The influence of row width, planting density and cultivars on seedling establishment of no-till spring wheat (Triticum aestivum L.) in Western Cape, South Africa
Low rainfall during the wheat growing season in Mediterranean climates leads to variation in growth period and this may constrain yield. Low seedling survival is among the factors that can limit yield in the Western Cape. Seedling survival rates of 50-70% are expected with conventional tillage, necessitating high sowing rates. Conservation tillage practices which can help to improve seedling survival have been readily adopted in the Winter Rainfall production region of South Africa, but require wider row widths than previously used in conventional tillage and seeding systems to facilitate stubble handling. Replicated, factorial experiments with split-split plot arrangements were established in commercial wheat fields during the 2005 and 2006 seasons at five localities. Treatments included three cultivars, split into row widths (250-350 mm) which were split into different planting densities. Seedling counts (3-4 weeks after planting) were used to determine seedling emergence and survival rates. Results indicated that seedling establishment was significantly reduced by increasing row widths (RW), higher planting densities (PD) and in PD × RW interactions in some trials, but that seedling survival of more than 80% were obtained when planting conditions were favourable. The lowest seedling survival of 63% occurred when dry conditions prevailed after planting at one locality in 2005. Anecdotally the no-till planting method as used in this region, can improve on the 50-70% seedling survival of previously used conventional planting methods.