Effect of water availability on growth, water use efficiency and omega 3 (ALA) content in two phenotypes of chia (Salvia hispanica L.) established in the arid Mediterranean zone of Chile

Chia (Salvia hispanica L.), has achieved economic importance due to the products which are obtained from its leaves with antioxidant capacity and especially its seeds, because they contain omega 3. However, there is a lack of information on optimal agronomic management practices and especially the influence of water availability on its establishment and production. The objective of this study was to evaluate the effect of different irrigation rates on growth and water use efficiency (WUE) in the production of leaf biomass, seeds and omega 3 in two phenotypes of chia, black and white. We applied three irrigation treatments calculated to be 100, 70 and 40% of the mean evaporative demand (ET0) calculated weekly, designated as T1, T3, T5 black phenotype and T2, T4 and T6 white phenotype; T1 and T2 irrigated to 100%; T3 and T4 irrigated to 70% and T5-T6 irrigated to 40% ETo. There was no difference between phenotypes, however, water treatment affected the gas exchange parameters photosynthesis, stomatal conductance and transpiration, which ranged from 26 to 4 μmol m−2 s−1; 4.5 to 1.5 mmol m−2 s−1 and 0.6 to 0.1 mol m−2 s−1 from treatment (54 days after sowing) to harvest, respectively. A significant effect of water availability on WUE was observed in biomass production and yield, with 0.87 and 0.11 kg m−3, respectively. Biomass production and yield were higher in plants irrigated at 100% ET0. Finally, reduced availability of water increased oil yield by 27% and the WUE for ALA from 3.4 to 8.6 mg L−1. These findings demonstrate that WUE for biomass and yield is a constant value; that chia is highly sensitive to water deficit but adopts adaptive strategies that maintains its yield andincreases the percentage of lipids and omega3.