Optimizing strip configuration improves intercropping productivity by integrating photosynthetic performance and water resource use and crop physiological adaptation

Oilseed flax production in northwest China’s drylands is constrained by simplistic planting systems and low water productivity. We conducted a three-year field experiment on the semi-arid Loess Plateau to evaluate intercropping as a sustainable intensification strategy. The objective was to assess the effects of different strip configurations in maize/oilseed flax intercropping on system productivity, soil water use, and crop physiological adaptation. A two-factorial randomized block design was used. The treatments comprised three cropping systems (maize monoculture, oilseed flax monoculture, and maize/oilseed flax intercropping) and three strip configurations with specific row ratios: I42 (2 rows of maize: 4 rows of oilseed flax), I63 (3:6), and I84 (4:8). Intercropping significantly increased biomass and grain yield relative to monoculture, with the I84 configuration achieving the highest land equivalent ratio (LER). Soil water storage (0 −80 cm) increased by 8.6% and 6.3% relative to maize and oilseed flax monocultures, respectively. I84 further improved storage by 6.5%−18.9% over narrower configurations. The I84 system alleviated shading stress, leading to significant increases in key photosynthetic parameters of 14.6%−45.2% ( P < 0.05) and leaf water use efficiency of 0.8%−44.0% ( P < 0.05). These physiological improvements coincided with a rebalancing of endogenous hormones (ABA, CTK, JA, SA). Optimized strip intercropping enhances system productivity by synchronously improving soil water retention and inducing coordinated aboveground-belowground physiological adaptations. This study demonstrates that optimized strip configuration (I84) enhances intercropping productivity by integrating photosynthetic performance, soil water utilization, and hormonal responses in a maize/oilseed flax system.