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- Herausgeber: John Wiley & Sons
- Kategorie: Fachliteratur
- Sprache: Englisch
Algae, macroalgae and microalgae can be valuable biological resources in a new, more environmentally friendly form of agriculture known as agrobiology. Indeed, the biological properties associated with algae are frequently relevant for agricultural and zootechnical purposes. It is this aspect that is behind the current popularity of algae in the development of new agricultural practices that are related to plant and animal production, which are referred to as agrobiology. Algae in Agrobiology offers a current and forward-looking account of algae use: in agriculture and in the sector of land and marine animal production, as algal extracts and molecules in the form of fertilizers or biostimulants for crops with agronomic interest, and as algal compounds in the area of plant and animal health. This book is based on advances in biochemical and agronomic research in order to explain the conventional practices associated with the use of algae in agriculture and livestock breeding. These advances make it possible to establish possible uses for marine algal resources in the agriculture of the future.
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Table of Contents
Cover
Table of Contents
Title Page
Copyright Page
Preface
Introduction
1 History
1.1. The different types of kelp
1.2. Historical applications
2 Traditional Applications of Algae in the Cultivation Plants
2.1. Uses for soil amendment
2.2. Soil fertilization
2.3. Improvement of composts for agricultural use
3 Biostimulation Activities on Plant Productions
3.1. Stimulation of growth
3.2. Tolerance to water stress
3.3. Tolerance to salt stress
3.4. Tolerance to thermal stress
3.5. The quality of the products
4 Feeding of Livestock
4.1. Ruminant nutrition
4.2. Pig nutrition
4.3. Horse nutrition
4.4. Poultry nutrition
4.5. Nutrition of rabbits
4.6. Nutrition of animals produced by aquaculture
5 The Biological Activities of Algae in Plant or Animal Health
5.1. Antiparasitic and antimicrobial activities
5.2. Induction of plant defense mechanisms
5.3. Activation of the immune system
Conclusion
References
Index
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List of Tables
Introduction
Table I.1. Classification of algae according to their pigment composition
Table I.2. Major classes of macroalgae associated with the phyla Chlorophytes,...
Chapter 1
Table 1.1. Examples of the names of the algal resource used historically in ag...
Table 1.2. Allocation of batches of kelp or wrack (vraic) according to the 171...
Table 1.3. Algal species constituting the sawn vraic and growing vraic accordi...
Table 1.4. Type of kelp and constituent species used in different regions of E...
Table 1.5. Correspondences between old species names and current names (from S...
Chapter 2
Table 2.1. Composition of minerals and mineral salts in 1 ton of dead maerl us...
Table 2.2. Trace element composition of 1 ton of dead maerl usable in agricult...
Table 2.3. Examples of some products (composts, powders, liquid extracts) with...
Table 2.4. Chemical composition of different composts with and without algae (...
Table 2.5. Trace element composition of a conventional agroforestry compost an...
Table 2.6. Composition of the different composts tested with and without ulva ...
Table 2.7. Main physico-chemical characteristics of algal compost obtained aft...
Table 2.8. Comparative efficacy of different composts on the germination of co...
Chapter 3
Table 3.1. Examples of some products marketed for their properties in stimulat...
Table 3.2. Example of liquid products with a base of seaweed extracts used for...
Table 3.3. Biostimulatory effect of microalgae or cyanobacteria* used alone or...
Table 3.4. Families of phytohormones produced by different genera of brown alg...
Table 3.5. Examples of commercial products in which the presence of phytohormo...
Table 3.6. Effect of green or brown seaweed extracts on germination of tomato ...
Table 3.7. Impact of Ascophyllum nodosum neutral extract (ANE 1) on relative l...
Table 3.8. Impact of neutral (ANE 1) and alkaline (ANE 2) extracts of Ascophyl...
Table 3.9. Effect of the application of Ascophyllum nodosum extract at several...
Table 3.10. Effect of dipping application of Sargassum sp. and Ulva sp. extrac...
Table 3.11. Effects of the application of Ascophyllum nodosum extract on the s...
Table 3.12. Effects of the application of Ascophyllum nodosum extract on the a...
Table 3.13. Effect of macroalgae (*), microalgae (**) and cyanobacteria (***) ...
Table 3.14. Effect of the IPME mutation on the growth of Arabidopsis thaliana
Table 3.15. Effect of the application of Ascophyllum nodosum extracts on the t...
Table 3.16. Effect of the application of a commercial seaweed extract (Expando...
Table 3.17. Effect of the application of an algal extract (AE) of Kappaphycus ...
Table 3.18. Effect of the pre-harvest application of macro- or microalgal extr...
Chapter 4
Table 4.1. Biological diversity of the ciliated protozoan flora contained in t...
Table 4.2. Degradation efficiency (%) of algal polysaccharides and Laminaria e...
Table 4.3. Effect of a diet supplemented with Ascophyllum nodosum on the lacta...
Table 4.4. Effect of Ascophyllum nodosum supplementation on the iodine content...
Table 4.5. Composition of lactose-based diets fed ad libitum to weaned pigs (f...
Table 4.6. Impact of adding laminarin-rich brown algae, fucoidans, alginates a...
Table 4.7. Antibacterial activities of laminarin contained in brown seaweed ex...
Table 4.8. Chemical composition of OceanFeed Equine (from Ocean Harvest Techno...
Table 4.9. Conditions of administration of OceanFeed Equine product by stage o...
Table 4.10. Effect of Ascophyllum nodosum on the carotenoid content (µg/100 g ...
Table 4.11. Effect of a 15% Ascophyllum nodosum diet on the carotenoid content...
Table 4.12. Effect of the addition of red algae flour (Chondrus crispus or CC,
Table 4.13. Examples of extracts of brown, green or red algae and algal polysa...
Table 4.14. Effect of feeding seaweed on the decreased mortality rate of broil...
Table 4.15. Effect of the dietary intake of the alga Laminaria japonica on the...
Table 4.16. Some examples of the impact of algal use on the growth of freshwat...
Table 4.17. Biochemical composition of some microalgae species and a cyanobact...
Table 4.18. Example of microalgae species used as forage algae for live prey f...
Table 4.19. Some species of microalgae used in hatcheries for filter-feeding m...
Table 4.20. Effect of Ulva rigida-based replacement diets on the trace element...
Table 4.21. Effect of Ulva rigida substitution diets on the bioavailability (%...
Table 4.22. Examples of microalgae used as a food source in the nutrition of c...
Table 4.23. Effect of nutritional feed on the organoleptic quality of Litopena...
Table 4.24. Effect of different inducers (biofilms, microalgae, macroalgae and...
Chapter 5
Table 5.1. Some examples of the use of extracts of brown, green or red algae f...
Table 5.2. Examples of major bacterial diseases affecting aquatic species that...
Table 5.3. In vitro viricidal activity of methanolic extracts of green, brown ...
Table 5.4. Examples of algal polysaccharides inducing the resistance mechanism...
Table 5.5. Some examples of algal-based products marketed for their resistance...
Table 5.6. Effect of supplementing Ascophyllum nodosum in the diet of ewes on ...
List of Illustrations
Introduction
Figure I.1. Photos of some algae on the foreshore belonging to Chlorophytes (a...
Figure I.2. Bathymetric distribution of some algae, for example, kelp, valued ...
Chapter 1
Figure 1.1. Wrecked kelp (a) and shoreline kelp (b) (photo credits © J. Fleure...
Figure 1.2. Former plots dedicated to food crops on the island of Aran (photo ...
Figure 1.3. Harvesting kelp on the Breton coast at the end of the 19th century...
Chapter 2
Figure 2.1. Lithothamnium calcareum (Phymatolithon calcareum) (photo credits ©...
Figure 2.2. Example of a consumer product with maerl as its basis marketed as ...
Figure 2.3. Effect of the addition of algae (Fucus serratus) on the internal t...
Figure 2.4. Evolution of the internal temperature of an agroforestry compost w...
Figure 2.5. Effect of adding increasing levels of C6 compost containing ulva p...
Chapter 3
Figure 3.1. Application modes of liquid or solid extracts of algae as biostimu...
Figure 3.2. Typical structure of a fucoidan from the brown alga Ascophyllum no...
Figure 3.3. Example of an alginate molecule (polymer of mannuronic acids or po...
Figure 3.4. Examples of mudflat sludge rich in microalgae and cyanobacteria us...
Figure 3.5. Effect of Lake Taihu microalgal sludge and cow manure on the growt...
Figure 3.6. Molecular structures of trans-zeatin (a) and trans-zeatin-9-β-D-ri...
Figure 3.7. Indole 3-acetic acid (auxin)
Figure 3.8. Abscisic acid (Fleurence 2022)
Figure 3.9. Effect of the commercial product Seamac on the increase in the num...
Figure 3.10. Cis-zeatin
Figure 3.11. Effect of Sargassum sp. (Sarg) or Ulva sp. extracts on photosynth...
Figure 3.12. Effect of the application of Ascophyllum nodosum extract (ANE) on...
Figure 3.13. Effect of Ascophyllum nodosum extract (ANE) application on the tr...
Figure 3.14. Structures of betaines contained in algal extracts: (a) glycine b...
Figure 3.15. Effect of salt stress on avocado plant height with and without As...
Figure 3.16. Effect of salt stress with or without application of an extract A...
Figure 3.17. Effect of salt stress with or without the application of Ascophyl...
Figure 3.18. Effect of salt stress with and without the application of Ascophy...
Figure 3.19. Effect of salt stress with or without the application of Ascophyl...
Figure 3.20. Effect of salt stress with or without the application of diluted ...
Figure 3.21. Effect of salt stress with or without the application of diluted ...
Figure 3.22. Effect of salt stress with and without the application of diluted
Figure 3.23. Effect of the application of Aphanizomenon extract (0.75%) on chl...
Figure 3.24. Effect of the application of Aphanizomenon extracts (0.25%; 0.50;...
Figure 3.25. Structure of 3-dimethylsulfuniopropionate
Figure 3.26. Impact of salt stress on root growth of wild-type and mutated (IP...
Figure 3.27. Effect of Ascophyllum nodosum extract (ANE) on the expression of ...
Figure 3.28. Effect of Ascophyllum nodosum PSI-494 extract on the expression o...
Figure 3.29. Dose effect of an algal extract (AE) of Kappaphycus alvarezii on ...
Figure 3.30. Post-harvest “Jonathan spot” disease on the Jonathan apple variet...
Figure 3.31. Effect of crop treatment with algal extract (AE) on the number of...
Figure 3.32. Seasonal effect of the treatment of Gala Must apple trees with co...
Figure 3.33. Seasonal effect of the treatment of Gala Must with commercial sea...
Figure 3.34. Effect of the application of a commercial algae-based product (Cy...
Chapter 4
Figure 4.1. Geographical location of the Orkney Islands (from Google Earth). F...
Figure 4.2. Orkney Islands sheep grazing on the foreshore (photo credit © Orkn...
Figure 4.3. Effect of selected algal polysaccharides on the bacterial growth o...
Figure 4.4. Effect of some diets on nitrogen digestibility in the rumen of rum...
Figure 4.5. In situ digestibility of the crude protein fraction of different a...
Figure 4.6. Effect of Ascophyllum nodosum (A. n) in the diet of dairy cows on ...
Figure 4.7. Effect of integrating the red alga Asparagopsis taxiformis in the ...
Figure 4.8. Impact of feeding Asparagopsis taxiformis on daily enteric methane...
Figure 4.9. Effect of the red alga diet Asparagopsis armata on enteric methane...
Figure 4.10. Effect of the red alga diet Asparagopsis armata on the enteric pr...
Figure 4.11. Effect of the red alga diet Asparagopsis armata on enteric hydrog...
Figure 4.12. Red alga Asparagopsis taxiformis (Passe Jarre jarron, Marseille) ...
Figure 4.13. Effect of the diet supplemented with OFS product on the carcass w...
Figure 4.14. Effect of a diet supplemented with Laminaria spp. extract on the ...
Figure 4.15. Effect of a diet supplemented with Laminaria spp. extract on the ...
Figure 4.16. Effect of the dietary supply of algal extracts, obtained from Lam...
Figure 4.17. Effect of providing the brown alga Macrocystis pyrifera as a diet...
Figure 4.18. Effect of supplying a mineral supplement (Calmin) based on red al...
Figure 4.19. Effect of a 15% Fucus sp. diet on egg yolk color according to the...
Figure 4.20. Effect of feeding red algal meal (Eucheuma spinosum) on the iodin...
Figure 4.21. Effect of feeding red algal meal (Eucheuma spinosum) on the iodin...
Figure 4.22. Impact after six weeks of algal polysaccharide (AP) administratio...
Figure 4.23. Impact after six weeks of algal polysaccharide (AP) administratio...
Figure 4.24. Red algae of the genus Polysiphonia in the center of a basin on t...
Figure 4.25. Effect of incorporating the alga Polysiphonia spp. (pellets or pu...
Figure 4.26. Effect of incorporating Polysiphonia spp. seaweed (pellets or pur...
Figure 4.27. Impact of algal (Laminaria spp.) diets on animal weight after 42 ...
Figure 4.28. Effect of diets with Laminaria algae (Laminaria spp.) as their ba...
Figure 4.29. Effect of diets based on Laminaria algae (Laminaria spp.) on the ...
Figure 4.30. Distribution of world aquaculture and fisheries production (wet t...
Figure 4.31. Effect of algal-based diets on the intestinal lipase activity of ...
Figure 4.32. Effect of algae-based diets on the activity of hepatic glutathion...
Figure 4.33. Effect of algal-based diets on the complement pathway in juvenile...
Figure 4.34. Effect of algal-based diets on lysosomal activity in juvenile sea...
Figure 4.35. Impact of the use of Gracilaria bursa-pastoris (GP), Gracilaria c...
Figure 4.36. Impact of using different percentages of the species Gracilaria c...
Figure 4.37. Effect of Verdemin (Ulva ohnoi) and Rosamin (Entomoneis spp.) die...
Figure 4.38. Effect of diets based on Verdemin (Ulva ohnoi) and Rosamin (Entom...
Figure 4.39. Effect of AquaArom (Laminaria sp.) diets on the daily weight gain...
Figure 4.40. Effect of AquaArom (Laminaria sp.)-based diets on plasma catalase...
Figure 4.41. Effect of Gracilaria arcuata diets on weight gain and specific gr...
Figure 4.42. Effect of Gracilaria arcuate-based diets on feed conversion rate ...
Figure 4.43. Rotifer Brachionus plicatilis used in aquaculture for feeding juv...
Figure 4.44. Effect of Ulva rigida-based substitution diets on lead and cadmiu...
Figure 4.45. Navicula sp. (photo credit © K. Peters, http://www.korseby.net/ou...
Figure 4.46. Abalone production system in Japan based on extensive aquaculture...
Figure 4.47. Survival rate of giant shrimp (Penaeus monodon) larvae in functio...
Figure 4.48. Effect of the rate of artificial feed in the diet of shrimp grown...
Figure 4.49. Impact of ulva co-culture and artificial feed provision on eicosa...
Figure 4.50. Effect over time of a natural or Ulvella lens biofilm on the perc...
Figure 4.51. Effect of microalgae diet on larval survival of Paracentrotus liv...
Figure 4.52. Effect of different diets based on microalgae or marine yeast on ...
Figure 4.53. Example of an integrated aquaculture system in which algae are us...
Chapter 5
Figure 5.1. Young nematode (Meloidogyne incognita) entering the root of a toma...
Figure 5.2. Effect of brown algal extract Ecklonia maxima (AE) on the number o...
Figure 5.3. Structure of eckols contained in brown algae of the genus Ecklonia...
Figure 5.4. Impact of foliar spray of eckol solution (10-6 M) on the myrosinas...
Figure 5.5. Impact of different concentrations of eckol on cabbage aphid morta...
Figure 5.6. Parasitic plant of broomrape (Phelipanche ramosa) (photo credit © ...
Figure 5.7. Effect of the product Algit Super (Ascophyllum nodosum) depending ...
Figure 5.8. Antibacterial activities against Xanthomonas axonopodis of the sub...
Figure 5.9. In vitro antifungal activity on Alternaria solani spores of differ...
Figure 5.10. Comparison of in vitro antibacterial activities between a synthet...
Figure 5.11. Seasonal variation of antibacterial activity (Vibrio harveyi) of ...
Figure 5.12. Decrease in viral load due to HNV and IPNV viral loads in splenic...
Figure 5.13. Hypersensitivity reaction resistance mechanism in Arabidopsis tha...
Figure 5.14. Structure of laminarin
Figure 5.15. Contribution of sulfated laminarin (1: 1.25 mg/mL; 2: 2.5 mg/mL; ...
Figure 5.16. Structures of ulvans. a) A ulvanobiouronic acid. b) B ulvanobiour...
Figure 5.17. Effect of the addition of Ulva flour on the phagocytic activity o...
Figure 5.18. Effect of the Ulva diet on the number of lymphocytes after immuni...
Figure 5.19. Impact of algal-supplemented diet on the spontaneous hemolytic ac...
Figure 5.20. Impact of feeding the alga Asparagopsis taxiformis as a whole or ...
Figure 5.21. Impact of feeding the alga Asparagopsis taxiformis in its whole o...
Figure 5.22. Effect of supplementing green (U. fasciata), brown (D. intermedia
Figure 5.23. Distribution of innate immunity-related activities by number of s...
Figure 5.24. Impact of the dietary intake of Gracilaria verrucosa at different...
Figure 5.25. Impact of dietary intake of Gracilaria verrucosa at different con...
Figure 5.26. Impact of different diets based on sulfated polysaccharides extra...
Figure 5.27. Impact of different diets based on sulfated polysaccharides extra...
Figure 5.28. Effect of different diets supplemented with algae, or with vitami...
Guide
Cover Page
Title Page
Copyright Page
Preface
Introduction
Table of Contents
Begin Reading
Conclusion
References
Index
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Series EditorsJack Legrand and Gilles Trystram
Algae in Agrobiology
Realities and Perspectives
Joël Fleurence
First published 2023 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.
Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address:
ISTE Ltd
John Wiley & Sons, Inc.
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www.iste.co.uk
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© ISTE Ltd 2023The rights of Joël Fleurence to be identified as the author of this work have been asserted by him in accordance with the Copyright, Designs and Patents Act 1988.
Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s), contributor(s) or editor(s) and do not necessarily reflect the views of ISTE Group.
Library of Congress Control Number: 2023938461
British Library Cataloguing-in-Publication DataA CIP record for this book is available from the British LibraryISBN 978-1-78630-919-8
Preface
The use of algae is an ancient practice in agriculture, carried out on the coasts of many countries. The algae resource, resulting from beaching, has sometimes been mixed with sand, or even manure, to constitute a humus suitable for crops. This is the case with the surface layer of soil found on the island of Aran located off the west coast of Ireland. Traditionally, algae known as “kelp” or “wrack” are used for soil amendment or fertilization. They are also integrated in the breeding process through their nutritional contribution in animal feed. This book reviews the traditional and current algae applications in agriculture and livestock breeding. The latter aspect is dealt with although it does not meet the strict definition of agri cultura (field culture). The implication of livestock in agricultural work and in the supply of food proteins has indeed contributed to the undeniable success of agriculture.
The role played by the use of algae in the development of food and vegetable crops on the European coasts (Ireland, United Kingdom, France) or in the feed of livestock (sheep, cattle, horses) is initially developed as a historical preamble to the book.
A report on the activities of agronomic or veterinary interest from macroalgae or cyanobacteria is proposed. In particular, it focuses on the description of hormones and algal oligosaccharides involved respectively in plant growth, tolerance to abiotic stresses (thermal shock, hydric stress, saline stress) and resistance to abiotic stresses (heat shock, water stress, salt stress) and biotic stresses (viral, bacterial and fungal infections).
This book also deals with the effect of algae, whether macro- or microalgae, on zootechnical performance (growth) and the health of livestock. It reports on the immunostimulant properties of polysaccharides or algal extracts in livestock or species of aquaculture interest (salmon, sea bream).
Used since time immemorial in agriculture, algae are inputs of biological origin and thus meet the expectations of a more ecological production activity. The agronomic studies associated with them fully meet the agrobiology, which is defined as “all biological research applied to agriculture”.
Another definition of agrobiology is “the whole of the agricultural techniques which aim to respect nature through the return to ancestral practices”.
Other definitions linking agrobiology to organic or reasoned agriculture are also frequently put forward.
But whatever the definition, the use of algae in agriculture is in line with the objectives of agrobiology. They also meet the expectations of the closely related sector of agriculture, which is the sustainable breeding of livestock, whether terrestrial or aquatic.
May 2023
Introduction
Algae are photosynthetic eukaryotic organisms that live mainly in aquatic environments. A distinction is made between unicellular algae or microalgae and multicellular algae or macroalgae. Microalgae are organisms that can be found in marine, brackish and fresh waters, as well as in humid air such as the atmosphere, in the form of aerosols, or on building facades (Fleurence 2021a). Macroalgae represent the resource traditionally used in agriculture, whether for improving crop yields or for breeding. Microalgae or sludge containing them are sometimes tested as biofertilizers for many crops. For nearly 70 years, microalgae have been used in the nutrition of animals produced by aquaculture (fish, shellfish, mollusks).
Algae are classically classified in botanical groups on the basis of their pigmentary composition (see Table I.1). With regard to phylogenetic systematics, this classification appears obsolete today and is therefore less applied by scientists. On the other hand, it is kept by naturalists, some biologists and professionals involved in the valorization of algae, because it proves to be very useful for taxonomic sorting of algae in the field.
In classical systematics, three major groups of algae or phyla distinguishing themselves by their pigment content have been established, namely Chlorophytes (green algae), Rhodophytes (red algae) and Chromophytes (brown algae) (see Figure I.1).
Phyla are organized into classes, the main ones of which are listed in Table I.2.
Table I.1.Classification of algae according to their pigment composition
Branch
Main pigment
Secondary pigments
Chlorophytes or green algae
Chlorophyll a
Chlorophyll b
Rhodophytes or red algae
Chlorophyll a
‒ Phycoerythrin‒ Phycoerythrocyanin‒ Allophycocyanin‒ Chlorophyll d
Chromophytes or brown algae
Chlorophyll a
‒ Chlorophyll c‒ Excess of carotenoids (carotene, xanthophyll, fucoxanthin)
Table I.2.Major classes of macroalgae associated with the phyla Chlorophytes, Rhodophytes and Chromophytes (from Dawes 2016)
Branch
Main classes
Chlorophytes (green algae)
‒ Chlorophyceae‒ Ulvophyceae
Rhodophytes (red algae)
Rhodophyceae
Chromophytes (brown algae)
Pheophyceae
This dichotomy based on pigment composition has been enriched by the application of the endosymbiotic theory to algae. According to this theory, it is now necessary to distinguish the phyla of Chlorobiontes (green algae), Rhodobiontes (red algae) and Chrysobiontes (brown algae) (Perez 1997, pp. 11−64).
For practical reasons related to the uses of algae, only the traditional classification previously described (see Table I.1) will be used as a basis of reference.
The branch Chlorophyta or green algae includes nearly 6,000 species occurring as micro- or macroalgae. The majority of these species live in fresh water (90%) and only 10% in marine waters (Dawes 2016). Among the latter are species belonging to the genus Ulva which are marine algae living on the top of the foreshore and easily accessible at low tide (see Figure I.2).
Figure I.1.Photos of some algae on the foreshore belonging to Chlorophytes (a, b), Rhodophytes (c) and Chromophytes (d, e): a) Ulva sp. b) Enteromorpha sp. (green algae). c) Palmaria palmata (red algae). d) Fucus sp. and Ascophyllum nodosum. e) Laminaria sp. (brown algae) (photo credits © J. Fleurence, 2010, 2019). For a color version of this figure, see www.iste.co.uk/fleurence/algae.zip
Figure I.2.Bathymetric distribution of some algae, for example, kelp, valued in agriculture (source: Y.-F. Pouchus after Fleurence (2018)). For a color version of this figure, see www.iste.co.uk/fleurence/algae.zip
Rhodophytes are considered one of the oldest groups of eukaryotic algae (1.7 billion years old) (Perez 1997, pp. 11−64; Baweja et al. 2016). Some species such as Lithothamnium calcareum (maerl) are intensively exploited for agricultural needs related to soil amendment (see section 2.1).
Chromophytes or brown algae are characterized by a very large morphological diversity. They constitute the group mainly represented in the subpolar and equatorial regions. The brown algae of the class Pheophyceae are the subject of many valuations, whether in the agricultural, food, pharmaceutical or cosmetic fields. The main species concerned are macroalgae of the order Fucales (Ascophyllum sp., Fucus sp.) or Laminariales (Laminaria sp., Undaria sp.). The Fucales are located towards the top of the foreshore and are easily accessible via on-foot fishing, which is not the case for the Laminariales, which generally grow at the limit of the subtidal zone (see Figure I.2). The species Ascophyllum nodosum and Fucus vesiculosus are the main species that make up the mixture of algae known to the public as kelp or wrack. These algae were harvested by coastal populations for many agricultural uses such as crop fertilization or livestock feed.
In addition to the ancient applications of algae in soil amendment and crop fertilization, algae is now used as a biostimulant for plant production and as an input for animal nutrition. These uses are justified by the presence in algae of original and varied molecules such as phytohormones, elicitors of defense mechanisms to biotic stresses and other substances involved in the physiology of plant or animal nutrition. All these activities of agronomic or zootechnical interest are at the origin of the current algae craze in agrobiology.
1History
1.1. The different types of kelp
Seaweed has often been used by coastal populations to improve the physical structure of the soil or to provide nutrients for flower beds. These are often algae washed up on beaches by storms and called wrecked kelp (see Figure 1.1(a)). The latter is very distinct from shoreline kelp (see Figure 1.1(b)) which is present on the foreshore and which is manually harvested during low tides. In addition to these two categories, there is also ground kelp which is harvested by dredging the bottom with boats (see section 2.1). Kelp has often been used as a soil amendment for crops. Depending on the region and time, the algal resource exploited for agricultural purposes has been given various and very different names (see Table 1.1).
Table 1.1.Examples of the names of the algal resource used historically in agriculture according to regions and the time period (from Lami 1941, Blench 1966 and Desouches 1972)
Country or region
Old name
Traditional name
Brittany
Gouesmon
Goémon
Normandy
Vraicq
or
Vraic
Varech
Island of Oleron
Gaymon
Sart
Channel Islands
Vraic
Varech
United Kingdom
Wrack
Kelp
The purpose of introducing algae into the soil is to change the composition and texture of the soil. This practice of soil preparation was used by the first inhabitants of the island of Aran off the coast of Galway (Ireland) to create a layer of humus necessary for the establishment of food crops (potatoes). This practice has shaped the landscape of the island, which appears as a succession of plots protected from ocean winds and dedicated to potato cultivation (see Figure 1.2). The stranded algae is preliminarily mixed with sand and sometimes with manure before being spread in the soil.
Figure 1.1.Wrecked kelp (a) and shoreline kelp (b) (photo credits © J. Fleurence, 2010, 2020). For a color version of this figure, see www.iste.co.uk/fleurence/algae.zip
This process of amendment is notably evoked in the 1934 documentary film by Robert J. Flaherty, Man of Aran1.
Figure 1.2.Former plots dedicated to food crops on the island of Aran (photo credit © J. Fleurence, 2010). For a color version of this figure, see www.iste.co.uk/fleurence/algae.zip
1.2. Historical applications
The direct use of algae or composted algae for crops is often related to a need for soil amendment and crop fertilization. Seaweed manure was used as early as the 1st century CE for growing cabbage (Craigie 2011). The Roman writer Columella recommended that cabbage plants in the six-leaf stage of development be contacted at the root level with seaweed manure, also used to mulch crops. Another Roman, Palladius, in the 4th century CE, also suggested the early spring application of algal manure to the roots of pomegranate and lemon trees (Arzel 1994; Craigie 2011).
On the English speaking island of Jersey, algae have been used in agriculture since the 12th century (Blench 1966). The algal resource used is referred to as “vraic” or “wrack”, which appears to be a distortion of the French word varech or the Old English wraec
