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Propagation of Canna

May 10, 2013
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canna seed pods - Propagation of Canna

Canna fruit (green) and a ripe seed pods

The propagation of canna is possible by sexual, asexual and by micro-propagation in the laboratory.

Sexual propagation – Propagation of Canna

  • Seeds are produced from sexual reproduction, involving the transfer of pollen from the stamen of the pollen parent onto the stigma of the seed parent.
  • In the case of Canna, the same plant can usually play the roles of both pollen and seed parents, technically referred to as a hermaphrodite.
  • However, the cultivars of the Italian Group and triploids are almost always seed sterile, and their pollen has a low fertility level.
  • Mutations are almost always totally seed sterile.
  • Canna seeds have a very hard seed coat, which contributes to their dormancy.
  • Germination is facilitated by scarification of the seed coat, which can be accomplished by several techniques.

Pollination

  • The species are capable of self-pollination, but most cultivars require an outside pollinator.
  • All cannas produce nectar and therefore attract nectar consuming insects, bats and hummingbirds that act as the transfer agent, spreading pollen between stamens and stigmas, on the same or different inflorescence.

Genetic changes

  • Since genetic recombination has occurred a cultivar grown from seed will have different characteristics from its parent(s) and thus should never be given a parent’s name.
  • The wild species have evolved in the absence of other Canna genes and are deemed to be true-to-type when the parents are of the same species.
  • In the latter case there is still a degree of variance, producing various varieties or minor forms (forma).
  • In particular, the species C. indica is an aggregate species, having many different and extreme varieties and forms ranging from the giant to miniature, from large foliage to small foliage, both green and dark foliage and many different coloured blooms, red, orange, pink, and yellow and combinations of those colours.

Asexual propagation – Propagation of Canna

Canna rhizomes - Propagation of Canna

Rhizome

Division of plant parts

  • Outside of a laboratory, the only asexual propagation method that is effective is rhizome division.
  • This is done by using material from a single parent, and as there is no exchange of genetic material such vegetative propagation methods almost always produce plants that are identical to the parent.
  • After a summer’s growth the horticultural cultivars can be separated into typically four or five separate smaller rhizomes, each with a growing nodal point (‘growing eye’).
  • Without the growing point, which is composed of meristem material, the rhizome will not grow.

Micro propagation - Propagation of Canna

Micropropagation

Micro-propagation

  • Micro-propagation, or tissue culture as it is also known, is the practice of rapidly multiplying stock plant material to produce a large number of progeny plants.
  • Micro-propagation using in-vitro methods that produce plants by taking small sections of plants and moving them into a sterile environment, where they first produce proliferations that are then separated from each other and then rooted or allowed to grow new stem tissue.
  • The process of plant growth is regulated by different ratios of plant growth regulators or PGRs, that promote cell growth.
  • Many commercial organizations have attempted to produce cannas this way, and specifically the “Island Series” of cannas was introduced by means of mass produced plants using this technique.
  • However, cannas have a reputation of being difficult micro-propagation specimens.

Virus elimination

  • Micro-propagation techniques can be employed on specimens infected with Canna virus and used to dis-infest plants of the virus.
  • It is possible to use a growing shoot tip as the explant; the growing tip is induced into rapid growth, which results in rapid cell division that has not had time to be infected with the virus.
  • The rapidly growing region of meristem cells producing the shoot-tip is cut off and placed in vitro, with a very high probability of being uncontaminated by virus, since it has not yet had contact with the sap of the plant which moves the virus within the plant.
  • In this way, healthy stock can be reclaimed from virus contaminated plants.

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