Author: Amod Thakur Title: Phenotypic Changes for Improving Crop Physiology under SRI Presented at: The 5th International Rice Congress (SRI research side event) Venue: Sands Expo and Convention Centre, Singapore Date: October 16, 2018

1. Amod K. Thakur
ICAR- Indian Institute of Water Management, Bhubaneswar
INDIA
Phenotypic Changes for Improving Crop Physiology under
SRI

2. What are phenotypic changes?
How it affects crop physiology?
and
Why SRI gives more yield?

3. Uphoff et al. (2015) The Crop Journal
3: 174-189
SRI: Phenotype

4. SRI: Phenotype
• Greater / robust root growth
• Improved shoot growth (Plant height, tillering, tiller thickness)
• Greater LAI (Greater leaf size and number)
• Favourable canopy structure (Open with erect leaves)
Thakur et al. (2010) Experimental Agriculture (Cambridge Univ Press) 46:77-98
Thakur et al. (2011) Paddy Water Environ (Springer) 9:13-24

5. Ciherang-223 tillers
Indonesia
Swarna-84 Panicles
India
Sri Lanka
Malaysia
Indonesia
Cuba
Bhutan
Mali
Vietnam Afghanistan

6. Punjab
Tripura
Odisha
Nepal Cambodia

7. Uphoff et al. (2015) The Crop Journal
3: 174-189
Physiological Changes
with SRI

8. Physiological Changes with SRI
Higher root activity (Xylem exudation)
Greater light interception by canopy
Increased LER (SRI leaves elongated 6 cm/day,
while leaves under conventional method elongated
at a rate of 4.4 cm/day- 36% greater.
Higher CGR
More SLW (mg/cm2): 5.50 vs. 4.89 - 13% greater
Higher levels of leaf chlorophyll
Increasing fluorescence efficiency
Photosynthetic rate of both flag and lower leaves
Delayed senescence
Thakur et al. (2010) Experimental Agriculture (Cambridge Univ Press) 46:77-98
Thakur et al. (2011) Paddy Water Environ (Springer) 9:13-24

9. LightInterception
SRI plants: intercept more light
without shading
CMP plants: in closed canopy,
lower leaves experiences more
shading
0
20
40
60
80
100
12 25 30 40 50 60 70
LightInterception
(%)
Days after seed germination
At PI stage: light
interception in CMP
canopies was only 78%,
while in SRI canopies it
reached 89% -- giving SRI
plants a 15% advantage
Thakur et al. (2010) Experimental Agriculture (Cambridge Univ Press) 46:77-98
Thakur et al. (2011) Paddy Water Environ (Springer) 9:13-24

10. Performance with SRI
• 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 (30-49%)
Thakur et al. (2010) Experimental Agriculture (Cambridge Univ Press) 46:77-98
Thakur et al. (2011) Paddy Water Environ (Springer) 9:13-24
0
20
40
60
80
100
Below15
15.1-16
16.1-17
17.1-18
18.1-19
19.1-20
20.1-21
21.1-22
22.1-23
23.1-24
24.1-25
25.1-26
Panicle length (cm)
Numberofpanicles(m-2
)
CMP
SRI

11. Cytokinins
Delayed senescence
Higher photosynthates
towards roots
Increased leaf N and
chlorophyll contents,
more RuBisCO
Increased leaf number &
leaf size
Greater light interception
Higher microbial activity
Enhanced panicle length,
more grain number & better grain filling
Greater root growth and activity
Increased effective tillers
Open hill structure,
more erect leaves
Higher LAI
Enhanced photosynthesis rate
Higher nutrient uptake
Higher
grain yield
SRI practices
[single, young seedling, wide spacing, inter-cultivation, organic
fertilization, AWD water management]
Thakur et al. (2016)-Adv
Agron. 135: 147-178

12. SRI practices need optimization under each and
every situation- according to local / field
conditions before adoption.
Needs to understood PRINCIPLES (not
PRACTICES)
WHY ? And WHAT ??

13. Practices Found best Reference
Optimized spacing under SRI 20 x 20 cm Thakur et al. (2010) J. Agron. Crop Sci. 196: 146-
159
Optimized water management 3-DAD Thakur et al. (2014) Paddy Water Environ 12:
424
Thakur et al. (2018) Agric. Water Manage. 206:
67-77
Optimized N-management 90 kg ha-1 Thakur et al. (2013) Plant and Soil 370:59-71
Farming System: Integrated SRI Rice + Horticulture +
Aquaculture
Thakur et al. (2015) Agric. Water Manage. 161:
65-76

14. SRI still has a long way to go…
Much more remains to be studied, understood,
adapted and innovated
SRI