Assessing the adaptive capacity of durum wheat cultivars to future climate

The perspective of climate change requires an analysis of the adaptation possibilities of species currently cultivated. A powerful tool for adaptation is the relevant intra-specific biodiversity of crops. The knowledge, for different cultivars, of the responses to environmental conditions (e.g. yield response functions to water regime) can be a tool to identify options for adaptation to future climate. Models of crop response to environmental forcing might be used for this purpose, but this approach is severely constrained by the scarce knowledge on variety-specific values of model parameters, thus limiting the evaluation of intra-specific biodiversity towards adaptation.We have developed an approach towards this objective that relies on two complementary elements. A database on climatic requirements of durum wheat varieties: the yield response functions to water availability were determined from scientific literature. These functions were applied to describe the behaviour of the cultivars with respect to the soil water availability; the simulations performed by the agro-hydrological model SWAP (soil-water-plant and atmosphere), to describe the future soil water regime at landscape scale.The case-study presented here shows how the yield response of durum wheat cultivars to soil water availability can be defined by means of variety-specific threshold values of evapotranspiration deficit. The soil water regime calculated by the model is compared with the threshold values to identify varieties compatible with expected climate. The operation is repeated for a set of realizations of each climate scenario. This analysis is performed for three soils. The selected study area is a hilly region of about 40,000 ha in Southern Italy (Fortore Beneventano, Campania Region). Future climate scenarios in the area were generated within the Italian National Project AGROSCENARI. Climate scenarios at low spatial resolution generated with general circulation models (AOGCM) were downscaled by means of a statistical model. The downscaled climate scenario includes 50 realizations of daily minimum, maximum temperature and precipitation data, on a regular grid with a spatial resolution of 35 km, for the 2021-2050 period. The downscaled climate scenario was further refined by using the hydrological model which describes the soil water regime in three soils. Soil water content and evapotranspiration deficit was determined for the 50 realizations of the daily time series, taking into account the three soils, and was compared with threshold values to evaluate cultivar' adaptability to the predicted future climate. The case study shows how, in the future climate scenario, the intra-specific variability will allow to maintain the current crop production system.