1. The System of Rice
Intensification (SRI):
Creating Opportunities for
Agroecological Development
JIRCAS Seminar
Tsukuba, November 16, 2009
Prof. Norman Uphoff, CIIFAD

2. Needs for rice sector in 21st
century
acc. to IRRI/DG, Intl. Year of Rice, 2004
• Increased land productivity-- higher yield
• Higher water productivity -- crop per drop
• Technology more accessible for the poor
• Technology more environmentally friendly
• Greater resistance to pests and diseases
• Tolerance of abiotic stresses (climate change)
• Better grain quality for consumers, and
• Greater profitability for farmers

3. SRI practices help meet all these needs:
• Higher yields by 50-100% -- or more
• Water reduction of 25-50% (also rainfed)
• Reduced capital expenditure (accessible)
• Little or no need for agrochemical inputs
• Induced pest and disease resistance
• Tolerance for drought, little/no lodging
• Better grain quality -- less chalkiness
• Lower costs of production by 10-20% --
which leads to higher farmers’ income

4. SRI is application of AGROECOLOGY,
which can be summarized this way:
1. ENHANCE the life in the soil,
i.e., in soil systems, recognizing the
precedence of soil biology, which is
shaping soil’s chemistry and physics
2.IMPROVE growing environment (E)
for crops, in ways that will work to
induce more productive phenotypes
from any given crop genotype (G)

5. Agroecological principle #1:
SUPPORT the recycling of
biomass to optimize nutrient
availability in the soil and balance
nutrient flows in the soil and
biosphere over time

6. Agroecological principle #2:
PROVIDE the most favorable
soil conditions which will
enhance the soil’s structure and
the functioning of soil systems,
esp. by managing organic matter
and by enhancing soil biotic
activity

7. Agroecological principle #3:
MINIMIZE losses of energy
and other growth factors
within plants’ microenvironments
both above and below
ground
in ways that can maximize
resource-use efficiency

8. Agroecological principle #4:
DIVERSIFY the species and
the genetic resources within
agroecosystems, both
over time and over space

9. Agroecological principle #5:
ENHANCE beneficial biological
interactions and synergies
among all of the components of
agrobiodiversity, thereby
promoting key ecological
processes and services
(Reijntjes et al., 1992; Altieri 2002;)

10. SRI is many things:
– SRI derives from a certain number
of INSIGHTS, based on experience
– SRI can be explained in terms of
PRINCIPLES having scientific bases
– SRI gets communicated to farmers in
terms of specific PRACTICES that
improve the growing environment
for their rice plants - at same time,
– SRI offers an alternative PARADIGM
a different approach to agriculture -
pointing toward post-modern agriculture

11. SRI is NOT A TECHNOLOGY
While SRI practices look like a PACKAGE
or even like a RECIPE, they are really
better understood as a MENU
• Farmers are encouraged to use as many of
the practices as possible, as well as possible
• Each practice contributes to higher yield
as seen from the accumulating evidence
• There is also evidence of a certain synergy
operating among the practices – so that the
best results come from using them together

12. SRI is NOT YET FINISHED
-- Since SRI was empirically developed,
we are continually improving scientific
understanding of SRI concepts/theory
-- Since SRI is farmer-centered, it is
being modified, improved, extended
• There are now also rainfed versions of SRI
and zero-till, direct-seed, raised-bed forms
• SRI ideas are extrapolated to other crops:
wheat, sugar cane, millet, teff, beans, etc.

13. System of Finger Millet Intensification
on left; regular management of improved
variety and of traditional variety on right

14. Liu Zhibin, Meishan, Sichuan province, China, standing in
raised-bed, zero-till SRI field; measured yield 13.4 t/ha.
In 2001, his SRI yield set provincial yield record: 16 t/ha

15. SRI was developed for
smallholders in Madagascar,
but it is relevant at all scales
- Fr. Henri de Laulanié came there from
France in 1961 – had agricultural training
- He started working with farmers to raise
yield without dependence on external inputs
- In 1983-84 season he learned effects of
young seedlings
- In late 1980s, when fertilizer subsidies
were removed, he switched over to compost

16. Fr. de Laulanié
making field visit

17. Status of SRI: As of 1999
Known and practiced only in Madagascar

18. SRI benefits have been demonstrated in 34 countries
in Asia, Africa, and Latin America
Before 1999: Madagascar
1999-2000: China, Indonesia
2000-01: Bangladesh, Cuba
Cambodia, Gambia, India, Laos,
Myanmar, Nepal, Philippines,
Sierra Leone, Sri Lanka, Thailand
2002-03: Benin, Guinea,
Mozambique, Peru
2004-05: Senegal, Mali,
Pakistan, Vietnam
2006: Burkina Faso, Bhutan,
Iran, Iraq, Zambia
2007: Afghanistan, Brazil
2008: Egypt, Rwanda, Ghana,
Ecuador, Costa Rica
2009: Timor Leste, Malaysia
Now in 2009, SRI benefits have been validated in
37 countries of Asia, Africa, and Latin America

19. The Six Basic Ideas for SRI
1. Transplant young seedlings to preserve their growth
potential -- but DIRECT SEEDING is now an option
2. Avoid trauma to the roots -- transplant quickly and
shallow, not inverting root tips, which halts growth
3. Give plants wider spacing -– one plant per hill and in
square pattern to achieve ‘edge effect’ everywhere
4. Keep paddy soil moist but unflooded –- soil should
be mostly aerobic and not continuously saturated
5. Actively aerate the soil as much as possible
6. Enhance soil organic matter as much as possible
1-2-3 stimulate plant growth aboveground, while
4-5-6 enhance growth of plants’ ROOTS and
of soil BIOTA  better PHENOTYPES

20. Cuban farmer with two plants
of same variety (VN 2084)
and same age (52 DAP)

21. Single-seed SRI rice plant
Variety: Ciherang
Fertile tillers: 223
Sampoerna CSR Program,
Malang, E. Java, 2009

22. Additional benefits of SRI practice:
• Reduced time to maturity,by 1-2 weeks,
less exposure to pests and diseases, and
to adverse climate; can replant sooner
• Higher milling outturn – by about 15%
•Human resource development for farmers
through participatory approach – want
farmers to become better managers of
their resources, experimenting, evaluating…
• Diversification and modernization of
smallholder agriculture; can adapt to larger-
scale production through mechanization

23. Requirements/Constraints
1. Water control to apply small amounts of
water reliably; may need drainage facilities
2. Supply of biomass for making compost – but
can use fertilizer if compost is insufficient
3. Crop protection may be necessary, although
usually more resistance to pests & diseases
4. Mechanical weeder is desirable as this can
aerate the soil at same time it controls weeds
5. Skill & motivation of farmers most important;
need to learn new practices; once techniques
are mastered, SRI can become labor-saving
6. Support of experts? have faced opposition

24. SRI
0
50
100
150
200
250
300
IH H FH MR WR YRStage
Organdryweight(g/hill)
CK
I H H FH MR WR YR
Yellow
leaf and
sheath
Panicle
Leaf
Sheath
Stem
47.9% 34.7%
Non-Flooding Rice Farming Technology in Irrigated Paddy Field
Dr. Tao Longxing, China National Rice Research Institute, 2004

25. Factorial trials by CNRRI, 2004 and 2005
using two super-hybrid varieties --
seeking to break ‘plateau’ limiting yields
Standard Rice Mgmt
• 30-day seedlings
• 20x20 cm spacing
• Continuous flooding
• Fertilization:
– 100% chemical
New Rice Mgmt (SRI)
• 20-day seedlings
• 30x30 cm spacing
• Alternate wetting
and drying (AWD)
• Fertilization:
– 50% chemical,
– 50% organic

26. Average super-rice yields (kg/ha) with new rice
management (SRI) vs.standard rice management
at different plant densities ha-1
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
150,000 180,000 210,000
NRM
SRM

27. AFGHANISTAN: SRI field in Baghlan Province, supported by
Aga Khan Foundation Natural Resource Management program

28. SRI field at 30 days

29. SRI plant with 133 tillers @
72 days after transplanting
11.56 t/ha

30. IRAQ: Comparison trials at Al-Mishkhab Rice Research Station, Najaf

31. Two Paradigms for Agriculture:
• GREEN REVOLUTION strategy was to:
* Change the genetic potential of plants, and
* Increase the use of external inputs --
more water, more fertilizer and insecticides
• SRI (AGROECOLOGY) instead changes the
management of plants, soil, water & nutrients:
* To promote the growth of root systems, and
* To increase the abundance and diversity of
soil organisms to better enlist their benefits
The goal is to produce better PHENOTYPES

32. MADAGASCAR: Rice field grown with SRI methods

33. CAMBODIA:
Rice plant grown
from single seed
in Takeo province

34. NEPAL:
Single rice
plant grown
with SRI
methods,
Morang
district

35. IRAN: SRI
roots and
normal
(flooded)
roots: note
difference in
color as well
as size

36. INDONESIA:
Rice plants of
same age and
same variety
in Lombok
province

37. Indonesia: Results of 9 seasons of
on-farm comparative evaluations of
SRI by Nippon Koei team, 2002-06
• No. of trials: 12,133
• Total area covered: 9,429.1 hectares
• Ave. increase in yield: 3.3 t/ha (78%)
• Reduction in water requirements: 40%
• Reduction in fertilizer use: 50%
• Reduction in costs of production: 20%
Note: In Bali (DS 2006) 24 farmers on 42 ha:
SRI + Longping hybrids → 13.3 vs. 8.4 t/ha

38. SRI LANKA: same rice variety, same irrigation system &
same drought -- left, conventional methods; right, SRI

39. VIETNAM:
Dông Trù village,
Hanoi province,
after typhoon

40. Nie Fu-qiu, Bu Tou village, Zhejiang
In 2004, SRI gave highest
yield in province: 12 t/ha
In 2005, his SRI rice fields
were hit by three typhoons
– yet he was still able to
harvest 11.15 tons/ha --
while other farmers’ fields
were badly affected by the
storm damage
In 2008, Nie used chemical
fertilizer, and crop lodged

41. Irrigation
method
Seed-
ling age
Spacing
(cm2
)
Time to
flowering
Time to
maturity
Plant lodging percentage
Partial Complete Total
Inter-
mittent
irrigation
(AWDI)
14
30x30 75 118 6.67 0 6.67
30x18 74.67 118.67 40.00 6.67 46.67
21
30x30 72.67 117.67 26.67 20 46.67
30x18 74.33 117 13.33 13.33 26.67
Ordinary
irrigation
(continu-
ous
flooding)
14
30x30 73.33 122 16.67 33.33 50.00
30x18 72 121 26.67 53.33 80.00
21
30x30 72 120.67 20 76.67 96.67
30x18 72.67 121 13.33 80 93.33
Time to flowering, maturity, and plant lodging percentage
as affected by AWDI and ordinary irrigation practice
combined with different age of seedlings and spacing
in Chiba, 2008 (Chapagain and Yamaji, 2009)

42. Incidence of Diseases and Pests
Vietnam National IPM Program: average of
data from trials in 8 provinces, 2005-06:
Spring season Summer season
SRI
Plots
Farmer
Plots
Differ-
ence
SRI
Plots
Farmer
Plots
Differ-
ence
Sheath
blight
6.7% 18.1% 63.0% 5.2% 19.8% 73.7%
Leaf blight
-- -- -- 8.6% 36.3% 76.5%
Small leaf
folder *
63.4 107.7 41.1% 61.8 122.3 49.5%
Brown
plant
hopper *
542 1,440 62.4% 545 3,214 83.0%
AVERAGE 55.5% 70.7%
* Insects/m2

43. Theory of Trophobiosis
(F. Chaboussou, Healthy Crops, 2004)
deserves more attention and empirical
evaluation than it has received to date
Its propositions are well supported by
published literature over last 50 years
-- and by long-standing observations
about adverse effects of nitrogenous
fertilizers and chlorinated pesticides
Theory does not support strictly ‘organic’
approach because nutrient amendments
are approved where soil deficits exist

44. Theory of ‘Trophobiosis’
Explains incidence of pest and disease
in terms of plants’ nutrition:
Nutrient imbalances and deficiencies
lead to excesses of free amino acids
in the plants’ sap and cells, not yet
synthesized into proteins – and more
simple sugars in sap and cytoplasm
not incorporated into polysaccharides
This condition attracts and nourishes
insects, bacteria, fungi, even viruses

45. Resistance to cold temperatures: Yield and
meteorological data from ANGRAU, A.P., India
PeriodPeriod Mean max.Mean max.
temp.temp. 00
CC
Mean min.Mean min.
temp.temp. 00
CC
No. ofNo. of
sunshine hrssunshine hrs
1 – 151 – 15 NovNov 27.727.7 19.219.2 4.94.9
16–3016–30 NovNov 29.629.6 17.917.9 7.57.5
1 – 15 Dec1 – 15 Dec 29.129.1 14.614.6 8.68.6
16–31 Dec16–31 Dec 28.128.1 12.212.2++
8.68.6
+ Sudden drop in minimum temp. for 5 days (16–21 Dec. = 9.2-9.9o
C )
SeasonSeason Normal (t/ha)Normal (t/ha) SRI (t/ha)SRI (t/ha)
Kharif 2006Kharif 2006 0.21*0.21* 4.164.16
Rabi 2005-06Rabi 2005-06 2.252.25 3.473.47
* Low yield was due to cold injury (see below)

46. Measured Differences in Grain Quality
Conv. Methods SRI Methods
Characteristic (3 spacings) (3 spacings) Difference
Chalky kernels
(%)
39.89 – 41.07 23.62 – 32.47 - 30.7%
General
chalkiness (%)
6.74 – 7.17 1.02 – 4.04 - 65.7%
Milled rice
outturn (%)
41.54 – 51.46 53.58 – 54.41 +16.1%
Head milled
rice (%)
38.87 – 39.99 41.81 – 50.84 +17.5%
Paper by Prof. Ma Jun, Sichuan Agricultural University,
presented at 10th conference on “Theory and Practice for
High-Quality, High-Yielding Rice in China,” Haerbin, 8/2004

47. Careful transplanting of single, young seedlings, widely spacedSRI LANKA: Best use of transplanting methods

48. SRI LANKA: Soil-aerating hand weeder costs <$10

49. Effect of Active Soil Aeration
412 farmers in Morang district, Nepal,
using SRI in monsoon season, 2005
SRI yield = 6.3 t/ha vs. control = 3.1 t/ha
• Data show how WEEDINGS can raise yield
No. of No. of Average Range
weedings farmers yield of yields
1 32 5.16 (3.6-7.6)
2 366 5.87 (3.5-11.0)
3 14 7.87 (5.85-10.4)

50. Mechanical
Weedings
Farmers
(N)
Area
(ha)
Harvest
(kg)
Yield
(t/ha)
None 2 0.11 657 5.973
One 8 0.62 3,741 7.723
Two 27 3.54 26,102 7.373
Three 24 5.21 47,516 9.120
Four 15 5.92 69,693 11.772
Impact of Weedings on Yield with SRI Methods
Ambatovaky, Madagascar, 1997-98

51. Mechanization
of weeding, i.e.,
soil aeration,
is also possible

52. Roller-marker devised by Lakshmana Reddy, East Godavari,
AP, India, to save time in transplanting operations; yield
in 2003-04 rabi season was 16.2 t/ha paddy (dry weight)

53. SRI seedlings ready for transport to
field, for mechanical transplanting
in COSTA RICA

54. Fig 1 Trasplantadora motorizada
AP100 Yanmar
Mechanical transplanter
used in COSTA RICA

55. Mechanically transplanted SRI field in Costa Rica – 8 t/ha yield

56. PAKISTAN: Making raised beds for rice-growing
with adapted SRI methods on laser-leveled field

57. Mechanical transplanter for dropping seedlings into holes made by machine,
Water is sprayed in hole after 10-day seedling is lput in, adding compost.

58. Mechanical weeder set for spacing 9x9 inch
(22.5x22.5 cm) – can give very good soil aeration

59. Rice crop at 71 days in Punjab, Pakistan
Seedlings planted into dry soil = 70% water reduction
Average yield = 13 tons/ha (7 to 22 tons/ha)

60. Role of Soil Biota
Bacteria and fungi perform many
services for crop (under aerobic
conditions)
• Nutrient cycling and mobilization
• Nitrogen fixation
• Phosphorus solubilization
• Water and nutrient acquisition
• Competition with pathogens
• Induced systemic resistance
Also previously unappreciated benefits
--

61. ENDOPHYTIC AZOSPIRILLUM, TILLERING,
AND RICE YIELDS WITH CULTIVATION
PRACTICES AND NUTRIENT AMENDMENTS
Results of replicated trials at Anjomakely, Madagascar, 2001 (Andriankaja, 2002)
Azospirillum
CLAY SOIL
(Methods of cultivation)
in roots
(103
/mg)
Tillers/ plant Yield
(t/ha)
Usual with no amendments
65 17 1.8
SRI with no amendments
1,100 45 6.1
SRI with NPK added
450 68 9.0
SRI methods with compost
1,400 78 10.5
LOAM SOIL
SRI with no amendments
75 32 2.1
SRI methods with compost
2,000 47 6.6

62. Treatments Total
microbes
(x105
)
Azotobacter
(x103
)
Azospirillum
(x103
)
PSM
(x104
)
Conventional (T0) 2.3a 1.9a 0.9a 3.3a
Inorganic SRI (T1) 2.7a 2.2a 1.7ab 4.0a
Organic SRI (T2) 3.8b 3.7b 2.8bc 5.9b
Org. SRI + BF (T3) 4.8c 4..4b 3.3c 6.4b
CFU = colony forming units PSM = Phosphate-solubilizing microbes BF = Bio-organic fertilizer
Values with the different letters in a column are significantly different by LSD at the 0.05 level.
Treatments: T0 = 20x20 cm spacing, 30 day seedlings, 6 seedlings/hill, 5 cm flooding depth of water, fertilized with
inorganic NPK (250 kg urea, 200 kg SP-18, 100 kg KCl ha-1
); T1, T2, T3 = All 30x30 cm spacing, 6-10 day seedlings,
1 seedling/hill, moist soil or intermittent irrigation, with different fertilization: T1 = same inorganic NPK as T0;
T2 = 5 t ha-1
of organic fertilizer (compost); T3 = Inorganic NPK as in T0 + 300 kg ha-1
bioorganic fertilizer.
Total microbes and numbers of beneficial soil
microbes (CFU g-1
) under conventional and SRI rice
cultivation methods, Tanjung Sari, Bogor district,
Indonesia, Feb-Aug 2009 (Iswandi et al., 2009)

63. ‘Ascending Migration of Endophytic Rhizobia,
from Roots and Leaves, inside Rice Plants and
Assessment of Benefits to Rice Growth Physiology’
Rhizo-
bium test
strain
Total plant
root
volume/
pot (cm3
)
Shoot dry
weight/
pot (g)
Net photo-
synthetic
rate
(μmol-2
s-1
)
Water
utilization
efficiency
Area (cm2
)
of flag leaf
Grain
yield/
pot (g)
Ac-ORS571 210 ± 36A
63 ± 2A 16.42 ± 1.39A
3.62 ± 0.17BC
17.64 ± 4.94ABC
86 ± 5A
SM-1021 180 ± 26A
67 ± 5A 14.99 ± 1.64B
4.02 ± 0.19AB
20.03 ± 3.92A
86 ± 4A
SM-1002 168 ± 8AB
52 ± 4BC 13.70 ± 0.73B
4.15 ± 0.32A
19.58 ± 4.47AB
61 ± 4B
R1-2370 175 ± 23A
61 ± 8AB 13.85 ± 0.38B
3.36 ± 0.41C
18.98 ± 4.49AB
64 ± 9B
Mh-93 193 ± 16A
67 ± 4A 13.86 ± 0.76B
3.18 ± 0.25CD
16.79 ± 3.43BC
77 ± 5A
Control 130 ± 10B
47 ± 6C 10.23 ± 1.03C
2.77 ± 0.69D
15.24 ± 4.0C
51 ± 4C
Feng Chi et al.,Applied and Envir. Microbiology 71 (2005), 7271-7278

64. Data are based on the average linear root and shoot growth of three
symbiotic (dashed line) and three nonsymbiotic (solid line) plants.
Arrows indicate the times when root hair development started.
Ratio of root and shoot growth in symbiotic
and nonsymbiotic rice plants (symbiotic
plants inoculated with Fusarium culmorum)
Russell J. Rodriguez et al., ‘Symbiotic regulation of plant
growth, development and reproduction,’ Communicative and
Integrative Biology, 2:3 (2009).

65. Growth of nonsymbiotic (on left) and symbiotic (on right) rice seedlings.
On growth of endophyte (F. culmorum) and plant inoculation procedures,
see Rodriguez et al., Communicative and Integrative Biology, 2:3 (2009).

66. Extensions of SRI to Other Crops:Extensions of SRI to Other Crops:
Uttarakhand / Himachal Pradesh, IndiaUttarakhand / Himachal Pradesh, India
Crop No. of
Farmers
Area
(ha)
Grain Yield
(t/ha)
%
Incr.
2006 Conv. SRI
Rajma 5 0.4 1.4 2.0 43
Manduwa 5 0.4 1.8 2.4 33
Wheat Research
Farm
5.0 1.6 2.2 38
2007
Rajma 113 2.26 1.8 3.0 67
Manduwa 43 0.8 1.5 2.4 60
Wheat
(Irrig.)
25 0.23 2.2 4.3 95
Wheat
(Unirrig.)
25 0.09 1.6 2.6 63
Rajma (kidney beans)
Manduwa (millet)

67. Sugar cane grown with SRI methods (left) in Andhra Pradesh
Reported yields of 125-235 t/ha compared with usual 65 t/ha

68. ICRISAT-WWF
Sugarcane Initiative:
at least 20% more
cane yield, with:
• 30% reduction in
water, and
• 25% reduction in
chemical inputs
‘The inspiration for putting
this package together is
from the successful
approach of SRI – System
of Rice Intensification.’

69. HIGH-TILLERING TRAIT IN TEFF WHEN
TRANSPLANTED WITH WIDER SPACING

70. 1ST
S.T.I. TRIALS, 2008
Duplication of Earlier Findings
VARIETYVARIETY SOWINGSOWING
METHODMETHOD
PELLETINGPELLETING YIELDYIELD
(Kg/Ha)(Kg/Ha)
Cross 37Cross 37 BroadcastBroadcast NoneNone 1,0141,014
BroadcastBroadcast YesYes 483483
20 cm x 20 cm20 cm x 20 cm NoneNone 3,3903,390
20 cm x 20 cm20 cm x 20 cm YesYes 5,1095,109
Cross 387Cross 387 BroadcastBroadcast NoneNone 1,1811,181
BroadcastBroadcast YesYes 1,0361,036
20 cm x 20 cm20 cm x 20 cm NoneNone 4,1424,142
20 cm x 20 cm20 cm x 20 cm YesYes 4,3854,385
YIFRU ( 1998 )
M. Sc. THESIS
Reported yield of 4-5
tons/ha for
non-lodged teff vs.
2-3 t/ha for lodged
teff

71. 2ND
S.T.I. TRIALS, 2009
COMPOUND FERTILIZER + SPACING
Variety: DZ-01-974 (3 replications I-III)
I II III TOTAL AVE.
YIELD
(kg/ha)*
DAP + UREA 57 49.5 34.2 140.7 46.9 6,700
DAP + NP + Zn 56.6 53.8 60.6 171 57.0 8,143
DAP + NP +
Cu 67.6 58.4 40.4 166.4 55.5 7,924
DAP + NP + Zn
+ Cu 76.2 50.9 53.3 180.4 60.1 8,591
SUKUBE
SUKUBE (NPK
+ Cu, Zn, Mn) +
UREA 68.6 61.8 54.1 184.5 61.5 8,786
CHECK: NO
FERTILIZER 5.3 11.2 3.2 19.7 6.6 938
* YIELD LEVELS NEVER REPORTED BEFORE

72. SRI is pointing the way toward
a possible paradigm shift to
‘post-modern agriculture’:
• Less ‘genocentric’ and more
profoundly ‘biocentric’
• Re-focus biotechnology and
bioengineering to capitalize
on biodiversity and ecological
dynamics
• Less chemical-dependent
and more energy-efficient
• More oriented to the health
of people and of environment
• Intensification of production
--not continued extensification
• Focus on factor productivity
and on sustainability !

73. THANK YOU
• Check out SRI website:
http://ciifad.cornell.edu/sri/
• Email: ciifad@cornell.edu
or ntu1@cornell.edu

76. How to “speed up the
biological clock”
(adapted from Nemoto et al. 1995)
Shorter phyllochrons Longer phyllochrons
• Higher temperatures > cold temperatures
• Wider spacing > crowding of roots/canopy
• More illumination > shading of plants
• Ample nutrients in soil > nutrient deficits
• Soil penetrability > compaction of soil
• Sufficient moisture > drought conditions
• Sufficient oxygen > hypoxic soil conditions

77. Root cross-sections of varieties:
upland (left) and irrigated (right)
ORSTOM research (Puard et al. 1989)

78. Current research in
Indonesia at IPB:
cross-sections of rice
roots at 4, 6, 8 and 10
weeks after planting –
with conventional mgmt,
SRI with fertilizer, and
SRI with organic inputs