Qualidade de feijão caupi em função de herbicidas dessecantes utilizados na pré-colheita e das condições de armazenamento

Abstract

Cowpea (Vigna unguiculata) is produced mainly in small properties in the northeastern region of the country. With the deficit in the supply of beans and the attractive prices observed in the off season, large producers of the central-west region began to grow cowpea beans, especially the Bico de Ouro variety. Because it is a dicotyledon with an indeterminate growth habit, the plants present dry pods, pods at the ideal point and green pods at the time of harvest. The manual harvesting on large properties is impracticable, being necessary the application of desiccants to standardize the senescence of the plants and the degree of maturation of the grains in order to allow the mechanized harvesting. Thus, this study aimed to: 1) To evaluate the consequences of using pre-harvest desiccants, end 2) Evaluate effects of storage temperature and atmosphere on the technological properties of cowpea, variety Bico de ouro. The herbicides glyphosate (GLI), glyphosate with carfentrazone (GLI/CAR), end paraquat (PAR) were tested in pre-harvest, in the first study. Cowpeas collected manually were used as control (SEM). The grains were also stored at 25°C for 8 months to evaluate the susceptibility to aging. In the second study, cowpea of the Bico de ouro variety were stored for 8 months under nitrogen or in a hermetic atmosphere at 15, 20 or 25°C. The application of herbicides in the pre-harvest changed the quality parameters of the cowpea. Cowpeas obtained from PAR and GLI treated plants showed darker coloration soon after harvest. However, in storage, the color of the cowpea coat treated with PAR remained more stable. The application of GLI provided accumulation at higher levels of phenolic compounds, especially complex compounds such as proanthocyanidins. It was possible to identify molecules of cowpea discrimination as a function of the herbicide used, being them: catechin-3- glycoside and epicatechin (for grains obtained from plants treated with GLI), Citric acid (for grains obtained from plants treated with GLI/CAR), end quercetin end gluconic acid (for grains obtained from plants not submitted to treatment with herbicides). Residual levels of glyphosate and paraquat were higher than the maximum levels tolerated by the Codex Alimentarius and the European Union. With regard to the second objective, the cowpea stored in nitrogen atmosphere at 20°C maintained color, firing and hardness attributes very close to the grains stored for the same period at 15°C.