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Management of field based screening for yield under stress
Venuprasad RamaiahRainfed Lowland Rice Breeder
A. Selection of location
SE ~ TPE
– Soil type, Temperature, ET similar to TPE– Season: DS (<380c), WS (rainfall?)– Rain-out shelter or field– Water source: good, regular supply, flexibility
• water table• distance from source• neighboring trials
Rain-out shelter
Distance from water source
Seepage from neighboring trial
Effect of water table
Heritability 0.51Mean yield 4502 kg/ha
Rotate with legume
B. Before the experiment
– Good quality seeds– Design, plot size, reps (to control variability in
field)– Effective bordering is essential– regular repeated check varieties– Irrigation method– Control trial (well separated)– Space between trials to avoid seepage (upland
vs lowland)
Germination
Border effect
Variation in field
Variation in field
Rep 1
Rep 2Rep 3
Variation in soil type at depth, Banfora, 2012
Variation in soil type at depth, Banfora, 2012
~60 m
Basin irrigation in lowland, IRRI 2005
Sprinkler irrigation in upland, IRRI 2007
Sprinkler irrigation
C. In the early stages
– Good land preparation– Levelling– Seeding– Uniform irrigation– Uniform plant stand– Control pest - weeds, insect, disease– Birds, rats, ducks– Fertilizer application
Lowland site, Ibadan 2011
Transplanting
Transplanting
Upland site, IRRI
Uniform seeding
Cover the seeds
Sprinkler irrigation
Sprinkler irrigation
Uniformity of irrigation
Uniformity of irrigation
Plant stand
Plant stand
Fertilizer application - basal dose
Fertilizer application – top dressing
Fertilizer application
Rodents
Weedy field
Weed-free field
Herbicide injury
Disease
• Initiate stress about a month after transplanting
• Screening protocol
D. During the stress period
Nonstress
Reliable screening protocol
Tensiometer: -50 KpaSoil water depth <70 cm
• Monitor stress level– Leaf rolling, performance of checks
D. During the stress period
Leaf rolling, IRRI 2007
Leaf rolling and drying, IRRI 2006
• Always record days to 50% flowering
D. During the stress period
• Monitor stress level– rainfall (amount & distribution).– Soil moisture (tensiometer, water depth,
diviner)
D. During the stress period
Tensiometer – soil moisture potential
Tensiometer reading during stress
01/F
eb
03/F
eb
05/F
eb
07/F
eb
09/F
eb
11/F
eb
13/F
eb
15/F
eb
17/F
eb
19/F
eb
21/F
eb
23/F
eb
25/F
eb
27/F
eb
01/M
ar
03/M
ar
05/M
ar
07/M
ar
09/M
ar
11/M
ar
13/M
ar
15/M
ar
17/M
ar
19/M
ar
21/M
ar
23/M
ar
25/M
ar
27/M
ar
29/M
ar
-120
-100
-80
-60
-40
-20
0
Date
K P
a
0
10
20
30
40
50
60
70
30 35 40 45 50 55 60 65 70 75 80 85 90 95
Days after transplanting
Soi
l wat
er te
nsio
n (-
kPa)
Soil water tension at 15 cm in trial of irrigated lowland lines and varieties under lowland stress and full irrigation: IRRI DS 2005
Piezometer to measure water table depth
Measuring moisture parameters15
-Feb
22-F
eb
29-F
eb
7-M
ar
14-M
ar
21-M
ar
28-M
ar
4-A
pr
11-A
pr
18-A
pr
-90.00
-70.00
-50.00
-30.00
-10.00
10.00
30.00 Rainfall (mm)Evaporation (mm)Ground water depth (cm)Tensiometer (KPa)
Venuprasad et al. 2009
Diviner 2000
Moisture level at different depths, Ibadan 2011
0 10 20 30 40 50 60 700.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
SevereModerateControl
Soil depth (cm)
Moi
stur
e co
nten
t (%
)
Weather station
Bird control
Bird scarer
E. Harvest and Post harvest• Record/rate
– Lodging– Pest damage: birds, rodent– Missing plots– Plant stand
• Early maturing plants. Ex- Vandana• Harvest all plants in a row + label• Cloth bag vs. paper bag• Dry to ~14%• Thresh & weigh
F. Data analysis
• Inspect the raw data; remove/correct outliers• Use mixed-model approach• Calculate heritability• Compare trial means• Compare means of checks & parents• Inspect correlation between days to flowering and
yield• If needed, use covariate analysis
Results of drought screening
DS 2014 DS 2015
Mean grain yield 130 g/m2 50
LSD 97 30
H 0.72 0.6
Results of drought screening
Grain yield (g/m2)Entries Site 1 Site 2ChecksApo 566.2 11.3FARO 57 420.4 13.0FARO 52 223.8 10.1IR77298-14-1-2-B-10 357.8 14.1
Trial Mean (n=148) 157.4 7.5LSD 103.2 5.3H 0.71 0.69
Thank you! Merci!