Endangered Durio spp. conservation and seed germination in Indonesia

Wild king fruit (Durio spp, Malvaceae) is a threatened native tree species in Kalimantan, Indonesia which needs significant and urgent cultivation. This study characterized the appearance, flavor, and germination rate of four durian species D. zibethinus, D. dulcis, D. kutejensis, and D. oxleyanus. The results showed that D. oxleyanus was one of the superior fruits with a very sweet flavor, smooth texture, and juicy flesh despite its green thorny exterior. Four months after sowing, the germination capacities (p-value 0.18) were as follows: D. kutejensis 7% (+/- 1.4%), D. dulcis 0%, D. oxleyanus 1% (+/- 0%), and D. zibethinus 21% (+/- 26.2%) at Banua. In Bogor, West Java, seed germination was: D. zibethinus 58% (+/- 2.8%) which developed into seedlings, D. kutejensis 10% (+/- 0%), and 0% for both D. dulcis and D. oxleyanus). Ex-situ conservation of the four Durio species by seed propagation needs to be conducted carefully to avoid the failure of seedling growth.