Bunching Onion 

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Table 1: Bunching onion links
Oregon State University	Purdue University, Indiana
Plants for a Future - UK	GPPIS (FAO)

Species: Allium fistulosum L.

Family: Liliaceae

Crop status: New

Varieties

Two main types of bunching onion are marketed in Japan, but there are more variations. Many varieties can also be grown as Spring onions (Nguyen 1992):

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• Short bunching onion: has four or five shorter pseudostems and tender leaves. Mostly summer varieties (Nguyen 1992).
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• It can be eaten after the plant reaches 5 cm in height, and the main product is the leaf / lamina (Vinning 1995).
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• Long bunching onion: has a single, long blanched pseudostem up to 50 cm in length and toughened leaves. Mostly winter varieties (Nguyen 1992).
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• The main product is the pseudostem / leaf sheath (Vinning 1995).

Genetic origins and distribution of the crop were studied by Friesen et al. (1999).

Agronomic trials

A variety x location x season trial is being conducted by Agriculture Western Australia (1999) and small plot trials are being conducted at Emerald and Biloela (David Midmore 1999, pers. comm.). Trial work has also been done at Gosford by Dr Vong Nguyen.

Production

Grown in all states of Australia (Lee 1995). Bunching onion is a perennial plant usually grown commercially as an annual. It does not develop a large bulb since it lacks any long day dormancy (Oyen and Soenoeadji 1994), but instead has a swollen shaft. Improved Japanese cultivars can no longer survive winter in cold climates (Grevsen 1989). Larkcom (1991) provides a range of production schedules for harvesting bunching onions at various stages of growth.

Climate: It can grow in a very wide range of climates, from Siberia to Java (Oyen and Soenoeadji 1994), and it is common to see it harvested from under snow (Larkcom 1991).

Daylength: Longer daylengths favour vegetative growth over flowering. The effect of longer daylength is reduced by cold temperatures (Yamasaki and Miura 1995).

Soil type: Well drained loams or sandy loams with a high organic matter and rich in phosphate are optimal (Warade and Shinde 1998). Heavy clays should be avoided (Larkcom 1991).

Mixed cropping and weeds: Bunching onions contain the allelopathic growth inhibitors vanillic acid and b-sitosterol which inhibit lettuce and chrysanthemum (Choo and Gan 1998) but promote rice seedlings (Choi 1993). Inhibition is greater when the mixed planting system is in boxes with drainage, than in boxes with open bottoms (Choi et al. 1999). There is some evidence of allelopathy against spiny amaranth (Amaranthus spinosus) by some varieties of bunching onion (Macharia and Peffley 1995). Roots also harbour the bacteria Burkholderia gladioli in Japanese soils, which has antifungal characteristics shown to affect Fusarium oxysporum f.sp. lagenariae (Kijima et al. 1998).

Bed preparation: Stems of long bunching onions should be covered by soil during growth to produce long white sheaths (Nguyen 1992). Plant seeds in furrows of 5 cm depth for short bunching onions, and 15 cm for long bunching onions, then mound soil over pseudostems 3-4 times as they grow, up to a height of 30 cm. First mounding 50 days after transplanting, last 20 days before harvest in summer, and 40 days in winter (Warade and Shinde 1998).

Temperature: Optimum temperature is 26-27°C during the day and 19-20°C at night (Hisatomi and Minegishi 1985) but it grows in a wide range of temperatures (Nguyen 1992). Bolting is usually induced by temperatures below 13°C and many varieties never flower in the tropics (Oyen and Soenoeadji 1994).

pH: Preferable range is 6.0 - 7.4 and it dislikes acid soils (Nguyen 1992, Oyen and Soenoeadji 1994).

Inoculation: Bunching onion varieties with long roots are less dependant on mycorrhizae (Glomus fasciculatum) for P uptake. All varieties benefit from inoculation, but short roots benefit more (Tawaraya et al. 1999).

Germination: Germination occurs in the cold but is faster in warmer temperatures. Seeds are usually sown in trays or beds and transplanted, but can be sown in situ. Sow about 6-12 mm deep and keep moist until emergence (Larkcom 1991). Optimum temperature for germination and seedlings is 15-25°C (Warade and Shinde 1998). Seed is best stored at low temperatures (-10 to 0°C) and water content (Dong et al. 1998). Glasshouse seedling growth can be enhanced by growing under 24 hour/day lighting, though the effect on plant vigour after transplanting is not known (Brewster 1990).

Plant density: Optimum plant density is higher for a smaller and/or younger product (see Larkcom 1991). For long varieties, plant at 3-15 cm within rows and 55-85 cm between rows (Warade and Shinde 1998). Sow at 8-16 kg/ha for direct seeding in the field (Oyen and Soenoeadji 1994) and 2-4 kg/ha in nurseries (Warade and Shinde 1998).

Transplanting: Short varieties are usually grown from seed, but very healthy clumps can be divided and replanted in their second season. Long varieties are often transplanted twice or more in China and Japan to save space and to increase plant strength. Plants from one sowing may also be transplanted at different times to stagger harvesting time. Transplanting increases root strength, making plants harder to pull (Larkcom 1991).

Water: Tolerant to water stress, but very susceptible to waterlogging (Oyen and Soenoeadji 1994)

Nutrition: Free ammonia is harmful to onions, so don't plant in freshly manured ground (Larkcom 1991). Recommended fertiliser in Japan includes 200-300 kg N/ha, 100-200 kg K/ha and 150-200 kg potash/ha, split across 3-4 doses (Warade and Shinde 1998). Inoculation with arbuscular mycorrhiza can improve P uptake, and therefore growth. Selection of fungal species depends on rate of P fertiliser, and both should be optimised for maximum crop growth (Tawaraya et al. 1996).

Harvest: Can be harvested year round (Oyen and Soenoeadji 1994). Harvest spring onions after 2 months, short bunching onions after 4 months, and long bunching onions 8 months after planting (Nguyen 1992). Profits are low because picking and bunching is very labour intensive (Hugh Allan in Daley 1998), but harvesting time can be reduced with mechanical lifting and manual pulling and loading (Sawamura et al. 1979).

Yield varies from an average of 22.5 t/ha in Japan (Figure 1) and similar in Korea, to 7 t/ha in Indonesia. The difference is partly due to different growing periods (Oyen and Soenoeadji 1994).

Postharvest

Handling: Harvested plants must be cleaned, and any dead or damaged leaves removed. Plants are then bunched and packed into boxes (Oyen and Soenoeadji 1994). Leaves may be trimmed to 10 cm of green (Nguyen 1992). Mechanical lifters have been developed, and trimmers to peel the outer leaves have been made using high pressure water or air (Warade and Shinde 1998).

Temperature: Store at 0°C (Nguyen 1992). Vacuum cooling is more effective at maintaining freshness than air cooling (Emura and Shimazaki 1984).

Humidity: Store at 90-95% relative humidity (Nguyen 1992).

Shelf life: Grown near population centres in Japan because freshness is important (Warade and Shinde 1998). Plants are stored for 4-5 months in northern Asia. They lose colour but retain much of the flavour (Larkcom 1991). Production of Propanethial S-Oxide can be used as a marker for freshness during storage, since production increases sharply when bunching onion starts to decay (Yamane et al. 1994).

Processing

A Japanese dehydration industry has commenced to supply as an additive for processed food (Warade and Shinde 1998).

Pests and diseases

Potential viruses are listed at Plant viruses online (Brunt et al. 1996).

Hardier than other onions, but still best to rotate every three years or less (Larkcom 1991). Bunching onion is resistant to many of the important pests and diseases of bulb onion, and has often been used as a souce of genetic resistance in breeding programs (Bark et al. 1994).

Downy mildew (Peronospora destructor). Common in moist weather. Causes pale oval spots on the leaves, which turn yellow and may later host a black secondary fungus (Nguyen 1992).

Alternaria leaf spot (Alternaria porri). Occurs in warm summer weather. Causes dark brown or black spots on the leaves, 3 mm diameter with a 1 - 3 cm yellow halo (Nguyen 1992).

Domestic market

Development potential was rated as high for the domestic processed (eg; dried) market (Vinning 1995).

Export market

(click here for exchange rates)

Development potential was rated as high for the export market. Production is common wherever there are Chinese, and major markets include Chinese communities and Japan (Vinning 1995). Current international trade is very limited (Oyen and Soenoeadji 1994).

It is a major crop in South Korea, with an annual production of 550 000 t. Prices are highest from June to November and reached 550 Won/kg, based on 1993 data (Vinning 1995). There may be a need for South Korea to import more materials for Kim Ch'i in both fresh and semi-processed forms (Nguyen 1998).

Figure 1: Japanese production of bunching onion (MAFF 1999).

Japanese consumption is about 4.5 kg/person/year (Otsubo 1996). This is lower per person than South Korea although production levels are similar at around 550 000 t (Figure 1), but it is one of the crops on which households spend the most money (JETRO 1995). Japanese value an extremely long (up to 50 cm) blanched stem. Imports are increasing to offset decreased production but the CIF price is falling, though not at the same rate. About 90% of imports are from China. There is a 5% tariff (Vinning 1995). Production fluctuates from 380 000 to 410 000 t, and is lowest from April to September (Pan 1995).

Taipei has an annual wholesale throughput of about 14 000 t. Prices rose in 1994 to about NT$33/kg from below NT$20/kg previously. There is a 40% tariff for fresh or chilled bunching onion (Vinning 1995).

Related projects

Tim O'Hare (1 July 1998 - 31 June 2001). Extending the shelf life of leafy vegetables. ACIAR Project Number 9416.

References

Bark, O. H., Havey, M. J. and Corgan, J. N. (1994). Restriction fragment length polymorphism (RFLP) analysis of progeny from an Allium fistulosum x A cepa Hybrid. Journal of the American Society for Horticultural Science 119(5): 1046-1049.

Brewster, J. L. (1990). The effect of the duration of daily irradiance on the growth rates of seedlings of leek (Allium ampeloprasum L.) and Japanese bunching onion (Allium fistulosum L.). Scientia Horticulturae 43(3-4): 207-211.

Brunt, A.A., Crabtree, K., Dallwitz, M.J., Gibbs, A.J., Watson, L. and Zurcher, E.J. (eds.) (1996 onwards). `Plant Viruses Online: Descriptions and Lists from the VIDE Database. Version: 16th January 1997.'

Choi, S. T. (1993). Studies on the biologically active substances from Allium fistulosum. II. Allelopathic substances from Allium fistulosum. [Korean]. Journal of the Korean Society for Horticultural Science 34(5): 355-361.

Choi, S. T., Ahn, H. G., Kang, S. W., Park, I. H., Jung, W. Y. and Chang, Y. D. (1999). Effect of root exudates of Allium fistulosum on growth of chrysanthemum. [Korean]. Journal of the Korean Society for Horticultural Science 40(3): 371-375.

Choo, K. T. and K. S. Gan (1998). Allelopathic substances from Allium fistulosum inhibit the growth of Compositae crops. [Korean]. Journal of the Korean Society for Horticultural Science 39(3): 333-337.

Daley, P. (1998). Giant radish shows promise. The Land (26 Feb): 8.

Dong, H. Z., Gao, R. Q., Yin, Y. P. and Li, S. F. (1998). Study on the physiological-chemical characteristics of Welsh onion (Allium fistulosum L.) seed under different storage and package conditions. [Chinese]. Scientia Agricultura Sinica 31(4): 59-64.

Emura, K. and A. Shimazaki (1984). Effect of precooling systems on the retention of freshness in Chinese onion, Allium fistulosum. [Japanese]. Bulletin of the Saitama Horticultural Experiment Station No(13): 43-49.

Friesen, N., Pollner, S., Bachmann, K. and Blattner, F. R. (1999). RAPDs and noncoding chloroplast DNA reveal a single origin of the cultivated Allium fistulosum from A-altaicum (Alliaceae). American Journal of Botany 86(4): 554-562.

Grevsen, K. (1989). Effects of sowing dates on different varieties of Welsh onion (Allium fistulosum L.) under temperate coastal climate. Acta Horticulturae 242: 319-324.

Hisatomi, T. and M. Minegishi (1985). Management evaluation for hoso-negi (Allium fistulosum L.) production in simple gravel culture. [Japanese]. Bulletin of the Nara Agricultural Experiment Station No(16): 36-42.

JETRO (1995). Fresh Vegetables: Access to Japan's Import Market - Mini Report 1995 August. Japan External Trade Organisation, Market Report

Kijima, T., Namai, K. and Goma, H. (1998). Biological control of soil-borne diseases by antifungal microorganisms. [Japanese]. Soil Microorganisms No(52): 65-71.

Larkcom, J. (1991). Oriental vegetables: the complete guide for garden and kitchen. London, John Murray 232 pp.

Lee, B. (1995). Audit of the Australian Asian vegetables industry. RIRDC Research Paper No. 95/13. Canberra, Rural Industries Research and Development Corporation 97 pp.

Macharia, C. and E. B. Peffley (1995). Suppression of Amaranthus spinosus and Kochia scoparia - evidence of competition or allelopathy in Allium fistulosum. Crop Protection 14(2): 155-158.

MAFF (1999). Abstract of statistics on agriculture, forestry and fisheries. Statistics and Information Department, The Ministry of Agriculture, Forestry and Fisheries of Japan. (URL: http://www.maff.go.jp/abst/form1/5ab.html).

Nguyen, V. Q. (1992). Growing Asian vegetables. Agfact, NSW Agriculture H8.1.37.

Nguyen, V. Q. (1998). Report on the study tour to Japan on pickling of Asian vegetables and attendance at an international symposium on vegetable quality in Seoul, Korea 1997. Gosford, Horticultural Research and Advisory Station. 96 pp.

Otsubo, M. (1996). Asian vegetables into Japan: export potential, opportunities and myths. In: Proceedings of an Asian Food Industry Conference (Ed; Lee, B. and Prinsley, R.). RIRDC Research Paper No. 96/9: 22-28.

Oyeni, L. P. A. and Soenoeadji (1994). Allium fistulosum L. In: Plant Resources of South-East Asia: Vegetables. (Ed; Siemonsma, J. S. and K. Piluek). Wageningen, The Netherlands, Pudoc Scientific Publishers 73-77.

Pan, C. (1995). Market opportunities for fresh and processed Asian vegetables. RIRDC Research Paper No. 95/14. Canberra, Rural Industries Research and Development Corporation 117 pp.

Sawamura, N., Inoue, K. and Karahashi, M. (1979). Mechanization of Welsh onion [Allium fistulosum] cultivation. [Japanese]. Journal of the Central Agricultural Experiment Station (30): 31-48.

Tawaraya, K., Imai, T. and Wagatsuma, T. (1999). Importance of root length in mycorrhizal colonization of Welsh onion. Journal of Plant Nutrition 22(3): 589-596.

Tawaraya, K., Kinebuchi, T., Watanabe, S., Wagatsuma, T. and Suzuki, M. (1996). Effect of arbuscular mycorrhizal fungi Glomus mosseae, Glomus fasciculatum and Glomus caledonium on phosphorus uptake and growth of Welsh onion (Allium fistulosum L.) in Andosol. [Japanese]. Nippon Dojohiryogaku Zasshi 67(3): 294-298.

Vinning, G. (1995). Market Compendium of Asian Vegetables. RIRDC Research Paper No. 95/12. Canberra, Rural Industries Research and Development Corporation 386 pp.

Warade, S. D. and Shinde, K. G. (1998). Other Alliums. In: Handbook of vegetable science and technology: production, composition, storage and processing. (Ed; Salunkhe, D. K. and Kadam, S. S.). New York, Marcel Dekker 415-432.

Yamane, A., Yamane, A. and Shibamoto, T. (1994). Propanethial S-Oxide content in scallions (Allium fistulosum L. variety Caespitosum) as a possible marker for freshness during cold storage. Journal of Agricultural & Food Chemistry 42(4): 1010-1012.

Yamasaki, A. and H. Miura (1995). Effect of photoperiod under low temperature on the growth and bolting of Japanese bunching onion (Allium fistulosum L.) (Japanese). Journal of the Japanese Society for Horticultural Science 63(4): 805-810.