Breaking Physiological Dormancy in Tubers of Solanum chacoense

Christian T. Christensen1,

Lincoln Zotarelli1,

Kathleen Haynes2 ,and Mihai Giurcanu3

1Department of Horticultural Sciences,

University of Florida, Gainesville, FL, 32611, 2USDA-ARS, Beltsville, MD 20705,

3Department of Statistics,

University of Florida, Gainesville, FL, 32611

Outline

Introduction

Current Challenges

Objective

Materials

Method

Preliminary Results

Conclusions

Dormancy Factors

Genetic Makeup

Stage of Tuber Development

Environmental Conditions during tuber growth and storage– Bethke (2013)

Hormone contributions:Abscisic acid (ABA) and Ethylene: induction

Cytokinin: loss of dormancy

– Suttle (2004)

Gibberellins

Exogenous gibberellins can be used to break dormancy in potato tubers– Brian et al. (1955) and Hemberg (1985)

GA3 is typically used in seed certification programs – Suttle (2004)

Current Challenges

Solanum chacoense (chc) has shown difficulty breaking dormancy which may result in uneven emergence

Objective

To determine an appropriate concentration of gibberellic acid (GA3) and soak time to encourage breaking dormancy in chc

Materials and Methods11 genotypes of chc across four accessions

Separated by size evenly across 12 treatments– Small (1.4g avg.)– Medium (2.5g avg.)– Large (5.8 avg.)

Accession Genotype PI # Country

Chc A A-3, A-5, A-6 PI 275136 Argentina

Chc B B-3, B-5, B-10 PI 320288 Argentina

Chc C C-6, C-8 PI 537025 Bolivia

Chc D D-6, D-7, D-8 PI 566738 Paraguay

Left to Right: Small, Medium, And Large

Materials and Methods

Treatments

ProtocolGA3 – Fischer Scientific International Inc.

GA3 dissolved in DI water for two hours

Tubers were treated with desired treatment

Tubers air dried for 30 minutes

GA3 (μg/ml) Soak Time (min.)

0 5

0 45

0 90

50 5

50 45

50 90

100 5

100 45

100 90

150 0

150 45

150 90

Materials and Methods

CRD with 3 replicates

Maintained in an incubator at 25 ºC

Sprout number every 2 days

Study duration of 46 DAT

Statistical Analysis

Binary logistic regression model- proportion of sprouting

SAS statistical package for Windows (SAS Systems for Windows Version 9.2, SAS Institute Inc. Cary, NC, USA)– PROC GLIMMIX

ResultsEffect Num DF Pr > F

GA3 3 0.0003

Minutes 2 0.6493

Size 2 <.0001

Genotype 10 <.0001

GA3*Minutes 6 0.2488

GA3*Genotype 30 <.0001

Minutes*Genotype 20 0.8862

GA3*Minutes*Genotype 60 0.8543

GA3*Size 6 0.8663

Minutes*Size 4 0.9118

GA3*Minutes*Size 12 0.9655

Genotype*Size 20 0.1041

GA3*Genotype*Size 60 0.9387

Minutes*Genotype*Size 40 0.8396

GA3*Minutes*Genotype*Size 120 0.9573

Main effects– GA3

– Genotype– Size

Interactions – GA3xGenotype

Main effects: GA3 Proportion of Sprouting

Effect Num DF Pr > F

GA3 3 0.0003

Minutes 2 0.5301

Genotype 10 <.0001

Size 2 <.0001

0 50 100 1500

10

20

30

40

50

60

70

80

90

100

Proportion of Tubers Germinated with in Concentrations

% Failure% Success

GA Concentration (µg/ml)

% T

ub

ers

B

A AA GA3 concentrations greater than 0 µg/ml were more successful at breaking dormancy overall

Time had no affect on % tuber sprouting

Main Effects: Genotype Proportion of Sprouting

A-3 B-10 B-3 A-6 B-5 A-5 C-6 C-8 D-8 D-6 D-70

10

20

30

40

50

60

70

80

90

100

Proportion of Tubers Germinated with in Genotype

% Failure% Success

Genotype

% T

ub

ers

Genotypes showed large variation in % tuber sprouting

Effect Num DF Pr > F

GA3 3 0.0003

Minutes 2 0.5301

Genotype 10 <.0001

Size 2 <.0001

A

B

BB

C CD D

D

E E E

Main Effects:Size Proportion of Sprouting

Small Medium Large0

10

20

30

40

50

60

70

80

90

100

Proportion of TubersGerminated with in Shape

% Failure% Success

Tuber Size Class

% T

ub

ers

A

B

C Direct Correlation between tuber size and % tuber sprouting

Effect Num DF Pr > F

GA3 3 0.0003

Minutes 2 0.5230

Genotype 10 <.0001

Size 2 <.0001

Interactions:GA3 x Genotype

0 50 100

150 0 50 100

150 0 50 100

150 0 50 100

150 0 50 100

150 0 50 100

150 0 50 100

150 0 50 100

150 0 50 100

150 0 50 100

150 0 50 100

150

A-3 A-5 A-6 B-3 B-5 B-10 C-6 C-8 D-6 D-7 D-8

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%% Tubers Sprouted with in Genotype

% Failure

% Success

Genotype

% T

ub

ers

AAB

C

BC

NS

A

BB

B

B

A

A

A

A

A

A

B

A

A

A

B

A

A A

B

AAA

BNS NS

NS

Conclusion

Direct Correlation between tuber size and % sprouted tubers

Genotypes showed variation in % sprouted tubers with D-6, D-7, and D-8 exhibiting the strongest dormancy

Genotypes from Argentina exhibited weaker dormancy mechanisms while those originating from Bolivia or Paraguay exhibited a stronger dormancy mechanism

Conclusion

GA3 concentrations greater than 0 µg/ml were more successful at breaking dormancy overall

Soak time had no affect on breaking dormancy

No single treatment combination broke dormancy across all genotypes

Questions

Literature Cited

Bethke, P. 2013. Potato Tuber Dormancy. USDA ARS Vegetable Crops Research Unit and UW Department of Horticulture

Brian, P.W., H.G. Hemming, and M. Radley. 1955. A physiological comparison of gibberellic acid with some auxins. Physiol Plant 8:899-912

Errebhi, M., C.J. Rosen, S.C. Gupta, and D.E. Birong. 1998b. Potato yield response and nitrate leaching as infl uenced by nitrogen management. Agron. J. 90:10–15.

Errebhi M, C.J. Rosen, F.I. Lauer, M.W. Martin, and J.B. Bamberg. 1999. Evaluation of tuberbearing Solanum species for nitrogen use efficiency and biomass partitioning. Amer JPotato Res 76:143-151.

Hemberg, T. 1985. Potato rest. In: PH Li(ed), Potato Physiology, Academic Press, New York. Pp 353-388

Opena, G.B. and G.A. Porter. 1999. Soil management and supplemental irrigation effects on potato: II. Root growth. Agronomy Journal 91, 426–431.

Suttle, J.C. 2004. Physiological Regulation of Potato Tuber Dormancy. Amer J of Potato Res 81:253-262

Acknowledgments

USDA-ARS Beltsville, MD– Kathleen Haynes: Committee Member– Karen Frazier: T.C. Technician

University of Florida– Lincoln Zotarelli: Advisor– Mihai Giurcanu: Statistician– Rebecca Darnell: Committee Member– Charles ‘Ethan’ Kelly: Lab and Field

Technician