Seeding rate influence on yield and yield components of irrigated winter wheat in a Mediterranean climate

It is difficult to establish agronomic practices for wheat (Triticum aestivum L.) production in Mediterranean regions because of high annual variability in rainfall. Plant density is a factor of particular importance in wheat production systems because it can be controlled. This study was conducted to determine the optimum seeding rates of Mediterranean types of wheat in irrigated Mediterranean systems. Field experiments were conducted under irrigation at two locations of the Ebro Valley, Spain, during two growing seasons, 1999-2000 and 2000-2001. Six seeding rates were compared: 150, 175, 250, 300, 400, and 500 seeds m(-2) with four adapted wheat varieties including a hybrid wheat. Seeding rate affected grain yield and yield components in three of the four environments, but its effect varied with the environment. The plant densities giving the highest yields were at least 400 to 500 plants m(-2) for most of the varieties studied. The results suggest that the rate of seeding under irrigation for Mediterranean areas might be higher than those used in other wheat-growing areas.