Gamma Irradiation of Bandera Espanola
Canna is the lone genus of the family Cannaceae which is only comprised of 20 species from Central and South America. The name originated from the Greek name for a certain type of reed. Since the type species, C. indica, can survive submerged in 6 inches of water, it behaves quite like the aquatic plant. However, it is not a native of India as the name implies, but of the West Indies. It reached India and the for human consumption in the Andes, the starch is made into glass noodles rest of Asia, and also Africa much later through Europe.
It is quite surprising that plant breeding of this tropical and subtropical genus was initiated and continuously done in temperate countries. The reason is more surprising because Cannas require a minimum of only six hours of sunlight in order to grow in almost any type of soil, and seedlings will produce flowers in less than a year. Once they bloom, artificial pollination may be done again.
THE PLANTS AND THEIR USES AND IMPORTANCE
Commonly known as Indian canna, Indian shot, edible canna, and arrowroot, the hard, round seeds of these plants are used by American Indians as bullets to kill their enemies. The rhizomes are harvested for the flour that is why the plants are cultivated as a root crop just like the arrowroot or uraro (Maranta arundinacea) but can also be eaten raw or cooked. In fact, it is still grown for human consumption in the Andes, Vietnam, and southern China where the starch is made into glass noodles or sotanghon.
In Spanish, its names are Bijao and Plantanillo, and in Tagalog, its names are kakuwintasan, kulintas, kuwintas-kuwintasan, saging-saging, tikas, or tikas-tikas, tikis-tikis, and tukas-tukas. Kuwintas means necklace or a string of beads. In fact, Spanish Christians use the seeds for rosary beads. Saging and plantanillo mean banana or plantain which the plant resembles.
The leaves of this herbaceous plant could grow up to 30 centimeters in length and 20 centimeters in width. These are arranged alternately in two opposite rows with the sheaths of the petiole covering the stem that carries the terminal inflorescence called a raceme or panicle. The large and showy flower of this plant which can reach a height of 1.5 meters is irregular and highly self-pollinated because pollen grains are shed at bud stage or before flower opening. Its anthers, on the other hand, are positioned near or above the stigma.
The plant is always bearing fruits and the seeds can be disseminated days after flower opening. The seeds can be used as material for jewelry and as source of purple dye. These are also used as moving elements of the kayamb, a musical instrument from Reunion, as well as the hosho, a gourd rattle from Zimbabwe. In India, the seeds are fermented to produce alcohol. Immature seeds are used as extender for tortillas.
On the other hand, young shoots that contain at least 10 percent protein are harvested and cooked as vegetable, while the stems and foliage are harvested for animal fodder. The fiber from stem is a good substitute for jute, while the fibers from leaves are made into paper. Even the rhizome has medicinal value. It is used as a diuretic when boiled and serves as a calmative in bladder spasms.
Canna x generalis (syn. C. hybrida)
This is the taxonomic name given to a group of plants that originated from C. indica then hybridized with other Canna species. Extensive natural and artificial backcrossing and intercrossing resulted in plants that are no longer distinguishable as distinctive species. The common names are Garden canna, Canna lily (although not a true lily), and Spanish flag or Bandera Espanola in Spanish.
There are hundreds of named cultivars. Plant height ranges from 30 inches (76.2 centimeters) to more than 8 feet (2.4 meters). Flower color varies from the rare white to creams and yellows, and to oranges and reds, as well as in combination of colors. Some cultivars have spotted, blotched or streaked flowers. The leaves are often green but the most striking cultivars have red, bronze, stripes or variegation. The flower of current cultivars is highly cross-pollinated owing to the lower position of anthers relative to the stigma.
It is one of the most popular flowering garden plants used in herbaceous border, patio or deck. The plants are also commonly used as landscaping materials. They are usually planted near irrigation or drainage canals or in wetlands to full sun and always watered. They are also grown in containers and grouped together for added impact. During the dry season, the foliage turns brown and dry up for the underground stem, actually a rhizome, to rest or become dormant until the onset of the wet season.
THE MUTANT VARIETIES
Caixiai, Caixui, and Huamei 1 are the first three mutant varieties listed in the International Atomic Energy Agency (IAEA) and the United Nation Food and Agriculture Organization (FAO) Mutant Variety Database (MVD). These were developed in China and registered in 1986.
Orange Siranut, Pink Peeranuch, and Cream Prapanpong are the products of gamma irradiation at Kasetsart University in Thailand. They are registered with the IAEA-FAO MVD in 1999 and named after the breeders. The flower color of the mutant variety is distinctly different from that of the original or control plant material. Yellow Arunee, also from Thailand, was registered in 2000, just two years after the irradiation of rhizome, selection of putative mutant, purification and multiplication of verified mutant clone. More mutant varieties were registered; six varieties were registered in 2001, 12 varieties in 2002, and 14 varieties in 2003. These were named after the Kasetsart University administrators and the research team members. The effective dose of gamma radiation ranged from 9.2 to 36.8 Gy with many desirable mutants developed by acute irradiation at 20 Gy. The registered mutant varieties have been released to ornamental growers and the public since 2000, and Filipinos visiting Thailand imported them as early as 2003.
Take note that gamma irradiation is an effective tool for improving Canna varieties when conventional hybridization could no longer be achieved due to pollen sterility and/or seedlessness. It is also valuable in creating variations among highly selfed C. indica.
GAMMA IRRADIATION OF CANNAS IN THE PHILIPPINES
Mutation breeding of Canna in the country was initiated on his personal capacity 4y Dr. Florencio Isagani S. Medina III in 1998 when he had communicated with Dr. Siranut Lamseejan of Kasetsart University. Although his profession is in animal science, mammalian cytogenetics to be specific, he wandered curiously into mutation breeding of Cannas after discovering the micronucleus in Tradescantia plants when working on mutation induction in fruitflies at the Philippine Nuclear Research Institute.
With the help of a student, Dr. Medina experimented on the rhizome of a red
variety of C. x generalis available during that time. The dose levels of gamma radiation tested were: 3, 7, 10, 30, 70, and 100 Gy. The two highest doses were lethal to the planting material while 3 Gy yielded similarly looking plants but with a different flower color. He hoped to produce dwarf mutants that are also free-flowering. At 30 Gy, many dwarf or slow-growing plants were obtained but they are difficult to propagate and not as floriferous. There were also changes in flower color, size, and shape of flowers, number of segments, color of the flower stalk and leaves in addition to the reduced plant height.
For C. indica, the author tried experimenting with seeds. Without scarification, dose levels up to 60 Gy resulted in germination of seeds 2-3 weeks earlier compared to unirradiated or control seeds (when scarified, unirradiated seeds germinate 10 days after sowing). This kind of result is often observed in seeds irradiated below the lethal dose level and it is very likely that gamma radiation destroyed the barriers for germination like the hard seed coat and/or the chemicals that inhibit germination. Flowering commenced four months after germination.
The resulting self-pollinated fruits are ripe a month later and can advance the mutant generation if it is viable for germination. In a year, the 7th vegetative generation can be attained. Therefore, the genetic stability of a putative mutant can be verified in less than two years as observed in Yellow Arunee.
CURRENT STATUS OF CANNA PRODUCTION IN THE COUNTRY
Old but dependable varieties of Canna x generalis grow abundantly like weeds along stretch of highways or national roads from Luzon to Mindanao. Occasionally, newly introduced varieties are planted in road islands or in a landscape.
In Silang, Cavite, several landowners raise different varieties of C. x generalis between coffee shrubs and under lanzones trees. In one Canna farm, at least 60 varieties were imported from The Netherlands for propagation and distribution to landscape plant suppliers.
Apparently, not many of us knew that a large “plantation” of Cannas is being tended by farm families in Mabalacat, Pampanga. The rhizomes are harvested regularly and exported by containerloads to England where it is most likely shipped to The Netherlands, the rest of The United Kingdom and elsewhere. At least 22 outstanding Canna cultivars are being grown in large quantities for international trade and Far East Plants Corporation is always on the lookout for something new or different with high potential for making money and a successful business.
On the Record
Much has been said about the ornamental value of Cannas. Let us know now its
unique features.
This is the only monocot plant whose seeds hibernate because of the hard seed coat that is impenetrable by air and water. The seed may remain in hibernation where there is a lack of its requirements for germination or when condition is harsh.
Canna indica is considered one of the world’s richest sources of starch. In fact, its rhizome has the largest starch particles of all plants. The size is thrice the size of a potato starch grain and it can be seen with the naked eye. The starch is also very digestible.
Aside from being an agricultural crop, Canna is also used to absorb many undesirable chemicals (elements and compounds) in the wetland environment. The plants have high tolerance to contaminants and can be used for soil remediation in polluted areas. However, Cannas not intended for consumption should be grown as phytoremediator.
The plants also absorb and break down organic pollutants such as pesticides, explosives, solvents, industrial chemicals, and other substances not normally found in plants and render these contaminants non-toxic. For this purpose, the ornamental C. x generalis is the best choice.
EPILOGUE
If I am also a mutation breeder of Canna, I will keep on subjecting rhizomes of the different varieties available to gamma irradiation to further improve their characteristics or to produce novel colors even if I have to pay for the irradiation services.
What is important is to have a constant supply of improved and new varieties of the ornamental plant. The global market is always looking for something new or different and there is always room for crop improvement such as drought tolerant varieties, plants with variegated leaves, dwarf, compact plants, and varieties that are resistant to pests and/or diseases to name a few.
If the mutant plants of Dr. Medina, now being propagated prior to registration, were mine, I would name the best selection or the clone with the most beautiful flower Victoria or Senora Carmen. He knows why.
