Adaptation mechanisms to water scarcity of two almond cultivars from different origin countries

Climate change is making the Mediterranean Basin particularly vulnerable to water scarcity and desertification. It is thus crucial to study the plant adaptation mechanisms to choose the most appropriate cultivars and the related agro-practices. This work aims at studying the behavior of two almond cultivars of different origin, ‘Filippo Ceo’ (Italy) and ‘Texas’ (America), managed following the Dry Farming Practices (DFP) principles in a high water-demanding environment. The trial was conducted in an experimental farm with an almond germplasm collection from Southern Italy (Puglia region). The germplasm collection included more than 500 genotypes, ensuring an effective cross-pollination of ‘Texas’. In 2015 and 2016, during the fruit growing season, fruit surface conductance, fresh weight and fruit volume were measured. In 2016, from April to July, leaf net photosynthesis, stomatal conductance, and leaf transpiration were monitored. In both years, fruit surface conductance was higher in ‘Texas’ than in ‘Filippo Ceo’, with high water use and theoretical low drought tolerance of the foreign cultivar compared to the local one. Both productivity and fruit quality were higher in ‘Filippo Ceo’ than in ‘Texas’. Both cultivars showed similar leaf gas exchange values during the fruit growth period (April-May), while they were higher in ‘Texas’ than in ‘Filippo Ceo’ in warmer months. The fruit growth period in almond is very short and susceptible to water scarcity. The limiting factor for ‘Texas’ productivity could be the high water demand for fruit transpiration rather than for leaf physiological functioning. However, this divergent behavior of source and sink organs should be investigated deeper in the future.