Effect of cultivation practices on the quality of onion bulbs (Allium cepa L.) produced at two sites in northern Senegal: Evaluation of morphological and physicochemical parameters

Abstract

In Senegal, onions (Allium cepa L.) are an important and widely consumed crop. Several varieties and speculations are cultivated, with yields and bulbs qualities depending on technical itineraries and cultivation areas. The aim of this study is to evaluate the quality of onion bulbs produced at the Kalassane and Nguéthioro sites, using morphological and physicochemical parameters. To this end, an optimized treatment based on the “Société Nationale d’Aménagement et d’Exploitation des terres du Delta” (SAED) technical data sheet, requiring water and fertilizer inputs to be controlled (4455.4 m3 of water/ha, 9 kg/9 m2 of organic matter applied before sowing and 224 g/m2 of N- P-K applied in 4 inputs), another based on the farmers' method using excessive quantities of water and fertilizers (6526.1 m3 water/ha, 12 kg/9 m2 organic matter applied after sowing and 748 g/m2 N-P-K applied in 5 applications), and their combinations were applied on Kalassane. Next, the best method for ensuring quality bulbs at Kalassane was also tested at Nguéthioro. The results show that at Kalassane, onion bulbs from the optimized method are small (67.96 ± 14.40 g) and less waterlogged (Wc 85.44 % ± 0.71, aw 0.83 ± 0.01), with a high total polyphenol content (7.01 mg/100 g ± 0.01), in contrast to those from the farmers’ method, which are 100.80 g ± 14.22; 87.14 % ± 0.69; 0.91 ± 0.01 and 2.11 mg/100 g ± 0.01 respectively. In short, this study leads to the conclusion that optimized practice is the best treatment guaranteeing better quality. In addition, the optimized method showed a difference between the results for the two sites. In the future, repeating this experiment coupled with edaphic characteristics will enable us to determine the influence of soil on the physicochemical and nutritional quality of onions.