Comparative analysis of water and salt stress-induced modifications of quality parameters in cherry tomatoes

Abstract

SummaryThe effects of moderate and comparable saline and water stresses on plant growth, water status, anti-oxidant activity and mineral composition were studied with the objective of identifying optimal conditions for improving the nutritional profile of tomato fruit. Cherry tomato plants were grown in plastic containers filled with a soil mix (84.4% sand; 10.7% silt; 4.9% clay). Three irrigation treatments were compared: non-stressed control (NSC) = irrigation with full-strength Hoagland’s solution when 20% of the available water was consumed [soil matric potential (ψm) = –36 kPa]; water stress treatment (WST) = irrigation with full-strength Hoagland’s solution when 40% of the available water was consumed (ψm = –72 kPa); salt stress treatment (SST) = irrigation with full-strength Hoagland’s solution plus 12 mM NaCl, when 20% of the available water was consumed (ψm = –36 kPa). The total soil water potential (ψs = ψm + ψπ), in both the WST and SST, declined before irrigation to –213 kPa on average, due either to a decrease in ψm (WST) or to a decrease in osmotic potential (ψπ; SST). Total leaf water potential, osmotic and pressure potentials decreased under water or osmotic stress. Both stresses significantly reduced stomatal conductance, leaf area and plant dry mass (DM) accumulation, but increased the percentage DM in leaves and fruits. At similar ψs, growth inhibition in water-stressed plants was greater than that caused by saline stress. These findings are important for assessing the physiological basis of plant responses to stress, which may involve different adaptation pathways. Water shortage and salinity reduced leaf N and K concentrations, whereas salinity also caused an increase in leaf Na and Cl concentrations.The concentrations of carotenoids and ascorbic acid decreased in fruits under water and osmotic stress.