Desempenho de híbridos top crosses de linhagens S3 de milho em três locais do Estado de São Paulo

Abstract

RESUMO ABSTRACT PERFORMANCE OF MAIZE TOP CROSS HYBRIDS FROM S 3 LINES IN THREE ENVIRONMENTS IN SÃO PAULO STATEThe present work aimed to evaluate the performance end high parent heterosis of 27 hybrids of partially endogamic lines (S 3 ) obtained from commercial hybrids, using top cross squemes with testers (IA 33). Also, the general combining ability (GCA) of the lines was evaluated. The 27 top cross hybrids, two commercial checks and the tester were evaluated by complete block design with three replications, in two years (2005/2006 e 2006/2007), and three locations (Campinas, Mococa and Palmital) of São Paulo State. The evaluated traits were: plant height (AP), ear height (AE), percentage of broken and loged plant (AC+Q), ear yield (PE) and grain yield corrected of 14% moisture (PG). Top cross hybrids of high yield performance that outperformed or did not differ from the commercial check were observed. Therefore top cross hybrids with high yield performance and with advantage of small production cost were identified. Also line S 3 with high value of GCA were observed.

Combining ability of S₃ progenies for key agronomic traits in popcorn: comparison of testers in top-crosses

“…The main consequence of this process is inbreeding depression and the consequent expressive gains in the exploitation of heterosis with hybrid production (Simon et al, 2004). The evaluation and selection of the generated hybrid takes into consideration both the behavior per se and in the hybrid combinations (Ferreira et al, 2009). The selection of superior lines based on traits that undergo inbreeding depression is limited due to the low correlation between their performance per se and of their subsequent hybrid combinations (Lima et al, 1984;Simon et al, 2004).…”

Inbreeding depression in single, three way and double-cross hybrids of maize

“…In the seed market, single-cross hybrid seeds stand out as the highest yielding, but high seed cost hinders their use by producers who cannot make use of more technically advanced growing practices and who use open-pollination seed varieties from their own corn cribs, and this results in low grain yield in Brazil (Ferreira et al, 2009). Low grain yield occurs because, in these cases, there is inbreeding depression, which is simply loss of vigor due to crosses between related individuals.…”

Desempenho agronômico e forrageiro de linhagens S4 de milho em topcrosses com híbrido simples

“…A utilização de híbridos comerciais para extração de linhagens de segundo ciclo é uma estratégia que vem sendo utilizada em programas de melhoramento no Brasil (FERREIRA et al, 2009;OLIBONI et al, 2013) e em outros países (TROYER, 1999). Para esse propósito, os híbridos comerciais apresentam a vantagem de já terem sido testados em vários ambientes, associando, dessa forma, alta produtividade com grande proporção de locos favoráveis já fixados (AMORIM; SOUZA, 2005).…”