Evaluation of effects of gibberellic acid on maize (Zea mays L.) in different planting dates

In order to study the effects of foliar application of gibberellic acid on maize (hybrid BC504) in different planting dates, a field experiment was carried out in Sarabchengaee Agriculture Research Station in Khorramabad, Iran in 2006. The experiment was laid out as a split plot design based on Randomized Complete Block Design with four replications, in which planting dates constituted the main plot with three levels (June 7, June 21 and July 5) and gibberellic acid constituted the sub-plot with four levels (control, 0 ppm, 5 ppm, 50 ppm and 250 ppm, amounting to 400 liters/ha). Results showed that variation in planting dates had a significant effect on plant height, grain yield, 1000-seed weight and days to flowering. Gibberellic acid and its interaction with planting date did not have a significant effect on the studied traits.