EVALUATION OF SHELF-LIFE AND NUTRITIONAL CHARACTERISTICS OF SEVEN YAM ACCESSIONS IN NORTHERN GHANA

Abstract

Yam (Dioscorea spp.) is a major tuber crop that serves as a staple for thousands of households particularly in the developing world. In Ghana, yam is major source of dietary energy to many households, and contributes to food security and income to many families; particularly in northern Ghana. In spite of the massive contribution of yam to the socio-economic development of Ghana, yam producers have over the years struggled with storage issues which often result in postharvest losses. Due to the rainfall pattern, yam is cultivated seasonally but consumed all year round, suggesting proper storage methods are necessary to promote all-year-round availability. Currently, farmers depend on traditional methods of storing yam which is associated with varying degrees of postharvest losses. As a result, postharvest losses have been highlighted as a major problem facing the actors (farmers, buyers and consumers) in the yam value chain. Interestingly, the Yam Improvement Section of CSIR-SARI is developing a number of improved varieties which are high yielding, early maturity, resistant to disease, and having good sensory qualities. This research was conducted to assess the storage stability and nutritional composition of seven yam accessions, which are being developed by CSIR-SARI and proposed for release to the National Variety Release Committee of the Ministry of Food and Agriculture. The specific objective was to assess the shelf-life and nutritional composition of seven advance yam accessions in northern Ghana. The experiment was conducted at CSIR-SARI’s storage room located at Nyanpkala (9 ̊ 42 ’ N latitude and 0 ̊ 92 ’ W longitude and 184 m altitude) in the Tolon District of Northern Ghana. Seven accessions of yam (SDr 1403074, SDr1403004, SDr1403017, SDr1403005, SDr1403003, SDr1403031, and TDr95/19177) were studied. Shelf-life data collected include decay incidence, physiological weight loss and sprouting. The compositional data collected include; moisture, crude ash, crude fibre, crude protein, and total carbohydrates. The experimental set-up was a single factor experiment in a completely randomized design with three replications. One-way analysis of variance (ANOVA) procedure was used for testing the effect of genotype using the Genstat (14th Edition) software. Fischer Least of Significant Difference (LSD) method was used to segregate treatments which were significantly different at 5% level of probability. The genotype varied significantly for tuber circumference (P< 0.01), tuber length (p<0.001) but no significant difference was observed for physiological weight loss (P<0.05). Tuber circumference ranged from 30.2cm - 21.7cm. The genotypes with larger circumference were SDr1403003 (30.2cm) and SDr1403074 (29cm). Tuber length ranged from 27cm - 36.9 cm. However, SDr1403031 was the longest (36.9cm) whiles TDR 95/19177 was the shortest (27cm). There was no significant difference in decay of the genotypes although SDr 1403074, SDr 1403005, and SDr 1403031 had no rot all. Variety and dormancy influenced the genotypes to be stored for 16 weeks with minimal eterioration however, these new genotypes from the Yam Improvement Section of CSIR-SARI are recommended to facilitates the choice of varieties with good storage stability to combat the pertinent short duration storage problem in Northern Ghana and Ghana as large.