Diallel among twenty eight varieties of maize.

Twenty eight varieties of maize of different maturities and types of endosperm were assessed together with 378 F1, and seven commercial hybrids (controls) in three locations: Sete Lagoas, MG, Goiania, GO, and Londrina, PR. The varieties represent germplasms adapted to different areas of Brazil, used in the breeding program at the National Maize and Sorghum Research Center at Sete Lagoas, MG. The joint analysis of variance for ear weight showed significance (P < 0,01) for environments, entries, varieties, heterosis, mean heterosis, variety heterosis, specific heterosis, environments x entries and environments x varieties. The average yield of the varieties varied from 2,322 to 7,704kg/ha, while for the intervarietal hybrids the variation was from 4,112 to 8,363 kg/ha. The mean heterosis was 489 kg/ha and the vrietal heterosis varied from 589 to 1,339 kg/ha. The highest specific heterosis was obtained for the BR 105 x BA III - Tuson crossing. Some intervarietal hybrids were higher yielding than the best control. This is promising for breeding purposes, since new synthetic varieties can be formed or used to begin programs to produce hybrids. No association was found between heterosis and endosperm type.