ag leaf

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Latitude effect on the development

of photoperiodic sorghums

Abdoulai, Lansah Kouressy, Mamoutou Vaksmann, Michel, Asch, Folkard Giese, Marcus B k H l Brueck, Holger

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Objectives

j

The forecast of the phenology of photosensitive cereals is complex because flowering depends on both temperature and day length.

3 i th d i t t t d th ff t f h t i d th

3 main methods exist to study the effect of photoperiod on the development:

• Studies in artificial light or phytotron • Multilocal trials on several latitudes • Sowing dates trials

The objectives of this work are to compare these two last approaches by measuring the effect of the latitude on the development of sorghum varieties sown at staggered planting date

varieties sown at staggered planting date.

We also wanted to verify the ability of crop models to forecast latitude

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Experiment Sites

: 3 locations among a latitudinal gradient

Cinzana station Sudano-Sahelian zone 13°15’N - 5°58’ W Alt. 280 m Rainfall : 600 mm Rainfall : 600 mm Sotuba station Sudano-Sahelian zone 12°39’N 7°56’ W 12°39’N, 7°56’ W Alt. 320m. Rainfall : 900 mm Farako station

North guinean zone 11°21’N, 5°41’ W Alt 441

Alt. 441m

Rainfall : 1000 mm

The sites are different for the latitude but climatically similar. We want to

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Experimental design (phenological garden)

The same experimental design was used in the three Sites.

A split plot arrangement with 3 planting date as main plot factor, 7 varieties as subplot factor and two replications were used during 2 years: 2009 et 2010.

years: 2009 et 2010.

Sowing dates : June 10th, July 10th and August 10th

These sowing dates surround the sowing period of farmers of the g g p

targeted zones and include the summer solstice when day length is maximal.

Sub-plot size was 3 m x 1.5 m p

(12 hills per sub-plot).

Irrigation for early sowings and late maturing varieties and late maturing varieties. Low density to avoid

competition between plants

(i i t ti ith i

(in interaction with sowing dates and plant height).

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7 studied Varieties :

a high morpho-physiological diversity

Noms Types Average

maturity maturity

V1 IRAT 204 Caudatum Improved Non photosensitive Dwarf 105

V2 CSM 63E Guinea Improved weakly photosensitive Tall 110

V3 Boiguel Durra Local Photosensitive Tall 130

G i

V4 Keninkeni

Guinea-Caudatum Improved Photosensitive Dwarf 130

V5 Grinkan Caudatum Improved Photosensitive Dwarf 140

V6 CSM 388 Guinea Local Photosensitive Tall 140

V7 Dancouma Guinea Local Photosensitive Tall 160

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Measurements

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E

i

t l

diti

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35 40 45

CINZANA

Temperature

Cinzana Sotuba Farako

15 20 25 30

Cinzana Sotuba Farako

Dec, Jan, Feb 24.4 25.1 23.6 Mar, Apr, May 32.6 31.3 29.4 Jun, Jul, Aug, Sept, Oct, Nov 28.6 27.9 26.2 10 J F M A M J J A S O N D 40 45

SOTUBA _{- A dry and cold season from December}

to February Very high thermal amplitude

20 25 30

35 to February. Very high thermal amplitude

of 15 à 35°C

- A dry and hot season from March to

M Hi h th l lit d f 26 t 40 10 15 J F M A M J J A S O N D 45 FARAKO

May. High thermal amplitude of 26 to 40 °C

- Rainy season from june to november.

20 25 30 35

40 y j

Low thermal amplitude of 22 to 30°C

Few differences between the sites

10 15 20

J F M A M J J A S O N D

Few differences between the sites. Slightly lower temperatures at Farako.

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Rainfall

350 CINZANA 2010 350 CINZANA 2010 300 350 SOTUBA 300 350 SOTUBA

Monomodal distribution of rainfall for the 3 sites

150 200 250 300 2010 Moy. 150 200 250 300 2010 Moy. 150 200 250 300 2010 Moy. 150 200 250 300 2010 Moy. 686 mm 891 mm 0 50 100

Janv Fév Mars Avril Mai Juin Juil Août Sept Oct Nov Déc 0

50 100

Janv Fév Mars Avril Mai Juin Juil Août Sept Oct Nov Déc

0 50 100

50 100

Janv Fév Mars Avril Mai Juin Juil Août Sept Oct Nov Déc Janv Fév Mars Avril Mai Juin Juil Août Sept Oct Nov Déc

Janv Fév Mars Avril Mai Juin Juil Août Sept Oct Nov Déc

250 300 350 FARAKO 2010 Moy. 250 300 350 FARAKO 2010 Moy. 1059 mm 100 150 200 250 y 100 150 200 250 y 0 50

50

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13.0 13.5 14.0 _CINZANA SOTUBA FARAKO

Day length

11.5 12.0 12.5 13.0 FARAKO

The variation of the day length is similar for the 3 sites. Photoperiods ranging between 11 and 13h.

10.0 10.5 11.0

The greatest difference is weak (5') and

12.8 _FARAKO

occurs on June 20th at the summer solstice: CINZANA 12h46’ 12.5 12.6 12.7 SOTUBA CINZANA _SOTUBA _12h44’ FARAKO 12h39’ ∆= 5’ ∆= 2’ 12.1 12.2 12.3 12.4 FARAKO 12h39’

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Photoperiodism modeling : Impatience model

Floral initiation takes place when the photoperiod goes under a threshold which depends of the variety and the age of the plant.

Mathematical formulation in SARRA

Mathematical formulation in SARRA--H

H

P

Pi

P

≥

−

⎟

⎞

⎜

⎛

11 1000

exp

Panicle initiation occurs when

Mathematical formulation in SARRA

Mathematical formulation in SARRA H

H

Psens

dtti

BVP i

≥

−

⎟

⎠

⎜

⎝

=

∑

11

5 .

13

the following condition is checked

is the thermal time calculated since the end of the juvenile stage

(BVP), p_i is the actual photoperiod,

P and P are two coefficients which depend on the variety

∑

=BVP

i

dtti

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150

200 Time to Flag leaf (days)

Measured Predicted 100 150 _Predicted 0 50 0 36 72 108 144 180 216 252 288 324 360 0 36 72 108 144 180 216 252 288 324 360 06/02 13/03 18/04 24/05 29/06 04/08 09/09 15/10 20/11 26/12 sowing dates

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1200 1400 1600 _Dancouma Cinzana Sotuba ₁₂₀₀ 1400 1600 _CSM 388 Cinzana Sotuba 400 600 800 1000 1200 Sotuba Farako 400 600 800 1000 1200 Sotuba Farako 200 400 150 160 170 180 190 200 210 220 230 200 150 160 170 180 190 200 210 220 230 1600 _Grinkan 1600 _Keninkeni 800 1000 1200 1400 Grinkan Cinzana Sotuba Farako 800 1000 1200 1400 Keninkeni Cinzana Sotuba Farako 200 400 600 150 160 170 180 190 200 210 220 230 200 400 600 150 160 170 180 190 200 210 220 230

For the photoperiodic varieties, thermal time from emergence to flag

leaf (TTFD) decreases if sowing is delayed. These varieties are much earlier at Farako.

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eaf 1200 1400 Kkni Cinzana Kkni Farako _ag l e af 90 100 Kkni Cinzana kkni Sotuba a l ti m e for fl ag l 600 800 1000 Kkni Sotuba m em rg en ce t o fl 70 80 kkni Sotuba Kkni Farako 150 160 170 180 190 200 210 220 230 The rm a 200 400 600 Du ra ti o n f ro m 40 50 60 Sowing dates 150 160 170 180 190 200 210 220 230 Sowing dates 150 160 170 180 190 200 210 220 230 35 m be r 25 30 35 Kkni Cinzana Kkni Sotuba Kkni Farako

For Keninkeni, between Cinzana and Farako, in june, thermal time for flag leaf decreases by 435°C.j what corresponds to a shorter

T o ta l le a f n u m 15 20

25 _{what corresponds to a shorter}

maturity of 3 weeks and 11 leaves of less !

Sowing dates

150 160 170 180 190 200 210 220 230 10

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Keninkeni September 4, sowing of june

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1400 1600 _Boiguel Cinzana ₁₄₀₀ 1600 _CSM 63 Cinzana 600 800 1000 1200 Sotuba Farako 600 800 1000 1200 Sotuba Farako 200 400 150 160 170 180 190 200 210 220 230 200 400 150 160 170 180 190 200 210 220 230

For the less photoperiodic varieties the For the less photoperiodic varieties the phenomenon is similar.

CSM63E (Jacumbe) seems insensitive

800 1000 1200 1400 1600 _IRAT 204 Cinzana Sotuba Farako

CS 63 (Jacu be) see s se s t e

at Farako and is photoperiodic at Cinzana. 200 400 600 800 150 160 170 180 190 200 210 220 230

There is a site effect even for the

insensitive sorghum IRAT204 but in this case it is at Sotuba that the vegetative

h i l t

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SARRA

SARRA--H calibration

H calibration

Site Variety Psens Pexp BVP CINZANA Boiguel 0 59 0 11 442

The genetic coefficients of SARRA-H

were calculated for each variety and each site (Base temperature 11°C).

CINZANA 0.59 0.11 442 FARAKO 0.67 0.14 442 SOTUBA 0.65 0.19 442 CINZANA 0.53 0.08 345 g CSM388

For each site, Sarra-h is able to forecast the sowing date effect but the behavior of the varieties varies between the sites.

FARAKO 0.59 0.05 345 SOTUBA 0.56 0.09 345 CINZANA 0.69 0.1 252 FARAKO 0.81 0.11 252

CSM63

the varieties varies between the sites. Genetic coefficients are not stable with latitude. FARAKO 0.81 0.11 252 SOTUBA 0.75 0.13 252 CINZANA 0.55 0.09 414 FARAKO 0.61 0.09 414 SOTUBA 0 57 0 13 414 Grinkan

The reduction of the vegetative phase at Farako is much more important than that envisaged by the model established with

h ffi i f S b SOTUBA 0.57 0.13 414 CINZANA 0.75 0.03 404 FARAKO 2 0.17 404 SOTUBA 1.14 0.29 404 IRAT204

the coefficients of Sotuba..

CINZANA 0.58 0.09 345 FARAKO 0.66 0.07 345 SOTUBA 0.6 0.11 345 CINZANA 0 44 0 07 485 Kkni LocSik CINZANA 0.44 0.07 485 FARAKO 0.49 0.05 485 SOTUBA 0.47 0.13 485 LocSik

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100 Cinzana Observed 70 80 90 o r flag lea f Cinzana Simulated Farako observed Farako Simulated 40 50 60 Time f o 150 170 190 210 230 250 Sowing dates

The model establishes in Sotuba envisages rather well the behavior of the varieties at Cinzana but always over-estimates the duration of the vegetative period at Farako

period at Farako.

This result explains the failure of photoperiodism studies based on trials with

various latitudes or with artificial light.g

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Correction of genetic coefficients according to the latitude

98 .

0 ²

.

0628

.

0 .

7532

.

1 0096

.

0 +

−

=

−

=

PsSot

Lat

R

Psens

Psens 0.83 0.73 v ed 0.53 0.63 obs e rv 0.43 0.53 0.63 0.73 0.83 predicted 0.43 predicted

Several mathematical formulas allows us to correct the Psens value obtained at Sotuba (PsSot) by taking latitude into account (for all varieties except the non photosensitive IRAT204)

non photosensitive IRAT204).

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Correction of genetic coefficients according to the latitude

98 .

0 ²

.

0628

.

0 .

7532

.

1 0096

.

0 +

−

=

−

=

PsSot

Lat

R

Psens

90 100 lea f Cinzana Observed Cinzana Simulated

Farako observed Without the correction, the

60 70 80 im e fo r flag l

Farako Simulated model overestimates the length

of the vegetative phase at Farako. 40 50 150 170 190 210 230 250 T Sowing dates

The correction improves the performance of the model

80 90 100 g lea f Cinzana Observed Cinzana Simulated Farako observed Farako simulated 50 60 70 80 Time fo r fl ag Farako simulated 40 150 170 190 210 230 250 Sowing dates

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Example : Correction effects for late variety IS 15401

To map varietal adaptation, we determine the zones for which flowering occurs in

TOMBOUCTOU

GAO AIOUN

KIFFA NEMA TOMBOUCTOU

GAO AIOUN

KIFFA NEMA

the 20 days preceding the end of the rainy season (Kouressy et al., 2008)

OUAGADOUGOU AERO DORI OUAHIGOUYA DEDOUGOU FADA N GOURMA BAMAKO VILLE MENAKA HOMBORI

NIORO DU SAHEL NARA

MOPTI KAYES SEGOU _SAN KITA KENIEBA KOUTIALA KANKOSSA SELIBABY TILLABERY NIAMEY AERO TOUKOUNOUS GAYA TAHOUA BAKEL KEDOUGOU 15 OUAGADOUGOU AERO DORI OUAHIGOUYA DEDOUGOU FADA N GOURMA BAMAKO VILLE MENAKA HOMBORI

NIORO DU SAHEL NARA

MOPTI KAYES SEGOU _SAN KITA KENIEBA KOUTIALA KANKOSSA SELIBABY TILLABERY NIAMEY AERO TOUKOUNOUS GAYA TAHOUA BAKEL KEDOUGOU 15 BOBO-DIOULASSO BOROMO GAOUA BOUGOUNI SIKASSO GAYA 10 BOBO-DIOULASSO BOROMO GAOUA BOUGOUNI SIKASSO GAYA 10 -10 -5 0 5 -10 -5 0 5

With the coefficients established at Taking account of the latitude effect

Sotuba, IS15401 is too late maturing type to grow in Mali.

g

allows us to better identify the true adaptation zone of this variety.

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Conclusion

There is a room for improvement in phenology modelisation The prediction of varietal adaptation is necessary for breeders and

agronomists to elaborate new ideotypes. to determine the optimal growing zones for the different varieties or to forecast the effect of a

l tit di l i ti

latitudinal migration. We showed that :

- Latitude effects on the development of photoperiodic sorghums is very strong.

E i ti d l d t ffi i tl t k i t t thi h

- Existing models do not sufficiently take into account this phenomenon. Genetic coefficients are not stable with latitude.

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The statistical fitting suggested could improve varieties studies in

Sudano-Sahelian zone but this adjustment does not propose a j p p

physiological explanation to the phenomenon.

Latitude effect must still be explained. Several assumptions could be proposed:

We could take into account the average photoperiod instead of

th d il h t i d

the daily photoperiod..

The photoperiod at emergence (Pem) could influence the threshold of photoperiod sensitivity (Pem and Lat are

proportional).

We could take into account the daily variation of the

photoperiod (though the differences are very weak between the

Further research are needed to understand the physiological

h i ( i l ?) f th d l tit d ff t

photoperiod (though the differences are very weak between the 3 sites).

response mechanisms (signals ?) of the pronounced latitude effects on sorghum phenology.