Role of in improving drought tolerance in .

Intercropping may improve community stability and yield under climate change. Here, we set up a field experiment to evaluate the advantages of cultivating with , and with as intercrops, compared with cultivating in monoculture. Effects of extreme drought stress conditions on morphological, physiological, and biochemical traits of the three crop species cultivated in the three contrasting planting systems were compared. Results showed that extreme drought conditions induced negative impacts on . grown in monoculture, due to reduced growth and metabolic impairment. However, limited stomatal conductance, reduced transpiration rate ( ), and increased water use efficiency, carotenoid content, catalase activity, and accumulation of soluble sugars in . indicated its adaptive strategies for tolerance of extreme drought stress conditions. Compared with cultivation in monoculture, intercropping with had positive effects on . under extreme drought stress conditions, as a result of improved crown diameter, leaf relative water content (LRWC), net photosynthetic rate, and proline content, while intercropping with under extreme drought stress conditions increased net CO assimilation rates, LRWC, , and superoxide dismutase (SOD) activity. In conclusion, . has an effective defense mechanism for extreme drought stress tolerance. Intercropping with enhanced this tolerance potential primarily through its physio-biochemical adjustments, rather than as a result of nitrogen fixation by .