Evaluation of resistance to root knot nematode (Meloidogyne incognita) in cotton cultivars

The root-knot nematode, Meloidogyne incognita , is one of the major limiting factors affecting plant growth and yield causing an estimated $100 billion loss per year worldwide. Synthetic pesticides, though instantaneously effective, are usually prohibitively expensive, not readily available, may cause hazards to both man and livestock, and inflict injury to the environment. Notable among the alternatives to nematicides is the use of resistant cultivars which are inexpensive and eco-friendly. In the present studies, thirty cotton ( Gossypium hirsutum ) cultivars were evaluated for resistance against Meloidogyne incognita under field conditions. Fourty days old cotton plants of test cultivars were inoculated with 1000 freshly hatched second stage juveniles of M. incognita . The nematode caused reduction in various growth parameters of all the cultivars to varying levels over their respective controls. None of cultivar was found highly resistant. Fourteen cotton cultivars were highly susceptible as >100 galls were recorded on roots. The cultivar PB-896 and MNH-554 were susceptible with 31-100 galls. Eleven cultivars were moderately susceptible with 11-30 galls and comparatively less reductions in growth. Cultivar FH-183 was rated as moderately resistant with 3-10 galls whereas cultivar BT-8 and P-11 were rated as resistant and showed less damage by nematode as compared to susceptible cultivars and their planting could provide a useful tool to control root not nematode.