Resumo

MANCERA RICO, Arturo et al. Physiological quality and physical damage of maize seeds subjected to impact. Agric. Téc. Méx [online]. 2007, vol.33, n.2, pp.125-133. ISSN 0568-2517.

Damage caused by physic impacts diminishes the physical and physiological quality of corn seeds. The object of this study was to evaluate the damage caused by an impact and an accelerated ageing test on the physical and physiological quality of corn seeds. The experiment was performed in the Seed Analysis Laboratory at the Colegio de Postgraduados, Montecillo, State of Mexico, Mexico in 2005. Seed samples from the apical, middle and basal portion of the cob were collected with 10 and 23% of moisture content. The seeds were placed on a table with the embryo upward and impacted by the free falling of an iron 243 g cylinder equivalent to 0.000, 0.141, 0.188 and 0.235 J; subsequently, half of the seeds were subjected to an accelerated ageing test. The highest physical and physiological quality was observed in seeds with 23 % of moisture content and from the middle and basal positions of the cob. In seeds impacted at 23 and 10% of moisture content, the percentages observed without visible damage were 34 and 25, standard germination percentages 80 and 69, germination after accelerated ageing test was 74 and 40% and the electrolyte loss (electrical conductivity per gram of seed) were 23 and 53 (µScm^-1, respectively. In seeds from the apical, middle and basal portion, the percentages of seeds without visible damage were 25, 31 and 31%, standard germination 62, 82 and 81%, germination after accelerated ageing test 3 0, 74 and 80% and electrolyte loss 54, 25 and 23 (µScm^-1, respectively. The percentages of seed damaged and the reduction of physiological quality were proportional to the impact applied, except for germination rate.

Palavras-chave : Zea mays L.; cob seed strata; seed moisture content.

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