Winter wheat lodging resistance characteristics as affected by nitrogen application time and the underlying mechanism

Wheat lodging is an agricultural problem causing severe yield loss and quality degradation. Therefore, it is needed to investigate the impact of cultivation practices on lodging to develop effective solutions to reduce yield losses. This study conducted a two-yield field experiment with modifying the nitrogen application time treatments to analyse if it is possible to reduce the risk of lodging without yield loss. Transcriptomic analysis was performed to investigate changes in the expression levels of lignin and cellulose biosynthesis-related genes in node samples. The results of the experiment showed that delaying the nitrogen application time until the Zadoks (Z) 45 (booting) stage significantly reduced the risk of lodging due to the minimal yield loss by 3.9% and 2.9% for 2019–2020 and 2020–2021, respectively. The increased lodging resistance at the Z45 stage was associated with a lower plant height and gravity centre height, an increased wall thickness and stem thickness of the two basal internodes, which increased the strength resistance and lodging resistance index (LRI) of the stem. Transcriptomic analysis between the lodging (Z30) and the lodging-resistant (Z45) stages was conducted to illustrate the underlying mechanism on lodging resistance. The total number of differentially expressed genes (DEGs) was 9,000, and the gene ontology (GO) analysis of DEGs indicated that cellular component biogenesis was the most enriched GO term. Also, 30 and 14 DEGs involved in lignin and cellulose biosynthesis were identified, respectively, indicating that the primary mechanism resulting in a high lodging resistance is the high expression of key genes involved in the phases of lignin and cellulose synthesis processes. The findings of the study indicate not only a potential cultivation approach for reducing lodging risk, but also potential genes for developing lodging-resistant wheat cultivars.