The document summarizes research on the System of Rice Intensification (SRI) management practices and their individual and combined effects on rice productivity in Tamil Nadu, India. Studies found that individual SRI components like young seedlings, reduced plant spacing, and intermittent irrigation increased yields by 17-29% compared to conventional practices. The synergistic effect of all SRI components together increased yields by 46-51%. SRI also improved grain quality, nutrient uptake, and factor productivity of inputs like water, fertilizer and labor. For wider adoption, the document recommends strengthening nursery practices, mechanizing weeding, and increasing awareness of nutrient management.

1. Individual and combined effect of management components of SRI on the productivity of irrigated rice R. Rajendran*, V. Ravi, N.Chelliah, and V. Balasubramanian * Professor (Agronomy), Tamil Nadu Rice Research Institute (TNAU), Aduthurai, India

3. Practices recommended for SRI Practices Seedling age (days) 15 Seedlings per hill 1 Plant spacing (cm) 22.5 x 22.5 Planting geometry Square Mechanical weeding/ soil stirring Two cono/rotary weeder + one HW (no herbicide) Intermittent irrigation 2.5 cm up to flowering intermittently Nutrient application OM + fertilizers

7. TRRI, Aduthurai Yield enhanced by 29% SWMRI, Thanjavur Yield enhanced by 46% Impact of inter-cultivation on yield, Cauvery Delta, Tamil Nadu, 2002-04

8. Impact of SRI +SSNM on irrigated rice productivity, Cauvery Delta, Kharif and rabi 2003- 04 Prob >F : F0, 0.07; LCCN, 0.02 and +K, 0.02 Rajendran et al ., 2006

10. Impact of SRI on pest incidence Ravi et al., 2006 Detail No. of valid seasons Conven-tional planting SRI method of planting Pest incidence Whorl maggot (%LD) 5 11.56 4.82 Leaf folder (% LD) 8 12.97 21.04 Gall midge (% DT) 2 4.52 2.72 BPH (no./hill) 4 7.52 1.84 Stem borer (% DT) 6 9.86 5.48 Crop yield (kg/ha) Grain yield 8 5,127 6,986

11. SRI + SSNM on N use efficiency, Cauvery Delta, Kharif and Rabi, 2003-04 Prob > F : For LCC-N & + K, 0.02 Rajendran et al ., 2006

12. Components of chlorophyll as influenced by SRI practices, Kharif, 2005* * Mean data Management / Variety Chlorophyll (a: b ratio) ADT 43 ADT RH 1 Conv. + flooding 1.27:1 1.21:1 Conv. + intermittent irrigation 1.33:1 1.43:1 SRI + flooding 1.52:1 1.34:1 SRI + intermitt. irrig. 1.56:1 1.59:1

13. Root growth as influenced by SRI (inter-cultivation), Kharif, 2006* * On-going experiment Treatments Root length (cm) Root volume (cc) ADT 43 PHB 71 ADT 43 PHB 71 Conv. + flooding 11.6 12.0 21.8 19.3 Conv. + inter. irrig. 15.2 15.1 23.3 26.3 SRI + flooding 16.3 16.1 37.7 39.2 SRI + inter. irrig. 16.5 16.5 51.0 57.7 CD (5%) 0.7 4.0

14. Nutrient uptake (kg/ha), TRRI Farm, Cauvery Delta, Kharif, 2005* * On-going research project Treatment Grain Straw N P K N P K Conventional 57.0 7.9 8.7 32.6 5.9 68.7 SRI 74.1 11.0 11.3 43.7 7.8 87.0 C.D. (5%) 4.4 0.7 1.5 4.2 1.3 10.4

15. TRRI, Aduthurai Yield reduced by 23% SWMRI, Thanjavur Yield reduced by 18% Impact of older seedling age, Cauvery Delta, Tamil Nadu, 2002 -04

16. Rajendran et al ., 2005 Seedling age on rice productivity and profit, Cauvery Delta, Tamil Nadu, Rabi, 2002-03 * % yield increase over aged seedling Seedling age Aduthurai Thanjavur Panicles/m 2 GY (kg/ha) B:C Panicles/m 2 GY (kg/ha) B:C Traditional nursery – 25 days 377 5874 2.6 344 5557 1.9 Modified mat nursery 15 days 452 7061* (20) 3.2 424 6583* (16) 2.7 C.D (5%) 25 163 n. a 21 121 n. a

17. Influence of seedling age when planted, based on leaf number, Cauvery Delta, Kharif 2006 & Kharif 2007 (in progress)

18. Panicle production No. of leaves per seedling Panicles / sq. m ADT 43 PHB 71 Seedling mean 2 391 404 398 3 438 456 447 4 397 423 410 5 350 402 376 Cultivar mean 403 425 C.D. (5%) 10 15

19. Rice grain yield No. of leaves per seedling Grain yield (kg/ha) ADT 43 PHB 71 Seedling mean 2 7595 7903 7749 3 9198 9457 9327 4 8016 8762 8889 5 7297 8299 7798 Cultivar mean 8277 8598 C.D. (5%) 145 230

20. TRRI, Aduthurai Yield reduced by 17% SWMRI, Thanjavur Yield reduced by 16% Impact of flooding, Cauvery Delta, Tamil Nadu 2002 -04

21. Synergistic effect of SRI on rice productivity, Cauvery Delta, Tamil Nadu, 2002 - 04 TRRI, Aduthurai Yield enhanced by 51% SWMRI, Thanjavur Yield enhanced by 46%

22. Factor productivity for SRI and conventional rice cultivation, kharif and rabi , Cauvery Delta, Tamil Nadu, 2002-04 Input use/cost Aduthurai Thanjavur SRI Conven. SRI Conven. Nursery cost efficiency (Rs./kg grain) 0.21 0.66 0.21 0.62 Water use (m 3 ) 8,964 14,193 11,952 15,687 Water use efficiency (kg grain m -3 water) 0.81 0.34 0.63 0.33

23. Factor productivity for SRI and conventional rice cultivation, kharif and rabi , 2002- 04, Cauvery Delta, Tamil Nadu Input use/cost Aduthurai Thanjavur SRI Conven. SRI Conven. Fertilizer cost efficiency (Rs./kg grain) 0.64 1.01 0.62 0.93 Weeding cost efficiency (Rs./kg grain) 0.20 0.31 0.19 0.29

25. Targeted yield attributes for enhanced grain yield in SRI Yield attributes Role of Modified SRI 3. Increased no. of spikelets/panicle Genotypic potential tapped through Improved grain filling which resulted in more grain weight than with traditional planting

26. Improved grain quality in SRI Cauvery Delta, Kharif, 2005 Treatments Grain length (mm) Grain width (mm) Kernel length (mm) Kernel width (mm) Conventional 8.79 2.38 6.39 1.99 SRI 8.85 2.41 6.51 1.98 C.D. (5%) 0.09 0.04 0.08 0.04

28. Key is the healthy crop establishment

29. T h a n k y o u