weed seed response to brassica juncea lefebvre1,2, maryse l. leblanc1 and alan k. watson2 5th...

Maxime Lefebvre1,2, Maryse L. Leblanc1 and Alan K. Watson2

5th international Symposium on BiofumigationSeptember 11th 2014

1Research and Development Institute for the Agri-environment (IRDA), Saint-Bruno-de-Montarville, J3V 0G7, Canada

2Department of Plant Science, McGill University, Ste-Anne-de-Bellevue, H9X3V9, Canada

Weed seed response to Brassica junceabiofumigation in a laboratory

experiment

• Weed seedbank

– Seed dormancy

• Different mechanisms for seed dormancy

– Well adapted to agroecosystems

– All ecological niches for emergence patterns

• Ecologically based weed management systems

Menalled, 2008. Montana State University-Bozeman, Department of Land Resources and Environmental Sciences

Gallandt et al., 1999. Journ. Crop Prod. 2 (1) 95-122.

Gallandt, 2006. Weed Science. 3. 588-596

Fenner, 2000. Seeds: the ecology of regeneration in plant communities. 2nd ed.

Agricultural weed ecology

Biofumigationto deplete the seedbank

• Biofumigation as a possible solution

• How act biofumigation on weeds?– 1) At the incorporation of the aerial biomass into the soil– 2) Secretion of glucosinolates via root system

– 3) Competition

• In seeds

– ITCs interaction with enzymes involved in glycolysis during the germination

Michel, 2008. Vitic. Arboric. Hortic. 40 (2) 95-99

Michel et al., 2000. Vitic. Arboric. Hortic. 39 (2) 145-150

Chemma, 2013. Allelopathy current trends and future applications.

Biofumigation and weeds

• Good potential for weed control

• Lack of information on key processes of annual weed dynamic

1. Seedbank persistence

2. Establishment

3. Interference

Haramoto and Gallantd, 2004. Renewable Agriculture and Food systems, 19 (4) 187-198

• What is known • Biofumigation delay/reduce germination

– Several experiments in laboratory, greenhouses, field

– Variable results (weed, biofumigant crop, technique, soil)

– Small seeds more susceptible (not always confirmed)

– Negative correlation between doses and germination

• What should be investigated– Mortality?

– Dormancy mechanisms (types of dormancy)

Peterson et al. 2001. Agronomy journal. 93 (1) 37-43

Haramoto et Gallandt, 2004. Renew. Agric. And Food Syst. 19 (4) 187-198.

Biofumigation and Seedbank Persistence

Objective and hypothesis

• Objective:

– Determine the susceptibility of different types of seed dormancy to isothiocyanate released by biofumigation.

• Hypothesis:

– Seed with physical dormancy should be less affected by biofumigation than seed with physiological dormancy, than seed with morphological dormancy

• Germination tests in Petri dishes

Treatment Control X/3 X/2 X 2X 3X

g Petri-1 0 0.153 0.228 0.456 0.912 1.368

Materials and methods

Brassica juncea cv. Caliente 199Dry (35°C) and finely chopped

50 seeds/Petri, 5 Petri/treatment , 2 replications in time

Matériel et méthode

• Experimental unit

• Selected weeds


Ambrosia artemisiifoliaAMBAR

Vicia craccaVICCR

Chenopodium albumCHEAL

Setaria viridisSETVI

Daucus carotaDAUCA

• Selected weeds


Physiological dormancy

Physical dormancy Morphological dormancy

Tetrazolium evaluation

Red coloration of living tissues

Variables et Stats

• Data:

– Cumulative germination

– % Germination, % Mortality, % Viable ungerminated (Dormant)

– Chemical analysis (Headspace and g.c.m.s.)

• Experimental design

– Completely randomized design

– ANOVAs, mean comparison and non-linear modelisation

Results

Compounds HeadSpace g.c.m.s

µg g-1 ± SE µg g-1 ± SE

allyl-isothiocyanate 2455 ± 53.1 2925 ± 556

allyl-thiocyanate 1431 ± 140.2 trace

butyl-isothiocyanate 131 ± 31.0 0.2 ± 0.2

others

butenyl-isothiocyanate trace nd

isoproypl-isothiocyanate trace nd

1-butene-4-isothiocyanate trace nd

Results of the chemical analysis performed on B. juncea var. Caliente 199

Results AMBAR

0

10

20

30

40

50

60

70

80

J4 J6 J8 J11

J13

J15

J18

J20

J21

J22

J25

J26

J27

Temoin

X/3

X/2

X

2X

3X

Percentage of cumulative

germination

Days post-treatment

Control

Results AMBAR

Percentage

Treatments

aabbccc

a ab b cd d

a aa

ab

bcc

Anova and Tukey-Kramer HSD, P = 0.05

Mortality

Viable ungerminated

Germination

Results CHEAL

0

10

20

30

40

50

60

70

80

90

100

J4 J6 J8 J11 J13 J15 J18 J20 J21 J22 J25 J26 J27 J29 J32 J33

Temoin X/3 X/2 X 2X 3X

Percentage of cumulative germination Percentage

aacc

bc

c cbaaa

a

bbc bc

cd d

MortalityGermination Viable ungerminatedControl

Results DAUCA

0

10

20

30

40

50

60

70

80

90

100

J4 J6 J8 J11 J13 J15 J18 J20 J21 J22 J25 J26


a a abcd

ba bc d d

a

a

b

b c c



Results SETVI

0

10

20

30

40

50

60

70

J4 J6 J8 J11 J13 J15 J18 J20 J21


abcccc

cbcab

aaa

a

abababab

b



Results VICCR

0

2

4

6

8

10

12

J4 J6 J8 J11 J13 J15 J18 J20


ab a ab b b

bbababab a

bba a aba



Results

2 Adjusted Mortality = %Mort. within treatment − (mean %Mort. in control )

Results

(1) Adjusted Germination = (% Germ.within treatment)

(mean % Germ.in control)X 100

Results

Discussion

• Induction of dormancy at non lethal doses- DAUCA : at X/2 and X/3 (4.7% 21.4%)- CHEAL: at X (9.4% 18.6%)

Discussion

• Sometimes observed in literature– Induction of secondary dormancy– ex: Amaranthus hybridus – PD

(Peterson et al., 2001)

• Hormetic dose response

***Could explain why germination is not alwaysdecreased after biofumigation

Peterson et al. 2001. Agron. Journ. 93 (1) 37-43

Conclusion

Dormancy SpeciesReduction of germination

Reduction of dormancy

MortalityOverallimpact

MD DAUCA

PD

AMBAR

CHEAL

SETVI

PY VICCR

0-24% Low; 25-49% Moderate; 50-74% High; 75- 100% Very High.

Conclusion




MD DAUCA Very high Very high Very high Very high

PD

AMBAR

CHEAL

SETVI

PY VICCR


Conclusion





PD

AMBAR Very high High Very high Very high

CHEAL

SETVI

PY VICCR


Conclusion





PD


CHEAL Very high Very high Very high Very high

SETVI

PY VICCR


Conclusion





PD



SETVI Very high Moderate Moderate High

PY VICCR


Conclusion





PD




PY VICCR High Moderate Low Moderate


Conclusion





PD




PY VICCR High Moderate Low Moderate

Biofumigation can reduced dormant seeds, so possibly deplete the weed seed bank


Acknowledgments

• Germain Moreau, Laurence Jochems-Tanguay

• Summer students

• Financially supported by – Canadian Agricultural Adaptation Program (AAC)– Organic Science Cluster II (AAC)– IRDA– Agrocentre Fertibec inc. Seminova

weed seed response to brassica juncea lefebvre1,2, maryse l. leblanc1 and alan k. watson2 5th...

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