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Are Nematodes a Problem in SRI? PowerPoint PPT Presentation


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

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Are Nematodes a Problem in SRI?

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Are Nematodes a Problem in SRI?

J.S. Prasad, Ch. Padmavathi,

R.M. Kumar, and L.V.Subba Rao

Directorate of Rice Research,

Rajendranagar, Hyderabad-500 030


INTRODUCTION

  • 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).

  • 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).

  • Under controlled irrigation, even small pest problems have great impacts on yields and farmers' income.


Nematode pests that could be associated with SRI

Uncontrolled irrigation can be associated with the rice root nematode

Hirschmanniella spp. – yield loss 8-23% (Kuriyan and Sheela, 1981)


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


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


Materials and methods

Field Experiment – Split Plot

Treatments: SRI, Eco-SRI, and Conventional

Varieties: Rasi and Jaya

  • Greenhouse studies

  • Treatments:

  • Continuous flooding

  • Optimum moisture (OM)

  • Flooding & OM alternated at weekly intervals


H.oryzaein soil as influenced by crop establishment methods


H.oryzae in root as influenced by crop establishment methods


Roots of freshly uprooted plant from a continuously inundated rice field


Roots showing galls developed 7 days after uprooting


Incidence of root-knot nematode at various moisture levels

Figures in parentheses indicate √X+0.5 transformed values


CONCLUSIONS

  • Under aerobic or saturated conditions, more gall formation on the roots by root-knot nematode was observed

  • In conventional rice cultivation, H. oryzae population is more

  • In SRI fields where no water control is possible, there is need to monitor for the root nematode H. oryzae

  • Existing root knot nematode infection may not express itself, but when aerobic conditions prevail, symptoms do appear


Possible impact of SRI cultivation on plant parasitic nematodes

  • Use of cono-weeder would destroy the nematodes that have invaded the roots of weed plants

  • The incorporation of weeds and organic nutrients deters movement, migration and infestation by nematode pests

  • Decomposing organic matter promotes beneficial predatory and saprophytic nematode populations


Thank You


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