Effect of elevated carbon dioxide on growth and development of Santalum album L. seedlings inoculated with plant growth promoting microorganisms in Open Top Chambers

Rising carbon dioxide (CO2) concentrations in atmosphere have a significant impact on plant growth and metabolism. Many plant growth promoting microbes play an important role in maintaining plant growth and vitality by facilitating nutrient translocation under adverse conditions. This study was carried out to investigate the effects of elevated CO2 on growth parameters (height of the seedlings, increment in height, collar diameter and number of leaves) in sandalwood (Santalum album L.) seedlings inoculated with beneficial microorganisms (Pseudomonas putida, Bacillus subtilis and Trichoderma harzianum) in the Open Top Chambers (OTCs). Sandalwood seedlings inoculated with P. putida, B. subtilis, T. harzianum were grown in OTCs at 600 ppm, 800ppm, 1000ppm and 1200ppm elevated concentrations of CO2. As compared to the non-inoculated (untreated/control) plants, inoculated one shows a high growth and development rate but non- inoculated plants were not able to handle stress at higher/elevated CO2 concentration (1000 & 1200ppm) and ultimately died after 60 days. P. putida showed a high growth rate on all growth and development parameters taken up to 1000 ppm concentration of CO2 followed by Bacillus subtilis. It is also observed that T. harzianum treatment could not withstand the elevated concentration of CO2 beyond 1000 to 1200 ppm whereas P. putida treatment was found to be effective at even at 1200 ppm of CO2. Through these experiments under OTCs at different elevated concentrations of CO2, we can predict the possibility of climate change and global warming effect on beneficial microbes and vis-a-vis their effect on growth, development and yield on crops. Hence, other plant growth microbes including mycorrhizal fungi can be analyzed for future research and bio-prospect under OTCs experimentation.