breaking physiological dormancy in tubers of solanum chacoense christian t. christensen 1, lincoln...
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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
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