Effect of Sowing Date on Yield and Some Agronomic Traits of Six Forage Maize Hybrids under Guilan Agro-climatic Conditions

In order to investigate the effects of sowing date on yield and some agronomic traits of six forage maize hybrids, two experiments were conducted in 2009 in two locations including Rasht and Fuman. The experimental design was randomized complete blocks with factorial arrangement and three replications. Treatments consisted of three levels of sowing date (31 May, 13 and 26 June) and six maize hybrids of early maturing (SC301 and DC370), medium maturing (SC400 and SC647) and late maturing (SC700 and SC704). The measured plant characteristics were fresh and dry forage yield, leaf dry weight, ratio of leaf dry weight to plant dry weight, ratio of stem dry weight to plant dry weight, ear dry weight, ratio of ear dry weight to plant dry weight and leaf to stem ratio. Results showed that forage yields for different planting dates were significantly different at the two locations.; The 13 June planting date in Fuman region and 26 June in Rasht region were better than other dates. Maximum dry forage yields for two locations of Fuman and Rasht in SC700 were 18862 and 23565 kg/ha dry weight (fresh weight of 90199 and 82642 kg/ha, respectively). The results of this experiment indicated that if SC700 hybrid is sowed at optimum date, it will produce more dry weight than other hybrids.