Jpn. J. Trop. Agr. 46(4): 247-258, 2002

Taro in Northern Vietnam: Its Uses, Cultivation, and Genetic Variation

Masahiko MATSUDAand Eiji NAWATA*

The Japan Center for Area Studies, National Museum of Ethnology, Osaka 565-8511, Japan * Graduate School of Agriculture , Kyoto University, Kyoto 606-8502, Japan

Abstract Uses and cultivation of species were investigated in the Red River Delta and the mountainous region of northern Vietnam, to analyze the present situation and to compare the two ecological areas. Morphological characteristics , ploidy, and ribosomal DNA (rDNA) variation were examined for the taro collected. esculenta var . esculenta, C. esculenta var, aquatilis, C. gigantea, Xanthosoma sagittifolium, X violaceum, macrorrhiza, and A, odora were detected in the surveys. The uses and habitats of C. esculenta var. aquatilis were linked to the agroecosystems of the delta. The was frequently found around canals and farmers' ponds in the delta, and its petioles and stolons were harvested for human consumption and pig fodder. Its importance as pig fodder seemed to have declined gradually, due to the recent social and economic changes . Colocasia esculenta var. esculenta was grown mainly as a cash crop in the delta. On the other hand, it was grown for local consumption in the shifting cultivation system at a mountainous site. Genetically close cultivars of var. esculenta were found within each ecological area , but not between the areas, based on the Restriction Fragment Length Polymorphism (RFLP) analysis of rDNA. This distribution in northern Vietnam may reflect the influence of differences in the dispersal in Asia. Xanthosoma spp. were found at all the sites, and there was a similarity in their uses and cultivation. The accessions of Xanthosoma spp. were genetically uniform. was not very common, but was widely distributed and used as a vegetable. Key words Agroecosystem, Alocasia, Colocasia, Ploidy, RFLP, Xanthosoma

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要 約 ベ トナ ム北 部 の 紅 河 デル タ と山 地 部 に お い て,タ ロ イ モ 数 種 の 利 用 と栽 培 につ い て 調 査 し た.そ の現 状 や 変 化 を農 業 生 態 ・ 社 会 ・経 済 的 な側 面 か ら考 察 し,ま た,異 な る生 態 地 域 間 で の 比 較 を お こな った.さ ら に,収 集 した30系 統 の タ ロ イモ につ い て は , 形 態 ・倍 数 性 ・リボ ゾー ムDNAに お け る制 限 酵 素 断 片 長 多 型(RFLP)の 調 査 か ら遺 伝 的 変 異 を 明 らか に した .本 研 究 で はColocasia esculenta var. esculenta, C.esculenta var. aquatilis, C.gigantea, Xanthosoma sagittifolium, X.violaceum, Alocasia macrorhizaお よ び A. odoraが 観 察 され た.デ ル タ の調 査 地 で は(C. esculentavar. aquatilis(2n=2x=28)が 灌 漑 水 路 脇 や 池 の周 囲 に 頻 繁 に群 生 して お り , その 葉 柄 や 匍 匐 枝 は 野 菜 や ブ タの 飼 料 と して利 用 され て い た .こ のvar. aquatilisは デ ル タの 農 業 生 態 系 で機 能 して い る こ と が わ か っ た が,近 年,水 路 や 池 の 舗 装 や 飼 料 の 多様 化 な どに よ り 、 その 重 要 度 が 低 下 して い た .C. esculenta var. esculenta(2n=2x,3x=28,42) は デ ル タ で は 商 品 作 物 と し て栽 培 され,一 方 ,山 地 部 で は 自給 用 に焼 畑 で 栽 培 され て い た.リ ボ ゾ ー ムDNAのRFLP分 析 よ り,デ ル タ地 域 あ るい は 山地 部 の 調 査 地 内 で は それ ぞ れ 遺 伝 的 に 近 縁 なvar . esculentaの 品 種 が み られ た.し か し,両 地 域 に 分 布 す る近 縁 な 品 種 はみ られ な か っ た.こ の 分布 の 傾 向 は,ア ジ ア に お け るC. esculentaの 複 数 の 伝 播 経 路 が この 地 域 に影 響 した 結 果 と考 え られ た.Xanthosoma spp.(2n=26)は す べ て の調 査 地 に 分 布 し,そ の 利 用 や 栽 培 に 類 似 性 がみ と め られ た.収 集 したXanthosoma系 統 も 遺 伝 的 に均 一 で あ っ た.Colocasia gigantea(2n=28)も それ ほ ど頻 繁 で は ない が野 菜 と して広 く複 数 の 調 査 地 に 分布 して い た.Alocasia odoya(2n=28)は 薬 用 と して用 い られ,A. macyoyyhizaは 山 地 部 で ブ タの 飼 料 と して 頻 繁 に採 集 され て い た . キ ー ワー ド 農 業 生 態,倍 数 性,Alocasia, Colocasia, RFLP, Xanthosoma

narrow sense, has been a very important crop Introduction among them, and is cultivated widely in Asia, The term taro in a broad sense is used for Oceania, and Africa. HOTTA5)classified it into two edible aroids including several genera: Alocasia, varieties, var. esculenta and var. aquatilis. Var. Colocasia, Cyrtosperma, Schismatoglottis, and aquatilis is a wild type taro with long stolons Xanthosoma6). Most of the species originated in which grows mostly in wild or ruderal habitats, Asia and Oceania, whereas Xanthosoma had whereas var. esculenta is a cultivated ones5). originated in the New World. Their leaf blades, Several taro species are distributed widely petioles, , and cormels have been mainly in Vietnam. HUE8)reported that C. esculenta, C. used for human consumption and animal gigantea, X. sagittifolium,X. violaceum,A. macrorrhiza, fodder7). Colocasia esculenta, which is taro in the and Cyrtosperma chammisonis were grown in Received Nov. 22, 2001 farmers' fields and home gardens under a wide Accepted May 18, 2002 range of environmental conditions throughout 248 Jpn. J. Trop. Agr. 46 (4) 2002

Vietnam. HODEL and GESSLER4)suggested that Methods taro was a key species to home gardens in Field surveys were carried out from October southern Vietnam, and reported the distribution 1998 to January 1999. Surveys of wide areas in of C. esculenta, X sagittifolium, A. macrorrhiza, northern Vietnam were conducted first, followed and A. odora from the Mekong Delta to the by surveys at the five sites selected. Information highland regions. about the uses, cultivation, and cultivars of taro In this paper, we report the utilization and was collected widely through direct observation cultivation of taro species in northern Vietnam. and interviews with the farmers and staff To analyze the present situation of taro species members of the communes and hamlets. from an agroecosystem as well as social and Thirty taro plants were collected from economic perspective, relevant information on farmers' fields, home gardens, local markets, the agriculture is broadly described. The surveys etc., and were grown in pots in a greenhouse at were mainly conducted at five sites, located in Kyoto University, Japan. Morphological data were the Red River Delta and the mountainous region, collected at the research sites and/or in the to compare different ecological areas. Additionally, greenhouse. Descriptions of the characteristics we indicate the morphological characteristics, were chiefly based on IPGRI criteria (descriptions)9). ploidy, and ribosomal DNA variation of taro plants Chromosome number and ribosomal DNA collected, to discuss the genetic relationship of (rDNA) variation were examined for 10 accessions taro among the sites. of C. gigantea, Xanthosoma spp., and A, odora using the methods described below. While in Research Sites and Methods the other 20 accessions of C. esculenta these

Research sites parameters had been surveyed previously using Five sites (hamlets) were selected for this the same methods, for discussion about study. The research sites were located in two dispersal routes of taro in Asia14). different ecological areas, i.e. the Red River Delta Somatic cell chromosome numbers were and the mountainous region, and the people determined according to the methods of COATEs living there belonged to various ethnic groups, et al.2) and KURUVILLA and SINGH11). Fresh root such as the Kinh, Dao, and Hmong people. tips were pretreated with 0.2% aqueous colchicine Ecological and ethnological information about or 2 mM 8-hydroxyquinoline for 4 hours and the five hamlets is briefly indicated in Table 1, fixed in a mixture of ethanol and acetic acid (3:1 and their locations are shown in Fig. 1. v/v). The tips were then hydrolyzed in 1 M HCl Elevation of the sites ranged from 0 m for 4 minutes at 60•Ž and stained with Schiff's above sea level (asl) in the delta to 1090 m asl in reagent. Each stained root tip was squashed in the mountainous region. Two hamlets, Noi 45% acetic acid and examined under an optical Hoang Tay and Ninh Binh, were located in the microscope. Red River Delta region defined by BINNIEet al.1). Restriction Fragment Length Polymorphism At the two sites of the delta, the Kinh people (RFLP) of rDNA was obtained as follows. DNA have lived and practiced mainly paddy rice samples (1.5 ƒÊg each), which were isolated using cultivation. Ninh Binh is located in the hill area the cetyltrimethylammonium bromide (CTAB) and at a higher elevation than Noi Hoang Tay. method of MURRAY and THOMPSON18) with some The other three sites, Suoi Nhung, Hua Tat, and modifications, were digested with a restriction Sao Do II, were selected in the mountainous endonuclease, Taq I, following the manufac- region. Minority ethnic groups, such as the Dao ture's instructions (Takara Co., Ltd.), and were and Hmong people, have lived, respectively, in electrophoresed in 0.8% agarose gels using TAE Suoi Nhung and Hua Tat. They have mainly (40 mM Tris, 40 mM acetic acid, 1 mM EDTA, practiced shifting cultivation on sloping land. In pH 8.0) as a running buffer. DNA fragments Sao Do II, the households of the Kinh people were transferred onto nylon membranes (Hybond who migrated from the delta region in the 1960s N+, Amersham Co., Ltd.) following the manufac- live and most of them are affiliated to a milk ture's instructions. To detect polymorphic company of the neighboring city, Thao Nguyen ribosomal DNA fragments, the DNA samples City were hybridized with a taro rDNA probe. The DNA probe was obtained from pCe 34.11, a MATSUDAand NAWATA:Taro in northern Vietnam 249 250 Jpn. J. Trop. Agr. 46 (4) 2002

Fig. 1 Research sites. Shaded portion for the sites in northern Vietnam corresponded to the area of the Red River Delta defined by BINNIE et al.1) pUC19 plasmid clone constructed by MATTHEws Taro in the Red River Delta et al.15). This plasmid contained a 2.8 kb Taq I Noi Hoang Tay, about 80 km east of Hanoi, fragment from the large intergenic spacer region which is one of the five hamlets belonging to of rDNA, between the 18S and 26S ribosomal bang Que Commune, Dong Trieu District in RNA genes. For hybridization, the Taq I fragment Quang Ninh Province, is located at the eastern was purified, labeled with digoxygenin-dUTP, and edge of the Red River Delta. Rice, which was detected enzymatically, according to the manufac- cultivated over 78% of agricultural land of the ture's instructions (Boehringer Mannheim Co., commune, was the major food crop and income Ltd.). source, as in most of the areas in the delta. Predominant cropping pattern in the commune Results and Discussion was rice double cropping, which had been Uses and cultivation of taro in northern Vietnam started in the 1970s, with a winter crop of maize The present utilization and cultivation of or sweet potato. Vegetables, such as cabbage, taro in northern Vietnam are described here in Chinese cabbage, onion, garlic, lettuce, soybean, detail (summarized in Table 1). Emphases was groundnut, and so on, were also frequently grown mainly placed on Noi Hoang Tay hamlet in the on a small scale as cash crops. Irrigation and Red River Delta and Suoi Nhung hamlet in the drainage in the commune were implemented at mountainous region, and the other research five pumping stations and through tidal power. sites were mentioned additionally. First, a brief Most of the households had a home garden and outline of agriculture at the sites will be a pond around their houses, and raised pigs introduced. Then after, the uses, cultivation and commercially. cultivars will be described. Ninh Binh hamlet belongs to Binh Khe Commune in the same district as Hoang Que MATSUDA and NAWATA: Taro in northern Vietnam 251

Commune. The elevation of the commune is fish powder, and purchased concentrate feed. higher than that of Hoang Que Commune, and The farmers mentioned that diversification of the commune consists of flat and hilly areas. In the cropping pattern after a series of renovation the flat land, double cropping of rice with winter policies in Vietnam had led to the diversification crop was mainly practiced. The area of single of pig fodder. In December in Noi Hoang Tay, cropping of rice, however, was as large as that of leaves of sweet potato cultivated as winter crop double cropping. Orchards of litchi have spread were used for pig fodder, and were sold at local in the hilly area in recent years. Pig raising and markets. MATTHEWSet al.16)suggested that due fishponds were frequently observed. to the introduction of the substitutes, e.g. sweet Colocasia esculenta var. aquatilis: C. esculenta potato, and the replacement of household pig var. aquatilis, which is a wild type taro with long husbandry by commercial piggeries, var, aquatilis stolons, grew frequently in the delta. It was most became ruderal in Okinawa Island, southern common and dominant among the taro species Japan. In our survey, some farmers have in Noi Hoang Tay. The people classified it into recently started to cultivate a leaf vegetable Rau Khoai Bong (soft taro) and Khoai Nuoc (water taro), Can (Oenanthe javanica) in their ponds for selling. based on the presence of a purple pigmentation The plant had been used for the maintenance in the center of the leaf blade surface (present of ponds. Farmers planted the variety around in the former and absent in the latter). Only their ponds for protection against the erosion of Khoai Bong was found in this survey at the site. the bank. It was planted around a repaired pond In Ninh Binh, this variety was less commonly at present, although the number of ponds paved observed than in Noi Hoang Tay, and it was with brick and concrete had increased from the called Khoai Dom (spot taro, •gspot•h in reference middle of the 1980s. to the purple pigmentation of the leaf center). Colocasia esculenta var. esculenta: C. esculenta Var. aquatilis in Noi Hoang Tay was mostly var esculenta, generally called Khoai So in found around farmers' ponds and along canals Vietnamese, was cultivated in small-scale upland in the village. It did not grow along canals that fields as one of the commercial crops at the were far from the settlements and the paved sites, for supply for urban areas. Since its lateral canals (although paved canals were rare). In Ninh cormels fetched a higher price than the , Binh it occurred around some farmers' fishponds. the farmers conducted earthing up to grow Its petioles were harvested as a vegetable food more cormels. The corms and cormels were and for pig fodder, and its stolon was used as a generally cooked with pig bones. Seed cormels vegetable food, mainly from spring to summer, were stored by the farmers on the ground by at both sites. The stolon was peeled and cooked covering them with straw in home gardens, as an ingredient for soup. In Ninh Binh some under litchi trees, and inside the house. farmers stored the petioles for pigs after drying. Cultivation for local consumption, however, was Growing of var. aquatilis had been promoted for not frequently observed even in home gardens human consumption and animal fodder by the at the sites. government in the 1960s20) It was possible to plant the crop all the year Wild plants from ponds for pig fodder round in the physical environment of the delta. included not only C. esculenta var. aquatilis but There were mainly two types of cropping also water hyacinth (Eichhornia cnassipes), Azolla patterns including taro at the sites. One common imbricata, Pistia stratiotes, Ludwigia adscendens, cropping pattern consisted of rainy season rice and so on, according to the farmers in Noi (cultivated from June to November) and taro. Hoang Tay, where the ponds in the village Taro was harvested from March to May. When played important roles in fodder production (i.e. the farmers cultivated early maturing cultivars growth of aquatic plants) and water supply to of taro, they could use the field for nursery beds people, as reported by RAMBO et al.21). The of rice after the harvest of taro. Another pattern importance of wild plants for pig fodder and the consisted of taro and maize as winter crop or role of ponds in fodder production, however, Brassica as leaf vegetable. In this pattern, taro may have declined relatively. The people fed was harvested from August to September, when pigs with wild plants and other various materials the market price was high, and late maturing such as sweet potato, rice powder, maize, cabbage, and high-yielding taro cultivars could be planted. 252 Jpn. J. Trop. Agr. 46 (4) 2002

Farmers at the sites grew several cultivars consumption was observed in Suoi Nhung. The of var. esculenta. They carefully observed the crop was usually grown in small swidden fields morphology, quality of the corm and cormels, (less than one a each) near the settlements, and yield ability as well as the maturation sometimes mixed with X sagittifolium. As HUE8) period. In Noi Hoang Tay, for example, there reported, it had been mixed-cropped in upland were two early maturing cultivars, Khoai Trung rice fields for a meal during works in the fields. (egg-shaped taro) and Khoai Trang (white taro), The corms and cormels were usually cooked as which were used for about four months and one an ingredient for soup with pig bones, boiled late maturing cultivar, Khoai Van (stripe taro), with rice, or just boiled without peeling. which were used for six months at least. Some The seed cormels, which were stored in farmers pointed out that the disadvantage of shallow pits covered with soil and rice straw in taro cultivation was its long growth period the fields, were planted using a digging stick compared with that of other leaf vegetables. with a steel tip (called Cam Chiu) from March to Other taro species: Xanthosoma spp. (called June. In the case of mixed-cropping with upland Mung Tia or Khoai Trang) were often cultivated rice, farmers planted the cormels after sowing of in home gardens at the sites for local consumption. upland rice (in May). After weeding several Their petiole, corm, and cormel were used for times, the farmers harvested the crop gradually both human consumption and pig fodder. C. from September to December. gigantea (called Doc Mung) was grown in the Three cultivars of the var. esculenta were home gardens, and its petiole was eaten as a observed at the site, and their morphological vegetable food. (called Ray) was characteristics are described in Appendix 1. Hau found on roadsides in Noi Hoang Tay, and the Doang (yellow taro) and Hau Doang Don (large corm was used as medicine for the treatment of yellow taro) were named due to their yellow common cold. corm flesh. Hau Doang had a multifaceted corm with small hammer-shaped cormels, and Hau Taro in the mountainous region Doang Don had a large round corm with round Suoi Nhung hamlet, Phuc San Commune, cormels. Since Hau Pe (white taro), with a white Mai Chau District in Hoa Binh Province, is corm flesh had a nice scent, so the people used located about 130 km west from Hanoi, and lies the term Hau Dang (aromatic taro) as a synonym. at around 380 m asl in the mountainous region. Other taro species: C. esculenta var. aquatilis One hundred and ninety-five people lived in this (called Hau Hap Bon) and C. gigantea (called Hau hamlet in 1997, and all of them belonged to the Hap) were seldom observed (only one case) at Dao Trien people, one group of Dao people. the mountainous sites, although they were They had been practicing shifting cultivation on frequently found in a basin with a large expanse slopes, and their fields were distributed from of paddy fields (no research sites in this study). 380 to 620 m asl at least. The swidden fields had C. esculenta var. aquatilis was not found around been cultivated for three to four years. Upland fishponds in contrast to the sites in the delta. It rice was first planted for two or three years, was considered that X sagittifolium had been followed by cassava or maize. The land area for introduced recently, and the species was called agriculture accounted for about 20% of the total Con Tay Hau (French child taro). This species land area of the hamlet, while approximately 80% was cultivated with C. esculenta var. esculenta in consisted of forests protected by a government small swidden fields near the settlements, for project for reforestation and forest conservation human consumption and pig fodder. A. macrorrhiza, that started in 1995, and people planted and called Hau Kleem (forest taro) or Hau Si Kleem grew bamboo with governmental support and (purple forest taro), was found in the village, and sold it as materials or source of paper. Edible was assumed to grow in the forest. Its petioles canna was a major commercial crop there that were commonly collected for pig fodder. Petiole of was processed into a powder in the neighboring banana, vein of sweet potato, cassava, pumpkin, hamlet. In recent years, paddy fields and rice powder, and other wild plants were also fishponds have appeared but they are still rare. cooked for pig fodder. Most of the households Colocasia esculenta var. esculenta: Small-scale raised pigs for local consumption. cultivation of C. esculenta var, esculenta for local Other sites in the mountainous region: Hua MATSUDA and NAWATA: Taro in northern Vietnam 253

Tat and Sao Do II hamlets belonged to Van Ho are listed in Table 2. The 20 accessions of C. Commune in Son La Province. The flower Hmong esculenta consisted of 10 diploid (2n=2x=28) and people, one group of Hmong, had practiced a 10 triploid (2n=3x=42) plants. All the 5 accessions shifting agriculture of upland rice in Hua Tat. of C. esculenta var. aquatilis were diploid (Table Maize, edible canna, and Job's tear were also 3), which is in agreement with previous reports cultivated commonly. Sao Do II was mainly on the ploidy of var. aquatilis5,12,16)Accessions of inhabited by the Kinh people who had migrated C. esculenta var. esculenta collected from the from the delta region. The formers in the hamlet mountainous region insisted of both diploid and grew maize, cassava, and sweet potato, and triploid plants, whereas only triploid plants were there were grasslands for dairy cattle. found in the accessions collected from the delta Colocasia esculenta var. esculenta and Xantho- (Table 2). Chromosome numbers of Colocasia soma spp. were sometimes cultivated in home gigantea, Xanthosoma spp., and Alocasia odora gardens for local consumption or both sites. were 28, 26, and 28, respectively, and all the plants Although a few farmers in Sao Do II cultivated were diploid3,7,22). C. esculenta var. esculenta commercially, in many Twelve rDNA patterns (PM001 to PM004, cases a small number of these crops were planted PM007, PM008, and MM013 to MM018) were with ginger under plum trees. Plum gardens had observed in 20 accessions of C. esculenta14)(Table been promoted for the replacement of opium 2 and Fig. 2). Patterns PM001 to PM004, PM007, cultivation with the government financial support and PM008 were found in from , in 1990s, and were often observed. According to , and Japan by MATTHEWSet al.15) and the farmers in Hua Tat, the cultivation of the var. MATSUDAand NAWATA14).Patterns MM013 to esculenta has declined gradually in recent years. MM018 were found only in Vietnam. The other Elderly people who had migrated from the taro species, Colocasia gigantea, Xanthosoma delta region to Sao Do II had a wide knowledge spp., and Alocasia odora, showed one rDNA of C. esculenta var. aquatilis, but the crop was pattern each, MMg001, MMx001, and MMa001, not found at the sites. C. gigantea was seldom respectively (Table 2 and Fig. 2). Two interspecific grown as vegetable in home gardens at the bands were observed: a band of 3.45 kb between sites. Sap from the petiole of A. odora had been C. esculenta (PM004) and C. gigantea (MMg001), used as medicine for common cold. and another band of 4.00 kb between C. gigantea (MMg001) and A. odora (MMa001). Ploidy and rDNA variations of taro species, The geographical distribution of the rDNA and genetic relationships among accessions patterns of C. esculenta is indicated in Table 3. of Colocasia esculenta Common rDNA patterns were found at the Chromosome numbers of 30 taro accessions research sites in the same ecological area,

Fig. 2 Ribosomal DNA patterns. 254 Jpn. J. Trop. Agr. 46 (4) 2002

Table 2. Accessions of taro species, and results of chromosome number determination and RFLP analysis.

* See Fig . 2.

whereas no common rDNA pattern was distrib- PM001 and PM002 of the mountainous region uted in both ecological areas, the delta region were frequently found in taros from inland China and the mountainous region. Compared with and the mountainous area of Japan, whereas taros from other Asian countries, the distribu- pattern PM004 of the delta region was observed tion in northern Vietnam may reflect the in taros from insular areas in eastern Asia: influence of differences in the genealogy and Taiwan, the Ryukyu Islands, and the coastal area dispersal routes of C. esculenta in Asia, although at main islands of Japan13,14,15)Pattern PM004 was recent introduction of the cultivar after commercial reported in taros from Madagascar and Sri Lanka, cultivation started should be considered. Patterns also17).Pattern PM007 was found at all the sites MATSUDA and NAWATA: Taro in northern Vietnam 255 256 Jpn. J. Trop. Agr. 46 (4) 2002 MATSUDAand NAWATA:Taro in northern Vietnam 257 of the mountainous region. The cultivars showing ponds, household pigs, and so on. The variety this pattern displayed common morphological was frequently found around canals and ponds characteristics in the corm and cormel shape, i.e. in a village, and had been used for pig fodder multifaceted corm with hammer-shaped cormels and human consumption. The present situation (Appendix 1). of the variety reflected social and economic Morphological characteristics of the culti- changes. Pavement of canals and ponds with vars of C. esculenta are described in Appendix 1. bricks and concrete replaced it in the protective Some of the cultivars had common rDNA patterns role against bank erosion of these structures, to those of the Japanese cultivar groups in terms and decreased its habitat, although the pavement of morphological and agronomic characteristics. was not common. The diversification of pig fodder A late maturing cultivar, Khoai Van, in Noi Hoang feed led to a decrease of the relative importance Tay showed pattern PM004, and an early maturing of the variety. cultivar, Khoai Trung, at the site showed pattern Small-scale cultivation of C. esculenta var. PM003. Pattern PM004 was observed also in a esculenta was observed at all the sites. In the Japanese cultivar group (Akame) that was late delta, the variety was grown mainly as a cash maturing in general and had colored veins on the crop. At a mountainous site, Suoi Nhung, on the lower surface of the leaf blade, colored petiole other hand, it was grown sometimes as a (similar to that of the cultivar Khoai Van), and component of a mixed crop in the shifting round cormels10,13) Pattern PM003 was found in cultivation system for local consumption. The three Japanese cultivar groups that were relatively cultivars were genetically different between the early maturing and one of the cultivar groups delta and the mountainous region. Genetically had a dark purple petiole and round cormels close cultivars were found within each ecological like the cultivar Khoai Trung10,13) area, but not in both areas, as shown by the Five accessions of C. esculenta var. aquatilis results of the RFLP analysis in rDNA, which showed four patterns (MM015 to MM018), may suggest differences in the genealogy of the indicating that the accessions of the variety in species between the areas. this study were genetically diverse. Morphological Xanthosoma spp. were found at all the sites, diversity in the petiole colour of the variety which and there was a similarity in their use and had been reported by NAKAO19)in Southeast Asia cultivation. They were genetically uniform too. was not conspicuous in the present study. The seven accessions showed only one rDNA There was no common rDNA pattern in pattern, MMx001, although the number of both C. esculenta var. esculenta and in var. aquatilis plants examined was small. These facts may be from Vietnam, and even no common band was attributed to the recent introduction into Asia found between them. This finding suggested and rapid spread of Xanthosoma spp. that var, esculenta had not been derived from var. Colocasia gigantea was not particularly aquatilis in Vietnam. According to MATTHEWSet common, but was widely distributed. It was al.15)and MATSUDAand NAWATA14),pattern PM008, usually consumed as a vegetable. Alocasia odora which was obtained in the Vietnamese var. was used as a medicine at two sites. Alocasia esculenta, was found in var. aquatilis from Australia macrorrhiza was observed only at one site in the and var, esculenta from Taiwan and the Ryukyu mountainous region, and was used for pig fodder. Islands, southern Japan. 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