Effect of elevated O₃ on rhizospheric enzymatic activities of ozone sensitive and tolerant wheat cultivars

ABSTRACT

Tropospheric ozone (O₃) is considered harmful to agriculture production and soil community. Wheat cultivars HD 2987 (O₃ sensitive) and Kharchiya 65 (O₃ tolerant) were grown under ambient and elevated (ambient + 30 ppb) levels of O₃ (EO) using open top chambers, and microbial biomass and enzymatic activities were investigated in soil rhizosphere. Elevated O₃ declined soil enzymatic activities related to carbon cycling viz. β-glucosidase, cellobiohydrolase, cellulase and amylase more in sensitive cultivar compared to tolerant. Enzymatic activities linked to nitrogen cycling like N-acetyl-glucosaminidase and urease decreased while protease and glycine aminopeptidase increased. Microbial biomass carbon and nitrogen declined more in sensitive cultivar by 11.1 and 21.2%, respectively. Root biomass reduced in wheat cultivars with an increase of their phenolics contents by 34.3 and 10.2% in HD 2987 and Kharchiya 65, respectively at 60 days after germination. Non-significant changes were observed in soil organic carbon and total nitrogen in both the cultivars. Redundancy analysis suggested that soil enzymatic activities were predominantly affected by O₃ induced changes in microbial biomass carbon and root biomass. Study also showed that rhizosphere of sensitive cultivar HD 2987 was affected more under EO as compared to tolerant Kharchiya 65.

KEYWORDS:

• Ozone
• Rhizosphere
• Soil enzymes
• Wheat

Acknowledgments

We thank Head of the Department of Botany and Department of Science and Technology (DST-FIST), Centre of Advanced Study (CAS) and Interdisciplinary School of Life Sciences (ISLS) for all the laboratory facilities. Authors acknowledge the Science and Engineering Research Board (Department of Science and Technology), New Delhi for providing financial support to the work in form of major research project (SERB/PO/PS-62/2013). Authors are also grateful to anonymous reviewers and editor for their valuable suggestions which helped in improving the quality of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by Science and Engineering Research Board, Department of Science and Technology, Government of India in form of major research project [SERB/PO/PS-62/2013].