Planting date effects on tassel differentiation of two maize hybrids

Abstract

Two maize hybrids (Zea mays L.) (Pioneer-309 B and Agroceres-28) were planted at Guaíba, Rio Grande do Sul, Brazil, to study the effects of tour planting dates on tassel initiation. The number of days between seeding and emergence and from that to tassel differentiation was decreased as planting date was delayed. Emergence date was mainly affected by soil temperature but air temperature had a larger effect on tassel initiation. The shortening of the period up to differentiation was due to temperature effects and not to daylength, although photoperiod was variable between dates of planting. This was determined by the number of fully expanded leaves at that phase and which remained constant for each hybrid in each date.