Plant growth and resilience require balancing an inherently oxidative metabolism with powerful antioxidant systems that help maintain homeostasis. When the environment changes, reactive oxygen species are potent indicators of that change, allowing adaptation through re-balancing metabolism and antioxidant systems. A large body of evidence supports the use of exogenously applied antioxidants to improve both plant growth and their resilience to stress. Notably, some phenotypic effects are similar upon the application of chemically diverse antioxidants, while others are distinct. In this review, we analyze research from antioxidant treatment experiments and highlight the similarities in their practical applications and their effects on plant stress tolerance, photosynthesis, native antioxidant systems, and phytohormones. We also briefly cover the specific effects of individually applied antioxidants and what is known about their potential modes of action. Given the strong potential of antioxidant applications, we discuss research needed to promote their agricultural use. Finally, we identify outstanding questions about how the exogenous application of antioxidants mechanistically affects plant growth.

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to the heterogeneity of habitats, all plants are exposed to at least some degree of shade during their lifetime. Reduced light intensity, drops in R:FR ratio, and limited blue light are cues for plants to perceive competition; the shade avoidance syndrome (SAS) is common for grassland species while shade tolerance (ST) is common for forest species when competition is perceived. SAS is characterized by elongation of stems and petioles, reduced branches, decreased leaf area, decreased shoot biomass, and increased number of ramets. ST is characterized by little elongation of stems and petioles, high chlorophyll content and high chlorophyll a/b ratio in leaves, low root-shoot ratio, and thinner leaves. In this study, germination of six native Asteraceae species was tested against 10%, 50%, and 100% of natural light in a greenhouse. Measurements of growth and reproduction were made in two species under the same light conditions. Shaded conditions decreased germinabilities of seeds in all species that were tested. Increased light conditions resulted in increased growth for both species. When exposed to shaded conditions, both species displayed several traits that are related with shade tolerance modifications such as little elongation of stems and petioles, higher specific leaf area, higher chlorophyll a/b ratio, reduced leaf area and root/shoot biomass, and fewer and thinner leaves. In summary, plants displayed unexpected strategies and a high resilience to grow and develop under shaded conditions.