Evaluation of the yield and germination indices of maize hybrid seed (Zea mays. L cv KSC704) in different sowing dates and plant density of parental lines

In order to study the effect of different sowing dates and planting densities of female parent on yield and seed quality of hybrid maize KSC704, an experiment was conducted as split plot during two years of 2012 and 2013 in Karaj. Sowing dates was selected as early, medium and late planting. Plant density selected in five levels for female parent B73. After harvesting the seeds that pollinated by male parent, yield and its components, laboratory germination, seed emergence in the field, mean emergence time (MET) and dry weight of emerged seedling was evaluated. The results showed that sowing date and plant density had significant effect on these traits in both years. The highest yield gained by early planting date and plant density above 50000 plants per hectare. The yield and its components in the first year (6130kg/ha) were greater than the second year (4990 kg/ha). The highest percentage of normal seedlings was observed in late sowing date and 40000 plants per hectare in both years. Because of heat stress in second year, the average indices of seed quality at the first year were higher than the second year, except MET. In general, to prevent the harmful effects of environmental stress especially heat stress at the critical stages of seed development, and for enhancement the seed quality, reasonable delaying at sowing date and plant population of 50000 per hectare might be recommended.