Respons of Hybrids of Maize (Zea may L.) to Density in the Five Phenological Stages

In order to investigate respond of yield and yield component of three maize hybrids on seven plant densities, an experiment was conducted during 2007-2006 growing season in Mashhed, Iran. Three maize hybrids including long season maize (704), medium season maize (504) and short season maize (260) and five growth stages includingV5, V7, Vt, R3 and R5 were compared in a strip plots design with three replications. There was significant difference among number of ear per plant, number of seed row on each ear, number of seed per each plant, seed weight per each plant, 100 seed weights weight of dry cob per each ear, yield and yield biology between thinned plants in the R3 و R5 stages and V5، V7 stages. However, yield and yield components were closed to optimum density per hybrids in thinned plants at the V5، V7 stages but there was significant difference among yield and yield components in thinned plants at the R3 و R5 stage