makes it very easy to control the quantities of nutrients that the plant absorb.
A small branch consisting of a growing tip with two or three leaves is cut and
immediately dipped in distilled water. Prior to dipping the cutting in a rooting
compound, a fresh cut is made just above thefirst cut. The cuttings are inserted one
inch deep into a rockwool cube or a hydrotone clay ball supporting medium. Plants
are supplied with vegetative fertilizer formula and exposed to a diffused light:dark
cycle (18 h:6 h) for vegetative growth. Rooting initiates in 2ā3 weeks, followed by
transplantation to a bigger hydroponic system (Fig.3.8).
3.3.1.5 Micropropagation
Cannabis is a wind pollinated plant which is highly allogamous in nature.
A significant amount of plant to plant variation in its cannabinoids profile and
content is observed, even though the crop is propagated through a single seed
variety. For the production of cannabinoids (or phytocannabinoids) female plants
are preferred over male plants since females produce higher amount of cannabi-
noids content. Once pollinated, female plants produce seeds at maturity whereas,
seed free plants (sinsemilla, a Spanish word for no seeds) are preferred to produce
higher yield of secondary metabolites. Therefore, to avoid formation of seeds,
removing male plants as they appear, screening of female clones for higher
metabolite content and, their conservation and multiplication using biotechnologi-
cal tools such as micropropagation is a suitable way to ensure the consistency in
chemical profile and mass-multiplication of aCannabiscrop for any pharmaceutical
interest.
In vitro regeneration is an efficient means of indoor conservation of plant
diversity. Moreover, this technique has the unique advantage of propagating the
desired taxon, independent of season, plant reproduction barriers and germination
hurdles. InCannabis, most of the in vitro regeneration protocols developed so far
has been via callus phase. Indirect organogenesis protocol developed forC. sativa
in our laboratory, is by using young leaves as source explant (Lata et al. 2010 ).
However, callus mediated regeneration is sometimes reported to lead to somaclonal
variations.
Although, different routes are available for plant tissue culture regeneration,
direct organogenesis is a common method of micropropagation that involves tissue
regeneration of adventitious organs or axillary buds directly from the explants.
Direct organogenesis holds advantages including less culture stages (no callus
stage), less or no chances of somaclonal variations thereby higher genetic stability.
We have successfully established direct organogenesis protocol forC. sativausing
nodal segments. Out of different concentrations of various growth regulators
(benzyladenine, BA; kinetin, Kn and thidiazuron, TDZ) tested, the quality and
quantity of shoot regenerants in cultures were better with 0.5lM TDZ. Elongated
shoots when transferred to half-strength MS medium supplemented with 500 mg
Lā^1 activated charcoal and 2.5lM indole-3-butyric acid (IBA, as compared to
3 Cannabis sativaL.: Botany and Horticulture 91