Climate change, effective water use for irrigation and adaptability of maize: a case study in southern Italy

Climate change may lead to differences in the distribution of precipitation and to reducedwater availability, with constraints on the cultivation of some crops. An analysis ofvulnerability and of opportunities for adaptation is required for crops in areas where theyare currently cultivated. The intra-specific biodiversity of crops is a significant resource forthe adaptation of agriculture, but requires better knowledge of the responses of cultivars toenvironmental stressors. Simulation models of water flow in the soil-plant-atmospheresystem can be coupled with future climate scenarios to describe the soil water regime,taking into account different irrigation scheduling options. The adaptive capacity of maizehybrids is evaluated in an irrigated district in Southern Italy. Two climate cases werestudied: "reference" (1961 e 1990) and "future" (2021 e 2050). The model SWAP was run todetermine the soil water balance for different irrigation levels. For each level the effec-tiveness of irrigation was evaluated by means of a performance indicator (IE). The RelativeEvapotranspiration Deficit (RETD) was used as an indicator of water availability. The yieldresponse to water availability of several maize hybrids was determined; their hydrologicrequirements were thus defined and compared with the simulated values of RETD inresponse to climate and irrigation. Soil moisture regime and irrigation performance werealso analysed. The adaptability of hybrids to the future water regime was assessed fordifferent irrigation levels. The study indicated how, in the future climate case, the intra-specific crop biodiversity, in combination with cropping patterns better adapted to soilcharacteristics, may allow the current production system to be maintained.