Effects of nitrogen fertilizer on protein synthesis, accumulation, and physicochemical properties in common buckwheat

Nitrogen(N)fertilization affects grain quality in common buckwheat(Fagopyrum esculentum Moench).But the effects of N fertilizer on various buckwheat protein parameters are not fully understood.This study aimed to investigate the synthesis,accumulation,and quality of buckwheat protein under four N application rates in the Loess Plateau,China.Optimal N application(180 kg N ha-1)improved yield,agronomic traits,and N transport and increased protein yield and protein component accumulation.Prolamin and glutelin accumulation first increased and then decreased with increasing N application.The relationships between the contents of protein components and the amount of applied N generally followed quadratic functions.Nitrate reductase and glutamine synthetase activities first increased and then decreased with increasing N levels.Optimal N fertilizer increased the waterholding capacity and thermal stability of buckwheat protein and reduced its emulsification capacity,but negligibly changed its oil-absorption capacity.Hydrophobic amino acids and glutelin content were the main factors affecting protein quality.