Talk:Canna indica

Missing data!
The tubers are cultivated for food... Someone upload a picture of the edible tuber of this plant!Undead Herle King (talk) 14:59, 21 November 2012 (UTC)

C. indica is not cultivated for food. C. discolor is the agricultural variety.

The photo supposedly of Indica var. flava is of an Italian Group cultivar. This is supposed to be a page devoted to the indica species in the canna family. Instead, it is trying to compete with the parent page, and I won't comment on the inaccurate information. I suggest that it reverts to its original intent. — Preceding unsigned comment added by Giantshoulders (talk • contribs) 21:56, 7 January 2020 (UTC)

Adding new sections
Hi! We are agricultural sciences students, and as part of a group project, we did a literature review about the cultivation of Canna indica. We would like to make the information available on Wikipedia. Any feedback is appreciated.--DelHas (talk) 06:57, 26 November 2020 (UTC)


 * In the meantime, I have added the new sections to the Wikipedia article as described below.--DelHas (talk) 11:58, 28 November 2020 (UTC)

''Firstly, we suggest to change the heading "As food" to "Uses" and then have subheadings "As food" and "As biodegradable plastics". For the "As food" section, we can contribute some information about China; we would put this below the paragraph beginning with "The Spanish took notice of achira in 1549 when...". And we want to add a new section "As biodegradable plastics".''

As food
In the 1950s, Canna indica was introduced to China as a perennial ornamental crop. It was mainly planted in parks and home gardens in Guizhou for ornamental purposes. From the late 1950s to the early 1960s, China suffered from a severe food shortage, known as the Great Chinese Famine. During this time, weeds, tree roots, tubers, etc., became an important food source. Canna indica was also part of this famine food. As a consequence, the plant became known as a food crop. Today, the rhizomes are processed to starch, vermicelli, white wine, and ethanol. Due to the use as a food crop and relatively low diseases and pests pressure, Canna indica has become a characteristic crop for large-scale cultivation in China. The research in China mainly focuses on processing methods, and additionally, there are few studies on varieties and cultivation techniques.

As biodegradable plastics
In China, Canna indica starch and polyethylene are used as raw materials to produce biodegradable plastics. This type of plastics is affordable and can degrade completely into fertilizer for crop production in just a few months. The method for producing Canna indica plastics consists of fusing 60 - 80% of Canna indica starch and 20 - 40% of polyethylene uniformly at 240°C.

Secondly, we want to add some sections to the existing "Cultivation" part.

Field and climate requirements
To cultivate Canna indica, the substrate should be rich, humiferous, and light. The optimal substrate consists of a deep, rich and well-drained soil in a sunny place with a pH between 5.5 - 7.5. The rhizomes should be planted at 10 cm deep, after the last frost. Although it can tolerate dry periods, occasional irrigation will be beneficial for the yield. Canna indica is a plant that can withstand low temperatures (down to -10°C in regions with a mild climate). Nevertheless, the foliage can already be affected at 0°C. Canna indica can be found at elevations up to 2,000 meters above sea level in humid tropical climates. The plant can also be cultivated in subtropical and warm temperate zones. The best climate for growing Canna indica is found in areas where annual daytime temperatures are between 12°C and 32°C. The plant prefers a mean annual rainfall between 1,000 - 4,500 mm, but it can tolerate 500 - 5,000 mm per year.

Propagation
Canna indica is usually propagated by putting either the rhizome tips or the whole rhizomes in the ground. Because the rhizomes are quickly perishable, storing them properly between the harvest and the next planting time is essential. The large rhizomes can be divided in spring before the new shoots appear. Additionally, Canna indica can also be propagated by seeds. Seedlings growing early in spring are able to flower the same year they are sown.

Sowing
The amount of rhizomes used for sowing is normally about 3000 - 4500 kg/ha, and the planting density should not exceed 22,500 plants/ha. When putting the rhizomes in the ground, the sprouts should point upwards. The ideal spacing between plants in a row is 60 - 70 cm, and the spacing between rows is 70 - 80 cm. Because Canna indica grows quite tall, it should be cultivated at locations with relatively low wind speed to prevent bending over. Germination begins when the soil temperature is above 16°C, while the optimal temperature is 20 - 25°C. 20 - 30 days after sowing, seedlings emerge.

Fertilization
Canna indica is reliant on fertilizer to achieve a good yield. In the early stages, seedling fertilizer should be applied during the first tillage and spread according to seedling conditions. Up to 750 kg/ha of ternary compound fertilizer (N, P, K) can be applied. When applying fertilizer, direct contact with the base and leaves should be avoided. Before flowering, the second tillage can be combined with the second fertilizer application to promote the growth of underground stems and roots. Applying fertilizer evenly on both sides of the roots helps them to absorb water and grow uniformly.

Weed control
Fast growing weeds can have a negative impact on Canna indica, especially before the 4th leaf appears. Two weed control methods are usually practiced: Firstly, applying herbicides to eradicate weeds and secondly, carrying out mechanical operations depending on the weed growth.

Harvest
About six months after planting, the crop can be harvested. At this time, the rhizomes are tender and succulent. However, the rhizomes are mainly harvested later, after 8 - 10 months, when they reach their maximum size. Canna indica is suitable as an emergency crop in case of shortfalls due to its long durability in the ground. It can be harvested during times when the cultivation of other crops is not successful.

Harvesting is done manually by pulling out the crop with a shovel or another digging tool, shaking off the soil, and then cutting the stems to separate the rhizomes.

Yield
The yield varies depending on the region of cultivation and its climate and soil conditions. In certain locations, the yield of Canna indica can be higher than other starchy crops like cassava and arrowroot. The average rhizome yield is believed to be around 22 - 50 tons per hectare, whereas the starch yield is about 2 - 5 tons per hectare and can reach up to 10 tons per hectare. Observations show that the highest yield in rhizomes does not necessarily correspond to the highest yield in starch.

Diseases
Cannas suffer from relatively few diseases compared to other species. Nevertheless, some diseases have been recorded to affect Canna indica. One of them is Canna rust (Puccinia thaliae), a fungus that causes orange spots on the leaves. In addition, plant viruses occur: Hippeastrum mosaic virus, Tomato aspermy virus, Canna yellow mottle virus and Canna yellow streak virus which can cause mild or strong symptoms from streaked leaves, stunted growth to distorted blooms. Furthermore, there is Botrytis (fungus), a mold that affects the flowers.

Many different Canna varieties exist, and some of them are resistant to a certain type of disease. To prevent mold, the soil should be well-drained without too much soil moisture or stagnating water. To diminish the risk of spreading diseases, dead and infected leaves should be removed.

Pests
The Canna leaf roller moth (Calpodes ethlius) has been seen on Canna plants in the US. It is a caterpillar known as the worst pest for this plant and primarily found in the Southern United States. This pest causes damages by laying its eggs in the bud of developing stalks. To protect the eggs from predators and insecticide, caterpillars use sticky webs to keep the leaves from unfurling. The pupate then feed on the leaves which can lead to losses of yield due to reduced photosynthesis.

The Japanese Beetle (Popillia japonica) is another leaf ragging pest with mainly small consequences for Canna plants. This beetle feeds on the part of the leaves between the veins. In its originating region in Japan, it does not cause a lot of damages. However, in the US it has no natural predator and can cause serious damages on Cannas and other plants.

The Bird Cherry Oat Aphid (Rhopalosiphum padi) has been recorded to affect stored rhizomes. Although this pest has not been causing severe damages yet, it can particularly affect plants grown in greenhouses and can be combatted with parasitical wasps. It is a more common pest on cereals.

Thirdly, we suggest to add a new section "Traditional starch production" after the "Cultivation" section.

Traditional starch production
Rhizomes for starch extraction should be processed within days after the harvest due to their perishability. The following steps of traditional starch production in Colombia show that the process is dependent on a significant supply of fresh water.

In rural areas in Colombia, the recently harvested rhizomes are packed up in sacks and transported to the processing site. The first step is cleaning the rhizomes by washing them in tanks. The second step is grating the rhizomes mechanically to disrupt the cell walls to release the starch. The third step is sieving to separate the starch from the rest of the rhizome pulp: The grated rhizomes and additional water are passed manually or mechanically through a sieve. The fourth step is separating the starch from the sieving water by letting the starch granules sink to the bottom of a tank. The fifth step is washing the starch multiple times with clean water. The last step is drying the starch by exposing it to the sun. The starch is now ready to be stored or transported.