Effect of planting date on phenological characteristics, yield grain and yield components of different maturity maize hybrids in Hamadan region

Considering the effect of temperature and day length on maize grain yield, knowing the appropriate planting date of different maize hybrids is necessary. In order to investigate the response of different groups of maize hybrids to planting date in Hamedan region, three early maturing hybrids (KSC201, KSC260 and KSC400), two medium maturing hybrids (KSC647 and BC678) and two late maturing hybrids (KSC703 and KSC704) were planted in Four planting dates (30 April, 22 May, 10 June and 1 July) into random plots based on a randomized complete block design during 2017 and 2018 at Ekbatan Research Station of the Agricultural and Natural Resources Research Center of Hamadan Province. Planting dates were placed in main plots and hybrids in sub plots. The highest grain yield of hybrids was observed on the second planting date and KSC703, KSC704, BC678 and KSC647 hybrids with grain yield of 18271, 18066, 17068 and 16491 kg.ha-1, respectively, were significantly superior to KSC400, KSC260 and KSC201 hybrids with grain yield of 13557, 1260 and 12291 kg.ha-1, respectively. With delay in planting time (third planting date), grain yield of all hybrids decreased and despite the reduction of planting to flowering period, other phenological characteristics include: grain filling period, day to grain physiological maturity and day to grain moisture of 20% (suitable time for mechanized harvesting) increased. At the last planting date (1 July), late maturing hybrids did not reach the physiological maturity stage of grain, and medium maturing hybrids were not able to reach the appropriate harvest moisture, while early maturing hybrids could be harvested before facing the severe autumn cold and among them, KSC400 showed the highest grain yield with 11110 kg.ha-1. In general, in case of delaying the planting time to 22 June-6 July in region such as Hamedan, planting early maize hybrids (especially KSC400 hybrid) is recommended due to desirable grain yield and the possibility of timely preparation of land for the next crop.