Grain yield stability of Zea mays L. varieties in the brazilian Middle-North region

Fifteen corn species and two triple hybrid (test) were evaluated in forty-one environments in the Brazilian Middle-North region, distributed in Piaui and Maranhao from 1999 to 2003. The objective was to study the adaptability and the stability of those materials for recommendation ends. We used a randomized block design with three replicates. The adaptability parameters and stability were made according to Cruz et al. (1989). The cultivars showed different behavior among themselves mainly at the level of environments, as in the average of the environments. Different behavior was also detected for these materials due to the environmental oscillations. The evaluated materials differed from adaptability and showed the same answer as for the yield stability, except the Assum Preto. They are very important to the Brazilian Middle-North region, because they have the best adaptation (bo > general average) and with b1 estimates equal to the unit (wide adaptability) as the triple hybrid BRS 3123 (test) and the species Sertanejo, AL 34, Asa Branca and San Francisco.