Induction of resistance in tomato against root-knot nematode Meloidogyne javanica with salicylic acid

The effect of salicylic acid (SA) on induction of resistance against root-knot nematode (Meloidogyne javanica) and the effect of M. javanica to induce biochemical defense responses in tomato (Solanum lycopersicum L.) roots at six-leaf stage were investigated. Meanwhile, the effects of different concentrations of SA on second stage juveniles of M. javanica were examined. Biochemical assays including changes in the activity of cytoplasmic peroxidase (POX), catalase (CAT) and phenylalanine ammonia lyase (PAL) enzymes in the tomato seedlings were tested within seven days after inoculation with M. javanica in greenhouse. SA besides two treatments including soil drenching and leaf spraying were used. The efficiency of treatments were evaluated by measuring diameter of galls, number of galls per plant, number of egg masses per plant, number of eggs per individual egg mass, root and foliage fresh weight. The results showed that the activity of the enzymes (POX, CAT and PAL) increased in comparison with plants that treated with distilled water. Overall, results showed that use of SA as plant defense inducer could be effective against M. javanica in tomato roots and reduced nematode damage in greenhouse. The maximum level of larva mortality observed in 7 mM concentration of SA but had no significant difference with 6 mM concentration. SA caused 21.2% mortality of larvae at concentration of 5 mM.