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

December 6, 2011r

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).

Facts about Rice…… A Preface

Scarcity of water is acute in the world’s ‘rice bowls’

1/3rd of the world’s population lives with water scarcity & this proportion will double by 2050

(a) Enhance Food Production

Dual challenges

(b) Under Water-Scarce Conditions

Objective-“More Crop per Drop”

SRISystem of Rice Intensification

It involves the use of certain management practices which together provide better growing conditions for rice plants, particularly in their root zones, compared with those for plants grown under conventional practicesIt is a system rather than a technology because it is not a fixed set of practices. While a number of specific practices are basically associated with SRI, these should always be tested and adapted according to local conditions rather than simply adopted.

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)

Practices

IRRI Rice Today, July-Sept, 2004

Energy for crop growth results from intercepted sunlight, and the amount of light intercepted translates directly into plant growth. High plant density enhances light interception, growth and yield. SRI suffers from poor light interception because of low plant densities, acc. to Sinclair.

Impetus for this research:

SRI has no inherent advantage over the conventional system

Sheehy et al. 2004 FCR 88:1-8

But trials had excessive application of N-fertilizer (180-240 kg N ha-1), causing lodging in some SRI plants (uncommon)

Herbicide was used-, so there was no active soil aeration as recommended in SRI practice

Comparison 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 practices have any effect on the grain yield or not?

If so, why?

How do SRI practices affect rice plants’ morphology, their physiology, and what are their implications for crop performance?

Methodology

Location: Deras Research Farm, Orissa, 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

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ICA

R),

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Management practices SRI TF/ RMPSeedling age (in days)

10-12 21-25

Plant spacing and density

20 x 20 cm One seedling /hill

20 x10 cmThree seedlings /hill

Weed control 3 weedings with cono-weeder @ 10, 20 and 30 DAT

3 manual weedings @ 10, 20 and 30 DAT

Water management

AWD after 3 DAD during vegetative stage

Flooding with 5-6 cm depth of water during the vegetative stage

Nutrient management (not a variable)

Organic manure @ 5 t ha-1

Chemical fertilizers: 80 kg N ha-1, 40 kg P2O5 ha-1, and 40 kg K2O ha-1

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Morphological Changes with SRI

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Ro

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wth

SRI hills had better root development (deeper roots, more dry weight, root volume and root length) than rice crop grown under RMP.

RMP SRI

Effects of rice management practices on root depth, root dry weight, root volume, and root length at early-ripening stage of development

Management practice

Root depth (cm)

Root dry weight (g hill-1)

Root dry weight (g m-2)

Root volume (ml hill-1)

Root volume (ml m-2)

Root length (cm hill-1)

Root density(cm-2)

SRI 33.5 12.3 306.9 53.6 1340.0 9402.5 2.7

RMP 20.6 5.8 291.8 19.1 955.0 4111.9 1.2

LSD.05 3.5 1.3 NS 4.9 180.1 712.4 0.2

Til

leri

ng

un

der

SR

I

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 morphological characteristics at early-ripening stage of development

Management practice

Plant height (cm)

Culm height (cm)

Ave. tiller number (hill-1)

Tiller number (m-2)

Ave. tiller perimeter (cm)

SRI 124.2 84.0 18.3 450.1 2.9

RMP 101.4 67.5 8.9 441.2 2.1

LSD.05 8.1 4.3 3.5 NS 0.3

Why?

SRI plants were able to complete more number of phyllochrons (completion of 10 phyllochrons in SRI plants and 8 phyllochrons in RMP) before the onset of reproductive stage of growth.

Phyllochrons1st 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 RMP

Prac-tice

12 DAG 30 DAG 40 DAG 50 DAG 60 DAG 70 DAG

SRI TP < 4th phyllo-chron

6th phyllo-chron

7– 8th phyllo-chron

8-9th phyllo-chron

9th phyllo-chron

10th phyllo-chron

RMP In mursery

Trans-planting

shock

6th Phyllo-chron

7th phyllo-chron

8th phyllo-chron

8th phyllo-chron

Lea

f d

evel

op

men

t The number of leaves/hill, leaf area/hill 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 characteristics of leaves at flowering stage of development

Management practice

Leaf number (hill-1)

Leaf number

(m-2)

Ave. leaf length (cm)

Ave. leaf width (cm)

Ave. flag leaf length

(cm)

Ave. flag leaf width (cm)

SRI 79.8 1997.6 65.25 1.82 39.45 2.10

RMP 35.6 1766.5 48.14 1.34 30.27 1.66

LSD.05 15.8 229.4 6.09 0.21 4.49 0.31

Can

op

y st

ruct

ure SRI plants had higher LAI than RMP.

Greater SLW of leaves under SRI shows greater thickness of leaf.

SRI: Open-type canopy structureRMP: Closed-canopy structure

Effects of rice management practices on LAI, SLW and canopy angle at flowering stage of development

Manage-ment practice

LAI SLW(mg cm-2)

Canopy angle

(°)

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 RMP

Management practice

1st leaf(flag leaf)a

2nd leaf 3rd leaf 4th leaf 5th leaf

SRI 7.5 4.9 7.5 10.7 15.9

RMP 9.2 7.3 9.9 13.7 19.9

LSD.05 0.8 0.6 0.8 1.3 1.8

a Angle between flag leaf and panicle axis

Physiological Changes with SRI

Dir

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Manage-ment practice

Amount of exudates per hill

(g hill-1)

Amount of exudates per area (g m-2)

Rate per hill (g hill-1 h-1)

Rate per area (g m-2 h-1)

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

Effects of rice management practices on xylem exudation rates at early-ripening stage of development

Cro

p G

row

th R

ate

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.

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30-40 40-50 50-60 60-70

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da

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Period (Days after germination)

Lig

ht

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nSRI plants: intercept more light without shading RMP plants: in closed canopy, lower leaves experiences more shading

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Ligh

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Days after seed germination

At PI stage: light interception reached 89% in SRI canopies, while in RMP canopies this was only 78% -- giving SRI plants a 15% advantage

Changes in leaf chlorophyll content at different growth stages in SRI and RMP

FL: Flowering stage; MR: Middle-ripening stage; LR: Late-ripening stage

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Stages

Flag SRIFlag TFFourth SRIFourth TF

% decrease

from FL-LR

SRI-Flag leaf

35.93

RMP- Flag leaf

48.94

SRI-4th leaf 39.44

RMP- 4th leaf

56.14

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Stages

Flag SRIFlag TFFourth SRIFourth TF

Changes in chlorophyll fluorescence (Fv/Fm) at different growth stages in SRI and RMP

FL: Flowering stage; MR: Middle-ripening stage; LR: Late-ripening stage

% decrease from FL-LR

SRI-Flag leaf 22.77

RMP- Flag leaf 31.81

SRI-4th leaf 27.55

RMP- 4th leaf 31.88

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FL MR LR

Ф P

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Stages

Flag SRIFlag TFFourth SRIFourth TF

Changes in chlorophyll fluorescence (Φ PS II) at different growth stages in SRI and RMP

FL: Flowering stage; MR: Middle-ripening stage; LR: Late-ripening stage

% decrease from FL-

LR

SRI-Flag leaf 9.93

RMP- Flag leaf 21.62

SRI-4th leaf 15.31

RMP- 4th leaf 24.27

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15

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FL MR LR

Pn (µ

mol

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s-1

)

Stages

Flag SRIFlag TFFourth SRI

Changes in photosynthesis rate at different growth stages in SRI and RMP

FL: Flowering stage; MR: Middle-ripening stage; LR: Late-ripening stage

% decrease from

FL-LR

SRI-Flag leaf 43.20

RMP- Flag leaf 51.09

SRI-4th leaf 52.98

RMP- 4th leaf 59.02

Performance with SRI

Dir

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Yie

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SRI: Longer panicles, more 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

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Short Medium Long Extra long

Pa

nic

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be

r/m

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Category of panicles

SRI TP

Short: >10 cm - 17 cm Medium: 17.1 cm - 20 cm Long: 20.1 cm - 24 cm Extra-long: 24.1 cm - <26 cm

Distribution of panicles according to their length under SRI and RMP

Panicle length

Grains per spike

Grain filling

Roots growth and activity

Canopy development

Light utilization

Higher Yield in SRI

Tiller number

Panicle number

A schematic model showing factors that may be responsible for higher grain yield of rice plant grown under SRI management practices. (CK: Cytokinins; LAI: Leaf area index; Rubisco: Ribulose-1,5-bisphosphate carboxylase/ oxygenase)

CK

Delayed senescenceMore photosynthates to the roots

Higher leaf N-content, More chlorophyll content More Rubisco

Increased leaf number & leaf size

Greater light interception

Higher microbial activity

Enhanced panicle length,More grain number & grain filling

Greater root growth and activity

Increased effective tillers

HIGHER GRAIN YIELD

Open hill structureMore erect leaves

Higher LAI

Enhanced photosynthesis rate

Higher nutrient uptake

Salient findings

Significant changes were observed in the morphological and physiological characteristics of 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 points

Improvement in grain yield under SRI is attributable to improved morphology and physiological features of the rice plant both below and above ground (better and positive root-shoot interaction).

SRI methods narrow the gap between genetic potential and in-field yield achievements through management practices.

Akenohoshi (a slowly-senescing and high-yielding cultivar) produces high dry matter production as a result of maintaining a high rate of photosynthesis, which is a consequence of the delayed senescence of its leaves, resulting from transport of large amounts of cytokinins from the roots to the shoots (Jiang et al. 1988, Soejima et al. 1995).

Factors for giving super-high yield in super high-yielding rice

Variety: Xieyou 9308

Maintain higher root activity and cytokinin content

Delayed senescence and highly efficient photosynthetic performance during grain-filling stage

(Shu-Qing et al. 2004 JACS 190, 73-80)

SRI plants had similar characteristics as that of the super high-yielding varieties- Xieyou 9308 and Akenohoshi – achieved through changes in management practices

SRI: ExperienceSRI: Experience

Objectives

Varietal performance

Impact of spacing

Effect of different N-level

Effect of water management practices

Evaluation of SRI components

Performance under Integrated SRI

Varietal performance

Khandagiri: Short-duration

Surendra: Medium-duration

CRHR-7: Hybrid

Lalat: Medium-duration (popular variety)

Savitri: Long-duration

• All the varieties performed better under SRI than conventional 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 TP

SRI: More panicle length, grains per spike and grain ripening percent are the major factors responsible for higher yield than TP.

Salient Findings

Salient Findings

Effect of spacing

Grain yield (t/ha) under different spacing in SRI and TP

Khandagiri Surendra Savitri

Treatment Yield (t/ha)

% Change in yield

Yield (t/ha)

% Change in yield

Yield (t/ha)

% Change in yield

M1:30 x 30cm

2.97c -1.65 2.94d -33.48 3.86d -19.79

M2:25 x 25cm

3.42b 13.12 4.26bc -3.58 6.31a 31.16

M3:20 x 20cm

4.44a 46.80 6.27a 41.89 6.06a 26.03

M4:15 x 15cm

3.01c -0.39 4.21bc -4.71 4.40c -8.53

M5:10 x 10cm

2.88c -4.80 4.16c -5.84 4.23c -12.10

M6: TP (15x10 cm)

3.02c - 4.42b - 4.81b -

Thakur, A. K.., S. K. Choudhari, R. Singh, and Ashwani Kumar. (2009). The Indian Journal of Agricultural Sciences 79 (6):443-447.

Experiment 1

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a.Short-duration variety (Khandagiri)

Panicle number /m2

Panicle length (cm)

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b. Medium-duration variety (Surendra)

Panicle number /m2

Panicle length (cm)

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c. Long-duration variety (Savitri)

Panicle number /m2

Panicle length (cm)

Optimum spacing: For short and medium-duration varieties for SRI, this was 20 cm x 20 cm (under the trial conditions)For long-duration varieties, it was 25 cm x 25 cm

Salient FindingsSalient Findings

At wider spacing (more than optimum): Yield was reduced due to lesser panicle number/m2

At closer spacing (less than optimum) : Yield was reduced due to shorter panicles

Experiment 2

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

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 P x S

LSD0.05 18.5 19.4 27.5

Grain Yield

Grain yield was significantly larger in the SRI than in the RMP when plants with the same planting spacing were compared.

Largest yield at 20x20 cm spacing; lowest at 30x30 cm.

0102030405060708090100

0.000.501.001.502.002.503.003.504.004.505.00

30x30 cm 25x25 cm 20x20 cm 15x15 cm 10x10 cm Ligh

t int

erce

ptio

n (%

)

LAI

Plant spacing

Flowering stage

LAI & Light Interception

Salient FindingsSalient Findings

At wider or closer than optimum, grain yield decreased in both practices. At wide spacing, yield reduction was due to the less number of hills/m2, and at closed spacing, yield reduction was due to shorter panicles with lower grain number.

Chlorophyll content and photosynthetic rate of both flag leaf and 4th leaf was significantly higher in plants at wider spacing than in the closer-spaced plants. At all the spacings, these physiological parameters were greater in SRI compared to RMP.

Performance of individual hills was significantly improved with wider spacing compared to closer-spaced hills.

Both SRI and TP gave their highest grain yield with spacing of 20x20 cm in these trials. However, SRI yielded 40% more than the recommended practice. Lowest yield was recorded at 30x30 cm spacing under both practices, due to less plant population (11/m2), in spite of the improved hill performance.

Wide spacing beyond optimum plant density does not give higher grain yield on an area basis.

For achieving this under SRI, a combination of improved hills with optimum plant population must be worked out under the specific soil and climatic conditions with the particular variety.

In some locations, e.g., East Java, Indonesia, the optimum spacing has proved to be 30x30 cm

Effect of different N-level

Methods: SRI and conventional transplanting flooded practice of rice cultivation method (TF)

N-doses: Four rates of N (0, 60, 90, and 120 kg N per ha)

Grain yield & HI

N rateStraw dry weight

(t ha-1)Grain yield

(t ha-1)Harvest Index

SRI TF Mean SRI TF Mean

SRI TF Mean

N0 2.76 2.29 2.52 2.32 1.36 1.84 0.46 0.37 0.41

N60 5.77 4.55 5.16 4.27 2.75 3.51 0.43 0.38 0.40

N90 6.49 7.64 7.06 6.31 4.20 5.25 0.49 0.35 0.42

N120 7.55 7.25 7.40 6.07 4.37 5.22 0.45 0.38 0.41

Mean 5.64 5.43 4.74 3.17 0.46 0.37

LSD0.05

Cultivation practice (CP)

ns 0.14 0.02

Nitrogen level (N)

0.31 0.14 ns

CP x N 0.44 0.20 0.03SRI increased yield by 49% compared to TFYield enhancement was due to improvement in HI

N-uptake & use-efficiency

N rate N uptake (kg ha-1) ANUE (kg kg-1) PFP (kg kg-1)

SRI TF Mean SRI TF Mean SRI TF Mean

N0 27.38 24.17 25.78 - - - - - -

N60 41.16 38.58 39.87 32.59 23.25 27.92 71.21 45.87 58.54

N90 58.32 54.30 56.31 44.32 31.55 37.94 70.07 46.62 58.35

N120 82.47 76.75 79.61 31.30 25.13 28.22 50.61 36.44 43.53

Mean 52.33 48.45 36.07 26.64 63.96 42.98

LSD0.05

Cultivation practice (CP)

2.49 3.10 1.89

Nitrogen level (N)

1.89 2.00 1.65

CP x N ns 2.84 2.34

Salient FindingsSalient 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 the greater root development under SRI

With SRI and TP management, one kg of added N produced 64 and 43 kg of grain, respectively

Higher nitrogen and chlorophyll content - reflecting delayed senescence - contributed to an extension of photosynthetic processes, which translated into increased grain yield under SRI

A.K. Thakur et al. (2011) Plant and Soil (under review)

Effect of different water level

Highest grain yield at 1 DAD under both cultivation methods

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As more water stress was imposed, grain yield reduced in both methods, but the reduction in grain yield was found to be greater in conventional TP than SRI.

This might be due to deeper and greater root growth under SRI, which enables the plant to extract water from deeper soil zones

SRI components and their synergies

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

 14 days  

 1 seedling

Organic 522.3 501.7 468.3 458.4 468.2 416.3 417.9 427.0

Org + Inorg

607.4 587.3 576.2 517.8 523.6 498.4 469.2 547.8

 3 seed-lings

Organic 428.7 416.3 478.7 476.8 398.7 387.6 447.7 397.6

Org + Inorg

475.4 412.7 376.9 397.4 368.9 447.1 311.9 377.6

 24 days  

 1 seedling

Organic 327.8 311.6 311.9 301.5 340.8 361.0 264.5 346.5

Org + Inorg

359.7 427.2 368.9 407.3 284.2 335.0 326.9 278.4

 3 seed-lings

Organic 311.4 288.2 343.3 380.0 318.2 296.0 368.1 316.8

Org + Inorg

359.0 317.8 412.0 434.2 422.3 378.4 307.4 258.4

AWD: Alternate wetting and drying; CF: continuous flooding; CW: weeding by cono-weeder; MW: manual weeding by hand

Grain yield (g/m2) Change in SRI

SRI practices

Conventional practices

(in g/m2)

(in %)

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

In summary, the effect of various SRI components on grain yield area as follows-

Salient FindingsSalient Findings

Significantly higher number of tillers and panicles per hill was recorded due to SRI practices like wider spacing, younger seedling, intermittent irrigation, and mechanical weeding

Grain yield was found significantly higher due to SRI practices like- single seedling, wider spacing, younger seedling, intermittent irrigation. and mechanical weeding

Plots that received only organic (FYM) fertilization gave lower yield than mixed inorganic-organic fertilized plots

Need more research

Performance evaluation of Integrated SRI

Treatments

T1 Rice grown following conventional methods; all rainwater was harvested in the field with no supplementary irrigation T2 Rice grown following SRI methods; all rainwater was harvested in the field with no supplementary irrigationT3 Rice grown following SRI methods; no stagnant was kept in the field (excess water was drained) and 3 supplementary irrigations were provided during flowering and grain filling stages T4 Rice grown following SRI methods; no stagnant was kept in the field (excess water was stored for fish culture in the refuge) and 3 supplementary irrigations were provided during flowering and grain filling stages through stored water

Treat-ments

Grain yield (t/ha)

Water required (m3/ha)

Total expenditure

(Rs./ha)

Income from rice (Rs./ha)

Income from fish (Rs./ha)

Net Profit (Rs./ha)

Net water Productivity

(Rs./m3 water)

Gross water Productivity

(Rs./m3 water)

T1 2.36 6509 16900 18880 - 1980 0.30 2.90

T2 4.21 6509 16500 33653 - 17153 2.64 5.17

T3 5.96 10009 17500 47653 - 30153 3.01 4.76

T4 6.22 6509 21500 36510 21360 36370 5.51 8.81

Units SRI RMP

Kg per kg seed 797.13 59.83

Kg per kg fertilizer 12.99 9.14

Kg per man-days 35 23

Kg per ha land 6377 4487

Liter water per kg 1571 2801

Estimated average productivity of inputs on SRI and RMP

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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

Sri Lanka

‘Swarna’ in AP:Ave. yield: 6.5 t/haSRI yield: 10.2 t/ha

Cambodia

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SRI Crop at IARI, 2004

Cuba – Two plants of the same age(52 DAP) and same variety (VN 2084)

Madagascar SRI field, 2003

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Eastern Indonesia - Nippon Koei Irrigation Project, 2004

Morang District, Nepal - 2005

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WTCER, Bhubaneswar - 2007

Punjab

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SRI Practices EffectsTransplanting single seedlings with wide spacing

Greater root growth, more cytokinin flux towards shoots, delayed senescence, higher photosynthesis (San-oh et al., 2004; 2006)

Transplanting young seedlings, quickly, carefully and at shallow depth

Early tillering, greater nutrient uptake (Mishra and Salokhe, 2008), greater yield (Pasuquin et al., 2008; Menete et al. 2008)

Intermittent irrigation /AWD

Water saving (Bouman et al., 2007; Satyanarayana 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 manure

Root growth and nutrient uptake enhanced (Yang et 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 with mechanical weeder

Aerobic soil condition improves root growth (Satyanarayana et al., 2007)

Some of the reported effects of different SRI practices

Future Research Needs 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).

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Roots are the key to a second green revolution Virginia Gewin (2010) ‘An underground revolution.’ Nature, 466, 29 July 2010

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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)

Effects of fluctuating aerobic and anaerobic 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?

Rice plant (cv. Ciherang) grown using System of Rice Intensification (SRI) methods in Indonesia, producing 223 tillers from a single seed, which means that it had reached into the 14th phyllochron of growth

SRI: Still has a long way to go…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

ThanksThanks

Rice field art in Japan, just using plants

Discussion?