Seed priming, genotype and sowing date effects on emergence, growth and yield of wheat in a tropical low altitude area of Zimbabwe

Low wheat yields in low altitude tropical areas result from short winter seasons, late planting and poor stand establishment. Field experiments were carried out over two winter seasons (2005 and 2006) in the south-eastern lowveld of Zimbabwe to investigate effects of seed treatment (non-primed and primed seed), sowing date (2 May, 16 May, 1 June and 16 June) and variety (Dande, Insiza, Kana and S95063) on wheat. In the first season, seed treatment significantly affected final emergence with 84.7 and 78.3% emergence for non-primed and primed seeds respectively. However, in the second season seed treatment had no effect on final emergence. Priming reduced time to 50% emergence by 7 and 14 h in 2005 and 2006 respectively. From the first sowing date to the last, wheat yields were reduced by a mean of 2387 kg ha-1 in both seasons. At the last sowing date, Insiza significantly yielded higher than other varieties in the first season while, seed treatment had no effect on yield in both seasons. It was concluded that wheat planting after 16 May reduced yields. Insiza may optimise yields for late sown wheat while seed priming does not improve yield of late sown wheat.