Abstract
The plant response to elevated ozone stress reveals inter-species and intra-species disparity. Ozone-induced crop yield loss is predicted to increase in the future, posing a threat to the world economy. This study aims to evaluate the cultivar specific variation in rice exposed to elevated ozone. Fifteen short-duration rice cultivars were exposed to 50 ppb ozone for 30 days at reproductive stage. The physiological, biochemical, growth and yield traits of all test cultivars were significantly affected in response to elevated ozone. On an average, ozone stress decreased the tiller number by 22.52%, number of effective tillers by 30.43%, 1000 grain weight by 0.62% and straw weight by 23.83% over control. Spikelet sterility increased by 19.26% and linear multiregression 3D model significantly fits the spikelet sterility and photosynthetic traits with the R2 of 0.74 under elevated ozone. Principal Component Analysis with total variance of 57.5% categorized 15 rice cultivars into four major groups, i.e., ozone sensitive (MDU6, TRY(R)2 and ASD16), moderately ozone sensitive (ASD18, ADT43, and MDU5), moderately ozone tolerant (ADT37, ADT(R)45, TPS5, Anna(R)4, PMK(R)3, and ADT(R)48), and ozone tolerant (CO51, CO47, and ADT36). This study indicates that the different responses of rice cultivars to elevated ozone stress through a change in plant physiology, biochemical, growth, and yield traits and the results directed to provide scientific information on plant adaptations to ozone stress and helps in efforts to search ozone tolerant gene for plant breeding.
Highlights
Tropospheric ozone is the third most important contributor of greenhouse radiative forcing (0.40±0.20 Wm–2) after CO2 and CH4 (IPCC, 2013)
Dhevagi), ORCID: The current study aimed to evaluate the cultivar specific variation in rice exposed to elevated ozone
Increment in proline content varied between 50.15% (PMK(R)3) to 145.15% (MDU6) (Fig. 2); proline accumulation increased by 98.38% over control might be correlated with participation of proline in reactive oxygen species (ROS) scavenging mechanism in plant tissues that would be beneficial for its tolerance to environmental stresses (Gill and Tuteja, 2010)
Summary
Tropospheric ozone is the third most important contributor of greenhouse radiative forcing (0.40±0.20 Wm–2) after CO2 and CH4 (IPCC, 2013). Right from the industrial revolution until today, there is a continuous alarming rise in ozone forming precursors (NOx,VOC) in the atmosphere, which in turn increases the tropospheric ozone (Monks et al, 2015). According to Intergovernmental Panel on Climate Change (IPCC) fifth assessment report, the developing Asian and African countries are in higher food security risk due to unplanned urbanization and industrialization which favours tropospheric O3 formation (Pachauri et al, 2014). In India, the ozone forming precursor, NOx level showed an increasing trend of 0.9ppb per year from 2010 to (Kumari et al, 2020). 3–5.6% per decade was observed over Indo Gangetic plains, while 1.2–2% per decade was noticed over southern regions of India (Lal et al 2012). Kumari et al (2020) reported that the annual mean ozone concentration increased by 19.2% from 2010-2015 over Indo Gangetic plains.
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