Optimizing the rhizosphere to enhance photosynthesis and functional traits of Cyperus esculentus in saline-alkali soils: A comparison between biochemical amendments and salt-tolerant plant intercropping

Soil salinization is a critical barrier to agriculture, especially in arid regions like Xinjiang, where it restricts crop growth. Cyperus esculentus, a moderately salt-tolerant oilseed crop with ecological and economic value, faces cultivation challenges under high saline-alkali soils. Although biological strategies have been proposed to alleviate salt stress, their effects on the crop's photosynthetic performance remain insufficiently studied. This study evaluated two approaches-biochemical amendments and intercropping with salt-tolerant plants-to assess their impact on soil properties and functional traits of C. esculentus. Microbial agents and humic acid improved the rhizosphere by reducing soil pH by 10-14 % and increasing available nitrogen by 29-51 %, thereby enhancing chlorophyll a synthesis and leaf nitrogen content. By lowering the salt content of the soil and possibly boosting beneficial microbial activity, intercropping enhanced the root environment. It increased net photosynthetic rates by 20-22 % and suggested better electron transfer. Through root interactions with companion plants, nutrient uptake was further enhanced. In comparison to CK, both treatments greatly boosted biomass, with leaf biomass increasing by 18-27 % at maturity. Although our data point to distinct primary pathways, intercropping was mainly linked to synergistic optimization of morphology and photosystem electron transport, whereas biochemical amendments were linked to improved nutrient status and photosynthetic efficiency, suggesting potential physiological stability. These findings provide insight into the physiological adaptation of C. esculentus under salinity and offer practical guidance for its sustainable cultivation in saline-alkali soils.