Protectants to ameliorate ozone-induced damage in crops – A possible solution for sustainable agriculture

Abstract

Elevated levels of tropospheric ozone (O3) are phytotoxic, inhibiting plant growth and production, and thus, compromising environmental health and sustainable crop production. It is therefore critical to devise strategies to protect plants from the negative effects of O3. However, the efficacy of different chemical or non-chemical methods to protect plants against O3 toxicities has not been critically reviewed. Hence, this study aimed at comprehensively reviewing various methods of crop protection against O3 stress. Ethylenediurea (EDU) is the most investigated and efficient protectant in ameliorating O3-induced phytodamage. However, plant protectants (e.g. pesticides, fungicides), antitranspirants (e.g. di-1-p-menthene), antioxidants (e.g. ascorbic acid, diphenylamine), exogenously-applied plant hormones (e.g. ethylene, kinetin, abscisic acid), and nutrient management strategies (e.g. varied level of nitrogen fertilizers, application of calcium acetate) were also found to offer some protection against O3. Hence, more studies are needed to comprehensively explore the potential of these methods, individually and in different combinations. Biological mechanisms that underlie the ameliorative effect of the different methods are discussed along with relevance of the concept of hormesis. This assessment also acknowledges major information gaps and suggests future options for dealing with O3 pollution. New insights into the efficacy of additional protectants provide a new dimension to plant protection against O3-induced detrimental effects, and suggest that future research should use a green chemistry approach and an ‘one health’ perspective.