Assessing the Impact of Higher Levels of CO₂ and Temperature and Their Interactions on Tomato (Solanumlycopersicum L.)

Climate change has increasing effects on horticultural crops. To investigate the impact of CO2 and temperature at elevated levels on tomato production and quality of fruits an experiment was conducted by growing plants in open top chambers. The tomato plants were raised at EC₅₅₀ (elevated CO₂ at 550 ppm) and EC₇₀₀ (elevated CO₂ at 700 ppm) alone and in combination with elevated temperature (ET) + 2 °C in the open top chambers. These elevate CO₂ and temperature treatment effects were compared with plants grown under ambient conditions. Outcome of the experiment indicated that growth parameters namely plant stature in terms of height (152.20 cm), leaf number (158.67), canopy spread (6127.70 cm²), leaf area (9110.68 cm²) and total dry matter (223.0 g/plant) were found to be high at EC₇₀₀ compared to plants grown at ambient conditions in open field. The plants grown at EC₇₀₀ also exhibited significantly higher number of flowers (273.80) and fruits (261.13), more fruit weight (90.46 g) and yield (5.09 kg plant^-1) compared to plants grown at ambient conditions in open field. The percent increase in fruit yield due to EC varied from 18.37 (EC₅₅₀) to 21.41 (EC₇₀₀) percent respectively compared to open field and the ET by 2 °C has reduced the fruit yield by 20.01 percent. Quality traits like Total Soluble Solids (3.67 °Brix), reducing sugars (2.48%), total sugars (4.41%) and ascorbic acid (18.18 mg/100 g) were found maximum in EC₇₀₀ treated tomato than other elevated conditions. Keeping quality was also improved in tomato cultivated under EC₇₀₀ (25.60 days) than the open field (17.80 days). These findings reveal that CO₂ at 700 ppm would be a better option to improve both quantitative as well as qualitative traits in tomato. Among the combinations, EC₅₅₀ + 2 °C proved better than EC₇₀₀ + 2 °C with respect to yield as well as for the quality traits. The tomato grown under ET (+2 °C) alone recorded lowest growth and yield attributes compared to open field conditions and rest of the treatments. The positive influence of EC₇₀₀ is negated to an extent of 14.35 % when the EC₇₀₀ combined with elevated temperature of + 2 °C. The present study clearly demonstrates that the climate change in terms of increased temperature and CO₂ will have a positive effect on tomato by way of increase in production and quality of fruits. Meanwhile the increase in EC beyond 700 ppm along with ET may reduce the positive effects on yield and quality of tomato.