Abstract
Projected warming and drying trends over the Mediterranean region represent a substantial threat for wheat production. The present study assesses winter wheat yield response to potential climate change and estimates the quantitative effectiveness of using early flowering cultivars and early sowing dates as adaptation options for the major wheat production region of Portugal. A crop model (STICS) is used for this purpose, which is calibrated for yield simulations before projecting future yields. Climate projections over 2021–2050 and 2051–2080 under two emission scenarios (RCP4.5 and RCP8.5) are retrieved from bias-adjusted datasets, generated by a ten-member climate model ensemble. Projected intensification of water deficits and more frequent high-temperature events during late spring (April–June), coinciding with the sensitive grain filling stage, primarily result in continuous mean yield losses (relative to 1981–2010) by − 14% (both scenarios) during 2021–2050 and by − 17% (RCP4.5) or − 27% (RCP8.5) during 2051–2080, also accompanied by increased yield variabilities. Of evaluated adaptation options at various levels, using earlier flowering cultivars reveals higher yield gains (26–38%) than that of early sowings (6–10%), which are able to reverse the yield reductions. The adopted early flowering cultivars successfully advance the anthesis onset and grain filling period, which reduces or avoids the risks of exposure to enhanced drought and heat stresses in late spring. In contrast, winter warming during early sowing window could affect vernalization fulfillment by slowing effective chilling accumulation, thus increasing the pre-anthesis growth length with limited effects on advancing reproductive stage. Crop yield projections and explored adaptation options are essential to assess food security prospects (availability and stability) of dry Mediterranean areas, providing crucial insights for appropriate policymaking.
Highlights
How to improve agricultural production to meet projected increasing demand of global food products by around 60% until 2050, due to growing population and economic development, represents a substantial challenge, in the context of climate change (Alexandratos and Bruinsma 2012)
Post-anthesis high temperature (> 30 °C), which is common in Alentejo (Scotti-Campos et al 2014), can cause significant grain yield reductions, resulting from a shortened grain filling phase and increased leaf senescence (Asseng et al 2011; Dias and Lidon 2009)
A modeling study in major wheat growing regions of Australia suggested that variations in mean growing season temperature by ± 2 °C could impose a substantial reduction on wheat grain production by up to 50% (Asseng et al 2011)
Summary
How to improve agricultural production to meet projected increasing demand of global food products by around 60% until 2050, due to growing population and economic development, represents a substantial challenge, in the context of climate change (Alexandratos and Bruinsma 2012). Wheat (Triticum aestivum L.) is the staple crop throughout the world, and Portugal is a country that still highly depends on the importation of wheat, e.g., used as fodder crop in many dairy farms In this context, satisfying internal demands via increased domestic production may play a vital social-economic role (Páscoa et al 2017). A previous analysis for this region revealed climatic water deficits in May and June, largely coinciding with the grain filling and ripening stages, could impose strong limitation on wheat yields (Páscoa et al 2017) Such a critical growing period is frequently exposed to extremely high temperatures, with clear detrimental effects on final grain yield (Dias and Lidon 2009; Scotti-Campos et al 2014). The observed warming and drying trends are likely to be strengthened in future climates (Páscoa et al 2017; Rolim et al 2017), with a concomitant increase in the frequency and intensity of extreme weather events, e.g., droughts (Santos et al 2016)
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