Adaptability and stability of ‘Valenciana’ onion populations in the Brazilian tropical semi-arid

Brown onions of the ‘Valenciana’ type are not available for short-day growing conditions in the Northeast of Brazil. The goal of this study was to estimate parameters of adaptability and stability in order to release ‘Valenciana’ onion cultivars in the Northeast of Brazil. Eight populations of onions derived from a cross between ‘Baia population’ בValcatorce INTA’ and improved by recurrent selection were associated with six commercial onion cultivars, included as controls; they were evaluated in five experiments carried out in the municipalities of Petrolina, Pernambuco, Juazeiro, Bahia and Belem do Sao Francisco, Pernambuco. The experimental design was a randomized block design with three replications. Total and commercial bulb productions were evaluated for adaptability and stability parameters according to the methodologies of Eberhart and Russell, Lin and Binns and Main Effects and Multiplicative Interaction (AMMI). Significant genotype × environment interaction was observed for the two analysed variables. Eberhart & Russell and AMMI showed similar results for the overall cultivars, while some discrepancies were observed under the Lin & Binns method. The three methodologies produced concordant results for the ‘Valenciana’ onion types. The 25CA10 and T811CR13B’Valenciana’populations demonstrated broad adaptability and stability, associated with bulb production close to some cultivars and the commercial hybrid, and will be protected and released as new cultivars in the Northeast region of Brazil.