Optimising the Morphology and Quality of Basal Stem Nodes to Improve Wheat Lodging Resistance and Yield

ABSTRACT Lodging is one of the main limiting factors threatening crop yields. Although the technology to modify plant morphology and improve lodging resistance using plant growth regulators (PGRs) is well developed, the understanding of the effects and underlying mechanisms of PGRs in regulating stem traits at different growth stages of wheat remains limited. In this study, two cultivars, Shidong 0358 (SD0358, a lodging resistant cultivar) and Xindong 18 (XD18, a lodging‐sensitive cultivar), were used to investigate the effects of chlorocholine chloride (CCC) and gibberellin (GA 3 ) treatment on wheat stem characteristics, lodging resistance, lignin and cellulose biosynthesis processes and yield during the jointing and booting stages. The results showed that in the lodging‐sensitive cultivar (XD18), exogenous CCC treatment (CC) at the jointing and booting stages shortened the second basal internode during the flowering and filling stages, while increasing lignin and hemicellulose content, stem breakage strength and stem lodging resistance index, resulting in a decrease in wheat lodging rate and an increase in total yield, compared with CK. However, exogenous CCC and GA 3 (CG) treatments during the jointing and booting stages increased the height of the gravity centre of wheat, reduced the activity of 4‐Coumaroyl‐CoA and Cinnamyl Alcohol Dehydrogenase, resulting in a decrease in cellulose and hemicellulose content, thereby increasing lodging rate. Meanwhile, under CC treatment, the lodging‐resistant cultivar (SD0358) showed enhanced stem breakage strength and enhanced yield with advantageous lignin biosynthesis ability. Interestingly, compared to CC, CG treatment showed an increase in cellulose and hemicellulose content in the stem of SD0358 and a further increase in final yield. Overall, the application of CCC during the jointing and booting stages improved stem morphology and quality, thereby enhancing lodging resistance and final grain yield, especially in lodging‐sensitive cultivars. The combined strategy of applying CCC during the jointing stage and GA 3 during the booting stage is an effective chemical regulation method to balance lodging resistance and yield potential in lodging‐resistant cultivars.