Trends in grain quality and responses to nitrogen application of japonica inbred rice released after the 1980s in east China

Abstract Background and objectives The past four decades have seen a dramatic increase in cropping area of japonica inbred rice after the 1980s and nowadays occupies 90% of the total cropping area in Jiangsu, east China. To date, little attention has been paid to the effects of genetic improvements of japonica inbred rice on grain yield and grain quality under different nitrogen (N) levels. Fifteen japonica inbred rice released from 1983 to 2014 were investigated to evaluate changes in grain yield and grain quality of japonica inbred rice under 180 kg N/ha (N180), 270 kg N/ha (N270), and 360 kg N/ha (N360) during genetic progress. Findings Genetic improvement increased ( p < .01) rice grain yield and annual gain was 47.1, 60.2, and 75.6 kg/ha under N180, N270, and N360, respectively. During genetic progress, milling quality (milled rice percentage and head rice percentage), appearance quality (chalky rice percentage, chalky degree, and grain length‐to‐width ratio), and cooking and eating quality (gel consistency, overall palatability, breakdown, and setback) have been improved, while nutritional quality has been declined because of a reducing trend of protein content. Generally, the application of N fertilizer improved nutritional quality but deteriorated milling quality, appearance quality, and cooking and eating quality. Higher N application increased grain protein content, gel consistency, and breakdown, while decreased setback, which resulted in poor overall palatability. Conclusions The results suggested great improvements in both grain yield and grain quality (especially milling, appearance, and cooking and eating qualities) of japonica inbred rice since the 1980s in east China. Modern rice cultivars respond more favorably to increased N application in terms of grain yield. N application improved nutritional quality but downgrades other quality traits. Significance and novelty Our results proved a great success in breeding high‐yielding and good‐quality japonica inbred rice in east China since the 1980s. Future rice breeding for higher grain yield and better grain quality should rely both on improvements of breeding selection and cultivation practices, particularly concerning N management strategies.