Resumo

TADEO-ROBLEDO, Margarita et al. Yield of landraces and hybrid maize under different planting dates and heat units. Rev. Mex. Cienc. Agríc [online]. 2015, vol.6, n.1, pp.33-43. ISSN 2007-0934.

Productive capacity of two corn landraces (Ixtlahuaca and Atlacomulco) were compared with two hybrids, H-50 and H-52, under two planting dates and harvest dates and the accumulated heat units were estimated by the classic residual method. The work was carried out in FESC-UNAM, in Cuautitlán Izcalli, located at 2 240 masl, during the spring cycle 2012. The highest yields corresponded to the first planting date (May 17) and harvested at 177 and 160 days (8 570 kg ha^-1 and 7 488 kg ha^-1, respectively). In contrast, the second planting date (01 June) and harvested at 162 and 145 days gave lower yields (7 185 kg ha^-1 and 6 082 kg ha^-1, respectively). The evaluated genotypes showed statistically similar yields even when they were established in two sowing dates and two different times of harvest. The four genotypes showed statistically similar values for the following variables: male and female flowering, and ear height. Accumulated heat units for the genotypes in this study, define that to achieve physiological maturity at estimated grain moisture of 35%, the sum of 1 093 and 1 104 heat units are required, which is reached between 160 and 162 days after planting.

Palavras-chave : hybrids; maize; productivity; seeds.

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