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!