Resumo

VACA PAZMINO, Eduardo Patricio et al. Effect of herbicides on the population of microorganisms in the cultivation of Theobroma cacao L., in the Luz de América parish, Ecuador. Siembra [online]. 2025, vol.12, n.1, e7320. ISSN 2477-8850.  https://doi.org/10.29166/siembra.v12i1.7320.

Conventional agriculture is characterized by excessive use of machinery, agrochemicals, and environmentally unfriendly practices. We aimed to determine the effect of herbicides (glyphosate and paraquat) on the population of rhizosphere microorganisms in Theobroma cacao L. crops in the municipality of Luz de América, Ecuador. The research was carried out between June and November 2019 in a seven-year-old crop planted in a 4x4 m arrangement, with 6.36 % organic matter, silt loam clay loam soil, and pH of 5.93 with identical management throughout the plantation. The treatments were: T1 = systemic herbicide-glyphosate (1.5 l/ha); T2 = contact herbicide-paraquat (1.5 l/ha); and T3 = mechanical control-mower-control; each with six replicates. Three soil subsamples were taken and sent to the laboratories of the Instituto Nacional de Investigaciones Agropecuarias (INIAP). The variables measured were population growth, genus identification, and fungal population growth of sample. Statistical analyses were carried out using Tinn-R. Day 28 marked a significant difference between all observations (P-value=0.0269); the presence of microorganisms had a higher concentration when paraquat was used (1,894,001 CFU/ml). The presence of Trichoderma (higher in paraquat) and Fusarium (higher in glyphosate) was noted when evaluating the population development of the fungi. Considering the treatments and the days of observation, it was confirmed that the population of Trichoderma decreased in greater proportion when glyphosate was applied. We conclude that the two herbicides increase the development of Fusarium, although paraquat to a lesser extent, while paraquat favors the presence of Trichoderma.

Palavras-chave : Population concentration; weed control; herbicides; rhizosphere microorganisms; Theobroma cacao L.

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