GENOTYPE BY ENVIRONMENT INTERACTION OF ADVANCED SOYBEAN BREEDING LINES IN LAMPUNG UPLAND SOILS

Availability of adapted cultivars is needed for the development of soybean cultivation in upland soil in Lampung, Sumatra. Twelve advanced soybean breeding lines and two check varieties (Tanggamus and Wilis) were tested on upland soils of Lampung Province. The trials were conducted in the District of Tulangbawang, Central Lampung, East Lampung and South Lampung during the late rainy season of 2003/2004. Two sites were selected per district for a total of eight sites for the four districts. A split plot design with three replications was used within each location. Plot size was 2.4 m x 4.5 m, plant spacing of 40 cm between rows and 15 cm within a row, and two plants per hill. The mainplot was fertilizer: A= Low inputs (22.5 kg N, 27 kg P2O5, and 40 kg K2O per ha), and B=Medium inputs (22.5 kg N, 36 kg P2O5, 53 kg K2O and 0.56 t CaO per ha). The fertilizers were applied before planting. The subplots were 12 soybean breeding lines together with two check soybean varieties. Results showed that soybean yields were affected significantly by locations, fertilizers, breeding lines, location x fertilizer and location x breeding line interactions. Plant height was affected siginificantly by locations, fertilizers, breeding lines and location x breeding interaction. Pods per plant  were affected by locations, fertilizers, location x fertilizer and location x breeding line interactions. All breeding lines and varieties were responsive to changing environments. Based on the smallest Pi parameter (the distance mean square between the cultivar’s response and the maximum response averaged over all locations), and the highest frequency of rank, three breeding lines, namely W3465-27-2 (released in 2004 as cv. Ratai), cv. Tanggamus and D3578- 3/K3911-66-3 were identified as wide adaptability genotypes with the yield potential of more than 2.4 t/ha with an average of 1.6 t/ha.