Use of high soil solution electrical conductivity to improve the quality of fresh market tomatoes from coastal New South Wales

Abstract

High electrical conductivity (EC) in the soil solution or hydroponic medium is thought to increase the concentration of total soluble solids (TSS) and thereby improve the flavour of tomato fruit. We used trickle irrigation in 2 field experiments (1988, 1989) to apply KC1 at rates up to 4.4 t/ha to tomatoes to raise soil solution EC and examine the effects on TSS and other components of fruit quality, as well as yield. The KCl was subject to leaching in both years and EC varied widely despite regular additions of KCl. Where a high EC was achieved in 1988 (3.9 mS/cm) there was no effect on fruit firmness or TSS, but titratable acids (TA) increased from 7.25 to 8.0 m.e./100 mL. In 1989, high EC (>7mS/cm) resulted in a small increase in TSS (0.3%) in 1 of 6 harvests but significant (P<0.05) increases in TA in 4 harvests. Yield was unaffected (P>0.05). We conclude that irrigation with salinised water is unlikely to be an effective means of raising the TSS of tomatoes grown on freely draining soils in the high rainfall environment of coastal New South Wales.