Effect of Nitrogen Topdressing on Seed Yield and Flour Protein Content in Semidwarf Common Buckwheat

Abstract

This study evaluated the effects of nitrogen topdressing on the semidwarf common buckwheat (line ‘18-601’), focusing on growth, seed yield, and flour protein content. We conducted a field experiment and applied four nitrogen topdressing treatments at different growth stages: basal fertilization alone (2-0-0), basal fertilization plus nitrogen at flower bud appearance (2-2-0), basal fertilization plus nitrogen at full flowering (2-0-2), and basal fertilization plus nitrogen at both stages (2-2-2), using a randomized complete block design, with each plot measuring 1.2 × 2.5 m. Basal dressing was applied at 2, 8, and 4.7 g m-2 N, P2O5, and K2O, respectively. Nitrogen topdressing significantly increased chlorophyll content. The branch number, seed yield, number of seeds per square meter, and flour protein content tended to increase with nitrogen topdressing. The highest seed yield and protein content were observed in the 2-0-2 treatment, suggesting that nitrogen application at full flowering optimizes the yield and nutritional quality of semidwarf buckwheat. These findings highlight the importance of timing in nitrogen topdressing to enhance the agronomic and nutritional value of semidwarf common buckwheat.