Peer review

Context: or problem: Wheat (Triticum aestivum L.) is a major cereal crop driving food security, but its production is hampered by drought and low soil fertility, which are worsening due to climate change. Understanding genetic gain and its closely related traits of wheat varieties in arid areas will provide a meaningful reference for optimizing breeding strategies. Objectives: This study aims to evaluate the genetic yield gain of wheat breeding materials based on robust data from National Wheat Regional Trials in arid and infertile areas of China over the past 14 years, and screened agronomic traits that contributed to grain yield (GY) increase. Methods: The trials were conducted at 17 sites in five provinces with Jinmai 47 as the check variety. The temporal variation trends of GY were assessed by regression analysis using the GY of Jinmai 47 as the covariate. The analysis of Pearson's correlation, path coefficient, and principal component were performed to investigate the association between GY and agronomic traits. Results: Average GY of advanced lines (ALs) and certified varieties (CVs) were 4377.3 kg ha−1 and 4647.7 kg ha−1, respectively and the breeding-driven yield gains of ALs and CVs were estimated as 28.2 kg ha−1 year−1 and 17.8 kg ha−1 year−1, accounting for 36.1% and 28.3% of the total observed yield gain, respectively. The effective spike number (ESN) and plant height (PH) are important causal traits leading to yield differences among ALs, and have pyramiding effect on GY. Remarkably, modern breeding practices have conducted positive selection for ESN and negative selection for PH. The yield stability of ALs exhibited an increasing trend, implying that genetic variations favorable for yield potential and adaptability could be pyramided by breeding. Moreover, Jinmai 47 has maintained its advantage in terms of yield stability, ranking in the top three of all ALs in nine years of trials. Conclusions: In arid and infertile areas of China during 2007–2020, approximately one-third of wheat yield gains rely on genetic yield potential improvement, and ESN and PH were the key traits confer yield gap among ALs. Jinmai 47 is an excellent germplasm resource with high and stable yield that may provide essential gene pool for wheat improvement. Implications or signifcance: This study reveals the current wheat breeding situation in terms of yield and agronomic traits in the arid and infertile areas of China, and provides valuable information for the development and deployment of new-generation wheat varieties.

Text in English