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Anthropogenic global change is driving an increase in the frequency and intensity of drought and flood events, along with associated imbalances and limitation of several soil nutrients. In the context of an increasing human population, these impacts represent a global-scale challenge for biodiversity conservation and sustainable crop production to ensure food security. Plants have evolved strategies to enhance uptake of soil nutrients under environmental stress conditions; for example, symbioses with fungi (mycorrhization) in the rhizosphere and the release of exudates from roots. Although crop cultivation is managed for the effects of limited availability of nitrogen (N) and phosphorus (P), there is increasing evidence for limitation of plant growth and fitness because of the low availability of other soil nutrients such as the metals potassium (K), calcium (Ca), magnesium (Mg), and iron (Fe), which may become increasingly limiting for plant productivity under global change. The roles of mycorrhizas and plant exudates on N and P uptake have been studied intensively; however, our understanding of the effects on metal nutrients is less clear and still inconsistent. Here, we review the literature on the role of mycorrhizas and root exudates in plant uptake of key nutrients (N, P, K, Ca, Mg, and Fe) in the context of potential nutrient deficiencies in crop and non-crop terrestrial ecosystems, and identify knowledge gaps for future research to improve nutrient-uptake capacity in food crop plants. info:eu-repo/semantics/acceptedVersion

Polar regions are predicted to undergo large increases in winter temperature and an increased frequency of freeze–thaw cycles, which can cause ice layers in the snow pack and ice encasement of vegetation. Early or late winter timing of ice encasement could, however, modify the extent of damage caused to plants. To determine impacts of the date of ice encasement, a novel field experiment was established in sub‐arctic Sweden, with icing events simulated in January and March 2008 and 2009. In the subsequent summers, reproduction, phenology, growth and mortality, as well as physiological indicators of leaf damage were measured in the three dominant dwarf shrubs: Vaccinium uliginosum, Vaccinium vitis‐idaea and Empetrum nigrum. It was hypothesised that January icing would be more damaging compared to March icing due to the longer duration of ice encasement. Following 2 years of icing, E. nigrum berry production was 83% lower in January‐iced plots compared to controls, and V. vitis‐idaea electrolyte leakage was increased by 69%. Conversely, electrolyte leakage of E. nigrum was 25% lower and leaf emergence of V. vitis‐idaea commenced 11 days earlier in March‐iced plots compared to control plots in 2009. There was no effect of icing on any of the other parameters measured, indicating that overall these study species have moderate to high tolerance to ice encasement. Even much longer exposure under the January icing treatment does not clearly increase damage.

The Arctic is experiencing the greatest climate change in winter, including increases in freeze–thaw cycles that can result in ice encasement of vegetation. Ice encasement can expose plants to hypoxia and greater temperature extremes, but currently the impacts of icing on plants in the field remain little understood. With this in mind, a unique field manipulation experiment was established in heathland in northern Sweden with ice encasement simulated in early March 2008, 2009 and 2010 until natural thaw each spring. In the following summers we assessed the impacts on flowering, bud phenology, shoot growth and mortality and leaf damage (measured by chlorophyll fluorescence and electrolyte leakage) of the three dominant dwarf shrub species Empetrum nigrum, Vaccinium vitis‐idaea (both evergreen) and Vaccinium myrtillus (deciduous). Two consecutive winters of icing decreased V. vitis‐idaea flowering by 57%, while flowering of V. myrtillus and E. nigrum remained unaffected. Vaccinium myrtillus showed earlier budburst but shoot growth for all species was unchanged. Shoot mortality of V. myrtillus and V. vitis‐idaea increased after the first year (by 70 and 165%, respectively) and again for V. myrtillus following the third year (by 67%), while E. nigrum shoot mortality remained unaffected, as were chlorophyll fluorescence and electrolyte leakage in all species. Overall, the sub‐arctic heathland was relatively tolerant to icing, but the considerable shoot mortality of V. myrtillus contrasting with the general tolerance of E. nigrum suggests plant community structure in the longer term could change if winters continue to see a greater frequency of icing events.

During the origin of agriculture in the Fertile Crescent, the broad spectrum of wild plant species exploited by hunter‐gatherers narrowed dramatically. The mechanisms responsible for this specialization and the associated domestication of plants are intensely debated. We investigated why some species were domesticated rather than others, and which traits they shared. We tested whether the progenitors of cereal and pulse crops, grown individually, produced a higher yield and less chaff than other wild grasses and legumes, thereby maximizing the return per seed planted and minimizing processing time. We compared harvest traits of species originating from the Fertile Crescent, including those for which there is archaeological evidence of deliberate collection. Unexpectedly, wild crop progenitors in both families had neither higher grain yield nor, in grasses, less chaff, although they did have larger seeds. Moreover, small‐seeded grasses actually returned a higher yield relative to the mass of seeds sown. However, cereal progenitors had threefold fewer seeds per plant, representing a major difference in how seeds are packaged on plants. These data suggest that there was no intrinsic yield advantage to adopting large‐seeded progenitor species as crops. Explaining why Neolithic agriculture was founded on these species, therefore, remains an important unresolved challenge.