Boonseng O.,¹ C. Rodjanaridpiched,²

Crop performance under a broad range of environments can be studied to reveal cassava varieties with high yield stability. The objective of this study was to recommend cassava varieties for either a wide range of environments or for specific environment. When the effect of variety x environment interaction was high, cassava variety yielded differently under different environments. Thai cassava varieties were grown in late rainy season (October), 1992 to assess their stability. Five cultivars, namely Rayong1, Rayong60. Rayong90, Sriracha1, and Kasetsart50, were planted under 11 environments. At each environment, the mixed fertilizer 15-15-15 was applied at the rate of 0, 313, 625 and 1,250 kilogram per hectare. Only the data on dry root yield were analysed. Results of the analysis, the Additive Main effects and Multiplicative Interaction (AMMI) (Gauch, l988), indicated that all cassava varieties gave the highest yield at the rate of mixed fertilizer 15-15-15 of 625 kilogram per hectare. Rayong90 was high in both mean yield and stability when compared to K asetsart50, Rayong60, Rayong1, and Sriracha1. For specific environment, Kasetsart50 gave the highest yield in low yielding environments, such as Burirum Farm, Dankhuntod Farm, Korat Farm, Ladbaukao Farm, Rayong Field Crops Research Centre, Sikhiu Farm and Seongsang Farm. Additionally, Rayong60 and Rayong90 gave the highest yield in high yielding environments, e.g. Khonkaen Field Crops Research Centre, and Mukdahan Field Crops Experiment Station for Rayong60 and Banmai Samrong Field Crops Experiment Station and Mahasarakham Field Crops Experiment Station for Rayong90