Intercropping ryegrass with ‘LingwuChangzao’ (Ziziphus jujuba Mill. cv. LingwuChangzao) enhances crop yield and quality in the arid regions of Northern China

Agroforestry systems that incorporate tree-grass intercropping have the potential to improve land use efficiency. Nonetheless, it is very necessary to evaluate the quality and yield of crops in the intercropping system to ascertain the viability of these systems in a given region. This study contrasted the quality and yield of Lingwu Changzao jujube and Perennial ryegrass in intercropping systems with low, medium, and high planting densities. A two-year field experiment was conducted. Assessments encompassed fruit grading, cracking rate analysis, nutritional quality evaluation, cell wall composition, and enzyme activity analyses. Furthermore, ryegrass yield and quality were evaluated, and quality indices were analyzed using the membership function method. The findings indicated that the low-density intercropping (M1) was more effective in maintaining jujube quality, while the medium-density intercropping (M2) increased jujube yield by 29.58–53.69% compared to monoculture control (CK). Additionally, M2 augmented the yield of top-grade fruit, while M1 diminished the cracking rate by 11.49–13.49%, thus better preserving fruit integrity. M2 also enhanced ryegrass quality by 12.13–12.26%. M2 exhibited a higher land equivalent ratio and system productivity, with Lingwu Changzao jujube showing a more pronounced competitive edge over ryegrass. These results imply that encouraging ryegrass and jujube intercropping in the arid, ecologically fragile northern regions of China could optimize resource utilization and bolster ecosystem resilience.