (60 DDE), which was 4.34 ton/ha and the highest yield loss was 93%, which occurred when the crop coexisted with weeds throughout the cycle, resulting in a yield of just 0.26 ton/ha. The period before interference (PBI) was 13 DAE and the total prevention period to interference (TPPI) was 46 DAE. Therefore, the critical period for weed control oc- curs between 13 and 46 DAE, totaling 33 days