Adaptation and Yield Stability of Eight Local Lowland Varieties. Abd. Azis Syarif and Syahrul Zen. The availability of improved rice variety adapted to high altitude areas and suitable for consumers preference in West Sumatra is very limited. Majority of rice farmers in high altitude area in West Sumatra grow many adapted local varieties. This activity aimed at estimating yield adaptability and stability of selected local varieties as a requirement for variety release. The yield and other agronomic traits of eight local and one improved varieties (Batang Sumani) were evaluated at six locations in Solok District, using a Randomized Complete Block Design with three replications at each location. Regression technique of varietal yields at each location on environmental index (mean yield of all varieties at correspondent location) was used to assess the adaptability and stability of particular varieties. The results showed that local varieties of Caredek Putih and Caredek Merah gave the highest mean yields, 5.39 and 5.18 t/ha (13.87 and 9.28% higher than that of improved check variety) respectively. These varieties were found to be stable, indicated by non significantly different of their regression coefficient from 1.0 and deviation from regression from 0.0.