0730 Are Nematodes a Problem in SRI?


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Presenter: J.S. Prasad, Ch. Padmavathi,
R.M. Kumar, and L.V.Subba Rao

Institution: Directorate of Rice Research, Hyderabad

Audience: 2nd National SRI Symposium, Agartala, India

Subject Country: India

Published in: Technology, Travel
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0730 Are Nematodes a Problem in SRI?

  1. 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
  2. 2. <ul><li>High yields of rice declined in Brazil and China after 3-4 years under aerobic conditions, possibly due to nematodes or toxic substances (Bouman, 2002). </li></ul><ul><li>Yield differences between aerobic and flooded rice ranged from 8 to 69%, the differences attributed to the build-up of nematodes (Peng et al., 2006). </li></ul><ul><li>Under controlled irrigation, even small pest problems have great impacts on yields and farmers' income. </li></ul>INTRODUCTION
  3. 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. 4. Controlled irrigation can be associated with the root-knot nematode Meloidogyne graminicola -- yield loss 21-64 % (Rao and Biswas, 1973)
  5. 5. Giant cell formation induced by the root-knot nematode in phloem
  6. 6. Materials and methods Field Experiment – Split Plot Treatments: SRI, Eco-SRI, and Conventional Varieties: Rasi and Jaya <ul><li>Greenhouse studies </li></ul><ul><li>Treatments: </li></ul><ul><li>Continuous flooding </li></ul><ul><li>Optimum moisture (OM) </li></ul><ul><li>Flooding & OM alternated at weekly intervals </li></ul>
  7. 7. H. oryzae in soil as influenced by crop establishment methods
  8. 8. H. oryzae in root as influenced by crop establishment methods
  9. 9. Roots of freshly uprooted plant from a continuously inundated rice field
  10. 10. Roots showing galls developed 7 days after uprooting
  11. 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
  12. 12. CONCLUSIONS <ul><li>Under aerobic or saturated conditions, more gall formation on the roots by root-knot nematode was observed </li></ul><ul><li>In conventional rice cultivation, H. oryzae population is more </li></ul><ul><li>In SRI fields where no water control is possible, there is need to monitor for the root nematode H. oryzae </li></ul><ul><li>Existing root knot nematode infection may not express itself, but when aerobic conditions prevail, symptoms do appear </li></ul>
  13. 13. <ul><li>Use of cono-weeder would destroy the nematodes that have invaded the roots of weed plants </li></ul><ul><li>The incorporation of weeds and organic nutrients deters movement, migration and infestation by nematode pests </li></ul><ul><li>Decomposing organic matter promotes beneficial predatory and saprophytic nematode populations </li></ul>Possible impact of SRI cultivation on plant parasitic nematodes
  14. 14. Thank You