Ferns
Ferns are perennial flowerless plants comprising more than 6,000 species divided into
several families and distributed worldwide. Two kinds of ferns are customarily
recognized: (i) hardy ferns, which are terrestrial species that can be planted
in places and conditions similar to their natural habitats, and (ii) greenhouse ferns,
which are tropical epiphytic species requiring special conditions for plant growth.
The most commercially grown ferns in greenhouses are found in the genera Adiatum,
Alsophila, Asplenium, Blechnum, Cibotium, Cyathea, Cyrtomium, Davallia, Dicksonia,
Lygodium, Nephrolepis, Platyaerium, Polystichum, and Pteris.
Ferns bear no flowers and therefore set no seeds. They reproduce from spores.
Ferns have rhizomes (which are actually the stems of the fern) and leaves. Some rhizomes
are short , medium , and long creeping or erect and tufted. The leaves or fronds
(the upper part of the frond is known as lamina, and the stalk from the rhizome to the
lamina is known as rachis) are important structural components of ferns. The spores
are found underneath the frond and are borne in sporangia which open to release the spores.
Ferns are customarily propagated by dividing the rhizomes. Rhizome pieces with a growing
apex are placed in suitable growing media and kept in warm and shaded conditions for
establishment. Ferns can also be propagated by sexual means which involve the germination
of spores.
Media requirements for ferns change depending upon species, plant age, and climatic factors.
For most cases, the ideal media consists of two thirds of organic materials and one third
of coarse sand. Organic materials used include milled pine bark, sawdust, shredded tree
fern fiber, rice hulls, and others. Ferns are quite sensitive to water stress and need
constant water supply but water-logging can increase the likelihood of root rot. Ferns
are also sensitive to direct lighting. If grown under full sunlight, ferns are stunted,
short, with an abundance of burnt fronds.
Anthuriums
The word anthurium is a Greek word for tail flower, in reference to the tail bike spadix
of most anthurium species. The genera Anthurium (family Areacea) comprise a large group
of tropical perennial herbaceous plants.
Anthurium andraeanum is native of the western Andean slopes in South America. It was
introduced to Hawaii in 1889. Many decades of breeding, developmental research, and
agronomic advances have contributed to a high quality production of anthuriums in Hawaii.
The anthurium flower is unique. It consists of a modified leaf, the spathe, and a
cylindrical inflorescence called flower spadix with over 300 spirally attached minute
flowers. The heart shaped spathe is about 7 cm wide and 10 cm long. Size, shape, and
color (red, pink, orange, coral, and white) of the showy spathe determine the
commercial value of anthuriums. Size and orientation of the spadix are also additional
criteria for quality.
Anthurium flowers are produced throughout the year after the juvenile phase has ended.
About 3 to 8 flowers per plant are produced per year with an interval ranging from 48
to 107 days. Flower production is significantly influenced by temperature and light.
Some cultivars produce basal suckers under warm temperatures (> 22 oC) and high humidity.
In general, anthuriums grow slowly producing only 6 to 8 new leaves and vegetative buds
on a stem per year.
Anthuriums are grown in growing media including sugarcane baggase, wood shavings, tree fern
fiber, taro peelings, macadamia nut hulls, coconut fiber, forest litter, and volcanic
cinders. The best media for anthuriums are sugarcane baggase and wood shaving followed
by black cinder base with baggase mulch amended with 448, 196, and 370 kg/ha/year of
N, P, and K, respectively.
Anthuriums require warm temperatures (> 22 oC) for initial development. Night temperatures
of 18 oC are recommended. Evidences indicate night temperatures higher than 22 oC actually
cause poor color development. Anthuriums grow best under shading (i.e., 73 to 80% shade)
with pink cultivars requiring 80% or more shading for best color development. Shading can
be attained by either growing the crop under trees or by using open structures
covered with shade cloth.
Fertilizers are customarily added to the media in NK ratios of 1:1.5 to 1:2.5. In Hawaii,
NPK ratios of 1:2:2 or 1:1:1 are widely used. Anthuriums are also likely to suffer from Ca
deficiency if grown in high rainfall areas. Calcium deficiency, however, can be easily
corrected by liming at 1.1 Mg/ha.
Heliconia
The genera Heliconia (family Musaceae) consists of about 250 banana like species. Heliconias
are propagated from seed or vegetative parts. Vegetative propagation proceeds by division
of the clums or by separation of the rhizomes into one or two pseudostem bases.
Heliconias are grown in media ranging from volcanic cinders to coarse or fine textured
soils. Heliconias prefer well drained, slightly acid, fertile soils, high levels of
nutrients, and adequate water supply. Rates of NPK of 3:1:2 and 3:1:5 are usually
recommended. To prevent water stress, daily applications of 4 mm (using overhead
sprinklers) are generally recommended.
.
Heliconias usually grow well under full sunlight although some species develop better
color under light shading. In general, plant development proceeds slowly during winter
because of low light and cool temperatures. Although most heliconias are from tropical
areas, some species are reported to survive, if not grow, at temperatures as low as
10 oC. In general, temperatures above 15 oC are suitable for plant growth and flowering.
Alpinia
Species of the ginger like genera Alpinia belong to the family Zingiberaceae. Red ginger
(Alpinia purpurata Viell) is the most widely commercial species grown in the tropics.
The vegetative propagation of red ginger is customarily done by splitting the rhizomes
or by rooting the aerial offshoots produced in the axils of the inflorescence bracts.
From rhizome divisions having 2 or 3 aerial stems, flowers can be harvested in one year
after establishment. Plantlets from the aerial offshoots, however, require about 2 years
for the production of marketable blooms.
Red ginger grows best under full sunlight although some yellowing of the foliage has been
reported at high light. Optimum temperatures for plant growth are about 16 oC or higher.
At temperatures above 21 oC, an emerging stalk will flower in about 4 to 5 months.
Although the nutrient requirements for Alpinia are not well defined, high nutrient levels,
particularly N, are required for the production of marketable flowers. In Florida,
N applications from 1,440 to 5,680 kg/ha/year increase market flowers by 59% while
in Hawaii, no yield differences are found with N applications from 0 to 600 kg/ha/year.
References
Manrique, L.A. 1993. Greenhouse crops: A review. J. Plant Nutrition 16:2411-2477.
Manrique, L.A. 1994. Technology for greenhouse systems. Manrique International Agrotech,
Honolulu, HI. 263p.
Luigi's
P.O. Box 61145
Honolulu, HI 96839
Phone: (808) 285-3128 (cell)
Phone: (808) 732-4986
http://www.lava.net/manrique/luigi.htm
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