Response of maize (Zea mays L.) different maturity hybrids to planting dates in Mashhad region

Twenty local and foreign maize (Zea mays L.) hybrids in five different maturity groups were evaluated in Mashhad, Iran for two years (2007-2009). Three planting dates (5th May, 20th May and 5th June) and hybrids were arranged in a randomized complete block design as split plot arrangements, with three replications. The planting dates were in main plots and hybrids in subplots. The results indicated that late maturing hybrids will have high risk in region. In 5 June planting, non of hybrids except early maturing group, failed to reach proper maturity. Results revealed that KSC 704 can be replaced by early hybrid, KSC 260 in 20 May and 5 June plantings, as well as medium-early hybrids such as KSC 400 in 5 May and 20 May plantings. Hybrid KSC 260 in 5th June sowing, produced 13.886 and 11.698 t.ha-1 grain with proper harvestable moisture in 2007 and 2008 respectively, while, late hybrid KSC 704 produced 13.007 and 16.243 t.ha-1 grain with very high moisture, without significant grain yield.