Warm nights in the Argentine Pampas: Modelling its impact on wheat and barley shows yield reductions

Efforts to anticipate how climate change and variability will affect future crop production can benefit from understanding the impacts of current and historic changes. This study aimed to quantify and compare the impact of increased night temperature on potential yield and phenology of wheat (Triticum aestivum L.) and barley (Hordeurn vulgare L.) crops modelled using APSIM with historical climate series (1961-2014) in sites representative of the Argentinean Pampas. For each site, the sowing date was adjusted to avoid frost and heat events at flowering, based on historical probability. The critical period was the more sensitive crop phase (shortened by 0.6 d decade(-1)) for the observed asymmetric warming; regional minimum temperature trend of ca. 0.14 and 0.16 degrees C decade(-1) in wheat and barley, respectively. Wheat and barley yields declined across the region between ca. 2% and 9% per degrees C increase in the minimum temperature during the critical period, linked to lower cumulative radiation capture as a result of a shorter crop phase and lower incident radiation due to displacement towards winter. Regional variability in the simulated yield response to the observed night warming was mainly explained by differences the response of incident solar radiation during the critical period to the minimum temperature increase.