1043 influence of system of rice intensification (sri) practices on grain yield and associated...
TRANSCRIPT
Amod K. Thakur, Sreelata Rath, Ashwani Kumar
Influence of System of Rice Intensification (SRI) practices on grain yield and associated
physiological changes in rice plants compared to conventional flooded rice
Directorate of Water Management (ICAR)Bhubaneswar, Orissa -751023, India
ObjectiveTo examine the extent to which making certain changes in crop management practices can alter phenotypical characteristics and induce physiological changes in rice plants.
How SRI practices affect rice plants’ morphology, their physiology, and their implications on crop performance?
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Methodology
Location: Deras Research Farm, Orissa, India
Season: Dry (January-May) 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) and Traditional flooding (TF) with standard management practices
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Management practices SRI TFSeedling age, days
12 21
Plant spacing and density
20 x 20 cm One seedling /hill
20 x10 cmThree seedlings /hill
Weed control Three, Cono-weeder; 10, 20 and 30 DAT
Manual, 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
Organic manure @ 5 t ha-1
Chemical fertilizers: 80 kg N ha-1, 40 kg P2O5 ha-1, 40 kg K2O ha-1
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Parameters studied
Root growth / Xylem exudation rate: Early-ripening stage
Number of leaves hill-1 / Av. Leaf length and width / Leaf angle / Leaf area index (LAI) / Specific leaf weight (SLW) / Canopy angle: Flowering stage
Light interception by the canopy / Crop growth rate (CGR): Vegetative stage
Chlorophyll content / Chlorophyll fluorescence (Fv/Fm and ΦPS II) / Photosynthesis rate - flag leaf and fourth leaf (from top): Flowering, Middle-ripening and Late-ripening stages
Tilering/ Harvest Index / Grain yield and yield-components
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Results
Ro
ot
Gro
wth
SRI- better root development - deeper roots, more dry weight, root volume, root length and root length density
Parameters SRI TF LSD0.50
Root depth, cm 33.5 20.6 3.5
Root dry weight, g hill-1 12.3 5.8 1.3
Root dry weight, g m-2 306.9 291.8 NS
Root volume, ml hill-1 53.6 19.1 4.9
Root volume, ml m-2 1340.0 955.0 180.1
Root length, cm hill-1 9402.5 4111.9 712.4
Root length density, cm cm-3 2.7 1.2 0.2
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Ro
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Act
ivit
y
Management 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 7.93
TF 2.46 122.95 0.10 5.12
LSD.05 1.45 39.72 0.06 1.66
Amount of exudates- 209% greater in SRI hills
Rate - 3 times faster in SRI hills
Thakur et al. (2010): Expl. Agric. 46: 77-98
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Til
leri
ng
un
der
SR
I
The number of tillers per hill significantly increased (2.5 times, up to 34 tillers) in SRI than TF
SRI plants were able to complete more number of phyllochrons (10th Phyllochron in SRI and 8th phyllochron in TF)
0
5
10
15
20
25
30
35
12 21 30 40 50 60 70
Tiller number/hill
Days after seed germination
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Thakur et al. (2010): Expl. Agric. 46: 77-98
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 TF
Management practice
12 DAG 30 DAG 40 DAG 50 DAG 60 DAG 70 DAG
SRI Transplanted< 4th
phyllochron
6th Phyllochron
7– 8th phyllochron
8-9th phyllochron
9th phyllochron 10th Phyllochron
TF In Nursery
Transplanting shock
6th Phyllochron
7th phyllochron
8th phyllochron 8th Phyllochron
DAG: Days after germination
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) are transported from roots.
0
10
20
30
40
50
60
30-40 40-50 50-60 60-70
CGR (g m-2
day-1
)
Period (Days after germination)
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Lea
f d
evel
op
men
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Management practice
Leaf number (hill-1)
Leaf number
(m-2)
Ave. leaf length (cm)
Ave. leaf width (cm)
LAI
SRI 79.8 1997.6 65.25 1.82 3.95
TF 35.6 1766.5 48.14 1.34 2.60
LSD.05 15.8 229.4 6.09 0.21 0.28
SRI hills - more than twice the number of leaves compared to TF hills
SRI leaves- longer as well as wider than TF leaves
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Can
op
y st
ruct
ure
&
Lea
f an
gle
SRI: Greater Canopy angle - Open-type canopy structure
TF: Closed-canopy structure
SRI leaves – more erect
Thakur et al. (2010): Expl. Agric. 46: 77-98
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Lig
ht
Inte
rcep
tio
nSRI: intercept more light without shading TF: In closed canopy lower leaves experiences more shading.
0
20
40
60
80
100
12 25 30 40 50 60 70
Light Interception (%)
Days after seed germination
At PI Stage- Light interception reached 89% in SRI plots, while it was only 78% in TF canopies, this giving SRI plants a 15% advantage.
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Changes in leaf chlorophyll content at different growth stages in SRI and TF
FL: Flowering stage; MR: Middle-ripening stage; LR: Late-ripening stage
0
0.5
1
1.5
2
2.5
3
3.5
4
FL MR LR
Chlorophyll content (mg g-1
FW)
Stages
Flag SRI
Flag TF
Fourth SRI
Fourth TF% decrease from FL-LR
SRI-Flag leaf 35.93
TF- Flag leaf 48.94
SRI-4th leaf 39.44
TF- 4th leaf 56.14
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0.3
0.4
0.5
0.6
0.7
0.8
0.9
FL MR LR
Fv/Fm
Stages
Flag SRI
Flag TF
Fourth SRI
Fourth TF
% decrease from FL-LR
SRI-Flag leaf 22.77
TF- Flag leaf 31.81
SRI-4th leaf 27.55
TF- 4th leaf 31.88
Changes in chlorophyll fluorescence (Fv/Fm) at different growth stages in SRI and TF
FL: Flowering stage; MR: Middle-ripening stage; LR: Late-ripening stage
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0.200
0.250
0.300
0.350
0.400
0.450
0.500
0.550
0.600
0.650
FL MR LR
Ф PS II
Stages
Flag SRIFlag TFFourth SRIFourth TF
% decrease from FL-LR
SRI-Flag leaf 9.93
TF- Flag leaf 21.62
SRI-4th leaf 15.31
TF- 4th leaf 24.27
Changes in chlorophyll fluorescence (Φ PS II) at different growth stages in SRI and TF
FL: Flowering stage; MR: Middle-ripening stage; LR: Late-ripening stage
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0
5
10
15
20
25
30
FL MR LR
Pn (µ mol m-2
s-1 )
Stages
Flag SRI Flag TF
Fourth SRI Fourth TF% decrease from FL-LR
SRI-Flag leaf 43.20
TF- Flag leaf 51.09
SRI-4th leaf 52.98
TF- 4th leaf 59.02
Changes in photosynthesis rate at different growth stages in SRI and TF
FL: Flowering stage; MR: Middle-ripening stage; LR: Late-ripening stage
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Yie
ld &
yie
ld-c
on
trib
uti
ng
C
har
acte
rist
ics
SRI - Longer panicles, more number of grains in spike (40%), higher 1000-grain weight and more grain ripening percent than the TF crop, responsible for higher grain yield (42%).
Parameters SRI TF LSD0.50
Panicles / m2 439.5 355.2 61.6
Ave. Panicle length, cm 22.5 18.7 2.3
Spikelet / panicle 151.6 107.9 12.9
Filled spikelet, % 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
HI 0.47 0.32 0.04
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0
50
100
150
200
250
300
350
Short Medium Long Extra long
Panicle number/m2
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 its length under SRI and TF
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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
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These factors contributed to
larger panicles (more spikelets per panicle),
better grain setting (higher % of filled grains)
heavier individual grains (higher 1000- grain weight),
higher grain yield
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Conclusion
Improvement in grain yield under SRI is attributable to improved morphology and physiological features of the rice plant below and above ground (Better Root-shoot interaction).
SRI methods narrow the gap between genetic potential and in-field yield achievements through management practices.
