Life Science Journal, 2011:8(S2) http://www.lifesciencesite.com 12 Effects of Seed Sowing Depth on Emergence and Early Seedling Development of Two African Indigenous Leafy Vegetables T.M. Seeiso 1 and S.A. Materechera 1 Crop Science Department, Faculty of Agriculture, Science & Technology, North West University (Mafikeng Campus), South Africa. Corresponding author email: thaky2009@yahoo.com Abstract: Depth of sowing can affect early crop establishment due to poor seedling emergence. A glasshouse study was conducted to investigate the effects of sowing depths (1.5, 3.5, 7, 10, 15, 20, 25, 30 mm) on emergence and early seedling development of two each of African indigenous (Amaranthus hybridus & Cleome gynandra) and exotic (Spinacia oleracea & Brassica napus) leafy vegetables. A split plot design with four replicates was used. Exotic vegetables had significantly higher (p<0.05) seedling emergence (95%) than the indigenous ones (60%). Among the indigenous species, Cleome gynandra had a higher emergence (70%) than Amaranthus hybridus (61%). However, there were no significant differences on emergence amongst the exotic vegetables. Exotic vegetables also had significantly higher (p<0.05) mean plant height (8.6 cm) than indigenous vegetables (1.01 cm). In all the vegetable species, both emergence and plant height decreased with deeper sowing due to higher soil strength. The biomass yields of the seedlings were reduced with deeper sowing although the differences were not significant. There were however significant differences (p<0.05) among the biomass yields of the vegetable species at different sowing depths. Generally, significantly higher biomass yields (6.4 g/plant) were obtained in exotic species compared with indigenous ones (0.2 g/plant). The results suggest that seeds of African indigenous leafy vegetables were more sensitive than the exotic ones to deeper (>5 mm) sowing and their emergence was more adversely affected by soil strength at this depth. It is concluded that seeds of African indigenous vegetables should be sown at shallower depths (1-5 mm) in order to ensure rapid emergence and early establishment of seedlings if sown directly into the soil. [T.M. Seeiso and S.A. Materechera. Effects of Seed Sowing Depth on Emergence and Early Seedling Development of Two African Indigenous Leafy Vegetables. Life Science Journal. 2011;8(S2):12-17] (ISSN: 1097 – 8135). http://www.lifesciencesite.com . Keywords: Crop establishment, soil strength, indigenous vegetables, seedling emergence, sowing depth Introduction Indigenous leafy vegetables (ILVs) have the potential to provide a valuable source of nutrition in areas with hot, dry climates (Flyman and Afolayan, 2006). ILVs could fill a valuable niche in the production of food in rural areas especially where the climate is not conducive to the production of exotic vegetables. ILVs can play a significant role in addressing the problems of low income, malnutrition, poor health and loss of biodiversity among resource- poor households in sub-Saharan Africa (Smith and Eyzaguirre, 2007). However, the indigenous leafy vegetables of Africa are being displaced in many areas due to land degradation, leading to a decline in production, use and diversity of vegetables being grown. Most rural farming families in sub-Saharan Africa have traditionally made conscious efforts to preserve indigenous vegetables around their homesteads, in crop fields and communal lands (Smith and Eyzaguirre, 2007). The integration of indigenous vegetables into agricultural production systems of many countries in sub-Saharan Africa has been promoted as a practical and sustainable way to achieve dietary requirements (Aphane et al. 2002). This is because such vegetables are efficient sources of important micronutrients, with respect to cost of production per unit area. However, most of the information on the production of indigenous and traditional leafy vegetables tends to be anecdotal (Smith and Eyzaguirre, 2007. Very little is known about the production of African leafy vegetables. Sowing depth is one of the important factors in crop management of field crops and vegetables (Campbell et al., 1991; Kirby, 1993). The depth of sowing seeds is important as it contributes to achieving a good crop stand establishment and higher yields (Karayel and Ozmerzi, 2008). The use of optimum sowing depth is generally viewed as a desired goal for all crop establishment systems. Too shallow sowing results in poor germination due to inadequate soil moisture at the top soil layer (Desbiolles, 2002). On the other hand, deep sowing can also significantly reduce crop emergence and yield (Aikins et al., 2006; Desbiolles, 2002; Mahdi et