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

Abstract

Onion is one of the most economically and nutritionally important vegetable crops in West Africa. However, high-yielding varieties that are accessible to farmers remain scarce. Onion lines from the World Vegetable Center’s Allium program were evaluated during the cool and dry season from September to March for three years to identify adapted onion lines suitable for sustainable intensi-fication of production systems in Northern Ghana and Southern Mali. Trials were implemented in the Upper East and Northern Regions of Ghana and in two districts in the Sudan savanna zones of Mali (Bougouni and Koutiala). 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 made to determine the most stable varieties using the line-superiority measure and ecovalence stability coefficients. Results indicated that lines AVON1310 and AVON1325 were most stable for yield performance over lo-cations and seasons. From the genotype main effects and genotype-by-environment interaction (GGE) biplot, the best performing lines were AVON1310 (33.32 t.h-1), AVON1308 (28.81 t.h-1) and AVON1325 (31.68 t.h-1). These lines are potential candidates for sustainable intensification of onion production in Ghana and Mali.