Pigeon pea intercropping and bacterial inoculation influence coffee rhizosphere communities and yield

Abstract

Coffee ( Coffea arabica L.) production in dry‐hot valleys is constrained by high‐temperature stress and limited soil nitrogen (N) availability. This study evaluated how pigeon pea [ Cajanus cajan (L.) Millsp.] intercropping and bacterial inoculation affected rhizosphere bacterial communities, soil enzyme activities, photosynthetic traits, coffee yield, and green coffee bean biochemical components, and how these variables were associated. A 3 × 3 factorial design combined coffee monoculture, 1:1 coffee–pigeon pea intercropping, and 1:3 intercropping with no inoculation, Delftia tsuruhatensis inoculation, and Azotobacter chroococcum inoculation. The results suggest that intercropping significantly improved coffee photosynthetic traits, with 1:1 intercropping generally showing higher values. Bacterial inoculation was associated with distinct rhizobacterial community structures and bacterial diversity. Delftia tsuruhatensis inoculation reduced α‐diversity but enriched taxa such as Sphingobacterium , Stenotrophomonas , and Flavobacterium , whereas A. chroococcum inoculation maintained relatively higher α‐diversity and enriched Nitrospira , Nakamurella , and SC‐I‐84. The combined treatments also increased soil urease, catalase, and sucrase activities, and improved coffee yield and green bean biochemical components. Compared with non‐inoculated coffee monoculture, annual yield increased by 17.1% and 17.2% with D. tsuruhatensis inoculation combined with 1:1 intercropping, and by 13.4% and 12.1% with A. chroococcum inoculation combined with 1:1 intercropping in 2023 and 2024. Mantel correlation analysis showed that yield was mainly associated with photosynthetic traits and microbial α‐diversity, whereas green bean biochemical components were more closely related to soil enzyme activity and net photosynthetic rate. Overall, pigeon pea intercropping and bacterial inoculation may represent potential agronomic management options for coffee production in dry‐hot valleys.