Micro-ridge-furrow planting enhances root lodging resistance and yield in high-density direct-seeded rapeseed by improving root spatial distribution

Restricted root growth and increased lodging risk are key constraints limiting further yield improvement in high-density direct-seeded rapeseed. This study evaluated micro-ridge-furrow planting (MR) against conventional flat planting (FC) under two densities (D3: 4.5 ×10 5 plants ha –1 ; D5: 7.5 ×10 5 plants ha –1 ) across five site-years. Under D5, MR increased the average lateral root angle by 20.8% and lateral root weight density by 47.8% and 74.1% in the 0–10 and 10–20 cm soil layers, respectively, compared with FC. Lateral-root tensile strength and elongation at break increased by 71.8% and 14.6% on average, respectively, and MR also increased elastic modulus, indicating greater stiffness. The soil-surface-area increment (ΔSSR) under MR was 25.4%–26.0% at sowing and 19.3%–20.0% at harvest; during the same period, furrow-bottom soil height increased by an average of 1.82 cm. Compared with FC, MR reduced the average root lodging angle by 18.3% at D3 and 18.0% at D5. Increasing density reduced FC yield by 6.2% but increased MR yield by 5.8%. MR increased the soil surface available for root growth and altered root spatial distribution. Together with improved lateral-root mechanical traits, these changes were associated with lower root lodging angles and higher yield, supporting MR as a promising planting strategy for high-density direct-seeded rapeseed.