Abstract

Growing temperatures and planting dates affect phenology and grain yields of maize varieties and farmers have to choose suitable varieties that fit into different planting dates and growing temperatures. A field experiment was conducted to investigate the response of different hybrid maize varieties to different growing temperatures through growing the varieties at different locations varying in altitudes (low land, mid altitude and highlands) under three planting dates. Results revealed that days to seed emergence were influenced by growing temperatures, with days to emergence difference of two weeks observed between Didesa/Uke (high temperature locations) and Holeta (low temperature location). Almost for all varieties except for BH546, days to tasseling and maturity were longer under low temperature at Holeta while they were shorter under high temperature at Didesa and Uke. Early planting resulted in higher grain yields especially at Uke, Bako and Ambo. Grain yield was influenced by the interaction effect of variety and temperature, with BH546 being more yielder than AMH851 under high temperature at Uke. Thus, for most of the tested varieties early planting is recommended, as this will enable the varieties to escape moisture stress that occasionally occurs at grain filling and maturation period, which can seriously affect grain yield.

Key words: Growing temperature, grain yield, maize phenology, maize varieties, planting date.