Download TOPIC COMPARATIVE ANATOMICAL, KARYOTYPIC AND

TOPIC
COMPARATIVE ANATOMICAL, KARYOTYPIC AND PYTOCHEMICAL STUDIES OF FOUR
CULTIVARS OF Caladium bicolor (AITON) VENT.
BACKROUND OF STUDY
Caladiums are native to tropical rainforest and the equatorial rainforest regions of South America
and Latin America from South Mexico to Peru (Michael et al, 1991). Taxonomically Caladium
(Aiton) Vent. is a genus in the Araceae (Arum) family which are commonly referred to as
elephant ear, heart of Jesus, Angel wings etc (Michael et al, 1991). Two main types of caladiums
are available -fancy leaved with large colorful somewhat heart-shaped leaves and lance or strap
leaved characterized by narrow, elongated leaf (Black and Tjia, 2003). Propagation is mainly
through bulbs which thrive best on slightly acidic mediums rich in organic matter: temperatures
between70-90℃; light intensity of 250-5000 foot candles (Raymond, 2004; Cover and pool,
1973; Steve, 2003; Lecoufle and Marcel, 1982). Caladiums are raised from seeds, tissue culture
or bulbs which are underground, flat, cylindrical to irregular-shaped tubers with numerous
vegetative buds (‘eyes’) from where the shoots emerge (Neal et al, 2010). The leaves are showy
with various markings. Caladiums lack stems as the leaves are borne on long, 6-12 in (15-30.5
cm), fleshy petioles (leaf stems) that arise directly from the underground tuber (Steve, 2003).
Petioles attaches to the showy broad leave in a peltate manner (Steve, 2003). The inflorescence
is solitary and arises synchronously with the first leaves or shortly after. The spadix, which is
about 1cm shorter than the spathe, comprises of two portions separated by a constriction
(Maia and Schlindwein, 2006). Mature spathe blade exhibits a uniformly white spathe blade of
about 8-12cm long (Maia and Schlindwein, 2006). There is substancial evidence to believe that
Caladium is pollinated by Cyclocephalni beetles which are attracted to the plant by the sweet
odour of heated spadix.The insects visits the plant and force their way into the floral chamber
through constricted areas of the spathe (Maia and Schlindwein, 2006). Insects are not generally
troublesome on caladiums. Occasionally aphids and thrips may become a problem. The most
serious insects on caladiums are chewing insects such as caterpillars, which chew leaves, making
the plant very unsightly. Caladiums can also be damaged by nematodes, which builds up as
plants are grown in the same area year after year and can be handles with soil treatment with
nematicide prior to planting. The most common disease of caladiums is tuber rot which occurs
when tubers are stored or held at temperatures below 60°F (15.5°). Chalking or dry rot of tubers
is also a disease which frequently occurs in storage, dough not too detrimental to the tuber
(Black and Tjia, 2003; Michael et al, 1991). The use of 6kg osmocote (14-14-14) or Nutricote
(13-13-13) applied per cubic meter of planting medium has been reported most suitable as
Caladium accepts many types of fertilizer (Cover and Poole, 1975). Magnesium deficiency may
result when planting medium attains a high pH i.e. above 7.0 (Michael et al, 1991; Evans et al
2006). Caladium when in contact with skin causes irritations, burning and swellings. Choking
occurs when eaten. These are due to the presence of oxalate crystals distributed throughout
the plant body (Nova Scotia Museum, 2007).The chromosome number has been reported to be
2n=2x=30 i.e. a diploid number o 30 and a haploid number of 15 (Darlington and Wylie, 1955).
In a bid to keep from predators (herbivores) caladiums produce irritating substances made of
raphides (oxalate crystals) which makes it difficult to be feed on. Also, they utilize the act of
mimicry, a situation whereby their multicoloured leaves makes them appear to herbivores as
variously spotted snakes (Dutta, 2009).Their colourful nature makes them ideal gifts especially
during celebrations. Also their striking contrast with evergreen plants enables their as
foreground of boarders and foundation plantings. Potted Caladiums are also used in interior
landscapes and acceptable widely in small plantings or planted in commercial and professional
buildings (Paul, 2009; Evans et al., 1992). Extracts of the plant are applied to the eyes for the
cure of convulsion and on the body for skin discolouration (NNMDA, 2008).
AIMS AND OBJECTIVES OF THE STUDY
i.
ii.
iii.
iv.
v.
To provide basic anatomical information for ease of identification of Caladium
bicolor cultivars from other plant species.
To assay plants for the presence and nature of oxalate crystals believed to be the
cause of plant irritation.
To analyze, through phytochemistry, the contents of medicinal value believed to be
useful in the treatment of skin discolouration and convulsion.
To determine and compare the chromosome number as this will be useful in the
taxonomy of Caladium bicolor.
To prepare and compare the karyotypes of the chromosomes of each cultivar which
will be useful in the cytotaxonomy of the plant.
METHODOLOGY
Source of materials
The plant materials will be collected from Amokwe Udi in local government of Enugu state.
Their corms will be dug up from the soil in a forest area around Amokwe udi, along Udi –Orji
river expressway.
Morphological studies
The morphological features of the plant cultivars will be studied so as to determine the floral
arrangement, nature of spathe and spadix, and corm structure. Pictures will be taken where
necessary.
Anatomical studies
The transverse sections of leaf stem and petiole of each cultivar will be studied using free hand
sectioning. The epidermal peels of the abaxial and adaxial layers as well as the presence of
oxalate crystals will be studied. The sections will be stained appropriately, examined and
photographed using the procedures outlined by Cutler, 1978 and Okoli, 1992.
Cytological Studies
Mitotic studies
Fresh roots will be harvested form cultivars between 8.am- 12pm from corms grown in
separate containers after about six (6) days of planting and will be cut about 6-10cm into
0.002M solution of 8-hydroxyquinoline for pre-treatment. They shall afterwards be transferred
into Carnoy’s fluid for fixation. Roots will also be stored in 70 % ethanol for future use. For
mitotic studies, the roots will be hydrolyzed in 5% HCL at 60℃ for about 5 minutes. Slides of the
specimen will be prepared and stained with lacto-propionic orcein for the observation of
metaphase chromosome under the microscope. The procedure is clearly outlined by Okoli,
1992.
Phytochemical studies
The photochemistry of the plant leaf extracts shall be analyzed and compared to assay for
contents of medicinal essence especially in the treatment of convulsion and skin burn.
EXPECTED OUTCOMES
i.
ii.
iii.
To provide accurate information on the nature and quality of chromosomes of
Caladium for cyto-taxonomy.
To encourage the use of the plant as drug for the cure of convulsion and skin
discolouration.
To provide informative research on the pant anatomy for taxonomical purposes.
REFERENCES
Conover, C. A. and R. T. Poole (1973). Influence of fertilizer level, apical bud removal and
tuber orientation on forcing of Caladium bicolor. Horticultural Science, 16:226227.
Cutler, D.F (1978). Applied Plant Anatomy. Longman Group Limited, London. 100pp.
Darlington, C.D. and A.P., Wilie (1955). Chromosome Atlas of Flowering Plants. George
Allen and Unwin, London.
Dutta, A.C. (2009). Botany for Degree Students. Oxford University Press. 708pp.
Evans, M. R., B. K. Harbaugh and G.J., Wilfret (2006). Caladium as potted and landscape
plants. Cooperative Extension Service, Institute of Food and Agricultural
Sciences, University of Florida.
Lecoufle, P. and L.O., Marcel (1982). Propagation (sic) of Caladium, Alocasia and similar
genera. Aroideana, 5:8-10.
Maia, A. C. D. and Schlindwein (2006). Caladium bicolor (Araceae) and Cyclocephala
celata (Celeoptra, Dynastinae): A well established pollination system in the
Northern Atlantic Rainforest of Pernambaco, Brazil. Plant Biology, 8:529-534.
Michael, E, J., Erwin and R. Heinz (1991). Caladium production. Minessota Flower Growers
Bulletin, 40(1):1-6
Nea. L., Evenhuis and G. E., Leuis (2010). Caladium bicolor naturalized on the island of
Hawaii bishop Records of Hawaii Biological summary. Bishop Museum
Occasional papers, 107: 44-45.
Nigerian Natural Medicine Development Agency-NNMDA (2008): Federal Ministry of
Science and Technology. Medicinal Plants of Nigeria, South-East Zone, 1:28-29.
Nova Scotia Museum (2007). The poison plant patch. Museum of Natural History, Halifax,
Nova Scotia.
Okoli, B. E (1992). Field Herbarium and Laboratory Techniques. Mbeyi & Associates
(NIG.) Limited. 236pp.
Paul, A, T. (2009).Growing Caladiums at Home, Cooperative Extension bulletin (726),
University of Georgia.
Raymond, J.H. Kessler Jr., (2004).Greenhouse Production of Caladiums. Alabama
Cooperatives Extensijon System-Alabama A&M and Auburn University. ANR1256 (www.aces.edu).
Steve
Christman (2003).
(floridata.com).
Caladium
bicolor.
Floridata-Tallabasse,
Florida,
USA.