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Plants (Basel). 2019 Jun 12;8(6). pii: E171. doi: 10.3390/plants8060171.

Photosynthetic Responses of Canola and Wheat to Elevated Levels of CO2, O3 and Water Deficit in Open-Top Chambers.

Author information

1
Unit for Environmental Sciences and Management, North-West University, Potchefstroom 2520, South Africa. bmaliba@gmail.com.
2
Eskom Research, Testing and Development, Cleveland 2022, South Africa. bmaliba@gmail.com.
3
Unit for Environmental Sciences and Management, North-West University, Potchefstroom 2520, South Africa. prabhu.inbaraj@gmail.com.
4
Department of Chemistry, School of Basic Sciences, Manipal University Jaipur, Jaipur 303007, India. prabhu.inbaraj@gmail.com.
5
Unit for Environmental Sciences and Management, North-West University, Potchefstroom 2520, South Africa. Jacques.berner@nwu.ac.za.

Abstract

The effects of elevated CO2 (700 ppm) and O3 (80 ppb) alone and in combination on the photosynthetic efficiency of canola and wheat plants were investigated in open-top chambers (OTCs). The plants were fumigated for four weeks under well-watered and water-stressed (water deficit) conditions. The fast chlorophyll a fluorescence transients were measured after 2 and 4 weeks of fumigation, as well as in control plants, and analyzed by the JIP-test, which is a non-destructive, non-invasive, informative, very fast and inexpensive technique used to evaluate the changes in photosynthetic efficiency. Biomass measurements were taken only after 4 weeks of fumigation. The performance index (PItotal), an overall parameter calculated from the JIP-test formulae, was reduced by elevated CO2 and O3 under well-watered conditions. In the absence of any other treatment, water stress caused a decrease of the PItotal, and it was partly eliminated by fumigation with elevated CO2 and CO2 + O3. This finding was also supported by the biomass results, which revealed a higher biomass under elevated CO2 and CO2 + O3. The decrease in biomass induced by elevated O3 was likely caused by the decline of photosynthetic efficiency. Our findings suggest that elevated CO2 reduces the drought effect both in the absence and presence of O3 in canola and wheat plants. The study also indicates that elevated O3 would pose a threat in future to agricultural crops.

KEYWORDS:

JIP-test; biomass; canola; drought; elevated CO2; open-top chamber; ozone; wheat

PMID:
31212826
DOI:
10.3390/plants8060171
Free PMC Article

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