Editorial: Abiotic Stresses in Agroecology: A Challenge for Whole Plant Physiology

Abiotic stresses in agroecology are caused by climatic factors (e.g., temperature and precipitation extremes), pollutants (e.g., heavy metals, gaseous pollutants) and salinity. In the context of global change, climatic factors become particularly important. The alarming, progressive alterations in climate caused by rising levels of carbon dioxide (CO2) and other greenhouse gases in the atmosphere are linked to well-known consequences of climate change; increase in average global temperature and the melting of the polar ice caps (IPCC, 2014). In addition to these global problems, increased frequencies and severities of extreme events including heat waves, drought periods or waterlogging have significant impacts at local and regional levels (Schär et al., 2004; IPCC, 2012; Kelley et al., 2015; Knutti et al., 2016). Such events may strongly influence crop yields and the quality of agricultural products. The effects of stresses imposed by these factors individually and in combination are relevant in the context of agroecology and in developing new agricultural concepts taking into account soil quality, biodiversity, sustainability as well as social and economic aspects (Tomich et al., 2011; Lai, 2015). This Research Topic focuses on the impacts of abiotic stress at the whole plant level, the mechanisms involved in the stress responses and the potential to increase stress tolerance in field crops and trees. Elevated CO2 in the atmosphere caused by human activities is the major driver for global climate change that affects ambient temperature and precipitation patterns on global and regional scales, and water availability in soils as well as the frequency and severity of extreme events (IPCC, 2012, 2014). Atmospheric CO2 may also directly influence primary metabolism and thereby plant growth and productivity as reported by Long et al. (2006), Centritto et al. (2011), Hasegawa et al. (2013), Haworth et al., Haworth et al., Martinez-Lüscher et al. Free-air CO2 enrichment (FACE) facilities have been used to establish the impact of elevated CO2 on the efficiency of radiation, water and nitrogen utilization, overall crop yields (Dugas and Pinter, 1994; Long et al., 2006), and the interactions between sink structures (Hasegawa et al., 2013). In this Research Topic, Martinez-Lüscher et al. investigated interactions between elevated CO2 levels, ambient temperature and water availability in grapevine (Vitis vinifera L.) phenology from bud break to fruit maturation, while Haworth et al. addressed interactions between elevated CO2, stomatal control and photosynthetic performance. Haworth et al. argue that because of the tendency in free-air CO2 (FACE) experiments to publish more of significant results and less of nonsignificant results, the meta-analyses of results of such studies might lead to overestimation of the physiological impacts of rising CO2 levels in the atmosphere. Therefore while the direction and significance of impacts 20 April 2017