Title: Vegetarian
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Permanent Link: http://ufdc.ufl.edu/UF00087399/00188
 Material Information
Title: Vegetarian
Series Title: Vegetarian
Physical Description: Serial
Creator: Horticultural Sciences Department, Institute of Food and Agricultural Sciences, University of Florida
Publisher: Horticultural Sciences Department, Institute of Food and Agricultural Sciences, University of Florida
Publication Date: September 1983
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Bibliographic ID: UF00087399
Volume ID: VID00188
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.


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A Vegetable Crops Extension Publicatior

\VeXablc Crops Department 1255 SPP Gainesville. FL 32611* Telephone 392-213

Vegetarian 83-09

September 8, 1983



A. Vegetable Crops



Tropical Root Crops Edible Aroids
Plant Nutrient Removal Full Bed Mulch Tomatoes


SA. Bitter Cucumbers

The Institute of Food and Agricultural Sciences is an Equal Employment Opportunity Affirmative Action Employer authorized to provide research,
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A. Vegetable Crops Calendar

1. 1983 Florida Tomato Institute
September 8, 1983

2. Florida Association of Extension Professionals
1983 Annual Conference
Don CeSar Beach Resort
September 7 9 1983

3. American Society for Horticultural Science
80th Annual Meeting
McAllen, TX
October 16-21 1983

4. Florida State Horticultural Society
The Plaza Hotel
Daytona Beach FL
Nov. 1 4 1983

B. New Publications

1. Slicer Cucumber Cultivar Trial, Research Report
SAN 84-1 by J.M. White

2. Carrot Production Trials, Research Report
SAN 84-2 by J.M. White

Both are available from Sanford AREC,
P.O. Box 909, Sanford, FL 32771

3. Broccoli and Cauliflower Production in Florida,
Extension Circular 555 by S.M. Olson and M. Sherman
is available from your local County Extension Office.



A. Edible Aroids ( Araceae)

The edible aroids include plants from several genera that store
starches in stem structures that generally develop into corms.
The most common include: taro (Colocasia esculenta (L.), Schott.),
cocoyam (Xanthosoma spp. (L.) Schott.), swamp taro (Cyrtosperma
chamissonis (Schott.) Merr.), giant taro (Alocasia macrorrhiza
(L.)Schott.) and elephant yam (Amorphophallus spp.). Taro
originated in Asia and is considered to be one of the first
domesticated food plants. Cocoyam originated in tropical America,
giant taro probably originated in Sri Lanka, swamp taro grows wild
in the Indo-Malaysian region and elephant yam grows wild in
Southeast Asia, suggesting those areas as centers of origin.
World edible aroid production is estimated at 4.4. x 10
Mt/annum. Major production regions include Nigeria, Ghana, Japan,
Papua New Guinea and Ivory Coast with 40, 28, 13, 5, and 4% of the
world production, respectively. The production is in mixed
cropping systems or in back yard gardens.

The first introduction of edible aroids into the southern part of
the U.S. is not well documented. Caribbean Indians probably
carried cocoyam planting material with them in their travels among
the islands. Taro arrived during the times of slave trade in the
Colonial period of the United States. Hawaiians probably brought
taro with them to Hawaii from Tahiti about AD 1100.

In the family Araceae, the edible aroids cover several genera with
the most widely grown being taro and cocoyam. The cultivated
species of cocoyam, known as tannia in the English-speaking
Caribbean, include: white-fleshed X. caracu and X.
sagittifolium, yellow-fleshed X. atrovirens and purple-fleshed
X. violaceum. Their separation into separate species needs
closer investigation, since fertile seeds can be recovered in most
interspecific crosses within this group.X. brasiliense is grown
only for its edible leaves and does not form a large stem or corm
as do the others. Additional less common species and several
varieties have been outlined by Coursey.

Taro cultivars are often divided into two groups: 1) wetland or
flooded taro that produces one large corm with few cormels, and 2)
dryland taro that produces several small cormels rather than one
large corm. The former, known by the name dasheen in the
English-speaking Caribbean, appears to have a shorter shelf life
and has been established as C. esculenta var. esculenta. The
latter, known as eddoe in the Caribbean, has been classified as
C. esculenta var. antiquorum. Other less common aroids include
swamp taro, giant taro and elephant yam. These are very regional
in their cultivation. Besides being eaten as a staple food the
edible aroids are also grown for ceremonial purposes, starch


production and security against times of famine. In the SoutI
Pacific and Caribbean, the aroids are often the only food plants
remaining after a hurricane has passed over the land. Cultivai
names are very regional and are often related to plant physical
characteristics such as pigmentation or places. For example,
'White' and 'Jamaica' are taro cultivars that are commonly found
in the Caribbean. Presumably, the latter was grown originally in
Jamaica and was carried to the other islands. Much confusion in
edible aroid taxonomy remains and research in this area would be
beneficial. Until such research is done, there is little use in
dividing the aroids into groups smaller than those described

The first organized introduction of aroids into the U.S. was
initiated by the U.S. Department of Agriculture Board of Plant
Introduction early in the twentieth century. Through regional
trials a cultivar of C. esculenta from Trinidad was selected for
advanced trials. This dasheenn" was adapted to production as far
north as the Carolinas, maturing in seven months. It was widely
tested in the Southeast over a 10 year period. However, a strong
market for the crop never developed, despite considerable
promotion of it as a new food.

Large scale cocoyam production in Florida began with the arrival
of Cuban exiles early in the 1960's. Acreage expanded to the
current estimated 2,000 ha of production in Dade County. Taro
production in Florida is limited to a few hectares. However,
there remains potential for greatly expanded production.
With a few exceptions, all edible aroid cultivars produce a
starchy main cylindrical corm, ranging up to 500 cm in height and
200 cm in diameter, depending on growing conditions, plant
genotype and age. Depending on species and cultivar, few to many
lateral starch-filled cormels develop below the soil surface at
the corm base as the plant matures. For the white and
purple-fleshed cocoyam, the preferred types are those that produce
large cormels with a distinct dormancy period, since sprouted
cocoyam cormels have a lower starch content and inferior eating
quality. In this case the corm is not eaten. These types have a
long shelf life and are better suited for shipping than the other

Although the starch-filled corms or cormels are the part most
often consumed, young unopened leaves and occasionally fully
expanded leaves as well as blanched petioles of selected clones
are eaten as cooked potherbs. Leaves are often used in the
preparation of callaloo, a popular soup in the Caribbean. The
starchy corm or cormel is prepared and consumed in many of the
same ways as the potato. However, peeling and boiling appear to
be the most common method of cooking. For populations dependent
on wetlands for energy foods, edible aroids may be a better choice
than rice from the standpoint of human nutrition. In fact, taro
equals the potato for amino acid content. Acridity, associated


with presence of a proteinaceous compound in all plant parts is a
problem in most genotypes. Although the acridity is usually
destroyed in processing, some genotypes require more processing
than others before they are edible.

The aroids grow best in warm, humid regions with regular
rainfall. Soil type is generally not a limiting production
factor. The ability to control water and drainage appears to be
more important. Some taro genotypes can be grown under flooded
conditions, provided that water is not allowed to overheat. Taro
has a better tolerance of saturated soils than cocoyam, which must
be grown on beds if flooding is likely. Taro also possesses some
degree of salt tolerance since it is grown on South Pacific

Soil is cultivated prior to planting to remove weeds. Cuttings
are planted in rows at up to 20,000 plants/ha in pure stand or
they are planted at various spacings in mixed plantings. The top
1 to 5 cm of the corm with 5 to 15 cm of the petiole attached is
usually used for planting material. For wetland taro, planting
material generally has a long petiole with a small portion of the
corm attached, while cocoyam cuttings have more corm and less
petiole. Once planted, growth quickly begins if moisture is
adequate. When planting material is in short supply, small
unmarketable cormels can be used or the corm can be divided into
several sections. These are stored until the wounds heal and one
or two buds have enlarged. When sections of the corm other than
the top are used, multiple shoots may develop. This is
considered to be undesirable and excess shoots are often removed.
Fertilizer at a rate and timing similar to cassava is recommended
with modifications determined by soil analysis and climatic
factors. The use of fertilizer late in the growing season is not
usually recommended. It has been suggested that late
fertilization leads to an undesirable texture change in the edible
portion. Generally the edible aroids are planted in areas where
irrigation is not needed or is easily applied if needed.
Supplemental irrigation is not cost effective unless the market
price is very high.

Weeds are controlled through cultivation by hand or tractor and in
the case of wetland taro, by flooding. Herbicides are being
tested and can be effective in controlling some weeds. However,
none are registered for use on the edible aroids. Insect pests
are mostly regional, causing varying degrees of damage. Aphids,
spider mites and whiteflies are common, but seldom cause yield
reduction. Meloidogyne spp. and Rotylenchulus reniformis nematode
associations are the most common of those observed on the edible
aroids. Damage appears to be quite variable. More research is
needed before the full impact of nematodes on the edible aroids
will be known. Diseases appear to cause greater problems, with
corm and root rots caused by Pythium spp., Sclerotium rolfsii,


Phytophthora spp.,Rhizoctonia spp. and Erwinia spp. being the
most important. Of these, leaf burning disease of cocoyam,
probably the same as "mal seco" in Puerto Rico, is reported to be
caused by Pythium myriotylum and results in root death and yield
reduction. Use of cormels rather than corms as propagative,
material reduces disease severity. Foliage diseases caused by
Alternaria tenuissima, Cerospora spp., Cladosporium colocasiae or
Xanthomonas spp. can cause damage on a regional basis. Virus and
virus-like diseases can result in a wide range of symptoms
including plant death. Dasheen mosaic virus (DMV) infection
appears to be world-wide causing leaf distortion and feather
mottling in some cocoyam genotypes, while taro is generally
symptom-free. Yield reduction from DMV infection has not been
documented in cocoyam or taro.

Aroid harvesting is labor intensive with little mechanization. It
begins 7 to 15 months after planting when the plants are mature.
Maturity is not a discrete event, but rather it is based on plant
age and growth patterns. When taro is mature, the main plant
produces progressively smaller leaves until the corm goes
dormant. It is considered to be mature and ready for harvest when
reduction in leaf size is noticeable. In cocoyam, maturity is
based on the size of the corm and cormels rather than leaf
development. For the white and purple-fleshed cultivars
harvesting begins when the cormels are of marketable size, 12 to
20 cm long and 6 to 9 cm in diameter. When grown in mixed
plantings, soil is removed from the base of the main plant and the
larger cormels are removed. The soil is then replaced to allow
the plant to continue growing. This process can be repeated 3 to
4 times after which the entire plant is usually removed.
Harvesting of the yellow-fleshed types is based on the main corm
development with the preferred diameter being at least 10 cm.

Flooded taro in Hawaii is drained prior to harvest, allowing the
soil to crack and break the roots. Fields are reflooded and corms
are harvested with the aid of hand tools. The leaves are then
removed and the corms are washed and later rafted to the road.
For cocoyam in Florida, plant tops are removed prior to
harvesting. A lifting device similar to the potato digger is used
to bring the corms and cormels to the soil surface. They are then
sorted and packaged by hand. Taro marketing is commercialized in
Hawaii with some being processed into poi, a cooked paste made
from the red pigmented cultivar 'Lehua maoli' and others into
chips. In southern Florida cocoyams are marketed in a similar
manner to other fresh vegetables. Otherwise, in the tropics,
corms and cormels are harvested as needed and a day's supply is
carried to the market for local sale, while so0e are exported to
Europe and North America. Refrigeration at 10 C with a high
relative humidity as well as treatment with a fungicide dip are
used to prolong storage life in shipment.
(Reprinted from article by S.K. O'Hair,AREC Homestead)


B. Plant Nutrient Removal-Full Bed Mulch Tomatoes

Extension agents, fertilizer field men and crop consultants
need to consider soil test results, fertilizer recovery and
crop removal when designing sound fertilizer programs for
vegetable growers. Most of the crop removal figures
available for vegetables are rather old, are from canning
crop studies, or are from western (arid) production areas.

A recent study by Extension workers in the Manatee-
Hillsborough area on full bed mulched tomatoes may be useful
to other areas with some modification. The study showed that
the fresh weight of the "average" plant grown commercially in
this area weighed 10.6 lbs. without fruit or roots. Several
hundred samples on 9 farms spring and fall crops are
averaged. The yield of 26.3 Ibs of marketable fruit and 13.1
Ibs. of immature fruit was from the high yielding grower
group but the top growers often exceeded this 39.4 lbs total
by 5 or 6 lbs.

The composition on a dry weight basis was found to be:

Element Plant(%) Fruit(%)

N 1.95 3.08
P 0.20 0.45
K 2.81 4.88
Ca 3.28 0.18
Mg 0.80 0.22

The average dry weight of the plants on a percentage basis
was 7.9% and for the fruit (mature and immature) average
3.9%. The dry weights are only important for calculation
purposes as recommendations are usually based on pounds of
nutrients per acre relating to the fresh weight of a growing

The calculations generated show the removal by 1,000 tomato
plants grown under similar cultural conditions. In most
tomato production areas of Florida the application rate of
240 Ibs of N, 150 lbs. of P205 and 360 lbs of K20 is used.
The acre unit is quite variable because distance between beds
can range from 5 to 12 feet; whereas, the number of plants
per 1,000 linear bed feet is much more constant (18 to 30
inches between plants).


The removal was as follows:








The next question is how can these figures help in
formulating fertilizer recommendations?

If we consider the rather widely accepted efficiency of
uptake figures: N- 50 to 70%, P- 20 to 30% and K- 50 to
60% we could develop a potential base need level of NPK:

Element Uptake Efficiency
of uptake
(Ibs) (%







These oxide requirements then must be translated into
material equivalents, of course. For instance, it would
require approximately 400 pounds of a 20% superphosphate to
supply the 81 lbs of P205 absorbed per 1,000 plants.

These needs would be modified considerably depending on soil
test results, whether the field is a new or old field, and
the yield level desired. These figures are for growers who
want to aim for high yields.

The 1,000 plant concept, or 1,000 feet of bed row, or even
the 100 lineal feet of bed, provides ready conversion for the
wide range of "acre" concepts that exist in the Florida
tomato industry.



A. Bitter Cucumbers

Both consumers who buy fresh cucumbers in the marketplace and
those who grow them at home are quite often able to taste an
objectionable amount of bitterness in the fruit. Many theories
have been advanced to explain the cause of bitterness and how to
deal with it.

Certain cultivars seem to be bitter more often than other
cultivars, but even the non-bitter types are sometimes bitter.
There is speculation that many cultural conditions contribute to
the bitterness. Irrigation frequency, plant spacing,
fertilization rates, and harvest period have all been considered
to have something to do with it. Most of these factors were
studied, but none were found to be influencing the degree of

Perhaps the best explanation was provided by Dennis Pittenger in
the California newsletter, Vegetable Briefs. According to
Pittenger, the bitterness is due to the formation of two terpenoid
compounds called "cucurbitacins" in the seedlings, roots, stems,
leaves, and fruit. The presence of this bitter-causing compound
in the plant tissue is controlled genetically. A dominant gene
produces extremely bitter fruit and a recessive gene inhibits the
formation of cucurbitacin in foliage and fruit.

Coupled with the cucurbitacin is an enzyme, elaterase, which
hydrolyzes the cucurbitacin to non-bitter compounds. It is this
elaterase activity that is thought to be governed by non-genetic
influences such as environment and cultural practices.

The amount of bitterness in cucumbers appears to vary from year to
year and from one location to another. Such a phenomenon may
occur because elaterase production is stimulated or depressed
under certain environmental conditions. Cool temperatures in
particular seem to enhance bitterness.

When the bitter principle accumulates in the fruit, it accumulates
non-uniformly among fruits and within the fruit. The bitterness
is always found in and just under the skin of the fruit, never in
the interior. The bitterness penetrates more deeply at the stem
end than at the blossom end.

To minimize the problem, cucumbers should be grown under cool
conditions whenever possible, and with optimum soil moisture and
fertilization. New varieties should be selected, since they tend
to have less bitterness than older varieties such as 'Straight


Since bitterness is in or near the peel, removing the peel is the
best way to remedy the situation. Direction of peeling makes no
difference, according to the results of peeling tests. In very
bitter cucumbers removal of a good portion of the stem end might
be necessary in addition to deep peeling.

Prepared by Extension Vegetable Crops Specialists

D.N. Maynard

G.A. Marlowe

M. Sherman
Associate Professor

S.P. Kovach
Assistant Professor

S.M. Olson
Assistant Professor

W.M. Stall
Assistant Professor

J.M. Stephens
Associate Profe


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