Bulb Yield Stability Study of Onion Lines over Locations and Seasons in Ghana and Mali

Onion is one of the most economically and nutritionally important vegetable crops in West Africa. Onions are very important for consumers due to the antioxidants and compounds they contain that may reduce inflammation, lower triglycerides and reduce cholesterol levels, resulting in lower risks of heart disease and blood clots. However, high-yielding varieties that are accessible to farmers remain scarce. The objective of the present study was to identify adapted onion genotypes for sustainable production in Northern Ghana and Southern Mali. Nine onion lines, including a check variety, were assessed for yield stability using a randomized complete block design. The trials were carried out in "technology parks" under the joint management of farmers and researchers. Onion bulb weight was recorded for each plot after harvest. Separate analyses of variances were performed for each location and season. Analysis of variance of combined locations, seasons and lines was performed to determine the most stable varieties using the line-superiority measure and ecovalence stability coefficients. Results indicated that the lines AVON1310 and AVON1325 were most stable for yield performance over locations and seasons (Wi = 2.20 and 11.60, respectively; Pi = 1.32 and 6.56, respectively). From the genotype main effects and genotype-by-environment interaction biplots, the best performing lines were AVON1310 (33.32 t.h(-1)), AVON1308 (28.81 t.h(-1)) and AVON1325 (31.68 t.h(-1)). The stability of these lines makes them potential candidates for commercial release in West Africa to contribute to sustainably intensifying onion production in the region.