Can Reduced Irrigation Mitigate Ozone Impacts on an Ozone-Sensitive African Wheat Variety?

Abstract

Ground-level ozone (O3) pollution is known to adversely affect the production of O3-sensitive crops such as wheat. The magnitude of impact is dependent on the accumulated stomatal flux of O3 into the leaves. In well-irrigated plants, the leaf pores (stomata) tend to be wide open, which stimulates the stomatal flux and therefore the adverse impact of O3 on yield. To test whether reduced irrigation might mitigate O3 impacts on flag leaf photosynthesis and yield parameters, we exposed an O3-sensitive Kenyan wheat variety to peak concentrations of 30 and 80 ppb O3 for four weeks in solardomes and applied three irrigation regimes (well-watered, frequent deficit, and infrequent deficit irrigation) during the flowering and grain filling stage. Reduced irrigation stimulated 1000-grain weight and harvest index by 33% and 13%, respectively (when O3 treatments were pooled), which compensated for the O3-induced reductions observed in well-watered plants. Whilst full irrigation accelerated the O3-induced reduction in photosynthesis by a week, such an effect was not observed for the chlorophyll content index of the flag leaf. Further studies under field conditions are required to test whether reduced irrigation can be applied as a management tool to mitigate adverse impacts of O3 on wheat yield.

Ethylenediurea (EDU) effects on Japanese larch: an one growing season experiment with simulated regenerating communities and a four growing season application to individual saplings

“…Several research projects have been directed to protect plants against O 3 damage, by using various methods or approaches: (1) introducing symbiotic microbes into the plant system to mediate plant response (Agathokleous et al 2020 ), (2) modifying the irrigation management practices to reduce O 3 uptake from stomata (Harmens et al 2019 ), (3) applying substances on leaf surface to create a protective “membrane” and prevent O 3 from entering the leaf tissue (Agathokleous et al 2016b ), and (4) treating plants with chemicals that systemically protect plants against O 3 damage (Tiwari 2017 ). However, only approach (4) has been widely researched and shown to produce sufficient protection.…”

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

“…Compared to individual effects of CO 2 and O 3 , combined interactive environment of CO 2 and O 3 affects growth and development of crops as well as yield and nutrient levels in different ways (Phothi et al., 2016). There has been studies on individual effects of CO 2 and O 3 on wheat, rice, maize and chickpea crops and their yield in India and in other parts of world (Mishra et al., 2013; Saha et al., 2015; Abebe et al., 2016; Chaturvedi et al., 2017; Harmens et al., 2019). Most of these studies have been conducted using open top chambers in field conditions.…”

Quantifying the impact of ozone on crops in Sub-Saharan Africa demonstrates regional and local hotspots of production loss

“…sowing date) strategies. Harmens et al (2019) investigated the effect of irrigation regimes on Kenyan wheat growing in low (30 ppb) and high (80 ppb) ozone treatments. Reduced irrigation stimulated grain weight and harvest index, which compensated for ozone induced reductions in well-watered plants.…”