Effects of Nitrogen Topdressing Stage on Quality,Yield and Other Physiological Traits in Strong Gluten Wheat

Strong gluten wheat cultivars Jimai 20 was used to study the physiological indexes,yield and some quality characteristics at different nitrogen topdressing stages.The results indicated that nitrogen topdressing stage could regulate protein content,grain yield and some physiological indexes of flag leave under the condition of the total amount of nitrogen application of 270 kg/ha and the ratio of base and topdressing of 5∶5.Nitrogen application at late stage of wheat development,especially at the flowering stage,could suppress chlorophyll's degrading,keep the activity of nitrate reductase(NRA) at high level,prolong the functional stage of leaf.There was a linear relationship between NRA and grain protein content during 14～21 days after flag leaf spreading.The correlation between chlorophyll content and grain yield was significant at the same time.Crude protein content increased with delaying of topdressing nitrogen and reached maximum at the flowering stage.Moreover,the contents of protein component increased with delaying of nitrogen top dressing stage,and the maximum value appeared at the three late stages.In this experiment,grain yield and protein yield were high in the treatment of nitrogen application at the flowering stage.Overall,for strong gluten wheat,the best stage of nitrogen topdressing that could coordinate the quality with yield was the flowering stage.