General information about ornamental bulbs.

1. Cairo University Dep. Of Horticultural Ornamental Plant Faculty of Agriculture
Ornamental Bulbs
by
mayada el-sabwa
Supervisors
Prof. Dr. Safia Hamdy El-Hanafy
Prof. Dr. Amal Abdo NAsr

2. Ornamental bulbs
2017-2018
The Geophyte Plant
A geophyte is a plant that has the ability to survive
unfavourable environmental conditions by dying back
to underground storage organs.
A number of reserved carbohydrates such as starch, soluble
sugars, glucomannans and fructans; proteins, mineral salts and
water may be found in their storage organs (Miller et al., 1997).
The geophyte uses these reserves to sprout when environmental
conditions become favourable.
In general, these storage organs are not physiologically
dormant, even though there may be no aerial growth. The aerial
parts of the plants die off when there is drought, or during the
winter season and the underground part, which is the storage
organ, is left buried in the soil. Propagation in most geophytes is
by division or proliferation of the underground portion of the
plant such as bulbs, rhizomes and the tubers (Isaak, 2010).

3. Ornamental bulbs
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The Geophyte Plant
According to Al-Tardeh et al. (2008), the evolution
of geophytes in climatic areas with marked seasonal
variations has resulted in their adaptation to
periods of high or low temperature or drought.
They are able to do this by exhibiting adaptations
such as increased capacity for water binding,
tolerance of, or resistance to desiccation and
drought, and formation of subterranean organs.

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The Geophyte Plant
Tardeh et al. (2008) also stated that the order in which the different organs of
geophytes are differentiated is very crucial.
Syanathy
In situations whereby flowers and leaves appear at the same time, or when the
foliage is produced before flowering (as in Hyacinthus, Tulipa, Lilium and
Narcissus).
The synanthous type of flowering occurs in late spring.
Hysterathous
Sometimes the leaves expand after the flowers have opened.
The hysteranthous pattern occurs at the end of summer.
The rate of photosynthesis is very low from flower emergence until anthesis
because the reserves found in the storage organ is sufficient enough to allow flower
stem elongation and flowering.
Proteranthous
Flowers of some geophytes appear before the leaves, or the foliage dies down
before the flower is produced, as occurs in Boophane haemanthides.
In proteranthous geophytes, all photosynthesis takes place before flowering
occurs.

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The Geophyte Plant

6. Ornamental bulbs
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The Flowering Bulb
A bulb is made up of
a modified stem
containing a complete
miniature plant,
including embryonic
leaf, stem, and flower
parts, and surrounded
by fleshy scales
which provide food
for the young plant
and a basal plate
which produces roots
(National Gardening
Association, 2005).

7. Ornamental bulbs
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The Flowering Bulb
The Tunicate and Non-Tunicate (Scaly) Bulb

8. Ornamental bulbs
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The Flowering Bulb
The Tunicate and Non-Tunicate (Scaly) Bulb

9. Ornamental bulbs
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The Flowering Bulb
Droppers (Stolon plus bulblets) Contractile Bulbs

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The Flowering Bulb
Resting periods may occur between the death of shoots and the
replacement by basal buds. This could perhaps occur by the
death of the mother axis root system and the failure of the
daughter bulbs to establish a new root system until soil moisture
conditions improved.
In order for this to occur, each new growth starts from an
underground lateral bud, and that the underground should
develop adequate storage tissues to enable survival during the
unfavourable period.
The replacement of aerial parts of limited height and duration
by basal shoots tends to give clumped or tufted growth.
The possession of summer dormancy and a cold requirement is
good for the development of storage temperature treatments
allowing controlled flowering. The dormant bulb, however, is a
convenient stage for handling, transport and treatments (Isaak,
2010).

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The Flowering Bulb
Spring-flowering bulbs
such as daffodils, crocus,
tulips and hyacinth are
planted in the fall for
spring bloom.
They are also called
hardy bulbs because they
survive cold winter
conditions and they need
exposure to cold
temperatures in order to
flower properly (National
Gardening Association, 2005).
The Spring (Hardy) Bulbs

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The Flowering Bulb
Blooming throughout the spring months, they produce
bright, cheery, and often fragrant flowers that herald the
return of warmer weather.
The exact timing for planting hardy bulbs varies by region,
but they need to be in the ground before it freezes. Proper
planting time is important not only for winter survival, but
to insure adequate root development, which results in better
flower production.
Roots are formed soon after planting, and then they lie
dormant during much of the winter. When the weather
begins to warm, they utilize the stored energy to produce
flowers and leaves.
The Spring (Hardy) Bulbs

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The Flowering Bulb
Some members in this group, such as crocus, require fewer cold hours and
less warming to bloom, so their flowers emerge in early spring. Others, such
as tulips, need a longer cooling period and warmer temperatures to emerge,
so that they can bloom later in the spring (National Gardening Association,
2005).
Differences in blooming times allow planning a bulb garden that will
bloom for a desired number of weeks.
If chilling is enough, hardy bulbs usually sprout leaves when the weather
warms, but if they bloom at all, the flower stalks will likely be stunted.
Bulbs, like all other plants absorb nutrients from the soil and manufacture
their food through photosynthesis. Assimilates not used for their daily
living is stored in their storage organs for next year‘s growth. Once there is
enough energy in these organs, leaves turn brown and die. The bulb enters a
dormant state through the summer, autumn, and winter months until it is
time to sprout out again the following spring (Isaak, 2010).
The Spring (Hardy) Bulbs

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The Flowering Bulb
Summer-flowering bulbs,
including dahlias, begonias,
lilies and gladiolus are
planted in the spring for
summer bloom.
They are tender and may
not survive when the
temperature is very low
resulting in extremely cold
winter conditions.
However, there are
summer-flowering lilies that
are hardy enough to survive
winters in some areas.
The Summer (Tender) Bulbs

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The Flowering Bulb
After planting these bulbs, they grow much the same way
as spring-flowering bulbs, and produce and store food for
next year.
A number of bulbs in this category may keep their leaves
and continue to photosynthesize until autumn temperatures
turn cool.
It is a common routine for people in northern climates to
dig up tender bulbs and store them in a dark place that stays
cool enough to keep them from sprouting prematurely.
However, where winters are warm enough, tender bulbs
could be left right in the ground but it is important that the
hardiness zone of the bulbs are known so as to determine
their proper care (Isaak, 2010).
The Summer (Tender) Bulbs

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The Flowering Bulb
Digging annually prevents overcrowding and produces better quality and
larger bulbs.
Dig tunicate bulbs, such as snowdrop and narcissus, after the leaves die
back. Earlier digging reduces bulb size and subsequent flower quality.
Avoid drying bulbs in the sun, as this can cause scalding.
Clean them well after drying by brushing off dried roots and soil.
Store tunicate bulbs in trays with wire mesh bottoms to provide adequate
ventilation.
To prevent root development and mold growth while in storage, maintain
a humidity that will keep the bulbs dry, but not so dry as to shrivel—
usually around 75 percent.
Unless otherwise specified, store tunicate bulbs at about (27°C) for the
first two weeks after digging to cure them, and then lower the temperature
to around (9°C) until you plant them. If stored at higher temperatures, the
bulbs may not flower properly.
An underground cellar usually provides a good storage temperature after
curing.
Propagation of Tunicate Bulbs

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The Flowering Bulb
Offsets:
The simplest way to produce
more plants from tunicate bulbs
is to use offsets. Offsets are
small bulbs that develop
naturally from parent bulbs.
You can enhance tunicate bulb
propagation by digging parent
bulbs, separating, and planting.
Small offsets will usually
produce only leaves the first
year; do not expect flowers until
the second year or later.
Propagation of Tunicate Bulbs

18. Ornamental bulbs
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The Flowering Bulb
Some plants, such as hyacinths, do not readily form offsets and
therefore require artificial stimulation in the form of scooping, scoring,
coring, or sectioning to induce new bulblets.
Propagation of Tunicate Bulbs

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The Flowering Bulb
Dig scaly bulbs like lily six to eight weeks after flowering (except as
mentioned previously) or after the first light frost. Replant scaly bulbs
immediately after digging. Drying of either the bulbs or roots will reduce
the flower quality.
Propagation of Non-Tunicate Bulbs

20. Ornamental bulbs
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The Flowering Bulb
Scaling: Propagate scaly bulbs
by removing their outer scales
and planting them one-half their
length in a medium. Wait to dig
these bulbs until after they
flower. Plant the scales about an
inch apart in rows 6 inches apart.
New bulblets will form at the
base of the scales by fall, when
they can be planted out. A
replanted mother bulb will
regenerate more scales in one or
two years. If you cannot dig scaly
bulbs until fall, store the scales
in moist sand until spring, and
then plant.
Propagation of Non-Tunicate Bulbs

21. Ornamental bulbs
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The Flowering Bulb
Bulblets: Bulbs will also
develop underground on
the flower stalks of some
lilies. Pull the stalk from
the plant after flowering
and cover the basal portion
with moist rooting
medium. Bulbs formed in
this way can be separated
and planted out to form
new plants that should
flower in one to two years.
Propagation of Non-Tunicate Bulbs

22. Ornamental bulbs
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The Flowering Bulb
Both tunicate and non-tunicate bulbs can be planted in pots
and “forced” to flower indoors.
Plant bulbs for forcing in the fall so that their tips are about
one-half inch below the soil (or growing media) surface.
Thoroughly water after potting and store in a cool, dark place
such as a cellar or basement with temperatures between (4°C)
and (7°C).
If this type of storage is not available, bury the pots about 18
inches deep outdoors and cover with soil or straw mulch.
After a good set of roots forms in three to ten weeks
(depending upon storage conditions and type of bulb), bring
the bulbs into your house and place in a sunny location.
Forcing Bulbs

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The Flowering Bulb
Forcing Bulbs

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Corms
Corms are often confused with bulbs, but the two differ substantially. Corms are the
swollen bases of flowering stems; each corm is enclosed by a few thin leaves. Solid
cores of enlarged stem tissue form beneath these leaves. Bulbs, on the other hand,
are made up almost entirely of fleshy leaves.

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Corms
If you want to propagate or replant from
corms, dig then in the fall while the leaves are
still somewhat green or after a light frost. Dry
rapidly either outdoors or indoors. Only after
the corms and leaves have thoroughly dried
should the corms be cleaned and the cormels
separated.
Store in perforated plastic or paper bags,
below (15°C), with about 70 percent relative
humidity. If corm diseases are a problem,
reduce the temperature to less than (4°C).
Plant hardy corms such as spring-flowering
crocus in the fall, and tender corms such as
gladiolus in the spring.
Plants which grow from corms produce a new
corm at the base of each shoot every year. The
old corm is used up producing the plant. More
than one flowering shoot may grow from a large
corm. As a result, two (usually more) corms of
smaller size will form from the original corm.

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Tuberous Stems
Some plants, such as the tuberous
begonia and gloxinia, have enlarged
stems between the regular stem and
roots. This area of a plant is known
as the hypocotyl region, which
means tuberous stems are
modified hypocotyls.
These enlarged stems grow
annually, and can be propagated by
cutting into sections with at least
one bud. Dry each section for
several days after cutting before
planting. Use fungicides as
per the manufacturer’s instructions.
Wear gloves to protect yourself
from the chemicals.

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Rhizomes
A rhizome is a swollen
modified stem that runs
horizontally just under or
partially under the ground.
Rhizomes are the main axis of a
plant and contain vegetative
buds.
Rhizomes can be used for
propagation by cutting into
sections that each has at least one
bud. Plant the sections
horizontally, the same way they
were growing in the parent plant.
Plants suitable for propagation
by rhizomes include bearded iris
and canna.

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Tuberous Roots
Tuberous roots are sometimes
confused with tubers. Tuberous
roots, however, are actually root
tissue and don’t have “eyes” or
buds (meristems) on them as
tubers do.
When propagating with
tuberous roots, include a section
of the crown or stem with a bud
on it.
Tuberous roots such as dahlia
are usually divided so that each
root has one bud from the crown
of the plant with it.
Divide the clumps before the
buds begin to grow in February
or March just before planting.

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Care After Blooming
The first thing to recognize is what occurs between
flowerings and when the foliage yellows in early to mid-
summer determines the next seasons flower crop. This is the
time to add nutrients to support healthy bulb growth. This
can be done by broadcasting a granular fertilizer like 5-10-5 or
5-10-10 at the rate of 2 pounds per 100 square feet across the
bed. If your plantings are scattered, this works out to about 1
to 2 tablespoons per plant sprinkled around the clump.
Removing the seed pods after the flowers fade will have a
positive effect upon new bulb formation and bud set. This is
especially true of daffodils and tulips. Failure to do this will
result in smaller bulbs because the seed pods will continue to
develop and set seed. This requires energy reserves which
otherwise would go into bulb growth.

30. Ornamental bulbs
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Care After Blooming
The foliage should be allowed to sprawl out to collect as
much sunlight as possible.
Daffodils are sensitive to premature leaf removal and
there should be at least 4 to 6 leaves per bunch to support
bulb growth.
So as long as you leave the bottom two leaves intact, new
bulbs produced will develop to normal size.
Generally, tulips can be cut back in mid-June while
daffodils often take a month longer. At this time cut the
leaves back to the ground level and compost the leaf
material.

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Care After Blooming
Most bulbs flower very well in the first year regardless of
where they are planted. This is because the storage reserves are
already in place for the first year’s growth.
The second year will be a reflection of the condition of the new
planting site. If flower production is poor in subsequent years,
this may be due to age. Older clumps that have become
overgrown will produce small flowers and stems because of
crowding.
Tulips fit this pattern more so than daffodils and it is
recommended to divide tulip plantings every 3 to 4 years.
Tulips have a tendency to be less showy after the first two years
of growth.
Daffodils can often go several years without much concern.
In either case, the remedy is to dig the clumps of bulbs and
divide them. This is commonly done in the fall.

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Care After Blooming
However, the bulbs could be lifted from the soil anytime
after the foliage has turned yellow.
If you replant, take the time to improve the bed by adding
organic matter such as leaf compost or aged manure at the
rate of 2 to 3 bushels per 100 square feet. This should be
tilled or worked into the soil to a depth of about 8 inches
along with one pound of complete fertilizer. Bulbs set in
this way will begin to develop a new root system through
the summer, fall and winter.
If you are not ready to prepare the bed immediately, the
bulbs can be lifted and air dried in a cool, dry place like a
garage or basement area until fall planting preferably prior
to November 1 (Missouri Botanical Garden).

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Light and Darkness
Stancato and Mazzafera (1995)
propagated commercially bulbs of Hippeastrum hybridum by
twin scales, which are cultured in wet vermiculite in the
darkness until bulbil appearance.
They showed that twin scales kept under sun light produced
bulbils, that once transferred to the field, did not undergo severe
light stress. They had higher bulb dry weight and due to the
presence of green leaves they grew faster when transplanted to
the field than bulbils produced from scales kept in the darkness.
An intermediary treatment (a period of darkness followed by
transference to light) confirmed the advantages of producing
bulbils under sun light conditions.
It appears that in the field, growth of bulbs from dark grown
bulbils was retarded due to the strong competition among
leaves and roots for nutrients and assimilates.

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The Role of Temperature in the Growth and Flowering of Geophytes
Nadezda and Michèle (2013)
revealed that among several naturally occurring environmental
factors, temperature is considered to play a predominant role in
controlling proper growth and flowering in geophytes.
Most of them require a “warm-cold-warm” sequence to
complete their annual cycle.
The temperature optima for flower meristem induction and the
early stages of floral organogenesis vary between nine and 25 °C,
followed, in the autumn, by a several-week period of lower
temperature (4–9 °C), which enables stem elongation and
anthesis.
The absence of low temperature treatment leads to slow shoot
growth in spring and severe flowering disorders.

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The Role of Temperature in the Growth and Flowering of Geophytes

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Micropropagation
Geert-Jan de Klerk (2012)
mentioned that conventional propagation of bulbous crops
must be supplemented with micropropagation to satisfy the
requirements of present-day horticulture with respect to fast
production of disease-free, superior starting material.
The successive steps in micropropagation of bulbous crops are
reviewed: initiation, multiplication, bulb formation,
dormancy breaking and planting.
In the first two steps, new shoots or bulblets are generated by
axillary bud outgrowth or adventitious regeneration. During
initiation, endogenous contamination may be a severe problem
since bulbs grow subterraneously and have often been
propagated vegetatively in the field for many years.

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Micropropagation
Other drawbacks are insufficient axillary branching, poor
adventitious regeneration and inferior growth. The later,
inferior growth, is likely the most significant problem and is
caused by poor translocation of medium ingredients to the
growing regions within the explant.
 In micropropagation in bulbous crops, bulblets should be
produced because of, among others, easy handling and
acclimatization.
For optimal performance after planting in soil, preparatory
treatments are required in particular a dormancy breaking
treatment. A phase-change from juvenile to adult and protective
pretreatments are also profitable.
It is concluded that when major problems like that of inferior
growth have been solved, commercial micropropagation of
bulbous crops will experience a second heyday.

38. Ornamental bulbs
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Micropropagation

39. Ornamental bulbs
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Micropropagation

40. Ornamental bulbs
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Micropropagation

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Flower bulbs worldwide: perspectives on the production chain and research
Miller (2017)
showed that Ornamental geophytes, more commonly
known as bulbs, corms, tubers, rhizomes, crowns, tuberous
roots, and others, comprise an important segment of the
world's floriculture industry.
The three main markets for flower bulbs are:
1) Cut flowers
2) Potted plants
3) Use in the landscape
One can estimate that the cut-flower industry consumes
70% of all bulbs produced, pot plants, 10%, and landscape
plantings, 20%. The percentages per segment vary by
country and past industry or societal tradition.

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Landscape

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Cut Flowers

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Pot Plants