The effects of elevated CO2 and elevated O3 exposure on plant growth, yield and quality of grains of two wheat cultivars grown in north India

Abstract

Global food security is challenged by increasing levels of CO 2 , O 3 and temperature trough their impacts on production and grain quality of wheat, one of the major C 3 crops and staple food across the world. The present study was conducted to assess the effects of elevated levels of CO 2 (EC; 550 ppm) and tropospheric O 3 (EO; 70 ppb) as well as of combined interactive treatment [EC X EO; ECO] on plant growth, yield and grain quality of two wheat cultivars (HD-2967 and C-306) grown during 2016-17 and 2017-18 using free air ozone and carbon dioxide enrichment (FAOCE) facility under field conditions. Individually, EC, increased leaf area index (LAI; 15.9-28.2%), photosynthetic rate (Pn; 11.4-20.3%) and yield (8.2-20.9%) whereas EO declined LAI (5.1-12.5%), Pn (2.8-11.8%) and yield (2.2-14.2%) over ambient conditions (Amb: 405.2 ppm CO 2 and 30.7 ppb O 3). Under ECO condition, EC increased LAI (2.2-17.1%), Pn (2.8-17.6%) and grain yield parameters (4.4-24.3%) across the cultivars in both years, but reduced the positive effects of EO on quality as compared to Amb. Dilution effect of increased yield under EC condition have reduced total protein, micro-and macro-nutrient concentrations whereas EO increased them notably compared to Amb. Starch in grains increased under EC but reduced under EO as compared to Amb. AOT40, the sum of averaged difference of O 3 h À1 concentration beyond 40 ppb for 7 hours (31233 ppb h À1) in FAOCEs rings during the crop growth period led to reduction in average grain yield of HD-2967 and C-306 by 11.6 and 8.5% or by 1.6 and 1.3% yield loss per ppb increase of O 3 , respectively. The growth, yield and quality parameters of both wheat cultivars responded similarly but to different extent to all treatments. EC was able to offset the negative effects of EO on yield and yield components only, but not those concerning the quality of grains. To stabilize global food security, precursor gases forming tropospheric ozone must be constrained.

Impact of Elevated CO2 and Temperature on Growth, Development and Nutrient Uptake of Tomato

“…Improved LAI at tasseling (17.5%) and silking stage (14.8%) at elevated CO 2 (550 ± 20 ppm) and decreased LAI by 5.4 to 13.2% at elevated temperature (+1.5 to 3.0 • C) was noticed in maize [15]. Irrespective of the cultivars, increased LAI of about 23% at both vegetative and flowering stages of wheat at elevated CO 2 (550 ppm) was revealed by Yadav et al [46]. In safflower, elevated CO 2 of 1000 µmol/mol maximized the LAI by 28% at anthesis stage over ambient CO 2 of 400 µmol/mol [47].…”

Assessing the evolution of wheat grain traits during the last 166 years using archived samples

“…About the carbohydrate content, studies conducted in controlled and FACE facilities showed that rising [CO 2 ] contributes to increases in starch and soluble sugar contents in wheat grains 29 – 31 . The larger photosynthetic rates of C 3 plants such as wheat under increasing [CO 2 ] may contribute to increased carbohydrate translocation from the source (leaves and stems) to the sink (grains), where the C is mainly stored in the form of starch.…”

Approaches to investigate crop responses to ozone pollution: from O3‐FACE to satellite‐enabled modeling

“…The FAOCE was installed in 2016 in New Delhi, India, and analyzed the response of yield and grain quality to the combination of elevated [O 3 ] and [CO 2 ] in wheat, maize, and chickpea (Cicer arietinum) (Singh et al, 2021;Yadav et al, 2019Yadav et al, , 2021. The FACE rings at FAOCE were 5 m in diameter and were divided into halves or quartiles to study different genotypes.…”

“…Bernacchi et al (2006) and Dermody et al (2008) included a combination treatment of elevated [CO 2 ] and [O 3 ] and showed that elevated [CO 2 ] ameliorated many of the negative effects of chronic O 3 stress in part because stomatal conductance is significantly lower in elevated [CO 2 ], and therefore O 3 flux is reduced. At FAOCE, researchers found that the interactive effect of elevated [O 3 ] and [CO 2 ] compensated for O 3 damage in wheat and chickpea by maintaining yields similar to those in ambient conditions (Singh et al, 2021;Yadav et al, 2019). Work in maize at the same research facility found that elevated [CO 2 ] helped to maintain yield when the plant was exposed to elevated O 3 (Yadav et al, 2021).…”