International Journal of Horticulture, 2015, Vol.5, No.21, 1-45
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Morphologically most of the ornamentals display a great diversity of types. Ornamental plants include a
heterogeneous and numerous groups of species with different reproducing systems, although mainly vegetative
propagated. The majority of them, including the most important cut flowers and potted plants are almost unknown
at the genetic level. Most of the ornamentals are landraces, cultivated in nursery, basically grown for
self-consumption or sale in markets. Proper characterization of these germplasm is needed in order to be useful for
breeders and farmers throughout the world. Systematic characterizations and evaluation of plant genetic resources
are prerequisites for the efficient use of material through conventional methods. Correct identification of
germplasm / new varieties is extremely important to protect plant breeder’s rights for commercial exploitation.
The existence of a large number of cultivars, maintained by vegetative propagation reinforces the need of a
reliable verification of cultivar identity for nurserymen and growers. One major problem in the floriculture
industry is that breeders do not disclose the parentage of new hybrids. Therefore, there is need for accurate
characterization system to trace out the parents of new varieties. The identification of cultivars or breeding lines is
very important in all horticultural and agricultural species in order to protect the rights of plant breeders (Wolff et
al., 1995).
Each cultivar of a cultivated crop species is expected to be unique in one or more specific characteristics. Mostly
plants are characterized and identified on the basis of qualitative or quantitative gross morphological characters.
Morphological, cytological and physiological attributes are normally considered as the primary criteria for
differentiating cultivars, but these characteristics alone have not always proven satisfactory. A more objective
method of identifying new cultivars was needed.
Various principles of taxonomic procedure developed from time to time regarding utilization of morphological
characters for characterization. Vegetative characters of leaves, stems, buds and growth habit of plants were
considered at the beginning for characterization. Leaf form, leaf apex, leaf margin, leaf petiole, leaf texture,
phylotaxy, spines or prickles, leaf coloration etc. were considered to be more reliable for characterization (Datta,
1986, Datta, 1987; Datta, 1993; Datta, 1999; Datta, 2004; Datta and Banerji, 1995;Datta and Singh, 1995; Datta
and Singh, 1999; Datta and Singh, 2001; Datta and Singh, 2002;Datta and Singh, 2003; Datta and Singh, 2004;
Datta and Singh, 2005; Singh and Datta, 1998; Singh and Datta, 1999; Singh and Datta, 2000). But these
vegetative characters were not stable due to environmental condition. Therefore, different features of reproductive
organs (flowers and fruit) were included in plant characterization and found to be more reliable. But
morphological characters were always found to be very important as it permit ready determination and correlation
of characters. Plant genetic resources play an important role in generating new crop varieties with the high yield
potential and resistance to biotic and abiotic stresses. Morphological, biochemical and molecular procedures are
currently being employed in evaluating plant genetic resources. Many works based on morphological characters,
cytology and enzyme electrophoresis have been used to study the diversity and phylogeny of different ornamental
species. Diversity and relationships of different taxa in various groups of crop plants have been worked out earlier
primarily on the basis of crossing and cytological data.
In addition to morphological characterization, molecular characterization is essential for elucidating the genetic
relationships among the different groups of this species. It is imperative that a set of descriptors need to be
developed to define the boundaries of a plant variety. The examination of a new variety (candidate variety) for
DUS generates a description of the variety, using its relevant characteristics (morphological, cytological,
biochemical and molecular) by which it can be described as a new variety.
Biochemical markers have received more attention as the data reflect more truly the genetic variability because
they are the direct products of genes (Perry and McIntosh, 1991). Chemotaxonomy, the concept of classifying
plants on the basis of their chemical constituents, is not new. However, at cultivar level little has been made of
chemical markers, although their importance to plant taxonomy at species and higher levels has been well
demonstrated. Many of the compounds which seem to have the potential for chemical markers are products of
secondary metabolism. Flavonoids and other phenolic are ubiquitous in higher plants and have been more widely
used in chemotaxonomy than any other groups of plant substances. Techniques most widely used for the
