chromosome segregation to daughter cells and cell wall formation, resulting in
larger than average daughter cells with multiple chromosome sets. Polyploidization
is a powerful tool for improving desirable plant characteristics and is an effective
breeding method to induce variation (Griesbach and Bhat 1990 ; Chakraborti et al.
1998 ; Nakano et al. 2006 ). Modifying ploidial levels, changes some morphological
and anatomical characteristics such as thickness of stomata, number of leaves,
stems and roots, leaf length to width ratio, pore size, size and texture of theflower,
the pollen offlowering and seed length, generating individuals that can cope with
fluctuating environments, exploit new niches or outcompete progenitor species
(Leitch and Leitch 2008 ).
Induction of tetraploidy can be an effective method to increase biomass and
improve the pharmacological characteristics. Leaves, stems and roots of herbs that
are useful organs in tetraploid plants are usually larger in diploid plants. Tetraploid
plants may also show increased biomass for the production of more products (Gao
et al. 1996 ).
17.1.3 Polyploidy inCannabis
Polyploidy has not been shown to occur naturally in Cannabis. However, it may be
induced artificially with colchicine treatments. We examined the induction of tet-
raploidy by colchicines and their effects on anatomical, morphological and bio-
chemical characteristics in Cannabis plants.
17.2 Methods
17.2.1 Tetraploid Induction inCannabis
There are two alternative methods for colchicine application. In the one method,
colchicine is applied directly to ungerminated seed. The disinfected seeds are
placed onfilter paper in Petri dishes and provided with an aqueous solution of
colchicine, so that thefilter paper is fully saturated. In the second method, col-
chicine is applied to the apical meristem of growing seedlings. We used latter
method for induction of polyploidy inCannabis.
17.2.2 Apical Tip Meristem Treatment of the Seedlings
Colchicine was applied to the apical meristem of growing seedlings. Immediately at
the emergence of true two type leaves seedlings had expanded (7 days sowing),
17 Induction of Polyploidy and Its Effect onCannabis sativaL. 369