Comparative Analysis of the Morphological Traits of Cucumis melo Seed Remains Discovered in the Graveyard of the Haihun Marquis in Nanchang and Modern C. melo Seeds Using Scanning Electron Microscopy

The graveyard of the Haihun Marquis in Nanchang is the largest and best-preserved Han Dynasty mausoleum discovered in China. Within the tomb's beam bank (M1), archaeologists have uncovered a variety of plant remains, such as melon seeds, the traits and origins of which warrant timely investigation. Cucumis melo L. has a long history of being cultivated and consumed in China. In this study, macroscopic identification techniques, scanning electron microscopy, and cluster analyses of the seeds of ancient C. melo and 16 varieties of modern melons (9 with thick skin, 6 with thin skin, and 1 thick/thin-skinned hybrid) were performed to compare their morphological trait indexes and seed coat ultrastructures. Through the measurement of various morphological parameters (length, width, upper one-third width, lower one-third width, thickness, and surface area) of each type of melon seed and subsequent cluster analysis of the morphological data, the ancient melon was determined to belong to the same cluster as the C. melo varieties "Lvbao", "Huangpi", "Boyang No. 9", "Malianzhuang", "Yangjiaomi", and "Zhimami", exhibiting the closest affinity to the thin-skinned types, particularly "Huangpi", "Malianzhuang", and "Zhimami". Scanning electron microscopy analysis of the epidermal ultrastructure revealed that the reticulated morphology of the seed coat of the ancient melon closely resembled that of the thin-skinned melon. Consequently, we hypothesize that the melon seeds excavated from the graveyard of the Haihun Marquis belong to the thin-skinned type of melon.