Effects of Cultivar, Botanical and Gibberellic Acid Treatment on Physico-Chemical Changes of Yam (Dioscorea rotundata Poir) Tuber in Storage

Abstract

A storage experiment was conducted in an improved yam barn at the National Root Crops Research Institute, Umudike, Nigeria. Five cultivars of yam namely; Nwaopoko, Amula, Pepa, Danacha and Ezakwukpolo were obtained from four major yam producing states in Nigeria. The plant parts (botanicals) of Azadiracdica indica A. Juss (leaf), Xylopia aethiopica (Dun) A. Rich (fruit), Occimum gratissimum L. var (leaf) and Zingiber officinale Rosecoe (stem tuber) were obtained locally while the gibberellic acid (GA3) was imported from Europe. The yam tubers were soaked in the chloroform extracts of the botanicals/GA3 solution for 3 hours, air dried and stored in the barn for both physical and biochemical observations. The botanicals and GA3 treatments significantly (p . 0.05) increased the moisture and dry mass contents of the stored tubers but had no effects on the crude protein, ash and fiber. Extension of dormancy period of the stored tubers by the storage treatments was in order of GA3 > A. indica > O. gratissimum whereas X. aethiopica and Z. officinale reduced dormancy. Among the yam cultivar, GA3 and Azadiractha indica always had the best effect of extending the dormancy, reduction in weight loss and rot incidence.

Keywords: Yam; storage treatments; Physico-chemical changes