Elevated Temperature and Carbon Dioxide alter the Tea Rhizosphere Soil Dynamics

Aim: The aim of this work is to explore the impact of climate change on the tea rhizosphere soil dynamics. The experiment sought to study the tea rhizosphere Soil Organic Carbon (SOC), Total Nitrogen (TN), Microbial Biomass Carbon (MBC) and Microbial Biomass Nitrogen (MBN) under elevated levels of temperature and Carbon Dioxide (CO₂). Materials and Methods: The experimental design was set up with two Open Top Chamber (OTC) facilities, creating localized conditions with increased temperature and CO₂. Both temperature and CO₂ were elevated in OTC-1 (eTemp+eCO₂), with CO₂ concentration of 550 ppm, while in OTC-2 (eTemp), only the temperature was elevated. Temperature was 1.5-2ºC higher than ambient. Four tea cultivars (TV1, TV20, TV22 and TV23) were placed inside the OTCs and rhizosphere soil samples were collected at regular intervals. Results: The results indicated that in eTemp+eCO₂ treatment, over the period of time, the rate of change in SOC showed significant increase (p<0.01) compared to control, while TN showed no significant variations, the rate of change in MBC showed significant increase (p<0.05) in eTemp treatment. No significant variation was observed in the rate of change in MBN. Overall, SOC and MBC, after 300 hr of treatments showed significant increase (p<0.001) in both eTemp and eTemp+eCO₂ treatments when compared to control. However, after 300 hr of treatment overall soil TN exhibited a significant increase (p<0.05) in eTemp+eCO₂ treatment. Conclusion: This study addresses the research gap through an evidence based experimental work that monitors the impact of temperature and CO₂ on tea rhizosphere. From the study, it can be concluded that elevated temperature and CO₂ alter the rate of change in soil organic carbon pool of tea rhizosphere soil along with the accumulation of biomass carbon, whereas no such alteration was found for microbial biomass nitrogen.