The physiological and biochemical responses of triploid Passiflora edulis Sims ‘Mantianxing’ seedlings to PEG 6000 simulated drought stress

Abstract

Elucidating the drought response mechanisms of polyploid Passiflora edulis Sims represents a novel approach to enhancing stress resistance in this economically important crop. This study provides a comprehensive comparison of drought resistance between triploid and diploid 'Mantianxing' cultivars, employing different concentrations of PEG6000 (15 %, 30 %, 45 %) to simulate different drought stress levels for evaluating key physiological and biochemical indicators. The superior performance of triploid seedlings, evidenced by significantly higher chlorophyll content, enhanced osmotic regulation, more robust chlorophyll fluorescence parameters, and stronger antioxidant enzyme activity, demonstrates their inherent drought resistance advantage. Importantly, the elevated malondialdehyde (MDA) levels and relative electrical conductivity (REC) in diploid counterparts further confirm their greater susceptibility to water deficit. The identified physiological markers (chlorophyll stability, osmoregulation capacity, and antioxidant activity) could support efficient screening of drought-tolerant genotypes in polyploid P. edulis breeding programs. Triploid lines could be considered breeding materials in the breeding program of P. edulis, which has high quality and yield in the drought area. These findings establish triploid P. edulis as valuable germplasm for drought-resistant cultivar development and provide a scientific framework for polyploid selection in arid cultivation systems.