Morphological, Physio-biochemical and Yield Responses of Ridge Gourd (Luffa acutangular L.) to Individual and Combined Exposure of Elevated Temperature and Elevated CO2

This study investigated the morphological, physiological, biochemical, and yield responses of ridge gourd ( Luffa acutangula L. var. Pusa Nutan) to individual and combined exposures of elevated temperature (31.5°C) and elevated carbon dioxide (533 ppm) using controlled environment chambers. Four treatments were imposed: ambient conditions, elevated temperature, elevated CO₂, and their combination. Elevated temperature alone significantly reduced leaf area, root-to-shoot ratio, flower production, fruit number, and protein content, while exacerbating oxidative stress. Elevated CO₂ alone improved root and leaf growth, photosynthetic efficiency, antioxidant activity, and fruit yield. However, the combination of elevated temperature and CO₂ only partially mitigated the negative impacts of heat, with high temperature dominating over CO₂ benefits, resulting in reduced yield and altered nutritional quality. To synthesize plant performance, a Ridge Gourd Response Index (RGRI) was developed, integrating multiple traits to assess resilience. Results identified elevated CO₂ as the most favorable regime with the highest RGRI value (1.36), while the combined effect of elevated temperature and elevated CO ₂ was most detrimental with the lowest value (0.36). These findings highlight the complex interplay of climate stressors on ridge gourd and underscore the importance of breeding climate-resilient cultivars to sustain crop health and productivity under future environmental challenges.