1. 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

2. 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.

3. 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)

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

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

6. 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

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
Treatment
No. of galls
Root
volume
Root length (cm)
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
Figures in parentheses indicate √X+0.5 transformed values

12. 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

13. 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

14. Thank You