Progress in Research and Development on Yams (Dioscorea spp.) in Maluku Islands, Indonesia: Achievements and Challenges

Abstract

Tuber crops, including yams (Dioscorea spp.) have been playing an important role in the menu of the community of Maluku islands. To optimize contribution of yams (Dioscorea spp.), a number of studies have been conducted at the Faculty of Agriculture, Pattimura University. The findings indicated that more than 100 cultivars belonging to five different species of Dioscorea namely D. alata L., D. esculenta (Lour.) Burkill., D. pentaphylla L., D. hispida Dennst and D. bulbifera L. distributed thoughout Maluku islands, in which, D. alata and D. esculenta are predominant and Central Maluku has the highest number of cultivars. In terms of field experiments, increasing seed size (cut tuber) from 40-50grams up to 190-200grams, increase the production of D. esculenta. Seed placement with the tuber skin faced-down provide higher yield for D. esculanta in comparison to that when the tuber skin faced-up. Soil fertilization with potassium fertilizer (K 2 O 5) of 80kg/ha give the highest production (7.72tons/ha) for D. esculenta while that for D. alata 100kg/ha K 2 O 5 give the highest production (50tons/ ha). The use of bamboo stakes with the hight of 2 m give the best production for D. alata (50.69tons/ha) in comparison to that of 1.5m and 1m stake hights. In case of tissue culture studies, 13 cultivars of D. alata can be stored for eight up to 14 Months in a half strengh Murashige Skoog (MS) medium suplemented with Kinetin (Kin) and Benzil Amino Purin (BAP) of 1 to 4ppm. Carbohydrate content of the tuber reach as high as 60% of tuber fresh weight. The diosgenin content, however, is very low, less than 1% on the average. When the corbohydrate content of the tuber is regressed against the tuber's specific grafity, a linear regression coefficient of 0.78 is obtained. Aside of the research findings, the role of yams (Dioscorea spp.) in terms of food diversification has not been improved until recently. Meanwhile, genetic erosion of yams germplasm appear to have occured rapidly among and within the species. There is, therefore, an urgency to prevent further erosion and if possible recover the lost germplasm.