170
A. D. BONEY
daily illumination was the most satisfactory ; continuous illumination
inhibited growth. Frond growth was also affected by water movement,
as well as temperature. Spore attachment was most effectively
obtained with a current velocity of 7 cm/sec, whilst growth of the frond
was equally satisfactory over a current velocity range of 7-26 cmlsec.
Variations in water temperature, degree of illumination and water
movement were all found to affect the colour, toughness and taste of
the laver frond. Plants grown in Tokyo Bay are predominantly of the
long-fronded type (Suto and Fujiyama, 1962).
Porphyra angusta. This species resembles P. tenera in having a
relatively short growth season in the year, but is a species more charmteristic of the “ outer ” seas in Japan. The fronds are elongate and
elliptical, tapering towards the base or at both ends. Their length may
reach 46 cm with a width of 8 cm ; the margin is undulate. According to
Kurogi (1961) the younger fronds are narrow and they broaden with
age. The plants are dioecious, with female plants reddish-brown in
colour and rounded at the apex. Male plants taper towards the base
and apex, and are pale yellow-brown in colour. Both spermatangia and
“ carpogonia ” are borne on the upper marginal part of the frond.
Monoecious plants (male or female) are found on occasions. Sexual
organs first appear on plants 4-6 cm in length. Whilst the carpogonia
are indistinguishable from vegetative cells in surface view, in transverse section they appear spindular. A Conchocelis-phase is obtained
on germination of the “ carpospores ”.
The young “ buds ” which first appear on the “ hibi ” attain a
filament length of 10-20 cells before commencing longitudinal division
with a subsequent broadening of the frond. The early production of
monospores by the young buds is observed after 10 days growth, and
this leads to some truncation of the apex of the juvenile plant. Spreading of the “ hibi ” between late September and early October results in
heavy spore settlements. Young plants reach a length of 1 cm after 4
weeks’ growth, and 2-4 cm after 3 months. Monospore production and
spore settlement from the young buds is observed from September until
the end of November, but only with young plants under 1 mm in
length. Once this length is exceeded monospore production ceases.
Formation of spermatangia and “ cqogonia ” commences in late
October and they continue to be formed until the end of the growth
season. The Conchocelis-phase obtained by germination of the “ carpospores ” grows through the summer, and liberation of the monospores
from this phase commences early in the autumn. The time of harvesting the plants is much the same as with P. tenera.
A. D. BONEY
daily illumination was the most satisfactory ; continuous illumination
inhibited growth. Frond growth was also affected by water movement,
as well as temperature. Spore attachment was most effectively
obtained with a current velocity of 7 cm/sec, whilst growth of the frond
was equally satisfactory over a current velocity range of 7-26 cmlsec.
Variations in water temperature, degree of illumination and water
movement were all found to affect the colour, toughness and taste of
the laver frond. Plants grown in Tokyo Bay are predominantly of the
long-fronded type (Suto and Fujiyama, 1962).
Porphyra angusta. This species resembles P. tenera in having a
relatively short growth season in the year, but is a species more charmteristic of the “ outer ” seas in Japan. The fronds are elongate and
elliptical, tapering towards the base or at both ends. Their length may
reach 46 cm with a width of 8 cm ; the margin is undulate. According to
Kurogi (1961) the younger fronds are narrow and they broaden with
age. The plants are dioecious, with female plants reddish-brown in
colour and rounded at the apex. Male plants taper towards the base
and apex, and are pale yellow-brown in colour. Both spermatangia and
“ carpogonia ” are borne on the upper marginal part of the frond.
Monoecious plants (male or female) are found on occasions. Sexual
organs first appear on plants 4-6 cm in length. Whilst the carpogonia
are indistinguishable from vegetative cells in surface view, in transverse section they appear spindular. A Conchocelis-phase is obtained
on germination of the “ carpospores ”.
The young “ buds ” which first appear on the “ hibi ” attain a
filament length of 10-20 cells before commencing longitudinal division
with a subsequent broadening of the frond. The early production of
monospores by the young buds is observed after 10 days growth, and
this leads to some truncation of the apex of the juvenile plant. Spreading of the “ hibi ” between late September and early October results in
heavy spore settlements. Young plants reach a length of 1 cm after 4
weeks’ growth, and 2-4 cm after 3 months. Monospore production and
spore settlement from the young buds is observed from September until
the end of November, but only with young plants under 1 mm in
length. Once this length is exceeded monospore production ceases.
Formation of spermatangia and “ cqogonia ” commences in late
October and they continue to be formed until the end of the growth
season. The Conchocelis-phase obtained by germination of the “ carpospores ” grows through the summer, and liberation of the monospores
from this phase commences early in the autumn. The time of harvesting the plants is much the same as with P. tenera.