Temporal Impact of Elevated CO₂ and Temperature on Solanum Lycopersicum L.: Insights into Growth, Phenology, Ultrastructure, Nutritional Quality and Metabolite Profile

Increasing atmospheric carbon dioxide levels since industrialization, and rise in global mean surface air temperature has led to adverse effects on crop plants across the world. Altered climatic parameters lead to change in phenology, shift in cropping cycle and change in primary and secondary metabolites of economically important parts of plants. However, only few studies have addressed the responses of vegetable crops to these changes globally. Current study was conducted to assess impact of the CO₂ enrichment, and combined influence of elevated CO₂ and temperature on the growth, phenology, ultrastructure, and primary and secondary metabolites of tomato (Solanum lycopersicum L.), at pre-flowering and maturity stage. Tomato was grown in Open Top Chambers at elevated CO₂ (750 ± 50 ppm), and high CO₂ (750 ± 50 ppm) and temperature higher than 2 °C of the ambient. Reduced crop duration, accelerated phenology and decreased biomass were the primary outcomes of exposure to CO₂ and temperature enrichment. While only CO₂ enrichment had some positive effects, high temperature counteracted these, indicating that plants in future may experience stress. We also observed stage-dependent response of tomato to both treatments, suggesting an adjustment in plant’s responses. Increased activity of antioxidants indicated activation of stress mitigating mechanism in tomato. Decreased protein levels and increased sugars suggest nutritionally compromised tomatoes in the future. Ultrastructure of the leaf revealed modification of chloroplast microanatomy to accommodate carbon accumulation in the form of starch. The study provides a comprehensive insight into the ultrastructural, biochemical, and phenological responses of tomato plants under projected climate change conditions.