Exploring the value of Dioscorea melanophyma: an orphan crop from China

Abstract

Dioscorea melanophyma is a wild relative of cultivated yam, and its development and utilization are strategically important for food security. This study aims to investigate the germplasm resources, ethnobotany, pests, and diseases of D. melanophyma, and to examine the impact of climate change on its distribution and survival. The study also assesses the nutritional value of the tubers and bulbils, and investigates the pattern of bulbil germination and associated changes in endogenous hormone levels. The survey finds that D. melanophyma is mainly distributed in southwest China, and its tubers and bulbils are recorded as edible. The major diseases of this species are white rust and anthracnose, and the pests are the species Lilioceris sinica, and the families of Arctiidae, Agromyzidae, and Elateridae. Temperature annual range (Bio7), elevation and min temperature of coldest month (Bio6) were found to significantly influence the distribution of D. melanophyma, with cumulative contribution and ranked importance of the MaxEnt model reaching 87.3 % and 89.5 %, respectively. In the future, the area of highly suitable habitats for D. melanophyma will decrease dramatically, while moderately and lowly suitable are will increase. The tubers and bulbils of D. melanophyma are rich in nutrients and have a higher nutritional value score than those of D. polystachya. Dioscorea melanophyma reproduces asexually, primarily through the numerous bulbils it produces. Early in the year (before March), high concentrations of abscisic acid in the bulbils inhibit germination through physiological dormancy. From April on, many bulbils begin to germinate, achieving a germination rate of 90 % within one month. In conclusion, D. melanophyma exhibits significant developmental potential, and is likely to serve as a crucial genetic resource for yam cultivation and play a vital role in food security. This comprehensive study on D. melanophyma aims to offer valuable information and insights to consumers, producers, and researchers alike.