Exploring the Optimal N Application to Improve the Yield, N Utilization, and Quality of Triticale (<i>Triticosecale</i> Wittm.) in the Chinese Loess Parent Material Area

The aim of this study was to investigate the effects of different N application rates on the yield, N accumulation, and grain quality of triticale and provide a theoretical basis for selecting the best N application rate for sowing triticale in the loess parent material area. This experiment was conducted at the experimental station of Shanxi Agricultural University in Jinzhong City, Shanxi Province, China, from 2021 to 2023 to study the effects and differences of different N application rates (N application rates 180, 210, 240, 270, and 300 kg ha⁻¹) on the yield formation, N utilization, and quality of the two triticale varieties Donghei10 (DH10) and Taizi6336 (TZ6336). The results showed that, compared with other N application rates, N240 increased the number of spikes and grains per spike of triticale and increased the yield by 6–19%. The yield increased most significantly when the N application range was 210–240 kg ha⁻¹; the yield change rate per 2 kg of N increase was the largest within this range, and the continued increase in yield with increasing N application was slow. N240 also improved the NUE, NUPE, nutritional quality, and processing quality of triticale. The results of the pathway analysis showed that the N application rate affected the spike number, grain number per spike, and 1000-grain weight of triticale. N accumulation at the anthesis and maturity stages affected GS and GOGAT activities in the flag leaf and grain, thus affecting the N efficiency, yield, and protein content. Overall, a N application at 240 kg ha⁻¹ increased the yield, nitrogen efficiency, and quality of triticale, and there was no significant difference in yield between DH10 and TZ6336.