Seletividade de sulfentrazone e diuron em feijão comum em dois solos do paraná

Abstract

The selection process for an herbicide must consider both successful weed control and selectivity for a cultivated species. Agronomic efficiency studies of herbicides (selectivity and control) are more informative and should preferably be carried out both in soils with distinct carachteristics and using distinct genotypes. Experiments carried out in a greenhouse at UTFPR, Campus Pato Branco, aimed to determine the selectivity of the herbicides sulfentrazone and diuron for Phaseolus vulgaris L., applied alone or in association with each other, in soils Argisol (sandy) and Oxisol (clay) types. The tests performed were: (a) preliminary dose-response experiment with the herbicide diuron; (b) dose-response experiments with the herbicides sulfentrazone and sulfentrazone+diuron, in Argisol and Oxisol. Relative tolerance, plant height, leaf area and shoot dry mass of common bean were determined. Data were subjected to analysis of variance using the F test (p=0.05) and the means were adjusted to the three-parameter logistic model. The cultivars showed high sensitivity to diuron herbicide and the minimum dose used, 87.5 g ha-1, was sufficient to reduce plant bean tolerance. The effect of treatments with sulfentrazone and sulfentrazone+diuron varied according to cultivar, dose and soil. In general, both in the Oxisol and in the Argisol, the associations of sulfentrazone+diuron reduced more the tolerance of the bean plants, compared to sulfentrazone alone. The selectivity of sulfentrazone and sulfentrazone+diuron to common bean was lower in Argisol than in Oxisol. The doses necessary to achieve 50% reduction in plant tolerance or development (D50) revealed much higher tolerance to herbicide treatments for cultivar BRSMG Talismã than for IAC Imperador. There was a protective effect of diuron on the phytotoxicity generated by sulfentrazone in some combinations between these herbicides, which should be better clarified in further studies.