In a preliminany evaluation of 254 topcrosses resulting from the combination of S3 and S4 lines from a group of CIMMYT hybrids with the open pollinated variety IBO-128 and two local checks, the best 30 lines were selected under conditions of scarce and favorable moisture conditions at Villamontes and Yacuiba, respectively. Three diallels were formed with 10 lines each, and 45 single-cross hybrids were made, denoted as diallel 1 (D1 = yellow grain), diallel 2 (D2 - white grain), and diallel 3 (D3 = drought tolerant). In 1994-95, evaluation trials were established with 134 crosses, planted under two contrasting moisture availability conditions. The experimental plot had 22 plants per row, with 0.75 cm between rows and 0.50 cm between plants. The design was random complete blocks with three replications. The best results were in Yacuiba with yields ranging between 7 and 8 t/ha for the three diallels, whereas in Villamontes yields where from 2 to 3 t/ha due to drought. Anthesis-silking interval was slightly less in Yacuiba than in Villamontes but all three diallels matured six days earlier in Yacuiba, perhaps because they escaped drought stress at the preflowering and grain-filling stages. The best 8-10 lines from each diallel will be used tom form hybrids and synthetics for each environment.

Spanish

9802|AGRIS 9702

Jose Juan Caballero

CIMMYT Publications Collection