S. Kumudini, C. Godoy, J. Board, S. Kumudini, C. Godoy, J. Board, and J. Omielan and J. Omielan Developing a Yield Loss Prediction Model for Asian Soybean Rust; A Crop Physiology Approach
S. Kumudini, C. Godoy, J. Board, S. Kumudini, C. Godoy, J. Board, and J. Omielanand J. Omielan
Developing a Yield Loss Prediction Model for Asian Soybean Rust; A Crop Physiology Approach
OutlineMultidisciplinary study - Develop yield loss prediction modelYield equationHow does SBR impact soybean yield
Study – the role of defoliation injuryStudy – the impact of SBR lesions on plant productivity
Summary
Rust causing premature defoliation
Pirapó, Paraguay – 2001
TreatedTreated ControlControl
MATO GROSSO, Brazil
ChallengeDevelop a yield loss prediction model for soybean rust
Project Website
Objective
To develop yield loss prediction model for soybean rust
Yb = ∫ (Q X Ia X ε) dt
Yg = Yb X HI
Yield
ObjectivesObjectives
I. Check assumption: Is SBR-induced yield loss due to defoliation injury?
II. Model building: Develop a model that can effectively predict SBR-induced yield loss
Yb = ∫ (Q X Ia X ε) dt
Embrapa Soja, Londrina, Brazil
Objective: Determine the role of defoliation injury on SBR-induced yield loss
Role of Defoliation injury in yield loss? Londrina, Brazil
04 February 2006First flower
Cultivar BRS 154 (MG VII) Rows 45 cm (~18 inches)Planted 20 December, 2005
1 st. fungicide application 02 February 2006 (Tetraconazole - Eminent 0.4L/ha - marketed in US as Domark)
Materials and Methods
RCBD design, 6 replicationsFive treatments
1. SBR - R1
Materials and Methods
RCBD design, 6 replicationsFive treatments
1. SBR - R12. Mimic “SBR” at R1
Materials and Methods
RCBD design, 6 replicationsFive treatments
1. SBR - R12. Mimic “SBR” at R13. SBR - R5
Materials and Methods
RCBD design, 6 repsFive treatments
1. SBR - R12. Mimic - R13. SBR - R54. Mimic - R5
Materials and Methods
RCBD design, 6 repsFive treatments
1. SBR - R12. Mimic - R13. SBR - R54. Mimic - R55. Control
Materials and Methods
Measured Leaf Area IndexDisease severityYield
Results and Discussion
Disease severity over time
0102030405060708090
100
40 50 60 70 80 90 100
Days After Planting (d)
Dis
ease
Sev
erity
(%)
ControlSBR at R1Mimic SBR at R1SBR at R5Mimic SBR at R5
R5R1
Plants infected at R1, leaf area over time
R2 = 0.94
R2 = 0.96
R2 = 0.92
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
45 55 65 75 85 95Days After Planting (d)
Leaf
Are
a In
dex
(m2 m
-2)
Control
SBR at R1
Mimic SBR at R1
R5R1
Plants infected at R5, leaf area over time
R5R1
R2 = 0.99
R2 = 0.96
R2 = 0.98
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
45 55 65 75 85 95Days After Planting (d)
Leaf
Are
a In
dex
(m2 m
-2)
Control
SBR at R5
Mimic SBR at R5
Role of defoliation injury in yield loss?
VS.
SBR-infected plot (SBR at R1) Mimic SBR at R1Fungicide treated, and manually defoliated to mimic SBR- plots
Plants at R5
Role of defoliation injury in yield loss?
VS.
Mimic SBR at R1Fungicide treated, and manually defoliated to mimic SBR- plots
SBR-infected plot (SBR at R1)
Plants around R6
Impact of SBR on yield
0
500
1000
1500
2000
2500
SBR at R1 SBR at R5 Control
Yiel
d (k
g ha
-1)
SBR Manual defoliation
Yield
Ye = Yb X HI
Yb = ∫ (Q X Ia X ε) dt
Relationship between LAD and yield
R2 = 0.4821ns
0
20
40
60
80
100
120
140
0 20 40 60 80 100 120
Leaf Area Duration (m2 d)
Yiel
d (g
m-2
)
1 year dataAssumption SBR-induced yield loss due to defoliation injury ?
VS.
SBR- plots at R6 (infected at R1) Fungicide treated, and manually defoliated to mimic SBR- plots
Close look at SBR-infected plot
Non-abscised SBR-infected leaf
Healthy leaf area index (HLAI)HLAI = LAI minus % diseased leaf area
Relationship between healthy leaf area index (HLAI) and yield
R2 = 0.7492*
0
20
40
60
80
100
120
0 20 40 60 80 100 120
Healthy Leaf Area Duration (m2 d)
Yiel
d (g
m-2
)
What is the role of necrotic lesions on plant productivity?
Objective: Impact of SBR Lesions on plant productivity
Preliminary study in Quincy FloridaNorth Florida Research and Education Center
Cultivar DP 72200-RRRow widths 36”Fungicide: Headline SBR
MeasurementsSelected leaves that showed a variation in disease severity
2nd or 3rd central trifoliolate from the topMost control were obtained from fungicide treated plotsHigh disease severity were obtained from non fungicide treated plots
Growth stage R6Net photosynthetic rate
400 CO2 reference side1500 µmoles m-2s-1 (PPFD)30oC temperature
Results and Discussion
W10 100%100% Full photosynthetic capacity
– 75%75% Full photosynthetic capacity
% of healthy leaf (x9) 50% Full photosynthetic capacity
w300 = 35% of healthy leaf35% Full photosynthetic capacity
X20 = 1% of healthy leaf3% Full photosynthetic capacity
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Rel
ativ
e Ph
otos
ynth
etic
rate
(%)
0 0-1% 2-3% 4-5% 6-7% 8-9% 10-11%
12-14%
20-21%
Necrotic lesions (% of area)
Impact of necrotic lesions on photosynthesis
Impact of SBR Lesions on plant productivity (preliminary)
SBR-induced necrotic lesions reduce plant productivity, and will likely be important in yield reduction
Impact of SBR lesions on plant productivity appears to be GREATER than that due to reduced light interception alone.
SummarySBR-induced yield loss was dependent on plant growth stage
SBR can cause severe defoliation injury and even limit achievement of maximum LAI
Lesions on non-abscised leaves have an important impact on yield
0
500
1000
1500
2000
2500
SBR at R1 SBR at R5 Control
Yiel
d (k
g ha
-1)
SBR
R2 = 0.94
R2 = 0.96
R2 = 0.92
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
45 55 65 75 85 95Days After Planting (d)
Leaf
Are
a In
dex
(m2 m
-2)
Control
SBR at R1
Mimic SBR at R1
Overall Summary
Based on 1 year of data
Yield is a function of healthy leaf area duration
Yield loss models must account for both defoliation injury and rust-induced lesions on non-abscised leaves
R2 = 0.7492*
0
20
40
60
80
100
120
0 20 40 60 80 100 120
Healthy Leaf Area Duration (m2 d)
Yiel
d (g
m-2
)
Acknowledgments
Funding USDA, Risk Mangement AgencySouthern Soybean Research Program
Project website:http://www.uky.edu/Ag/Agronomy/Department/sbr/index.htm