Nematodes can negatively impact rice yields under the System of Rice Intensification (SRI) method. Studies found yield reductions of 8-69% attributed to nematode build-up under aerobic rice cultivation compared to flooded conditions. Controlled irrigation in SRI may be associated with the root-knot nematode Meloidogyne graminicola, which can cause yield losses of 21-64%. A field and greenhouse study examined the effects of different irrigation treatments on root galling and nematode populations caused by the root-knot nematode. The results showed greater gall formation and nematode populations under aerobic or saturated conditions compared to alternate flooding.

1. Are Nematodes a Problem in SRI? Directorate of Rice Research, Rajendranagar, Hyderabad-500 030 J.S. Prasad, Ch. Padmavathi, R.M. Kumar, and L.V.Subba Rao

3. Uncontrolled irrigation can be associated with the rice root nematode Hirschmanniella spp. – yield loss 8-23% (Kuriyan and Sheela, 1981) Nematode pests that could be associated with SRI

4. Controlled irrigation can be associated with the root-knot nematode Meloidogyne graminicola -- yield loss 21-64 % (Rao and Biswas, 1973)

5. Giant cell formation induced by the root-knot nematode in phloem

7. H. oryzae in soil as influenced by crop establishment methods

8. H. oryzae in root as influenced by crop establishment methods

9. Roots of freshly uprooted plant from a continuously inundated rice field

10. Roots showing galls developed 7 days after uprooting

11. Incidence of root-knot nematode at various moisture levels Figures in parentheses indicate √X+0.5 transformed values Treatment No. of galls Root volume Root length (cm) Root weight (g) Control 0.00 (0.707) 1.600 (1.448) 8.080 (2.928) 1.280 (1.333) Continuous flooding 0.760 (1.119) 1.500 (1.413) 14.620 (3.887) 0.682 (1.084) Optimum moisture (OM) 8.80 (3.048) 1.680 (1.476) 3.180 (1.911) 0.650 (1.072) Alternate flooding & OM at weekly intervals 2.32 (1.662) 0.820 (1.145) 15.840 (4.040) 0.560 (1.029) CD (p = 0.05) 0.23 0.088 0.192 0.076

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