Saline Irrigation Effects on Cynara cardunculus L. Plants Grown in Mediterranean Soils

Cynara cardunculus L., known as cynara for industrial application, is a versatile plant for Mediterranean regions. Irrigation with non-conventional salty water sources is a common practice in these water-scarce regions. However, the research performed on cynara salt-stress response is limited and solely tested under soilless conditions. Thereby, the aims of the current experiment were to ascertain the effect of saline irrigation on cynara growth and mineral nutrition in Mediterranean soils. The influence of soil was considered using two typical agricultural soils, mainly differing in their salinity status. Plants were grown under controlled conditions from November until July in pots filled with soil amended with sewage sludge compost. Three saline irrigation treatments were applied (0.7, 2, and 3 dS.m(-1)) with increasing concentrations of NaCl (4, 13, and 23 mM). Saline irrigation started in January and ended in June. Plants growth parameters (height, dry biomass, heads number, seed yield) declined with saline irrigation. Aboveground dry biomass of plants irrigated with 3 dS.m(-1) was reduced approximately one-third regarding the control value, whereas seed yield was reduced in 57%. Despite growth reduction induced by salinity, no symptoms of nutritional deficiency were observed in leaves. Saline irrigation was the main driving factor regarding cynara mineral concentration, except for potassium (K) and manganese (Mn), which were related to soil type. Chlorine (Cl) and sodium (Na) concentration increased at the whole-plant level, whereas magnesium (Mg) showed the opposing trend. Similar trends were observed in the mineral content of cynara aboveground biomass. Interaction effects between soil type and saline irrigation were marginal. Cynara exhibited high K selectivity, which might be associated with a mechanism of salt tolerance, whereas Mg is suggested as a potential indicator of salt stress in cynara plants grown in calcareous Mediterranean soils. We concluded that cynara growth and mineral nutrition were mainly affected by saline irrigation, probably as a result of the accumulation of Na and Cl.