Nitrogen efficiency indexes association with nitrogen recovery, utilization, and use efficiency in spring barley at various nitrogen application rates

The nitrogen use efficiency (NUE) is the ratio of N uptake by plant to total amount applied fertilizer. optimization NUE essential for sustainable agriculture, especially in breeding programs improve yield barley (Hordeum vulgare L.). We investigated variation 32 genotypes and examine response relationship between phenotypic traits level determine selection optimize NUE. was 2 yr under field conditions using three levels (60, 120, 180 kg ha−1). Growth, physiological agronomic traits, efficiency-related parameters were determined. significantly affected application its interactions with traits. Plant height, biological yield, spike length, grain number (GN) increased at higher levels, but 1,000-grain weight decreased. lowest 2,000.7 ha−1 60 ha−1, highest 8,607.9 120 ha−1. An increase rate from associated a chlorophyll content (CHLSPAD) (from 19.04 23.13), no significant change CHL seen (ANUE), fertilizer recovery utilization both reduced an rate. A path analysis revealed that GN most trait program due high direct effect (0.72) on ANUE. linear discriminant showed d after sowing best distinguishing low levels.