Transcript OWC/OWRF Use of Sensors and Spectral Reflectance Water Indices to

OWC/OWRF
Use of Sensors and Spectral
Reflectance Water Indices to
Select for Grain Yield in Wheat
Dr. Arthur Klatt
Dr. Ali Babar
Dr. B. Prasad
Mr. Mario Gutierrez R.
Plant Breeding Methodology
• Selection in classical plant breeding is based on yield
• Breeding and release of new wheat cultivars or varieties have been
based on grain yield measurements
• A large number of genotypes or advanced lines have to be evaluated
for yield potential
• Promising high yielding genotypes require repeated testing across
locations and years to make a final selection decision = costly and time
consuming
• Yield has low heritability and a high genotype-environment interaction,
which can lead to imprecise results
• Breeders are searching for new indirect selection tools to improve
efficiency of selecting for yield
(Richards, 1982)
Spectral Reflectance
Technique
Spectral reflectance from the canopy provides information
about several physiological traits of the wheat plant
Spectral reflectance measurements are convenient and can be used
to screen a large number of genotypes, with limited cost and minimal
time commitment
Many indices have been developed from spectral reflectance
measurements of the canopy
Are there spectral reflectance indices (SRI) that differentiate wheat
genotypes for yield potential, and do so consistently across years
and environments?
THE LIGHT SPECTRUM
Visible spectrum (400-700 nm)
The human eye is sensitive to this region
NIR (near infrared) (700-1300 nm)
Human eye not able to see it
Scattered by atmosphere
(i.e., clouds, particles, smoke)
Energy
source
Absorbed by atmosphere
(CO2, H2O, etc.)
Reflected radiation
by ground surface
Plant canopy
1
2
Absorbed by ground surface
3
Reflected radiation in
Visible region (400-700 nm)
NIR region (700-1300 nm)
Absorbed radiation in the visible
region (400-700 nm)
Chlorophyll
Xanthophylls
Carotenoids
Transmitted radiation to the ground
Reflected radiation
a) Visible region (400-700 nm)
b) NIR region (700-1300 nm)
Canopy reflectance
Refλ=
EReflected
EIncident
Radiometer
computer
Canopy Reflectance
NDVI=
R900+R680
R900-R680
Near infrared
Red
Green
Blue
Visible
(Lillesand et al., 2004)
Canopy Reflectance
Leaf pigments
Cell structure
Chlorophyll
Water absorption
band at 970 nm
Xanthophylls
Green biomass
Visible
Near infrared
(Lillesand et al., 2004)
Spectral Reflectance in Wheat
1.0
Reflectance
0.8
Well irrigated
0.6
0.4
Drought
Reflectance
1.0
0.8
Control
0.6
N-deficient
0.4
0.2
0.2
0.0
0.0
400 500 600 700 800 900 1000
Wavelength (nm)
Water stress deficit
400
500
600 700 800 900 1000
Wavelength, nm
Nitrogen status
Canopy Spectral Reflectance
Chlorophyll strongly absorbs radiation in the visible region
The absorbed radiation is influenced by
• Overall area of leaves
• Other photosynthetic organs (stem and spike)
• Pigment concentration
Canopy spectral reflectance provides information to estimate other
parameters
• Green biomass
• Leaf area index (photosynthetic area)
• Absorbed radiation (photosynthetic potential)
• Nutrient deficiencies
• Chlorophyll content
(Knipling, 1970; Osborne et al., 2002)
Spectral reflectance indices
Vegetation indices
NDVI=900-680/900+680
RED-NDVI=780-670/780+670
GREEN-NDVI=780-550/780+550
NVI=555-680/555+680
NDVI-2=820-700/820+700
GNDVI=820-550/820+550
IVEST=780+550/680
VI 700=700-680/700+680
SR=900/680
NR=550/850
NRVI=850-550/850+550
NDVI-3=880-590/880+590
Grain yield
Green Biomass
Leaf area index
Intercepted radiation
Nitrogen content
Photosynthetic capacity
Chlorophyll indices
RARSa=675/700
RARS2a=680/800
RARSb=675/650*700
RARSc=760/500)
Datt1=780-710/780-680
Datt2=850-710/850-680
mND=750-705/750+705-2*445
mSR=750-445/705-445
Gitelson1=750-705/750+705
Gitelson2=750/700
NPQI=415-435/415+435
SIPI=800-435/415+435
Chlorophyll a, b
Carotenoids
Nitrogen content
SPAD readings
Green biomass
Water indices
WI=900/970
NWI-1=970-900/970+900
NWI-2=970-850/970+850
NWI-3=970-880/970+880
NWI-4=970-920/970+920
Grain yield
Relative water content
Canopy temperature
(Aparicio et al., 2002; Araus et al., 2001; Babar et al., 2006; Knipling, 1970; Osborne et al., 2002; Prasad et al., 2007)
Water index
Water index (WI)
• Peñuelas et al. (1993) established a water index
based on the water absorption at 900 and 970 nm (as
a reference)
WI=R970/R900
It is related with
• relative water content in canopy,
• leaf water potential,
• and canopy temperature
970 nm wavelength is a water absorption band
900 nm is used as reference
(Peñuelas et al., 1993)
Water index as selection criteria
• Babar et al. (2006) proposed two normalized water indices
NWI-1=R970-R900/R970+R900
NWI-2=R970-R850/R970+R850
• They showed high relationship with yield in spring wheat genotypes (r=0.40 to -0.88)
• Prasad et al. (2007) proposed other two normalized water indices
NWI-3=R970-R880/R970+R880
NWI-4=R970-R920/R970+R920
• They found a strong correlation with yield (r=-0.40 to -0.86) in winter wheat
(Babar et al., 2006; Prasad et al., 2007)
Water Index as Selection
Criteria
They compared the water indices at booting compared with heading-grain
filling
They determined that using the average SRI from the heading and grain filling
stages can be used for predicting yield of the individual genotypes
The normalization removes
Soil interference
Position of sun (illumination)
Angle of view
Reflectance Calibration from a Radiometer
1
0.9
0.8
Reflectance
0.7
0.6
0.5
0.4
0.3
0.2
0.1
Handheld
sensor
0
400
500
600
700
800
900
1000
1100
B)
Wavelenght (nm)
Maximum reflectance
Foreoptic
Growth stages
• Booting
• Heading
(anthesis)
• Grain filling
50 cm
25o
A)
Portable
spectroradiometer
(UV/VNIR FieldSpec)
No radiation
(dark)
Barium sulfate panel
HTWYT Yield (n=18)
Grain yield (Kg ha-1)
range
Well-irrigated
Drought
High
temperature
2006
2007
5700-8290
4610-7850
-
1000-1800
1870-3800
1110-3900
HTWYT Well-irrigated (n=18)
Relationship between spectral indices and grain yield
Booting
Vegetation indices
0.10
RNDVI
0.21
GNDVI
SR
0.01
Water indices
WI
-0.18
NWI1
-0.18
NWI2
-0.16
NWI3
-0.16
*Significant at p=0.05
**Significant at p=0.01
2006
Heading-Grain
filling
Booting
2007
Heading-Grain
filling
0.39
0.39
0.38
0.42
0.27
0.19
0.27
0.49
0.40
-0.35
-0.33
-0.38
-0.36
-0.69**
-0.69**
-0.65**
-0.64**
-0.61**
-0.62**
-0.59**
-0.55*
Relationship Between Spectral Indices
and Grain Yield
Low water index value means high
Yield
Water content in canopy
Transpiration rate
Photosynthesis rate
Cooler canopies
HTWYT-Drought
Relationship between spectral indices and grain yield
2007
Booting
Heading-Grain filling
RNDVI
0.62**
-0.05
GNDVI
0.33
-0.12
0.57**
-0.03
WI
-0.26
-0.57*
NWI1
-0.26
-0.52*
NWI2
-0.37
-0.63**
NWI3
-0.32
-0.61**
Vegetation indices
SR
Water indices
*Significant at p=0.05
**Significant at p=0.01
HTWYT-High Temperature (n=18)
(> 39oC at midday)
Relationship between spectral indices and grain yield
2006
Booting
2007
Heading-Grain
filling
Booting
Heading-Grain
filling
Vegetation indices
RNDVI
0.69**
0.63**
0.75**
0.52*
GNDVI
0.69**
0.62**
0.78**
0.51*
0.68*
0.58**
0.56*
0.44
WI
-0.76**
-0.51*
-0.85**
-0.78**
NWI1
-0.77**
-0.50*
-0.85**
-0.77**
NWI2
-0.76**
-0.42
-0.89**
-0.71**
NWI3
-0.75**
-0.48*
-0.88**
-0.77**
SR
Water indices
*Significant at p=0.05
**Significant at p=0.01
SAWYT Yield (n=50)
Grain yield (Kg ha-1)
range
Well-irrigated
Drought
2006
2007
3330-12650
3830-9450
510-2490
490-3130
SAWYT-well irrigated (n=50)
Relationship between spectral indices and grain yield
2006
Booting
2007
Heading-Grain
filling
Booting
Heading-Grain
filling
Vegetation indices
RNDVI
-0.04
-0.09
-0.01
-0.10
GNDVI
0.04
-0.01
0.03
-0.07
SR
-0.02
-0.13
0.19
-0.20
WI
-0.31*
-0.43**
-0.17
-0.55**
NWI1
-0.31*
-0.43**
-0.16
-0.55**
NWI2
-0.33*
-0.41**
-0.19
-0.53**
NWI3
-0.32*
-0.42**
-0.18
-0.52**
Water indices
*Significant at p=0.05
**Significant at p=0.01
SAWYT-Drought (n=50)
Relationship between spectral indices and grain yield
2006
Booting
2007
Heading-Grain
filling
Booting
Heading-Grain
filling
Vegetation indices
RNDVI
-0.08
0.26
-0.17
0.18
GNDVI
-0.05
0.18
0.01
0.05
SR
-0.16
0.06
-0.16
0.06
WI
-0.32*
-0.41**
-0.50**
-0.51**
NWI1
-0.32*
-0.40**
-0.49**
-0.50**
NWI2
-0.32*
-0.43**
-0.48**
-0.49**
NWI3
-0.32*
-0.44*
-0.50**
-0.49**
Water indices
*Significant at p=0.05
**Significant at p=0.01
CONCLUSIONS
• The potential of the water indices for predicting grain yield in wheat has
been demonstrated repeatedly in diverse environments
• The water indices have an inverse relationship with grain yield
• The water indices have shown a consistently good association with yield
under well-irrigated, drought and high temperature conditions
• There is essentially no difference in accuracy between the different water
indices in predicting yield and total biomass
• These indices may prove to be an efficient and low cost indirect selection
tool for wheat breeders
• May be especially effective in selecting at the preliminary yield trial level—
testing is now being done!
THE NEWEST HAND-HELD SENSOR