Rapid elongation of stems during the bolting stage reduces the lodging resistance of late-sown rapeseed

In the rice–rapeseed cropping system in the Yangtze River Basin, late rapeseed sowing increases lodging. To identify the mechanisms of reduced lodging resistance, a two-year field experiment compared four rapeseed cultivars with differing lodging resistances under normal and late sowing. Rapid stem elongation during bolting in late-sown rapeseed reduced stem plumpness, vascular bundle development, and lignin accumulation, weakening lodging resistance. Slowing stem elongation and promoting vascular bundle formation and lignin synthesis could increase lodging resistance in late-sown rapeseed.