1. Assessment of novel ι-carrageenan hydrogel blends as environmentally friendly seed coating agents for durum wheat seeds
Maya Hotta B.Sc. (Hons)
Athlone Institute of technology
Supervisors:
Dr. Noreen Morris
Dr. James Kennedy
Prof. Clement Higginbotham
Supervisors:
Dr. Noreen Morris
Dr. James Kennedy
Prof. Clement Higginbotham

2. Feeding 9 Billion People…
United Nations1 estimated human population to reach 9.6 billion by the year 2050
Food production must increase to meet food demand
Pollution caused from agriculture is currently a major concern
Climate change – drought also becoming a threat
Greener solutions without reducing food productivity is essential
Hydrogels are potential materials for sustainable agriculture

3. What is a Hydrogel? Polymers forming a gel-like material
Absorbs fluid into its 3D network
Takes up water from 20 % up to thousands of times their dry weight2
Releases water when exposed to dry environment
Fig. 1 Dry hydrogel (left) swells (right) after soaking up water3.

4. Agriculture/Horticulture application
Hydrogels are used as soil conditioners or “water crystals”
Works as water reservoir for plant growth
Plants can grow in dry sandy soils
Helps water conservation
Target delivery systems
Controlled pesticide/nutrient release
Reduces application frequency
Minimize spreading of toxic materials and exposure
Helps environment and soil conservation
Fig. 2 Hydrogels known as water crystals4.

5. Iota-carrageenan
Fig. 3 Carrageenan5 (right) obtained by extraction with water or aqueous alkali from some members of the class Rhodophyceae6 (left).
Natural polysaccharide derived from red seaweed (Fig. 3)
Cheap
Eco Friendly
Non-toxic
Easy to handle
1% (w/v) ι-carrageenan hydrogel had shown promising results: Faster and higher seed germination rate (Fig. 4)
Fig. 4 Grass growing better in the presence of 1% (w/v) ι-carrageenan hydrogel (right) but less in the pot without the hydrogel (left).

6. Hypothesis
Ι-Carrageenan hydrogel coating on seeds can contribute in sustainable agriculture by:
Speeding up germination
Promoting seed growth in dry soils
Reducing amount of water required for crops
Biodegradable and non-toxic
Minimize environmental impact
Low material cost*
* 1KG of ι-Carrageenan cost € from Sigma Aldrich (Purchased 2013)

7. Problems with ι-carrageenan
Fig. 5 Re-swelling studies of ι-carrageenan (left) and agar (right) compared after 1 hr in distilled water.
Very weak hydrogel
Dissolves too fast in water
Evaporates water quickly at 30°C

8. Project Aim Formulate new seed coating agent based on ι-carrageenan:
Increase gel strength
Prolong hydrogel life-span in excess water
Increase water retention capacity (30 °C)
Maintain environmental friendliness
All ingredients natural, non-toxic and
Composition based on synergistic effect between polysaccharides
Evaluate two hydrogel blends for seed coating application
Germination tests on commercially important seeds
Film coating seeds with conventional coating methods

9. Development of new hydrogels
Two hydrogel blends were prepared for analysis:
Table 1. The composition of hydrogels tested for characterisation
Hydrogel Code
Components
ι-carrageenan (%)
agar
(%)
xanthan
κ-carrageenan (%)
Control
1.5 -
Blend 1 1
0.5
Blend 2
0.25
Hydrogel characterisation methods:
Swelling studies – Water uptake, life-span and water retention
Rheological analysis – Gel strength

10. Characterisation Results (Refer to Table 2)
6 hr
24 hr
Fig. 6 Summary of hydrogel characterisation results for control, Blend 1 and Blend 2 hydrogels
*Hydrogels were observed at room temperature (< 25°C)
**Hydrogels were observed at 30 °C
Improvements:
Blend 2 showed the highest water uptake and life-span (24hr)
Blend 1 showed the highest water retention capacity
Blend 2 showed the highest gel strength

11. Seed tests
Durum wheat (Triticum durum Desf.) is a cereal crop widely cultivated today
They grow in a warm, dry climate where drought may be a problem
Effect of hydrogel on germination % and seed growth rate investigated
The hydrogel blend type giving the best germination % was determined
Conventional coating methods: spray and pan coating compared

12. Seed test results Effect of Hydrogels:† * **
***
Data: Mean ± SE
*p < 0.05 vs Water treatment
**p < 0.05 vs Blend 2 treatment
***p < 0.05 vs Water treatment
†1 % (w/v) ι-carrageenan
Fig. 7 Summary of seed testing results compared with four different treatment types
Effect of Hydrogels:
Hydrogel treated seeds performed better than distilled water
Ι-carrageenan proven to increase seed germination % and speed of germination

13. Seed coating comparison
Fig. 9 Spray coated seed with green colorant (Blend 1)
Fig. 8 Non-treated seed
Fig. 10 Pan coated seed with green colorant (Blend 1)

14. Current work…
Collaboration with the Department of Agriculture and Food Laboratories (Backweston, Celbridge)
Investigating optimum coating conditions
Comparing natural vs. synthetic hydrogel coating effect
Stress test of seeds under dry conditions

15. References
United Nations. World Population Prospects The 2012 Revision.; Available at: [Accessed October 18, 2013]
Hoffman AS. Hydrogels for biomedical applications. Adv. Drug Deliv. Rev. 2012;64:18–23. Available at: [Accessed July 14, 2014]
Don Carr Company. Polymer Crystals. Water-Gel Cryst Available at: [Accessed September 10, 2014]
HGTV Gardens. How to Plant a Container Garden - Planting a Small Container Garden Available at: [Accessed September 10, 2014]
PureNature. Carrageenan Gum, Iota - Gums & Resins - Raw Materials Available at: [Accessed September 10, 2014]
Danisco Cultor. Introduction to GRINDSTED TM Carrageenan. 2nd ed. Danisco A/S; 2003:1–6. Available at:

16. Acknowledgements: President’s Seed Fund AIT and Agri Aware
Department of Agriculture, Food and the Marine (Seed testing laboratory, Celbridge)
Gold Crop Ltd. (Cork)
RAGT Semences (France)
Teagasc Oak Park Crop Research Centre (Carlow)
Bejo Zaden B.V. (Netherlands)

17. Thank You!
Any Questions?