Genetic improvement has promoted wheat’s grain yield and nitrogen use efficiency (NUE) during the past decades. In China, the Yangtze River Basin is an important wheat production region, constituting 16% of the total wheat production area and accounting for 25% of total production. The current wheat cultivars exhibit higher grain yield and NUE than previous cultivars in this region since the 2000s.

However, the agronomic traits of the high-grain yield and high-NUE cultivars that were released in recent years have not been characterized, and the mechanisms by which higher grain yield and NUE levels have been achieved are not known. In the present study, 21 weak-winter wheat cultivars (Triticum aestivum L.) that were released in the Yangtze River Basin after 2000 were cultivated for three seasons from 2016 to 2019.

Significantly positive correlations were observed between grain yield and NUE in the three years. The cultivars were grouped into high (HH), medium (MM), and low (LL) grain yield and NUE groups. The HH group exhibited significantly high grain yield and NUE.

High grain yield was attributed to more effective ears by high tiller fertility and greater single-spike yield by increasing post-anthesis single-stem biomass. Compared to other groups, the HH group demonstrated a longer leaf stay-green ability and a greater flag leaf photosynthetic rate after anthesis. It also showed higher N accumulation at pre-anthesis, which contributed to increasing N accumulation per stem, including stem and leaf sheath, leaf blade, and unit leaf area at pre-anthesis, and promoting N uptake efficiency, the main contribution of high NUE.

Moreover, tiller fertility was positively related to N accumulation per stem, N accumulation per unit leaf area, leaf stay-green ability, and flag leaf photosynthetic rate, which indicates that improving tiller fertility promoted N uptake, leaf N accumulation, and photosynthetic ability, thereby achieving synchronous improvements in grain yield and NUE.

Therefore, tiller fertility is proposed as an important kernel indicator that can be used in the breeding and management of cultivars to improve agricultural efficiency and sustainability.