Chemical Inducers: A Tool for Management of Root-Knot Nematode; Meloidogyne incognita Infecting Okra (Abelmoschus esculentus L.) Under Field Conditions

摘要

Various natural or synthetic substances are inducers of systemic resistance in both monocotyledonous and dicotyledonous crop plants against a wide variety of pests and pathogens including plant parasitic nematodes. It is reported that exogenous application of certain chemicals reduces the root-knot nematode damage by the induction of systemic resistance on crops and recently considered to be potential nematode management strategy. Hence, chemical inducers viz. salicylic acid (250 ppm) and ascorbic acid (500 ppm) were tested as seed soaking (12 hours) and foliar spray (30 and 60 days after sowing) treatments separately as well as in combination for the management of root-knot nematode, Meloidogyne incognita on okra in field having an initial inoculumof 410-460 larvae per 100 cc soil during two consecutive Kharif seasons. Chemical treated (monocrotophos 500 ppm) and untreated checks were also maintained for comparison. The observations on number of galls/plant, egg masses/plant, eggs and larvae/ eggmass, final nematode population/100 cc soil and yield were recorded at harvest. Results revealed that ascorbic acid when applied as seed soaking + foliar spray was found most effective in reducing infection of root-knot nematode, M. incognita on okra and to increase crop yield (27.66-29.81 %) followed by salicylic acid as seed soaking + foliar spray (21.15-23.40%) and ascorbic acid as foliar spray (15.38-17.02 %) over untreated control during Ist and IInd year, respectively.