Physiological maturity effects on seed quality, seedling vigour and matureplant characteristics of maize in a tropical environment

Kernel dry matter accumulation, milk line and black layer formation which a re regarded as indices of physiological maturity were compared and effect o f maturity on viability and seedling vigour was investigated. Pattern of dr y matter accumulation in the two hybrids used for the study was similar. Th e indices gave different estimates of the time physiological maturity was a ttained in the two hybrids. Cubic regression equations gave more realistic estimates than linear and quadratic ones, 41 and 48 days after silking in O ba Supa 1 and Oba Supa 2, respectively. Performance of seed of Oba Supa 1 h arvested at 45 days after silking and with seed dry weight less than maximu m, was better in laboratory and field investigations than that harvested be fore and after this time. There was no significant maturity-stage effect on viability of seeds. But seeds harvested before full maturity, irrespective of kernel dry weight, germinated faster, having significantly lower emerge nce indices than those harvested at full maturity. The rate at which seedli ngs accumulated dry matter during the first 30 days after planting in the f ield was closely related to seed dry weight.