RESUMO -Este trabalho teve como objetivo avaliar os efeitos do arranjo espacial e da densidade de semeadura na produtividade de cinco híbridos de milho, em dois locais no cultivo de verão. Foram utilizados espaçamentos de 80 cm e de 45 cm entrelinhas, e densidades de semeadura de 42.000, 52.000, 62.000 e 85.000 plantas ha
COMBINING ROW SPACING AND POPULATION DENSITY IN INCREASING MAIZE YIELDABSTRACT -This study aimed to evaluate the effects of spatial arrangement and plant density from five corn hybrids at two locations in the summer season. Row spacing used were 80 cm and 45 cm between rows and plant densities were 42,000, 52,000, 62,000 and 85,000 plants ha -1 . The evaluations were conducted in Cascavel, State of Paraná, and RioVerde, State of Goiás, Brazil. Significant effects were observed for the main effects (hybrid, row spacing and density), but there were no interactions between the main effects, with the exception of the interaction between density x hybrid in Rio Verde. There was a greater effect of row spacing than the population density on yield of all hybrids. With the row spacing at 45 cm the hybrids yielded, on average, 36% more than at a spacing of 80 cm, in the two locations. There was a trend for increased productivity with increased seeding rate up to 75,000 plants ha -1 in Cascavel, and up to 85,000 plants ha -1 in Rio Verde.
ResumoO objetivo deste trabalho foi comparar três testadores para a discriminação e avaliação da capacidade combinatória de 49 famílias S 2 , oriundas do híbrido de milho-pipoca IAC 125. As famílias foram avaliadas por seu desempenho per se e em seus cruzamentos com os testadores BRS ANGELA, IAC 125 e Linhagem 3.3. O experimento foi conduzido em látice simples, em Maringá, PR, no ano agrícola 2007/2008. Os parâmetros genéticos e fenotípicos de capacidade de expansão e rendimento de grãos foram obtidos e comparados entre si por meio das estimativas procedentes das progênies obtidas, isto é, dos topcrosses com cada testador e das famílias S 2 per se. As capacidades geral e específica de combinação foram estimadas segundo o modelo de dialelo parcial. Foram avaliadas também as heteroses dos topcrosses em relação aos testadores per se, a capacidade de discriminação dos testadores comparada por meio do índice de diferenciação e desempenho proposto por Fasoulas (1983). O testador mais adequado para avaliar as famílias S 2, em relação do rendimento de grãos e capacidade de expansão foi a linhagem 3.3. Palavras-chave: Topcross, dialelo parcial, índice de Fasoulas, comportamento híbrido
AbstractThe objective of this work was to compare three testers for discrimination and evaluation of the combining ability of 49 S 2 families, derived from the topcross popcorn hybrid IAC 125. Families were evaluated by their per se performance and their crosses with the testers BRS ANGELA, IAC125 and Line 3.3. The experiment was conducted in lattice design, in Maringá, PR, Brazil, during 2007/2008 cropping season. Genetic and phenotypic parameters was estimated for grain yield and popping expansion, and compared using the topcrosses between families and testers and the families per se. General and specific combining ability were estimated according the partial diallel model. Topcrosses heterosis was also evaluated, and the capacity of discriminating the families was compared among testers using the differential index from Fasoulas (1983). The tester line 3.3 was the most suitable to evaluate the S 2 families in respect to grain yield and popping expansion.
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