Resumen

GUTIERREZ, W et al. Evaluation of different herbicides on weeds control, development, yield and relative net benefit of cassava crop Manihot esculenta Crantz under agro ecological conditions at Maracaibo plain. Rev. Fac. Agron. [online]. 2008, vol.25, n.1, pp.26-42. ISSN 0378-7818.

An experiment was carried out at the experimental field "Ana Maria Campos" of the Facultad de Agronomia of la Universidad del Zulia, Agronomy Faculty, University of Zulia, located at San Francisco municipality Km. 7; with the aim of evaluating the effect of the herbicides type on the percentage of weeds control, development, yield and relative net benefit of cassava crop Manihot esculenta Crantz, "tempranita" cultivar, under agro ecological conditions of Maracaibo plain. Area is characterized by having precipitations of 400-600 mm.year^-1, average temperature of 28ºC and soils with sandy and loamy texture, classified as very dry tropical wood. A split plot design with nine treatments and three replications was used. The experimental unit was represented by a plot with three rows of 8 m length and 2 m of division between them, sowed in both sides. Analysis of variance determined a significant effect (P<0.01) of the herbicide type on variables percentage of weeds control, plant's height, stem's diameter, photosynthetically active leaves number, weight of commercial roots per hectare and relative net benefit. Among different herbicides evaluated, the best weeds control (99.4%) was obtained with the application of oxifluorfen 840 g i.a.ha^-1 on pre-emergency in both the weed and in the crop. This treatment also allowed a better development of the crop, plant height (94.1 cm), stem diameter (12.0 mm), number of leaves (78.7), higher yield of roots (24.000 kg.ha^-1) and relative net benefit (10.576,64 Bs.F.ha^-1).

Palabras clave : Manihot esculenta; weeds control; herbicides.