Salicylic acid-mediated defense response against root-knot nematode in tuberose

Root-knot nematode (Meloidogyne incognita) poses a considerable threat to tuberose cultivation. Biological compounds, such as salicylic acid (SA), act as systemic acquired resistance (SAR) elicitors and may contribute to the resistance of host plants against nematodes. The study investigated the effects of SA at varying concentrations on inducing resistance in tuberose against M. incognita via tuber soaking, foliar spray, or a combined method. Plant growth parameters indicated that pretreatment of the SA exhibited no significant negative effect on the shoot length, shoot weight, number of leaves, tuber weight and root weight. The root image analysis revealed a positive effect of 10 mM SA on root length, number of root tips, forks, and crossings compared to the inoculated control plants. Leaf spray with SA is the most effective treatment, as it markedly reduces both root galling (54.8-71.6%) and infestation (66.8–72.6%). Using the simple, quick, and cost-effective SA spray approach, a 64 to 76% reduction in the multiplication factor (MF) of nematode infestation was observed. This is the first evidence of the use of SA in tuberose to induce resistance against M. incognita.