1184-The Science behind SRI Practices

Dr. Amod K. ThakurDirectorate of Water Management (ICAR), BhubaneswarCrop & Soil Sciences Dept. Seminar, Cornell University December 6, 2011r

Facts about Rice…… A Preface Rice is main source of directly-consumed calories for about half of the world’s population Rice provides 23% of all calories consumed by world’s population Rice productivity has stagnated since the mid-80s It is estimated that by the year 2025, the world’s farmers will need to produce about 60% more rice than at present to meet the food demands of the expected world population at that time (Fageria 2007).

Scarcity of water is acute in the world’s ‘rice bowls’1/3rd of the world’s populationlives with water scarcity & thisproportion will double by 2050

Dual challenges(a) Enhance Food Production(b) Under Water-Scarce Conditions Objective- “More Crop per Drop”

SRI System of Rice IntensificationIt involves the use of certain managementpractices which together provide better growingconditions for rice plants, particularly in their rootzones, compared with those for plants grownunder conventional practicesIt is a system rather than a technology because itis not a fixed set of practices. While a number ofspecific practices are basically associated withSRI, these should always be tested and adaptedaccording to local conditions rather than simplyadopted.

Practices Transplanting young seedlings Minimize time gap between uprooting & transplanting Transplant seedlings singly rather than in clumps Wider spacing in square pattern Keep soil well drained (moist) rather than flooding Weeding by mechanical weeder (aerate soil) Organic inputs like compost or mulch (optional)

Impetus for this research: IRRI Rice Today, July-Sept, 2004Energy for crop growth results from intercepted sunlight,and the amount of light intercepted translates directly intoplant growth. High plant density enhances lightinterception, growth and yield. SRI suffers from poor lightinterception because of low plant densities, acc. to Sinclair.

Sheehy et al. 2004 FCR 88:1-8SRI has no inherent advantage over the conventional system

But trials had excessive application of N-fertilizer (180-240kg N ha-1), causing lodging in some SRI plants (uncommon)Herbicide was used-, so there was no active soil aerationas recommended in SRI practiceComparison was made of yield between 11 SRI plants/m2(30 x30 cm spacing) with 25 plants/m2 (20 x 20 cm) If 16 or 25 SRI plants would have been used, maybe the results would have been different?

Research question: Whether SRI practiceshave any effect on the grain yield or not?If so, why?How do SRI practices affect rice plants’morphology, their physiology, and what aretheir implications for crop performance?

Methodology Location: Deras Research Farm, Orissa, IndiaDWM (ICAR), India Season: Dry (January-May) 2006, 2007 & 2008 Soil: Aeric Haplaquepts, sandy clay-loam in texture, pH 5.5. Design: RCBD - five replicates Plot sizes: 20 × 10 m2 Variety: Surendra Crop management systems: System of Rice Intensification (SRI) compared with Traditional flooding (TF) using Recommended management practices (RMP) proposed by Central Rice Research Institute

Management practices SRI TF/ RMP Seedling age 10-12 21-25 (in days) Plant spacing 20 x 20 cm 20 x10 cmDWM (ICAR), India and density One seedling /hill Three seedlings /hill Weed control 3 weedings with 3 manual cono-weeder @ 10, weedings @ 10, 20 and 30 DAT 20 and 30 DAT Water AWD after 3 DAD Flooding with 5-6 management during vegetative cm depth of stage water during the vegetative stage Nutrient Organic manure @ 5 t ha-1 management Chemical fertilizers: 80 kg N ha-1, (not a variable) 40 kg P2O5 ha-1, and 40 kg K2O ha-1

Directorate of Water Management, Bhubaneswar, INDIA Morphological Changes with SRI

Root Growth SRI hills had better root development (deeper roots, more dry weight, root volume and root RMP SRI length) than rice crop grown under RMP. Effects of rice management practices on root depth, root dry weight, root volume, and root length at early-ripening stage of developmentManagement Root Root dry Root dry Root Root Root length Rootpractice depth weight weight volume volume (cm hill-1) density (cm) (g hill-1) (g m-2) (ml hill-1) (ml m-2) (cm-2)SRI 33.5 12.3 306.9 53.6 1340.0 9402.5 2.7RMP 20.6 5.8 291.8 19.1 955.0 4111.9 1.2LSD.05 3.5 1.3 NS 4.9 180.1 712.4 0.2

Tillering under SRI The number of tillers per hill significantly increased (by 2 times, up to 34 tillers) in SRI compared to RMP. But the number of tillers per unit area was found not to differ significantly in SRI vs. RMP.Effects of rice management practices on morphologicalcharacteristics at early-ripening stage of developmentManagement Plant Culm height Ave. tiller Tiller number Ave. tillerpractice height (cm) (cm) number (hill-1) (m-2) perimeter (cm)SRI 124.2 84.0 18.3 450.1 2.9RMP 101.4 67.5 8.9 441.2 2.1LSD.05 8.1 4.3 3.5 NS 0.3 Why?

SRI plants were able to complete morenumber of phyllochrons (completion of10 phyllochrons in SRI plants and 8phyllochrons in RMP) before the onsetof reproductive stage of growth.

Phyllochrons 1st 2nd 3rd 4th 5th 6th 7th 8th 9th 10th 11th 12th New Tillers 1 0 0 1 1 2 3 5 8 12 20 31 Total tillers 1 1 1 2 3 5 8 13 21 33 53 84 Comparison between numbers of phyllochrons completed under SRI and RMPPrac- 12 DAG 30 DAG 40 DAG 50 DAG 60 DAG 70 DAGticeSRI TP < 4th 6th 7– 8th 8-9th 9th 10th phyllo- phyllo- phyllo- phyllo- phyllo- phyllo- chron chron chron chron chron chronRMP In Trans- 6th 7th 8th 8th mursery planting Phyllo- phyllo- phyllo- phyllo- shock chron chron chron chron

 The number of leaves/hill, leaf area/hill Leaf development and area of flag leaves significantly higher in SRI than RMP.  The size of individual leaf under SRI is more than leaves under RMP.Effects of rice management practices on morphological characteristicsof leaves at flowering stage of developmentManagement Leaf Leaf Ave. leaf Ave. leaf Ave. flag Ave. flag leafpractice number number length (cm) width (cm) leaf length width (cm) (hill-1) (m-2) (cm)SRI 79.8 1997.6 65.25 1.82 39.45 2.10RMP 35.6 1766.5 48.14 1.34 30.27 1.66LSD.05 15.8 229.4 6.09 0.21 4.49 0.31

Canopy structure SRI plants had higher LAI than RMP. Greater SLW of leaves under SRI shows greater thickness of leaf. SRI: Open-type canopy structure RMP: Closed-canopy structure Effects of rice management practices on LAI, SLW and canopy angle at flowering stage of development Manage- LAI SLW Canopy ment (mg cm-2) angle practice ( ) SRI 3.95 5.50 33.1 RMP 2.60 4.89 17.8 LSD.05 0.28 0.34 3.6

Comparison of leaf inclination at early-ripening stage under SRI and RMPManagement 1st leaf 2nd leaf 3rd leaf 4th leaf 5th leafpractice (flag leaf)aSRI 7.5 4.9 7.5 10.7 15.9RMP 9.2 7.3 9.9 13.7 19.9LSD.05 0.8 0.6 0.8 1.3 1.8 a Angle between flag leaf and panicle axis

Directorate of Water Management, Bhubaneswar, INDIA Physiological Changes with SRI

Effects of rice management practices on xylem exudationrates at early-ripening stage of developmentManage- Amount of Amount of Rate per hill Rate per areament exudates per hill exudates per (g hill-1 h-1) (g m-2 h-1)practice (g hill-1) area (g m-2)SRI 7.61 190.25 0.32 7.93RMP 2.46 122.95 0.10 5.12LSD.05 1.45 39.72 0.06 1.66

60 CGR (g m-2 day-1) 50 40 30 20 10 0 30-40 40-50 50-60 60-70 Period (Days after germination)Crop Growth Rate The increase in CGR in SRI crops was mainly due to maintenance of leaf area (lower leaf senescence). Lower rate of leaf senescence might be due to larger amounts of cytokinins (xylem exudates) transported from roots.

Light Interception SRI plants: intercept more light without shading RMP plants: in closed canopy, lower leaves experiences more shading 100 At PI stage: light Light Interception 80 interception reached 89% 60 in SRI canopies, while in (%) 40 RMP canopies this was 20 only 78% -- giving SRI 0 plants a 15% advantage 12 25 30 40 50 60 70 Days after seed germination

Changes in leaf chlorophyll content at different growth stages in SRI and RMP % 4 Flag SRI decrease 3.5 Flag TF from Chlorophyll content (mg g-1 3 Fourth SRI FL-LR Fourth TF 2.5 SRI-Flag 35.93 leaf 2 FW) 1.5 RMP- Flag 48.94 leaf 1 0.5 0 SRI-4th leaf 39.44 FL MR LR RMP- 4th 56.14 Stages leafFL: Flowering stage; MR: Middle-ripening stage; LR: Late-ripening stage

Changes in chlorophyll fluorescence (Fv/Fm) at different growth stages in SRI and RMP 0.9 Flag SRI Flag TF % decrease 0.8 from Fourth SRI Fourth TF FL-LR 0.7 SRI-Flag leaf 22.77 RMP- Flag leaf 31.81Fv/Fm 0.6 0.5 SRI-4th leaf 27.55 0.4 RMP- 4th leaf 31.88 0.3 FL MR LR Stages FL: Flowering stage; MR: Middle-ripening stage; LR: Late-ripening stage

Changes in chlorophyll fluorescence (Φ PS II) at different growth stages in SRI and RMP 0.650 Flag SRI Flag TF 0.600 Fourth SRI % Fourth TF 0.550 decrease from FL- 0.500 LR 0.450 SRI-Flag leaf Ф PS II 9.93 0.400 RMP- Flag leaf 21.62 0.350 0.300 0.250 SRI-4th leaf 15.31 0.200 RMP- 4th leaf 24.27 FL MR LR StagesFL: Flowering stage; MR: Middle-ripening stage; LR: Late-ripening stage

Changes in photosynthesis rate at different growth stages in SRI and RMP 30 Flag SRI Flag TF % decrease 25 Fourth SRI from 20 FL-LR Pn (µ mol m-2 s-1) SRI-Flag leaf 43.20 15 10 RMP- Flag leaf 51.09 5 0 SRI-4th leaf 52.98 FL MR LR Stages RMP- 4th leaf 59.02FL: Flowering stage; MR: Middle-ripening stage; LR: Late-ripening stage

Directorate of Water Management, Bhubaneswar, INDIA Performance with SRI

Yield & yield-contributing SRI: Longer panicles, more Characteristics number of grains in spike (40%), higher 1000-grain weight, and more grain-ripening percent than the RMP crop, responsible for higher grain yield (42%) Parameters SRI RMP LSD0.50 Panicles / m2 439.5 421.2 ns Ave. panicle length (cm) 22.5 18.7 2.3 Spikelets / panicle 151.6 107.9 12.9 Filled spikelets (%) 89.6 79.3 5.1 1000-grain weight (g) 24.7 24.0 0.2 Grain yield (t/ha) 6.41 4.50 0.23 Harvest Index (HI) 0.47 0.32 0.04

Distribution of panicles according to their length under SRI and RMP 350Panicle number/m2 300 SRI TP 250 200 150 100 50 0 Short Medium Long Extra long Category of panicles Short: >10 cm - 17 cm Medium: 17.1 cm - 20 cm Long: 20.1 cm - 24 cm Extra-long: 24.1 cm - <26 cm

Tiller number Panicle numberRoots growth and activity Panicle lengthCanopy development Higher YieldLight utilization Grains per spike in SRI Grain filling

HIGHER GRAIN YIELD Increased effective tillers Enhanced panicle length, More grain number & grain filling Open hill structure Greater light interception More erect leaves Enhanced photosynthesis rate Higher LAI Higher leaf N-content, Increased leaf More chlorophyll content number & leaf size More Rubisco Delayed senescence More photosynthates to the roots Higher nutrient uptake CK Higher microbial activity Greater root growth and activityA schematic model showing factors that may be responsible for higher grain yield ofrice plant grown under SRI management practices. (CK: Cytokinins; LAI: Leaf areaindex; Rubisco: Ribulose-1,5-bisphosphate carboxylase/ oxygenase)

Salient findingsSignificant changes were observed in themorphological and physiological characteristicsof SRI plants:• Greater root growth & activity• Improved shoot growth• Greater LAI• Favourable canopy structure• Higher levels of leaf chlorophyll• Increasing fluorescence efficiency• Photosynthetic rate• Delayed senescence

These factors contributed to : Larger panicles (more spikelets per panicle) Better grain setting (higher % of filled grains) Heavier individual grains (higher 1000- grain weight), and consequently Higher grain yield

Take-home pointsImprovement in grain yield under SRI isattributable to improved morphology andphysiological features of the rice plant bothbelow and above ground (better and positiveroot-shoot interaction).SRI methods narrow the gap between geneticpotential and in-field yield achievementsthrough management practices.

Factors for giving super-high yield in super high-yielding riceAkenohoshi (a slowly-senescing and high-yielding cultivar) produces high dry matterproduction as a result of maintaining a highrate of photosynthesis, which is aconsequence of the delayed senescence ofits leaves, resulting from transport of largeamounts of cytokinins from the roots to theshoots (Jiang et al. 1988, Soejima et al. 1995).

Variety: Xieyou 9308Maintain higher root activity and cytokinincontentDelayed senescence and highly efficientphotosynthetic performance during grain-filling stage(Shu-Qing et al. 2004 JACS 190, 73-80)SRI plants had similar characteristics as that ofthe super high-yielding varieties- Xieyou 9308 andAkenohoshi – achieved through changes inmanagement practices

SRI: Experience

 Varietal performance  Impact of spacingObjectives Effect of water management practices  Effect of different N-level  Evaluation of SRI components  Performance under Integrated SRI

Varietal performance

Khandagiri: Short-durationSurendra: Medium-durationCRHR-7: HybridLalat: Medium-duration (popular variety)Savitri: Long-duration

• All the varieties performed better under SRI thanconventional transplanted rice.• SRI showed 36-49% higher yield than TP• Short-duration variety (Khandagiri): 36%,• Medium-duration and hybrid varieties: 42-45 %,• Long-duration: 49% more yield than TPSRI: More panicle length, grains per spike and grainripening percent are the major factors responsiblefor higher yield than TP.

Effect of spacing

Experiment 1Grain yield (t/ha) under different spacing in SRI and TP Khandagiri Surendra Savitri Treatment Yield % Yield % Change Yield % (t/ha) Change (t/ha) in yield (t/ha) Change in yield in yield M1: 2.97c -1.65 2.94d -33.48 3.86d -19.79 30 x 30cm M2: 3.42b 13.12 4.26bc -3.58 6.31a 31.16 25 x 25cm M3: 4.44a 46.80 6.27a 41.89 6.06a 26.03 20 x 20cm M4: 3.01c -0.39 4.21bc -4.71 4.40c -8.53 15 x 15cm M5: 2.88c -4.80 4.16c -5.84 4.23c -12.10 10 x 10cm M6: TP 3.02c - 4.42b - 4.81b - (15x10 cm) Thakur, A. K.., S. K. Choudhari, R. Singh, and Ashwani Kumar. (2009). The Indian Journal of Agricultural Sciences 79 (6):443-447.

a.Short-duration variety (Khandagiri) 450 30 400 25Panicle number/m2 Panicle length (cm) 350 300 20 250 15 200 150 10 100 5 50 0 0 M1 M2 M3 M4 M5 M6 Treatment Panicle number /m2 Panicle length (cm)

b. Medium-duration variety 450 (Surendra) 30 400 25Panicle number/m2 Panicle length (cm) 350 300 20 250 15 200 150 10 100 5 50 0 0 M1 M2 M3 M4 M5 M6 Treatment Panicle number /m2 Panicle length (cm)

c. Long-duration variety (Savitri) 450 30 400 25Panicle number/m2 Panicle length (cm) 350 300 20 250 15 200 150 10 100 5 50 0 0 M1 M2 M3 M4 M5 M6 Treatment Panicle number /m2 Panicle length (cm)

Salient FindingsOptimum spacing:For short and medium-duration varieties for SRI, thiswas 20 cm x 20 cm (under the trial conditions)For long-duration varieties, it was 25 cm x 25 cmAt wider spacing (more than optimum): Yield wasreduced due to lesser panicle number/m2At closer spacing (less than optimum) : Yield wasreduced due to shorter panicles

Experiment 2Variety: Surendra (medium-duration)Method: SRI and RMPSpacing: 5 spacings (30x30 cm; 25x25 cm; 20x20 cm; 15x15 cm; 10x10 cm)

Grain Yield Plant spacing Grain yield (g m-2) SRI RMP Mean 30x30 cm 295.4 247.0 271.2 25x25 cm 426.3 397.9 412.1 20x20 cm 627.7 448.1 537.9 15x15 cm 421.8 403.4 412.6 10x10 cm 388.2 342.9 365.6 Mean 431.9 367.9 Practice Spacing PxS LSD0.05 18.5 19.4 27.5Grain yield was significantly larger in the SRI than in the RMPwhen plants with the same planting spacing were compared.Largest yield at 20x20 cm spacing; lowest at 30x30 cm.

LAI & Light Interceptio Flowering stage 5.00 100 4.50 90 Light interception (% ) 4.00 80 3.50 70 3.00 60LAI 2.50 50 2.00 40 1.50 30 1.00 20 0.50 10 0.00 0 30x30 cm 25x25 cm 20x20 cm 15x15 cm 10x10 cm Plant spacing

Salient Findings At wider or closer than optimum, grain yield decreased in bothpractices. At wide spacing, yield reduction was due to the lessnumber of hills/m2, and at closed spacing, yield reduction was dueto shorter panicles with lower grain number. Chlorophyll content and photosynthetic rate of both flag leaf and4th leaf was significantly higher in plants at wider spacing than inthe closer-spaced plants. At all the spacings, these physiologicalparameters were greater in SRI compared to RMP. Performance of individual hills was significantly improved withwider spacing compared to closer-spaced hills. Both SRI and TP gave their highest grain yield with spacing of20x20 cm in these trials. However, SRI yielded 40% more than therecommended practice. Lowest yield was recorded at 30x30 cmspacing under both practices, due to less plant population (11/m2),in spite of the improved hill performance.

Wide spacing beyond optimum plant densitydoes not give higher grain yield on an area basis.For achieving this under SRI, a combination ofimproved hills with optimum plant populationmust be worked out under the specific soil andclimatic conditions with the particular variety.In some locations, e.g., East Java, Indonesia, theoptimum spacing has proved to be 30x30 cm

Effect of different N-level

Methods: SRI and conventional transplantingflooded practice of rice cultivation method (TF)N-doses: Four rates of N (0, 60, 90, and 120 kgN per ha)

Grain yield & HI Straw dry weight Grain yield Harvest IndexN rate (t ha-1) (t ha-1) SRI TF Mean SRI TF Mea SRI TF Mean nN0 2.76 2.29 2.52 2.32 1.36 1.84 0.46 0.37 0.41N60 5.77 4.55 5.16 4.27 2.75 3.51 0.43 0.38 0.40N90 6.49 7.64 7.06 6.31 4.20 5.25 0.49 0.35 0.42N120 7.55 7.25 7.40 6.07 4.37 5.22 0.45 0.38 0.41Mean 5.64 5.43 4.74 3.17 0.46 0.37LSD0.05Cultivation ns 0.14 0.02practice (CP)Nitrogen level 0.31 0.14 ns(N)CP x N 0.44 0.20 0.03 SRI increased yield by 49% compared to TF Yield enhancement was due to improvement in HI

N-uptake & use-efficienN rate N uptake (kg ha-1) ANUE (kg kg-1) PFP (kg kg-1) SRI TF Mean SRI TF Mean SRI TF MeanN0 27.38 24.17 25.78 - - - - - -N60 41.16 38.58 39.87 32.59 23.25 27.92 71.21 45.87 58.54N90 58.32 54.30 56.31 44.32 31.55 37.94 70.07 46.62 58.35N120 82.47 76.75 79.61 31.30 25.13 28.22 50.61 36.44 43.53Mean 52.33 48.45 36.07 26.64 63.96 42.98LSD0.05Cultivation 2.49 3.10 1.89practice (CP)Nitrogen level 1.89 2.00 1.65(N)CP x N ns 2.84 2.34

Salient Findings Overall, grain yield increase with SRI practices was 49% N uptake, N use-efficiency, and partial factor productivity (PFP)from applied N was higher in SRI, which was attributable to thegreater root development under SRI With SRI and TP management, one kg of added N produced 64and 43 kg of grain, respectively Higher nitrogen and chlorophyll content - reflecting delayedsenescence - contributed to an extension of photosyntheticprocesses, which translated into increased grain yield under SRIA.K. Thakur et al. (2011) Plant and Soil (under review)

Effect of different water level

7 6 Grain yield (t/ha) 5 4 3 2 1 0 CF 1 3 5 7- CF 1 3 5 7 DAD DAD DAD DAD DAD DAD DAD DAD TP SRIHighest grain yield at 1 DAD under both cultivation methods

20 10 % change over CF 0 CF DAD DAD DAD DAD CF DAD DAD DAD DAD 7- 1 3 5 1 3 5 7 -10 TP SRI -20 -30 -40 -50As more water stress was imposed, grain yield reduced in bothmethods, but the reduction in grain yield was found to be greater inconventional TP than SRI.This might be due to deeper and greater root growth under SRI, whichenables the plant to extract water from deeper soil zones

SRI components and theirsynergies

Grain Yield Treatments Grain yield (g/m2) AWD CF 25 × 25 cm 20 ×10 cm 25 × 25 cm 20 ×10 cm CW MW CW MW CW MW CW MW 1 Organic 522.3 501.7 468.3 458.4 468.2 416.3 417.9 427.014 seedling Org + 607.4 587.3 576.2 517.8 523.6 498.4 469.2 547.8days Inorg 3 seed- Organic 428.7 416.3 478.7 476.8 398.7 387.6 447.7 397.6 lings Org + 475.4 412.7 376.9 397.4 368.9 447.1 311.9 377.6 Inorg 1 Organic 327.8 311.6 311.9 301.5 340.8 361.0 264.5 346.524 seedling Org + 359.7 427.2 368.9 407.3 284.2 335.0 326.9 278.4days Inorg 3 seed- Organic 311.4 288.2 343.3 380.0 318.2 296.0 368.1 316.8 lings Org + 359.0 317.8 412.0 434.2 422.3 378.4 307.4 258.4 Inorg AWD: Alternate wetting and drying; CF: continuous flooding; CW: weeding by cono-weeder; MW: manual weeding by hand

In summary, the effect of various SRI components on grain yield area as follows- Grain yield (g/m2) Change in SRI SRI Conventional (in (in %) practices practices g/m2) No of seedlings 416.28 378.48 37.80 9.99 Seedling age 456.49 338.27 118.22 34.95 Fertilization 383.12 411.65 -28.53 -6.93 Spacing 403.10 391.67 11.43 2.92 Weeding method 397.70 397.07 0.63 0.16 Water management 417.63 377.14 40.49 10.74 Mean 412.39 382.38 30.01 7.85

Salient Findings Significantly higher number of tillers and panicles perhill was recorded due to SRI practices like widerspacing, younger seedling, intermittent irrigation, andmechanical weeding Grain yield was found significantly higher due to SRIpractices like- single seedling, wider spacing, youngerseedling, intermittent irrigation. and mechanical weeding Plots that received only organic (FYM) fertilization gavelower yield than mixed inorganic-organic fertilized plots Need more research

Performance evaluation of IntegratedSRI

TreatmentsT1 Rice grown following conventionalmethods; all rainwater was harvested in thefield with no supplementary irrigationT2 Rice grown following SRI methods; allrainwater was harvested in the field with nosupplementary irrigationT3 Rice grown following SRI methods; nostagnant was kept in the field (excess waterwas drained) and 3 supplementary irrigationswere provided during flowering and grainfilling stagesT4 Rice grown following SRI methods; nostagnant was kept in the field (excess waterwas stored for fish culture in the refuge) and 3supplementary irrigations were providedduring flowering and grain filling stagesthrough stored water

Treat Grain Water Total Income Income Net Profit Net water Gross water- yield required expenditure from rice from fish (Rs./ha) Productivity Productivityment (t/ha) (m3/ha) (Rs./ha) (Rs./ha) (Rs./ha) (Rs./m3 (Rs./m3s water) water)T1 2.36 6509 16900 18880 - 1980 0.30 2.90T2 4.21 6509 16500 33653 - 17153 2.64 5.17T3 5.96 10009 17500 47653 - 30153 3.01 4.76T4 6.22 6509 21500 36510 21360 36370 5.51 8.81

Estimated average productivity of inputs on SRI and RMP Units SRI RMP Seed Kg per kg seed 797.13 59.83Fertilizer Kg per kg fertilizer 12.99 9.14 Labour Kg per man-days 35 23 Land Kg per ha land 6377 4487 Water Liter water per kg 1571 2801 SRI methods enhance paddy yields, increase returns, and save labour and water. They enhance productivity with respect to all of the key inputs in terms of paddy output per unit of seed, fertilizer, labour-days, and water

Directorate of Water Management, Bhubaneswar Sri Lanka Cambodia ‘Swarna’ in AP: Ave. yield: 6.5 t/ha SRI yield: 10.2 t/ha

SRI Crop at IARI, 2004Directorate of Water Management, Bhubaneswar Madagascar SRI field, 2003 Cuba – Two plants of the same age (52 DAP) and same variety (VN 2084)

Directorate of Water Management, Bhubaneswar Eastern Indonesia - Nippon Koei Irrigation Project, 2004 Morang District, Nepal - 2005

Directorate of Water Management, Bhubaneswar PunjabWTCER, Bhubaneswar - 2007

Some of the reported effects of different SRI practices SRI Practices EffectsTransplanting Greater root growth, more cytokinin flux towardssingle seedlings shoots, delayed senescence, higherwith wide spacing photosynthesis (San-oh et al., 2004; 2006)Transplanting Early tillering, greater nutrient uptake (Mishra andyoung seedlings, Salokhe, 2008), greater yield (Pasuquin et al., 2008;quickly, carefully Menete et al. 2008)and at shallowdepthIntermittent Water saving (Bouman et al., 2007; Satyanarayanairrigation /AWD et al., 2007; Zhao et al., 2009) Greater root growth (Satyanarayana et al., 2007) Improves ROA, cytokinin concentration in roots and shoots, leaf PS rate, and activities of key enzymes involved in sucrose-to-starch conversion in grains (Zhang et al., 2009)

Some of the reported effects of different SRI practices SRI Practices EffectsUse of organic Root growth and nutrient uptake enhanced (Yang etmanure al., 2004) Microbial biomass and activity increased (Gayatri, 2002) Compost application (@12 t/ha) increased the rice grain yield by 12-13.5% (Menete et al., 2008)Weeds controlling Aerobic soil condition improves root growthwith mechanical (Satyanarayana et al., 2007)weeder

Future Research NeedsDirectorate of Water Management, Bhubaneswar Reason for the phenotypic alterations/tillering in SRI plants: what are the physiological, biochemical, hormonal, and genetic changes in plants responsible for these alterations Study grain-filling, source-sink relationships, and grain quality in rice grown through SRI methods There is considerable evidence for stimulating effects of soil aeration on N mineralization, like intermittent drainage favouring the accumulation of nitrate with subsequent denitrification. In view of current trends to minimize water use in rice cultivation, it is a challenging research issue to re-examine the quantity of N losses via nitrification-denitrification (nutrient budgeting).

Effects of fluctuating aerobic and anaerobicDirectorate of Water Management, Bhubaneswar conditions on microbial populations, their activity, C and N dynamics, GHG emissions, and crop N supply. How do SRI practices affect diversity and functioning of soil microbial populations, what is effect of these populations in turn on crop performance, with consideration of the role of micronutrients? Roots are the key to a second green revolution Virginia Gewin (2010) ‘An underground revolution.’ Nature, 466, 29 July 2010 Need for breeding crop plants with deeper and bushier root ecosystems could simultaneously improve both the soil structure and its steady-state carbon, water, and nutrient retention, as well as sustainable plant yields. (Douglas Kell (2011) Annals of Botany)

Rice plant (cv. Ciherang) grown usingSystem of Rice Intensification (SRI)methods in Indonesia, producing 223 tillersfrom a single seed, which means that it hadreached into the 14th phyllochron of growth

SRI: Still has a long way to go…

Acknowledgement• USDA, CSS, Cornell University and ICAR• Norman Uphoff, Janice Thies, Francine, Harold, John Duxbury, KV Raman, Erika, Lucy• My friends at Cornell: Jin, Charles, Pulver, Lu, Shafiq, Aisha, Nicole, Rao, Vinod, Dr. Mehta All of You

ThanksRice field art in Japan, just using plants

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1184-The Science behind SRI Practices

by SRI-Rice, CIIFAD, Cornell University

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