Abstract
The present work aims to quantify the impact of climate change (CC) on the grain yields of irrigated cereals and their water requirements in the Tensift region of Morocco. The Med-CORDEX (MEDiterranean COordinated Regional Climate Downscaling EXperiment) ensemble runs under scenarios RCP4.5 (Representative Concentration Pathway) and RCP8.5 are first evaluated and disaggregated using the quantile-quantile approach. The impact of CC on the duration of the main wheat phenological stages based on the degree-day approach is then analyzed. The results show that the rise in air temperature causes a shortening of the development cycle of up to 50 days. The impacts of rising temperature and changes in precipitation on wheat yields are next evaluated, based on the AquaCrop model, both with and without taking into account the fertilizing effect of CO2. As expected, optimal wheat yields will decrease on the order of 7 to 30% if CO2 concentration rise is not considered. The fertilizing effect of CO2 can counterbalance yield losses, since optimal yields could increase by 7% and 13% respectively at mid-century for the RCP4.5 and RCP8.5 scenarios. Finally, water requirements are expected to decrease by 13 to 42%, mainly in response to the shortening of the cycle. This decrease is associated with a change in temporal patterns, with the requirement peak coming two months earlier than under current conditions.
Highlights
Climate changes (CC), mainly attributed to the human-induced increase of greenhouse gases, e.g., carbon dioxide CO2, are expected to cause global warming in certain regions over the century[1]
Www.nature.com/scientificreports increased temperature can negatively impact plant production because of the heat stress[9]. This is the case if it occurs at sensitive phenological stages, e.g., pollination for wheat[10] and because it reduces the length of the crop season, leading to less radiation intercepted by the plants[11]
In order to assess the impact on yields, we choose the AquaCrop model[30] because (1) it was calibrated on wheat grown in the study region during a previous investigation[31]; (2) it has already been used in impact projection studies[32,33,34,35]; (3) the CO2 fertilizing effect has been parameterized based on Free Air Carbon dioxide Enrichment (FACE) experiment results[36,37]
Summary
Climate changes (CC), mainly attributed to the human-induced increase of greenhouse gases, e.g., carbon dioxide CO2, are expected to cause global warming in certain regions over the century[1]. Www.nature.com/scientificreports increased temperature can negatively impact plant production because of the heat stress[9] This is the case if it occurs at sensitive phenological stages, e.g., pollination for wheat[10] and because it reduces the length of the crop season, leading to less radiation intercepted by the plants[11]. In order to address this large uncertainty, impact projection studies of climate change on crop production are usually based on two experiments: one taking into account the fertilizing effect and another that does not[25], in addition to considering several CO2 emission scenarios. The objective of the present work is to study the impact of climate change, including rising atmospheric CO2 concentration and temperature, and changes in rainfall, on the optimal grain yield and water requirements of irrigated wheat in the Tensift region (Morocco). In order to assess the impact on yields, we choose the AquaCrop model[30] because (1) it was calibrated on wheat grown in the study region during a previous investigation[31]; (2) it has already been used in impact projection studies[32,33,34,35]; (3) the CO2 fertilizing effect has been parameterized based on FACE experiment results[36,37]
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