Cultivation and utilization of tropical seaweed Kappaphycus alvarezii in warm waters of Japan
Masao Ohno: Emeritus Prof. Kochi University
Large-scale joint investment project between the Ministry of Agriculture, Forestry and Fisheries
and the private sector was established in 1991. A decade of research to extract and commercialize
has begun. Because the lectin is a protein, the study required K. alvarezii raw samples throughout
the year. K. alvarezii did not have a Japanese name and was named Nettai Kirinsai ( Yano,M.etal.2007).
The cultivated green type and reddish brown type materials of 2kg wt. K.alvarezuii fronds
were transplanted from Philippines. They were grown in the sea from May to November for 12years since May 1992 ( Ohno & Largo, 2020), and used as experimental samples. Theirmaterials were cultivatied in the sea for summer season).
From December to spring of the following year, the temperature their matrieals were culture in
the aquatron which is adjusted to 23°C in aquatron (50 cm x 50 cm x 50 cm constanttemperature, closed, aerated acrylic tank with occasional water changes) owned by Kochi
University.K. alvarezii strains managed at Kochi University since 2020 when the project.
These seedlings were kept on ropes in fish pen frames. The seedings had started in the sea inMay. Sea water temperature reached excellent 25-30 ℃ in August. Tank culture was performed
when the water temperature reached 22°C in December.
The tank cultured K.alvarezii seedlings were kept at 22°C during the winter season. outdoor(roofed) tank culture under natural light, which was adjusted with a heater and a temperature
control device. K.alvarezii cultivation was successfully established using small cages and net for
30 years in Tosa Bay, warm sea in Japan.
Cultivation with fish cultivated cage
K.alvarrezii cultivation was done by ropes with 10mx10m fish net floating cage and 20 ropes
were used. The cultivated ropes were sanked at a depth of about 50 cm with anchors attached toboth ends. The water temperature in the cultivation area reaches over 20°C in early May, 23°Cin June, 24-28°C in July and 29-32°C in August. The water temperature dropped fromSeptember to 25-28°C, and gradually dropped from October to December until it reached 22°C,
when the sea surface culture was finished.
In June, the growth rate of frond increased with the rise of water temperature, and the daily
growth rate reached 3-4 %. In September, the daily growth rate was more than 5%, and the leaf
length and weight more than doubled in one week. Rainfall and lack of light slowed the growth,and the daily growth rate also fluctuated during the rainy season in June, the salinity dropped
significantly to 19-24 psu due to rainfall, and the growth rate slowed down. Salinity increased to29 ~32 psu in summer. Their growth slows when water temperatures exceed 30°C in summer.
The highest growth rate became during the period from September to November, when thewater temperature is 23-28°C.

This period was split with harvest and again palm-sized fronds were attached to the rope. In
the past sea aquaculture, when 1 kg of overwintered seedlings were cultured in the sea, the yieldwas 70 to 100 kg at the end of the aquaculture in December. The decrease in salinity in the rainyseason and the high temperature in summer greatly affected the production.
Net cultivation method
Eucheumatoid cultivation are using ropes currently. This method is carried out using the longline method in the open sea, but a large amount of fronds fall off the rope due to the waves.
Therefore, The method cultivated K. alvarezii by putting the leaves in a net bag has tried for theopen sea. New leaf bodies elongated outside the net. The problem was the material of the net. If
the thread (material of cotton thread and synthetic thread) is thick, it will get very dirty. Nori net
have been used K. alvarezii cultivation, but the net is less dirty, so it is better to insert larger
seedlings.
In future open sea K.alvarezii cultivation, the development of cultivation methods that insert
seedings into nets will be an issue.
Over winter tank culture
Overwintering tank culture of seedlings from the end of November, when the watertemperature drops below 20 degrees, the growth of algae stops and the leaves become softer andlose color. It becomes yellowish green. Every year when the sea surface temperature approached
20°C, they started preparing for wintering. Approximately 20 kg of alga bodies were stored in a
one-ton tank installed in a breeding building with a roof, and seawater was added little by little.
The water temperature was kept at 23°C by a heater, and the water was aerated. The fronds werecultured in an outdoor tank culture in winter in a state in which the fronds grew slightly. Everyyear, when the seawater temperature reaches 20 ℃ in May, the fish are transferred to the sea
surface culture method, and the preserved stock has been maintained. Prospects for tropicalK,alvarezii in Japan The growth rate of them has doubled in a week when the water temperaturereaches 23-28 °C in Tosa Bay for many years, and the daily growth rate often exceeds 4%. The
daily growth rate in commercialized euchuematoid cultivation in the Philippines was 4-5%,
similar to the growth rate of K,alvarezii in Tosa Bay (Trono & Ohno,1989)
It was confirmed that the growth rate of them slows down when the water temperature drops
below 23°C in November, and the green color from alga bodies decreases. However, it was
found that even at a water temperature of 18°C in winter, the growth was retarded or grewnormally. Therefore, if seedlings are secured by tank culture, it will be possible to cultivate
K.alvarezii in many sea areas in Japan where the temperature is over 20℃ from May toNovember. However, the growth is better in a state of high salinity. It was found that they cansurvive even at low salinity of 15 psu and continue to grow. Sandy sea areas where algae-eatingfish do not exist are suitable for farming ( Yano &Ohno,2007).

ADGBCEFHI

Fig.1. Cultivation methods of Kappapycus alvarezuii with sishe cage in Tosa Bay in Japan
A: Brown type frond of K.alvarezii B, Green type frond cultivated of K.alvarezuii
C: Green type frond of K.alvarezii
D: Fish cage ( 10m X10ｍ size)
E: Hanging seeding with anchor
F: seeding ropes hanged at one m depth from surface water
G: K.alvatezii seeding fixed interval of 20cm
H: Seeds grown aftter about two weeks in June (rain season)
I;. seeding ropes fixed each 20 lines ( in summer seaｓon)

ADGBECF

H:I

Fig.2 Cultivation methods of Kappapycus alvarezii with fish cage in Tosa Bay in Japan

A:Kappaphycus products of the ropes in autumn. B: Harvested products of the ropes in Decmber
C: Harvested products in the boat
D, E: The tank culture of K.alvarezii fronds with control of water temperature
F: The disease frond which the epidermis has pee off (white color)
G: Net method of Kappaphycus alvarezii cultivation. H: Growing fronds from the nets after twoweeks after seeding. H: Growing frond from the net afｔer one month after seeding.

Uses of Japanese euchuematoid products
Fields of use as ingredients
The reason why K.alvarezuii cultivation has been able to continue in Tosa Bay is because of
the demand for it as an ingredient in Italian and French cuisine. Adding a small amount of thedry powder to kamaboko (fish paste) and jelly is popular for its viscosity and texture, so it islikely that applications in this field will be developed in the future. Currently, it is also
recognized as effective as a seaweed fertilizer. If demand for these increases, K.alvarezii
cultivation in Japan will continue as fields of use as ingredients in the sea in Japan.
It is also recognized as effective as a seaweed fertilizer., K.alvarezii cultivation in Japan willcontinue, if demand for these increases.

Fig 3 Italian１dishes with K.alvaresii materials
Effects of seaweed liquid fertilizer (Bio-Stimulant）
Kelp species live in cold waters and thrive in large areas of the world's oceans. Since the1990s, liquid seaweed fertilizer has been produced by squeezing Ascophyrum notodum andEcklonia maxima, which have grown in Northern Europe and South Africa. Became
K.alvarezii juice was prepared by the following method.
About 60% of juice could be obtained by squeezing raw K.alvarezii fronds, and about 80% ormore of juice could be obtained from their frozen fronds. The juice that was filtered from theraw material became clear and pale yellow-green. Excess juice from the frozen leaf becomes apink liquid. This pink pigment is sensitive to light, and when stored at room temperature, it
gradually fades to a pale, transparent yellow-green color similar to the juice of raw K.alvrezii.
There was not difference in the fertilizing effect in the test examples up to row K.alvarezii liquid
prepared in this way was transparent with a slight odor when stored at room temperature, andcould be stored for a long period of time.
Effect of K. alvarezii liquid
Flowers:It was compared daisies of similar size with 100 cc of K.alvarezii liquid fertilizer (500fold dilution) added once a week with no addition. The added strains had thicker stems andslightly longer leaves. The condition after 3 weeks is shown in the photograph(Fig. 4). A florist
who sells cut flowers commented that adding a small amount of K.alvarezii liquid fertilizer tocut flowers would make them last longer.：
Melon: juice (500-fold dilution) was added to melon cultivation by greenhouse farmers from thetime of planting seedlings. In melon cultivation, a plastic tube is run along the base of the melon,
and a moderately small hole is opened in the tube. This time, K.alvarezii liquid fertilizer wasadded to the conventional liquid fertilizer once a week. As for the melon fruit, in the area to whichjuice was added, the fruits were enlarged more than in the area to which no juice was added. The
pericarp was thin, sweet and soft enoughTomato: Add K/alvarezii juice( 500-fold dilution )to the conventionally used liquid fertilizer andsprinkle it on the roots. Tomatoes have become sweeter and richer.
Sweet potato: Since the spring of 2020, an agricultural corporation in Okayama has been
experimenting with sweet potato cultivation in sandy fields using K.alvaezii liquid fertilizer
diluted 500 times. The growth of sweet potatoes is better than the non-fertilized area. The growthof the vine is remarkably good, and the growth of the rhizome is also having a good effect.
Sweetness and umami are judged after the potatoes are dried and fully ripe (4-6 months afterdigging), but good results are expected.
K.alvarezii liquid fertilizer contains more potassium than other seaweed fertilizer, as shown in
the table 1. It featured quite a few things. It is presumed that the fact that the potassium
content is higher than that of kelp and sargassum species promotes the growth of roots, stems,and leaves as a liquid fertilizer, and increases the sweetness component. Iron is a component ofchloroplasts and activates photosynthesis.Alginic acid from brown seaweed, which is aviscous polysaccharide, and carrageenan from red alga K.alvarazii iswell when they absorb
water, and have the property of forming a highly viscous aqueous solution. This property
works effectively when soil improvement is carried out. When the content of the viscous
polysaccharides in the soil increases, the water holding capacity increases, the soil moisture isstabilized, the propagation of useful microorganisms is promoted, and the soil becomes a goodenvironment. In ordinary fertilizers, amino acids and enzymes are synthesized in the plant
body from nitrogen components absorbed from the roots, and then phosphoric acid is
combined to synthesize proteins and the like. After the amino acids of seaweed are absorbed asthey are from the leaves and roots, they are immediately involved in the synthesis of proteins
and the like. Seaweed liquid fertilizer containing amino acids promotes the growth of crops
more efficiently than inorganic fertilizers. Plant hormones involved in plant growth play a very
important role in the growth of plants in general, such as increasing flowering, promoting
branching and elongation of roots and stems, improving cold resistance, promoting fruit
maturation, and preventing aging. ing. Plant hormones are also necessary ingredients to
produce amino acids. The kelp (Ecklonia maxima) liquid fertilizer collected in Cape Town isdescribed as auxin (11 mg/L) and cytokinin (0.03 mg/L) (Rotmann KWG.2001)). Eucheuma
muricatum grows at almost the same growth rate as these species, so it is speculated thatK.alvarezii also contains a large amount of plant hormones.
Table. 1 Composition table of seaweed liquid fertilizer
1000g unit
K.alvarezuii

JapaneseKelp, Sargassum Ascophylum
Laminaria
hornrinodosummoisture

88.8g

95 g

＊

＊

protein

1.2g

1.1 g

1.62ｇ

0.53ｇ

Lipid

0.1ｇ

0.1 g

0.15ｇ

0.24ｇ

carbohydrate

5.3g

6.4 g

5.11ｇ

7.33ｇ

Ash4.6g

2.0 g

3.0ｇ

1.9ｇ

Sodium

280 mg

260 mg51.9 mg*

Potassium

1600 ㎎

610 mg

117 mg＊Calcium

13 ㎎

78 mg

18 mg

＊

Magnesium

32 ㎎

53mg

19 mg

＊

Phosphorus

16mg

18mg

＊

＊

Iron0.7 ㎎

0.3mg

＊

＊

Content＊:no data(According to the materials of each fertilizer company)

A

BC

EFDF

G

Fig. 4. K.alvarezuii juice: A; filtered K.alvarezuii juice; B; filtered juice of frozen K.alvarezuii
fronds
C: Flowers: daisies, characterized by large leaves
D: Tomatoes: dark fruit color, sweeter
E; Greenhouse farming: Injecting liquid fertilizer at the base of the tube
D: Melon: Larger in size and sweeter
E; Sweet potato: bigger and sweeterReferences:Ohno,M, Largo DB, Ikumoto, M. Growth rate, carrageenan yield and gel properties ofcultured Kappa-carrageenan producing red alga Kappaphycus alvarezii (Doty) Doty in thesubtropical waters of Shikoku, Japan. J.Applied Phycol. 1994. 6:1-5.
Trono, GC, Ohno,M. Seasonality in the biomass production of the Euchuema strains inNorththen Bohol Philippines. In :Umezaki(ed.) Scientific Survey of the Marine Algae andand their Resources in the Philippines Islands. Japanese Ministry of Education, Science andCulture. 1989,71-81.
Yano, M., Ohno,M.M. The growth rates of cultivated Green and Brown type of K.alvarezii.
Bull. Mar. Sci. Fish Kochi Univ. 2007:23,59-62. (in Japanese)
Yano, M.,Ohno, M., Hiraoka, M. The technology of tank culture of Kappaphycus alvarez ii(Japanese name: Nettaikirinnsai). Bul.Mar.Sci. Fish Kochi Univ. 2010, 26, 23-28.( InJapanese).
Ohno, M, Danilo B. Largo. Footprints of tropical seaweed Kappaphycus alvaezii cultivationin Tosa Bay. Algal Resources 2020, 13, 127-132.