3. Effect of High Temperature Stress on Wheat and Barley Production in Northern Tunisia

Increasing temperatures due to global warming have raised concerns about food security in the southern Mediterranean region. This work attempts to study the limitation to cereal production in Tunisia. Data from six governorates were used to develop relationships between cereal yields and the sum (STx) of maximum temperatures over the threshold of 15 °C. The data envelopment analysis method was used to identify the attainable regional production among seasons having a total rainfall over 350 mm. Results showed that yields of bread wheat, durum wheat and barley decreased, respectively, by 0.4, 0.26, and 0.32 t ha⁻¹ for each 100 °C-day increase in STx, over the 1973–2013 period. An increasing trend in STx was observed for the major synoptic stations of the studied areas over the last 40 years but with different speeds. Future projections to 2050 showed a 15% rise for STx with a low radiative forcing scenario resulting in cereal yield gaps up to 0.26 t ha⁻¹.