Developmental morphology of tuberisation in milk yam (Ipomoea digitata L.)

Milk yam (Ipomoea digitata L.) tubers are used as an ingredient in Ayurvedic formulations and indigenous dietary supplements used for general wellness, diabetes, post-partum care etc. The plant is a climber having perennating tuberous roots. The objective of the study is to assess the right stage of harvesting milk yam tubers for ensuring optimum tuber quality. The study was performed by planting rooted cuttings of milk yam in polybags placed 50 cm apart and the climber was trailed in trellies. Ideal harvesting stage of the tubers were identified through comprehensive analysis of tuber morphology and macroscopic features of the tubers at periodic intervals for a period of 24 months. The ideal harvesting stage of the tubers were identified as 21 months after planting. At this stage, the plant possessed more than two (2.33) tubers having mean tuber length (29.50 cm), girth (21.90 cm) and weight (983.33 g). The tubers were sub-cylindrical in shape, brownish in colour, having characteristic agreeable odour, slightly sweet to taste and had slight presence of milky white latex.