Acquisitive trait strategies enhance resistance in wheat under combined microplastic and water deficit

Understanding crop responses to simultaneous environmental stressors is critical for safeguarding agricultural productivity. Yet, how microplastics (MPs) contamination interacts with water deficit to affect crop physiology, and which functional traits mediate such responses, remains poorly understood. We quantified crop growth parameters and 22 functional traits in two wheat varieties differing in drought sensitivity-drought-sensitive ('SL') and drought-tolerant ('SN')-under four treatments: control, single MPs, single mild water deficit, and combined stress. We characterized associations among leaf economic traits, water-relations traits, and eco-physiological performance. Combined stress reduced shoot dry weight by 28.32% in 'SN' and 41.25% in 'SL'. Under combined stress, 'SN' exhibited more acquisitive trait strategies than 'SL', thereby alleviating growth suppression. The leaf economics spectrum (PC1) showed positive correlations with root activity and water-use efficiency, whereas transpiration rate, stomatal conductance, and leaf water potential were negatively associated with root activity. Our results reveal that wheat resistance to combined MPs and water deficit is enhanced through acquisitive strategies that promote drought avoidance mechanisms, contrasting with the drought tolerance conventionally linked to conservative strategies. The tight coupling between leaf economics and water-relations traits underpins adaptive strategies, emphasizing the importance of trait-based optimization for improving crop performance under emerging multi-stressor environments.