Can Seeding Rate Affect the Grain Yield of Two Winter Wheat Genotypes with Contrasting Root System Size?

Background and aims: A large root system wheat was a ‘strong competitor’, and take up more belowground space, which may reduce plant density. A two years field studies were conducted to determine whether the grain yield could be differ in two wheat genotypes with contrasting root system size sown at varying seeding rates.

Methods: Two winter wheat genotypes (CW134 with a large root system, and CH58 with a small root system) were sown at three seeding rates (180, 225 and 280 seeds m⁻²) on the Loess Plateau of China. We measured grain yield, shoot and root biomass, root length density, and water use before and after anthesis.

Results: The grain yield in CW134 decreased with increasing seeding rate, but CH58 had more yield under 225 and 280 seeds m⁻² in both seasons. Increasing seeding rate increased the root biomass and root length density (RLD) in the top 40 cm soil layer in CW134, but not in CH58. However, a strong positive correlation between seeding rate and RLD in deep soil layers (40–100 cm) of CH58 were observed in both seasons.

Conclusion: The higher proportion of roots in topsoil layer and water consumption before anthesis in CW134 leading to grain yield reduced; while higher RLD in deeper soil profile in CH58 captured more soil water after anthesis as water became scarce. A large root system was an important factor to limit the seeding rate of winter wheat, the genotypes with larger root systems should not be sown at relatively higher seeding rates on the Loess Plateau.