Screening of superior wheat lines under nitrogen regulation and factors affecting grain quality improvement under high yield

High yield and quality are crucial goals of wheat production. In this study, Ning7840 (high protein content) and Clark (low protein content) as parents to develop recombinant inbred lines (RILs), and used to investigate the differential responses to different nitrogen (N) levels (0, 150, and 300 kg N ha⁻¹). The results showed that the RILs exhibited transgressive segregation in yield and grain quality traits. A comprehensive index of grain quality response to N (quality response index, QRI) was computed by entropy weight-fuzzy membership function method, two types of high yield and quality genotypes were screened based on yield and QRI: quality-sensitive wheat lines in response to N (SWLs) characterized by high yield and high QRI, and quality-tolerant wheat lines in response to N (TWLs) with high yield and low QRI. SWLs were particularly adept at combining high yield with quality enhancement under N application. Partial least square - structural equation modeling (PLS-SEM) analysis identified leaf dry matter accumulation at anthesis, and N recovery efficiency were main factors affecting wheat grain quality improvement. Overall, screening high-yield and high-quality genotypes with the entropy weight - fuzzy membership function method is a useful strategy. These results provide a theoretical basis for breeders to select high yield and quality wheat.