Adjusting interspecific competition in wheat/alfalfa strip intercropping system through alfalfa cutting times and rows

Abstract Productivity in strip intercropping systems is influenced by interspecific competition. Most research focused on initial design factors such as species combinations, row ratios, and sowing times; the potential to enhance productivity by regulating interspecific competition through altering crop growth within the system has been underexplored. A 2‐year field experiment compared sole wheat ( Triticum aestivum L.), sole alfalfa ( Medicago sativa L.), and wheat/alfalfa strip intercropping under different alfalfa cutting times and numbers of border rows cut. In this study, we defined the human active intervention targeting crop growth itself in the strip intercropping system as internal regulation. Results demonstrated that internal regulation significantly enhanced system productivity by altering interspecific competition, increasing yield by 21.2% in 2022 and 31.0% in 2023 compared with weighted monoculture yields. The land equivalent ratio for all internal regulation treatments was greater than 1. Internal regulation can change the border row effect of alfalfa and make wheat become the dominant crop in wheat/alfalfa strip intercropping system; the minimum competitive ratio values of alfalfa against wheat were 0.64 and 0.66 for 2022 and 2023, respectively. The treatment, which involved cutting the first border rows and the second border rows of alfalfa at 10 days before the first flowering stage, achieved the highest system yield and land use efficiency. Thus, internal regulation via suitable alfalfa cutting during the co‐growth period in wheat/alfalfa strip intercropping can adjust the interspecific relationship and increase the system yield, providing a reasonable method to increase the strip intercropping yield and ensure food security.