Seed longevity of shrubby Russian thistle
Salsola vermiculata L. under different storage
temperatures and seed moisture content
By
Abdoul Aziz Niane, Paul C. Struik and Z. Bishaw
Presentation layout
• S. vermiculata ecosystem significance
• Objectives of the study
• Material and methods
• Results
• Conclusions
Why S. vermiculata?
• Endangered due to high palatability
• High self sowing and survival rate under arid conditions
• High seed and biomass productivity
• Distributed over arid, semiarid, saline and hyper saline
ecosystems
• Short seed longevity under ambient storage conditions
Potential geographical distribution of S. vermiculata in the Syrian and
Tunisian rangelands under present climate and the HADCM3 global
circulation model for 2020 and 2050.
Source: Ouled Belgacem, A., & Louhaichi, M. (2013). Climatic Change.
doi:10.1007/s10584-013-0701-z
Study objectives:
• Under ambient conditions, Salsola loses viability in < a year? Is it recalcitrant?
• Is it Temp or %MC more significant for Salsola seed longevity?
Germination proportions
Seed longevity curves at 10.7% MC for Salsola under 24
°C in 2007 and 08
1
0.8
0.6
0.4
0.2
0
1
0.8
0.6
0.4
0.2
0
2007
2008
Storage time (Months)
Research material
• Syrian ecotypes of S. vermiculata L.
• Fresh seed stored at 10.7% & 7.0% RH in yr1 and
9.6% and 6.5% RH in Yr2
• Aluminium foil and polypropylene bags used for
packaging
• Vacuum packaging machine (Quick 2000)
• Storage facilities set at -21°C, +4°C and at 24°C
Research method
• The experiment was repeated twice using different seed stocks
• Non-vacuum (control) and vacuum packaging with aluminium foil
(treatment)
• -21°C, +4°C and 24°C storage temperatures
• 1140 days and 720 days in the 1st and 2nd experiment respectively
• Each month, 2 x 50 seeds each germinated from each treatment
according to the ISTA rules
• At the end of the trial period, seeds transferred from hermetic to
ambient conditions
• tested for germination at monthly interval for 6 months to check
on post hermetic speed of deterioration in seed longevity
Statistics
• CRD with 4 factor levels
• i.e. seed type (winged and de-winged), a confounded
seed moisture content and packaging, temperature and
storage period
• Germination data subjected to Restricted Maximum
Likelihood (REML) and probit analysis to model treatment
effects, interactions and seed longevity curves using
GenStat 14.1.
Results
• De-winging increased percentage of germination in S. vermiculata
Fig1. Effect of fruit bract on % germination of S.
vermiculata L.
0.90
Germination proportion
0.80
a
a
0.70
0.60
b
0.50
b
0.40
0.30
0.20
0.10
Salsola seed with and without fruit bracts
0.00
De-winged
Winged
2002/04
De-winged
Winged
2003/05
Germination proportion
Results (viability)
• Regardless of MC% and packaging longevity extended under -24 & 4 °C
• Vacuum packaging improved longevity of low and high MC% seed under 24 °C
2003/05
2002/04
1
0.8
0.6
0.4
-21°C
-21°C
0.2
0
1
0.8
0.6
0.4
0.2
0
1
4°C
4°C
LOW MC% & vacuum
High MC% & vacuum
High MC% & no vacuum
0.8
0.6
0.4
0.2
24°C
24°C
0
Storage period in days
Figure 3: Proportion of germination of de-winged seeds of Salsola vermiculata L. with a moisture content (MC) of 7% and vacuum packaging
(VP) (solid line with diamonds), with MC=10.7% and VP (dashed line with circles), and with MC=10.7% and no VP (dotted line with
triangles) stored at -21, 4 and 24°C for 1140 and 720 days in 2002/04 (left panels) and 2003/05 (right panels), respectively.
Results (germinability)
• Germination inhibitors in fruit bracts significantly reduced %germination
• Simultaneous breakdown of germination inhibitors in fruit bracts & deterioration
seem to produce a cyclic trend of change in germination
1
0.8
2002/04
-21°C
0.6
2003/05
-21°C
0.4
Germination proportion
0.2
0
1
0.8
4°C
4°C
24°C
24°C
0.6
0.4
0.2
0
1
0.8
0.6
0.4
0.2
0
Storage period in days
Figure 2: Proportion of germination of winged seeds of Salsola vermiculata L. with a moisture content (MC) of 7% and vacuum packaging (VP)
(solid line with diamonds), with MC=10.7% and VP (dashed line with circles), and with MC=10.7% and no VP (dotted line with
triangles) stored at -21, 4 and 24°C for 1140 and 720 days in 2002/04 (left panels) and 2003/05 (right panels), respectively.
1
1
0.9
0.9
Germination proportion
Germination proportion
Results
• Greater seed longevity decline along de-winging and MC gradients compared to T°C
• Greater mean %germ. of de-winged seed at low T°C, vacuum packaging and high MC
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.1
0
-21C
4C
24C
-21C
Winged
4C
24C
De-winged
Seed type, moisture and packaging
Vacuum with 7MC
Vacuum with 10.7MC
No vacuum with 10.7MC
0
-21C
4C
24C
-21C
Winged
4C
24C
De-winged
Seed type, moisture and packaging
Vacuum with 6.5MC
Vacuum with 9.6MC
No vacuum with 9.6MC
Results for de-winged seeds
• Low & positive intercepts at low MC% & vacuum attributable to desiccation damage
• Consistently negative slopes indicating decrease in germination with time.
• Higher initial %germination and higher rate of decline at high MC% and vacuum
Year T (°C) MC% Packaging Gradient
P50 Intercept (probit)
Slope
7 Vacuum
0.00032 3007 ±1065
1.5±0.07 -0.0005±0.0001***
1
0.00011
8740 ±*
1.6±0.1 -0.0002±0.0002ns
-21 10.7 Vacuum
No vacuum -0.00007
18621 ±*
1.4±0.07 -0.0001±0.0002ns
7 Vacuum
0.00011
8747 ±*
1.4±0.07 -0.0002±0.0002ns
10.7 Vacuum
0.00002
44069 ±*
1.7±0.09 -0.00004±0.0002ns
4
No vacuum 0.00058 1738 ±222.5
1.5±0.06 -0.0009±0.0001***
7 Vacuum
0.00096 1040 ±66.2
1.4±0.06 -0.001±0.0001***
10.7 Vacuum
0.00311 321.5 ±5.7
1.9±0.08 -0.006±0.0002***
24
No vacuum 0.00650 153.8 ±2.9
3.151±0.2
-0.02±0.001***
6.5 Vacuum
0.00020
5075 ±*
1.7±0.09 -0.0003±0.0002ns
2
9.6 Vacuum
0.00014
7190 ±*
2.0±0.1 -0.0003±0.0003ns
-21
No vacuum
0.0004
2491 ±2
1.9±0.1 -0.0008±0.0002***
6.5 Vacuum
0.00028 3562 ±3419
1.7±0.1 -0.0005±0.0002***
9.6 Vacuum
0.00033 3041 ±1616
1.9±0.1 -0.0006±0.0002***
4
No vacuum 0.00108 929.2 ±43.9
2.0±0.1 -0.002±0.0002***
6.5 Vacuum
0.00164 610.4 ±12.5
2.0±0.08 -0.003±0.0002***
9.6 Vacuum
0.00365 274.2 ±4.9
2.0±0.09 -0.007±0.0003***
24
No vacuum 0.00620 161.4 ±3.4
2.6±0.2
-0.02±0.001***
Results for winged seeds
• Low & negative intercepts due to low initial %germination as result of fruit bracts
• High initial %germ at low MC% suggest fruit bracts minimize desiccation damage
• Positive slopes show increase in germination with time due to dormancy breaking.
Year T (°C) MC% Packaging
1
-21
7 Vacuum
10.7 Vacuum
No vacuum
4
7 Vacuum
10.7 Vacuum
No vacuum
24
7 Vacuum
10.7 Vacuum
No vacuum
2
-21
6.5 Vacuum
9.6 Vacuum
No vacuum
4
6.5 Vacuum
9.6 Vacuum
No vacuum
24
6.5 Vacuum
9.6 Vacuum
No vacuum
Gradient
P50 Intercept (probit)
Slope
0.00061
1665 ±*
0.5±0.1 0.0003±0.0002ns
0.00244
410.3 ±7
-0.2±0.05 0.001±0.0001***
0.00131 766.2 ±774
-0.2±0.05 0.0003±0.0001**
-0.00108 -930.1 ±1464
0.3±0.05 0.0003±0.0001**
0.00277 361.1 ±62.2
-0.2±0.05 0.0006±0.0001***
-0.00080
-1246 ±*
-0.1±0.05 -0.0001±0.0001***
0.00083 1203 ±1170
0.3±0.05 -0.0003±0.0001***
0.08621 11.9 ±21.6
0.04±0.07 -0.003±0.0002***
0.02849
35.1 ±7.9
0.4±0.1
-0.01±0.001***
0.00137 729.8 ±236
-0.3±0.05 0.0004±0.0001***
0.00068 1481 ±1160
-0.5±0.05 0.0003±0.0001***
0.00053 1877 ±5365
-0.5±0.06 0.0003±0.0001**
0.00089 1120 ±8802
-0.3±0.05 0.0003±0.0001**
0.00025
4031 ±*
-0.3±0.05 0.0001±0.0001ns
0.00061 1640 ±776.9
-0.6±0.06 0.0004±0.0001***
0.00045
2211 ±*
-0.3±0.05 0.0002±0.0001ns
-0.02915 -34.3 ±22.1
-0.1±0.06ns -0.003±0.0002***
-0.05244 -19.1 ±14.9
-0.2±0.1 -0.009±0.001***
Results
• Under 24 °C, drop in seed longevity to 50% significantly and consistently increased
with vacuum packaging and reduction in seed MC
2002/04
1.0
1.0
0.8
0.8
Germination proportion
2003/05
10.7%MC
No vacuum
24 °C
P50:156 days
r=-0.956***
0.6
0.4
9.6 %MC
No vacuum
24 °C
P50:161 days
r=-0.963***
0.6
0.4
0.2
0.2
0.0
100
200
300
400
500
600
700
800
900
1000
1100
200
300
400
500
600
700
800
600
700
800
600
700
800
0.2
0.4
0.4
0.6
9.6 %MC
Vacuum
24 °C
P50:274 days
r=-0.909***
0.6
10.7%MC
Vacuum
24 °C
P50:321 days
r=-0.914***
0.8
Germination proportion
100
0.8
1.0
0.0
0.2
0.0
0
Germination proportion
0
1.0
0
100
200
300
400
500
600
700
800
900
1000
0
1100
1.0
1.0
0.9
0.9
0.8
0.8
7% MC
Vacuum
24 °C
P50:1262 days
r=-0.840***
0.7
0.6
100
200
300
400
500
6.5 %MC
Vacuum
24 °C
P50:610 days
r=-0.925***
0.7
0.6
0.5
0.5
0
100
200
300
400
500
600
700
Storageperiodindays
800
900
1000
1100
100
200
300
400
500
Storageperiodindays
Seed longevity curves for S. vermiculata under fixed temperature and variable seed moisture content
Longevity of seed transferred to ambient after 720 days under hermetic
storage had a shorter seed longevity than fresh seed
Seed
Winged
T (°C) Packaging
-21 Vacuum
Vacuum
MC (%)
6.5
9.6
No vacuum 9.6
4 Vacuum
Vacuum
6.5
9.6
No vacuum 9.6
De-winged
Intercept Slope
P50
-0.1±0.2sn -0.01±0.002*** -5.6±23.7a
-0.3±0.2ns -0.01±0.002***
-47.74±69a
-0.7±0.2*** -0.01±0.003*** -88.8±95.7a
-0.2±0.2ns -0.01±0.002*** -19.5±29.5a
0.1±0.2ns -0.01±0.002***
4.2±13.7a
-0.8±0.2*** -0.01±0.003*** -96.2±103.1a
24 Vacuum
-21 Vacuum
6.5
-0.1±0.2ns -0.01±0.003***
-6.5±16.5a
6.5
1.5±0.2*** -0.02±0.002***
71±3.4a
Vacuum
9.6
1.8±0.3*** -0.03±0.002***
71±2.9a
No vacuum 9.6
0.8±0.2*** -0.02±0.002***
48±5.4c
6.5
1.3±0.2*** -0.02±0.002***
65±3.7ab
9.6
1.4±0.2*** -0.02±0.002***
59±3.2b
No vacuum 9.6
0.9±0.2*** -0.02±0.002***
36±4.5d
0.1±0.2*** -0.02±0.003***
6±10.2e
4 Vacuum
Vacuum
24 Vacuum
6.5
Conclusions
• Higher seed longevity means and regression line intercepts at higher MC%
showed
• short seed longevity of S. vermiculata observed in the field seems to
arise from its sensitivity to desiccation. Important for S. vermiculata
seed storage
• Negative regression lines intercepts and positive slopes for winged seeds
• indicate germination inhibitors in fruit bracts minimized initial rate of
germination and deterioration. Important for S. vermiculata seed
storage
• Drying and vacuum packaging only
• Resulted in 3.8 to 8.1 fold increases in seed longevity. A significant step
towards a more cost effective and environmentally friendly storage for
rangeland rehabilitation
• Poor performance of the seed transferred to ambient conditions
• Such seed should be sown late when the probability of rainfall is high
or used in the rangeland nurseries under irrigation
Acknowledgement
This research was carried out with full support from
• The International center for Agriculture Research in the Dry
Areas (ICARDA)
• The United Nations’ Food and Agriculture Organization (FAO)
• The Wageningen University of the Netherlands
Thank you all