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Submitted to the Journal of South Pacific Agriculture – July 2002 SURVEY TO DETERMINE THE EXTENT OF GENETIC EROSION OF TARO LANDRACES IN FIJI. Vilikesa T Masibalavu 1, Danny Hunter 2 , Mary Taylor2 and Prem Mathur3 1 Koronivia Research Station, PO. Box 77, Nausori, Fiji; 2 Taro Genetic Resources: Conservation and Utilisation (TaroGen), Secretariat of the Pacific Community (SPC), Private Mail Bag, Suva, Fiji; 3 South Asia Associate Coordinator, International Plant Genetic Resources Institute (IPGRI), Office for South Asia, NASC Complex, Pusa Campus, New Delhi, India ABSTRACT The increasing market demands and use of taro hybrid varieties by many farmers in Fiji poses a serious threat of genetic erosion to local taro landraces. A study to investigate the extent and reason for erosion suggests that about 13% erosion has occurred within the past 15 years. Another 26% of the total landraces are currently under threat. The highest rate of erosion is recorded in the Rewa province. This is mainly due to its location, topography and proximity to Koronivia Research Station where taro hybrid varieties are developed. Naitasiri and Bua still have more diversity in landraces but many varieties are currently under threat and could be lost if the current trend in production continues. Keywords : Genetic erosion, Taro, Landrace, Fiji, Hybrid. 1 INTRODUCTION Taro (Colocassia esculenta (L) Scott) commonly known in Fiji as Dalo is a root crop of the family Araceae that is found worldwide. It is a very important Fijian staple as it is cultivated by more than 23,000 farmers where 85% are Fijians while the rest are Chinese and Indian farmers (MAFF 2000). Taro production has continued to increase in the past decade because of a continuing demand in the export market. This has led farmers to select modern varieties and hybrids due to their outstanding growing qualities compared with local landraces. After the “green revolution” during 1960’s, the spread of modern cultivars of corn, wheat, rice, sorghum, pearl millet and other crops has rapidly squeezed out landraces of these crops in India and other parts of the world (Rao et al. 1998). Modern varieties and hybrids have been adopted on most of the farming lands since their release. In Southeast Asia, more than 80% of farmers now plant new varieties This narrowing of the genetic base in the farming system and the impact of loss of genetic diversity within crop species will lead to genetic vulnerability to biotic and abiotic stresses. Erosion of traditional taro landraces is evident in many countries in the Pacific including Fiji but there is little documentation as to the extent or reasons of erosion. These landraces provide enormous diversity important for future sustainable development. Though Fiji currently has a collection of 72 local landraces conserved at Koronivia Research Station, there is a growing concern that most of these landraces are no longer with the farmers due to various factors such as pest and disease, human selection, increased popula tion, poverty, land degradation, environmental change, urbanization and agricultural intensification including the introduction of modern crop varieties. It is therefore imperative that Fiji assess its genetic diversity and develop methods of sustaining them. This investigation aims to: · Determine the extent of taro genetic erosion in different agroecological zones of Fiji. · Determine the factors that contribute to genetic erosion. · Collect indigenous knowledge on the various landraces grown in Fiji. 2 METHODS AND MATERIALS A survey questionnaire (Appendix I) was used to obtain information by personal interview in three selected provinces. The three provinces selected were Site 1 - Rewa (area believed to have hybrid varieties dominate), Site 2 - Naitasiri (area believed to have both hybrids and landraces cultivated side by side) and Site 3 - Bua (area where landraces still dominate). Five villages were selected from each site and a total of seven taro farmers from each village were interviewed. The five villages selected from each site included Toga, Lokia, Burebasaga, Nalase and Nakorovou in Site 1; Nadakuni, Serea, Naivucini, Taulevu and Nakini in Site 2; Nubunikadamu, Dama, Vuya, Nagadoa and Nawaca in Site 3. The criteria used for selecting the sites included proximity to Koronivia Research Station (KRS) where hybrids were developed, accessibility to market centers, size and topography of the province and infrastructure. Site 1: Rewa province was selected as an area where hybrid varieties predominate. It was also the nearest to KRS, market centers, and mainly flatland hence there were more semi commercial and commercial farmers who needed to plant high yielding varieties to meet market demand. Site 2: Naitasiri province was selected because of how large and diverse it was extending from the coast (Suva) up to the highlands (Monasavu). Though KRS and market centers are within the province, about two thirds of the land area as well as population are in the rural part of the province. Therefore, there are more subsistence oriented taro farmers than commercial ones. Site 3: Bua province was selected because it was located in Vanua Levu – the second largest island in Fiji. It is far from the market (Savusavu and Labasa) and infrastructure is a problem. Hence it was believed to be an area where landraces were predominant. 3 RESULTS The overall result shows that out of the 90 varieties identified by the farmers to be cultivated in the past, 13 has been lost within the past 15 years (Table 1). A total of 26 varieties are currently under threat (ie. the variety is found in only one survey village). This accounts for about 33% of our total current landraces. Only three varieties were found to be common in all the survey villages. Table 1: Overall Survey Summary No. of varieties cultivated in the past: 90 No. of varieties currently cultivated: 77 No. of varieties lost: 13 % Varieties lost: 14 Number of varieties currently under threat: 26 % Variety under threat 34 Most common varieties: (Found in all the survey villages) 3 Genetic erosion has actually occurred within sites. Results in Table 2 indicate that there were a lot of varieties lost from each site. The highest genetic erosion is found to have occurred in the province of Rewa having 38% of its varieties lost followed by Naitasiri (19%) and then Bua with 16%. More diversity in taro landrace existed in the province of Bua in Vanua Levu, recording an average total of 27 varieties followed by Naitasiri with an average of 25 varieties. Though Bua currently has more taro landraces, results show that 30% of these landraces are currently under threat; (ie. when a variety is cultivated by only one farmer). 4 Table 2 Summary of survey within sites Site Village Varieties Varieties Varieties Varieties % % cultivated currently lost currently Varieties Varieties in the past cultivated under lost under threat threat 1 1. Toga 23 14 9 0 2. Lokia 18 12 6 5 3. Burebasaga 23 18 5 6 4. Nakorovou 12 5 7 2 5. Nalase 14 6 8 3 Mean 18 11 7 3 38.0 27.0 2 1. Taulevu 24 16 8 2 2. Nadakuni 37 29 8 4 3. Nakini 23 20 3 7 4. Serea 33 29 4 8 5. Naivucini 39 30 9 8 Mean 31 25 6 6 19.0 24.0 3 1. Nawaca 32 24 8 9 2. Nagadoa 26 21 5 9 3. Nubunikadamu 34 33 1 12 4. Dama 31 25 6 5 5. Vuya 34 31 3 7 Mean 31 27 5 8 16.0 30.0 5 DISCUSSION Overall Taro Diversity The overall results of the experiment suggest that Fiji is losing it's taro genetic diversity. This is due to factors such as the introduction of hybrid varieties, increase in market demand, mechanization, easy access to market centers, high cost of living, more young farmers than older ones and the poor suckering ability of local taro landraces. There are more varieties recorded from the study (90) than that which are conserved at Koronivia Research Station (72). This shows that there is a need to collect the remaining varieties and conserve them in-situ, ex-situ and in-vitro. During the survey four more varieties were collected from Bua province which has increased the collection to a total 76 varieties. Traditional landraces are found to be scattered throughout the survey area implying that there should be more diversity in many other parts of Fiji. Some landraces that have been lost from a particular site could be found in another site as the result shows. Diversity within Sites The provinces of Bua (Site 3) and Naitasiri (Site 2) have more diversity than Rewa (Site 1) recording an average total variety of 27, 25 and 11 varieties respectively. Both site 2 & 3 had an average of 31 varieties cultivated in the past but a slightly higher rate of erosion has occured in Site 2. This was mainly due to the fact that Naitasiri like Rewa has both Suva and Nausori market accessible and also near to Koronivia Research Station. In Naitasiri, more than 50% of farmers interviewed have their age above 50 years. These old farmers do possess a wealth of knowledge in taro varieties as compared to the younger farmers with some education background. Age also affect the way farmers value the crop. Taro being a crop significant to Fijian culture and tradition is very much treasured by older farmers. 6 Erosion within Sites Genetic erosion has clearly occurred within sites with the province of Rewa, recording the highest loss of 38% followed by Naitasiri 19% and Bua 16%.. The four most common reasons that accounted for the high losses in the Rewa province are: (1) market demand, (2) introduction of hybrid varieties and (3) land area for cultivation and (4) waterlogged condition.