Evaluation of inducers for tomato resistance against Meloidogyne incognita

The potency of the some chemicals from different groups known as inducers of systemic acquired resistance (SAR) viz., acetylsalicylic acid (ASA), DL-3-aminobutyric acid (BABA), 2,6-dichloroisonicotinic acid (INA), 5-chlorosalicylic acid (CSA), nitrosalicylic acid (NSA), salicylic acid (SA), ascorbic acid (AS) and selenium (SE) in reducing development and reproduction of Meloidogyne incognita in tomato plants cv. Castel Rock was investigated under greenhouse conditions. All inducers were applied as soil drench to tomato plants grown in 25 cm-diam. earthen pots. Three days-before nematode inoculation time treatment maximized the efficacy of tested chemicals in reducing nematode galls, egg-masses and eggs numbers followed by synchronized addition with inoculation. While, post-inoculation treatment was less effective. Reiterative doses post-inoculation were improved the efficacy of single dose revealed that three doses remained more effective than one or two. While, differences between two or three time doses were insignificant. On the other hand, plant fitness was slightly impaired with third dose than second one. INA and SE showed pronounced effect in inhibition nematode population after third dose compared with the rest chemicals. However, three doses of SE were reduced plant fitness after enhanced by double doses. While, INA showed phytotoxicity gradually increased by repeating doses. Gathering between the most effective application time (before inoculation) and the proper activated dose after inoculation was studies for emphasized their action and comparing with pre-inoculation only in suppressing M. incognita population. Enzyme activity of both peroxidase and polyphenol oxidase were elevated in infected tomato roots than healthy ones. Chemical activators showed enhancing in these antioxidant activities, indicating the SAR four chemicals was occurred. In conclusion, CSA, NSA, BABA and SA have potential to suppress root-knot nematode infection in tomato plants through induced systemic resistance.