Based on reports by the IPCC (Intergovernmental Panel on Climate Change), atmospheric CO2
concentration is rising. Plant growth is nearly always stimulated by elevation of CO2
and it has been found to ameliorate water stress in the majority of species studied. A pot culture experiment was conducted with three varieties of tomato i.e, Manulakshmi, Vellayani Vijay, Anagha with the objective to study the growth parameters contributing to increased drought tolerance responses in tomato (Solanum lycopersicum
L.) under elevated Carbon dioxide using the Open Top Chambers (OTC) system. One month old potted tomato plants after shifting to OTC were subjected to water stress and then were allowed to recover. Various growth parameters like root weight, shoot weight, root shoot ratio, specific leaf area, total dry matter content were analysed both after stress and recovery. Elevated CO2
was found to increase growth parameters like root weight, shoot weight, specific leaf area and total dry matter production. Significantly higher values were recorded for root weight (0.92 g), shoot weight (6.88 g), total dry matter production (5.74 g) under elevated CO2
compared to open control. The challenges extended by the changing climate situations along with the global warming and reducing water availability, studies on drought tolerance responses as modified by elevated CO2
environments is highly significant. The results of this study will also help to design improved production technologies with suitable varieties for a changing climatic scenario.