Sorghum drought and heat stress patterns across the Argentinean temperate central region

Argentinean current sorghum management is similar across the entire temperate region, and no environmental characterization is assisting breeding and management decisions. Crop growth and development simulation models are a valuable tool for generating this characterization. Our study calibrated and validated APSIM-sorghum for our genetics and production environments, and used it to characterize the main water and heat stress patterns at our temperate central region. The calibration and validation provided accurate phenology, biomass, and yield estimations. Long-term weather records (44-61 years per site) and soil data were used to simulate the seasonal drought patterns at seven representative sites across the region. Clustering analysis identified three major drought environmental types (ENVT): (i) a pre-flowering drought stress, showing large occurrence frequency (39%), (ii) a low terminal drought stress, showing similar frequency (38%), and (iii) a grain-filling drought stress, showing lower frequency (23%). The most frequent ENVT at individual sites agrees with the spatial distribution of annual rainfall. However, most sites evidenced variable frequency of all ENVT. Flowering heat stress ( > 33 degrees C) showed an intermediate occurrence frequency (20-50%) only at lower latitudes, and was independent of drought ENVT. Defined ENVT helped explain observed genotype x environment (GxE) interactions for yield in an independent data set, showing they have practical implications for optimizing breeding and management strategies across the region of interest. Grouping sites of similar frequency can help to handle the spatial variability when defining these strategies, but dealing with seasonal variability will be challenging in the context of no predominant ENVT.