Mechanisms underlying the enhancement of Pandanus amaryllifolius Roxb. quality by intercropping with Hevea brasiliensis under cold spell stress

Pandanus amaryllifolius Roxb (pandan) is a valuable aromatic industrial crop in Southeast Asia. Its secondary metabolites are an important source of high-quality aromatic raw materials in the fields of cosmetics and daily chemicals. Pandan can be cultivated as an understory intercropped species, while it exhibits disrupted physiological and secondary metabolism under cold stress, which impairs its quality and commercial cultivation. To explore how intercropping regulates cold tolerance and leaf quality, a field experiment was conducted in Danzhou city, Hainan island. Under natural cold spell conditions (15-day event, 15–29 December 2023; local meteorological station minimum, 8 ℃) agronomic traits, leaf volatile organic compounds (VOCs), and comprehensive quality were systematically monitored and compared between Hevea brasiliensis (rubber)-pandan intercropping and monoculture systems. Low-temperature stress reduced chlorophyll content by 11.8% and altered VOC profiles. Intercropping was associated with less pronounced cold-induced changes in growth and VOC profiles compared with monoculture. Compared with monoculture, intercropping significantly improved leaf length, leaf area, dry matter content, and specific leaf area by 26.3%, 37.8%, 27.7%, 45.6%, respectively. Intercropping was associated with 56.69% higher 2-AP content and higher neophytadiene content. Grey relational analysis ranked intercropped pandan as having superior comprehensive quality under cold stress. Collectively, rubber-pandan intercropping may contribute to maintaining pandan leaf quality under cold spell conditions, as indicated by superior agronomic traits and more stable VOC profiles relative to monoculture. This composite planting mode may provide a sustainable development path for stress resistant cultivation of tropical industrial crops in subtropical marginal regions, supporting expanded planting ranges and industrial development.