Effects of Root-volume Restriction and Salinity on the Fruit Yield and Quality of Processing Tomato

Abstract

The effects of four root-volume restrictions (1, 6, 16, and 26 L per plant) and water and salinity stresses on the yield and quality of processing tomato (Solanum lycopersicum Mill. ‘NDM051TM’), including the γ-aminobutyric acid (GABA) content, were investigated under open-field and greenhouse conditions with a fertigation system. In open-field conditions, salinity treatment of EC 5 dS/m in nutrient solution did not increase the total soluble solids (TSS) or GABA content. In salinity treatment of nutrient solution (EC 7 dS/m), TSS (Brix %) was 57% higher and GABA content was 22% higher than non-salinity treatment in a greenhouse. Under open-field conditions, salinity treatment (EC 7 dS/m) and the soil water level of pF 2.7 increased the TSS, but only to 7.0 Brix %, lower than that observed under the salinity-stress conditions in a greenhouse. In addition, salinity stress did not increase the GABA content of tomato fruits under open-field conditions, but tended to increase TSS and GABA under salinity stress with 1 and 6 L root-volume restriction treatment than in 16 L and 26 L treatment. In addition, root-volume restriction suppressed the growth of shoots, especially lateral-shoot elongation, and also decreased the number of tomato fruits produced, but the effects of root-volume restriction on fruit yield were less than salinity stress.