Abstract

Cocoyam is an herbaceous perennial plant belonging to the family Araceae. It is grown primarily as a staple for its edible tuber which is very rich in carbohydrates. After harvest the tuber of this crop deteriorates fastly in storage as a result of disease/ infestation causing a reduction in quality and market value.

This study therefore, was aimed at using botanicals known to have anti-microbial property to mitigate disease infections on this crop thereby, increasing its shelf life, quality and availability. The study was carried out at the Faculty of Agriculture and Veterinary Medicine Teaching and Research Farm between March and June 2021. It was a complete randomized design in 4 replicates including a control. 3 botanicals that include pawpaw, bitterleaf and onion at 10% of concentration were applied to apparently healthy cocoyam tubers fortnightly for 2 months in a clean and sterile room.

During this time samples were observed for diseases symptoms weekly for a month. Diseases incidence, weight loss of the tubers, sprouting, shrinkage and rot was observed. Data was subjected to descriptive statistics, and one-way ANOVA at 5% probability.  Disease symptoms observed on cocoyams include rot and mold.

Most cocoyam samples showed either of these symptoms but at different intervals. The most prominent symptom noticed on cocoyam was rot. ANOVA result showed that cocoyam samples treated with onion and pawpaw was least attacked by disease compared to samples treated with water and bitterleaf. There was no significant difference at 5%.

The most infected was samples treated with water for rot incidence and bitterleaf for shrinkage. The fastest deterioration was sampled treated with water. Samples treated with bitterleaf came third in terms of disease infestation. At 4 weeks, 44 out of 56 tubers were infected. Out of these were rot 30%. 20% were sprouted, and 20% were shrinkage. There was no significant difference in rot, sprouting, shrinkage, and fresh weight loss across

CHAPTER ONE

INTRODUCTION

1.1 Background statement

Cocoyam, (Xanthosoma sagittifolium (L.) Schott) is an herbaceous, monocotyledonous crop that belongs to the Araceae, grown in tropical and subtropical regions in moist and shady habitats (Damilola et al., 2020). It provides food and it  an income generating crop for about 200 million people in the tropics (Ramanalha et al., 2010; FAO, 2012).

Africa is the major producer with West and Central Africa, notably. Nigeria. Ghana, and Cameroon contributing to over 60% of the total African production (Onyeka, 2014). Thus, the importance of cocoyam to regional food security cannot be overstated. It is a staple in Cameroon and used also as livestock feed. In Cameroon, it is the third most cultivated food after cassava and plantain (Dominic et al., 2020).

The crop has high production levels with up to 19 tons/hectare and 35 tons/ hectare reported in China and Egypt, respectively (Onyeka, 2014). Nigeria is rated the highest producer of cocoyam in the world with an annual production capacity of 3.450 million metric tonnes in 2012, representing 72.2 %, 57.7 % and 45.9 % of total production in West Africa, Africa and the World, respectively (Falade and Okafor (2015).

It remains a neglected food resource despite its nutritional benefits (Falade and Okafor, 2015;Onyeka, 2014). According to Onyeka (2014),  Africa is the major producer with West and Central Africa, notably, Nigeria, Ghana, and Cameroon contributing to over 60% of the total African production.

Natural flowering of cocoyam is rare and so its cultivation is essentially by vegetative propagation, the corms and to a lesser extent the cormels. As population pressure on land continues to increases, the importance of cocoyam in ensuring household food security is given adequate recognition even though the present yield are still below expectation. This could be attributed to a lot of factors such as climate variation, drought, poor cultural practices among cocoyam growers, pest and diseases infestation (Ezenwu, 2010).

According to (Taylor et al. (2019), the agro-ecological range of cocoyam will shift under climate change because the crop prefers wet, humid environment with little to no ability to tolerate drought. This was confirmed by a modelling study by Kodis et al. (2018) who concluded that potential for cocoyam production will be drastically reduced in Hawaii especially under high emission scenarios. cocoyam production systems are based on small but high-density production systems in lowlands, on slopes or under trees in the fields. It prefers high rainfall areas (1,500 mm) with a uniform distribution through-out the year (Mwenye 2009).

Cocoyam is warm season crop, adapted to warm temperatures above 21 °C and minimum temperatures that do not fall below 10 °C (Lim 2015). Cocoyam has a high moisture requirement, growing well in margins of wet fields and along streams (Ganança et al. 2015).

Cocoyam is cultivated  solely for its edible corms, cormels, leaves and inflorescence (Vaneker and Slaats, 2013;Boakye et al., 2018) and occupies a central role in ensuring food security especially in West African region including Nigeria, Ghana, and Cameroon (Onyeka, 2014). Cocoyam is postulated to have superior nutritional value over other major root and tuber staples of West Africa, especially in terms of their protein digestibility and mineral composition (Calcium, Phosphorous and Magnesium) (Chukwu, Ekwe, & Anyaeche, 2008; Ekwe, Nwosu, Ekwe, & Nwachukwu, 2009; Lim, 2016; Opara, 2003).

According to Opara (2003)  Cocoyam plays an important role in the nutritional and economic status of millions of farmers in Africa (Vaneker and Slaals. 2013). The conns, cormels and leaves are important sources of carbohydrate and other minerals for human and animals. It has high carbohydrate content (70 – 80%) in the form of digestible starch (Pinto, and Onwaeme, 2000). According to (Owusu-Darko el al., 2014). this high digestible starch content provides energy and increases satiety in consumers. This crop also contains a reasonable amount of good quality protein, vitamin C, thiamine, riboflavin, niacin and some essential amino acids (Lewu and Adebola, 2010).

In West Africa, cocoyam is an important root crop (Gudjonsdottir et al. 2016). Cocoyam has more crude protein than roots and tuber crops (Lyonga and Nzietchueng, 2008). It plays both nutritional and cultural roles with a specialized method of preparation from different parts of the country having very strong traditional links. Cocoyam is grown mostly for its edible corm. cormels and leaves (Pinto and Onwaeme, 2000): the leaves are used as vegetable in soup, the corms and cormels are fried or boiled and eaten as a snack or a whole meal.

In sub-Saharan Africa, cocoyam leaves are utilized as pig feed (Rodrıguez et al.,2006), poultry feed, vegetables, or potherb (Osei and Mintah, 2003). The petioles are more useful as feed for pregnant sows due to their ability to deal with large and wieldy feeds (Rodrıguez et al., 2006). Young cocoyam leaves and petioles are rich in calcium, phosphorus, iron, vitamin C, thiamine, riboflavin, andniacin, with about 23% protein based on a dry weight estimate (Ndon et al., 2003; Asante et al., 2017).

The crop is nutritionally superior to cassava and yam, with more readily digested starch and higher protein, mineral, and vitamin contents (Odebunmi et al., 2007).  Cocoyam is used in essentially the same way as yam, it can be eaten boiled, fried or pounded into fufu. It can also be made into porridge, as well as chips and flour.

It is also used in preparing soups, by boiling whole and the skin peeled while hot, then pounded into a paste and used in soups as a thickener for soups. Generally, all plant parts (cormels, petioles, leaves, and inflorescence) of cocoyam are edible (CABI 2014; Vaneker & Slaats, 2013). The wide distribution of the crop in different geographical areas and cultures has

In spite of its high productivity levels and better storability compared to other tropical root and tuber crops (Opara, 2003; Opoku- agyeman, Bennet-Lartey, & Markwei, 2004; Quaye, Adofo, & Nimoh, 2010; Ramanatha et al., 2010), Xanthosoma sagittifolium has been marginalized in agricultural policies and research interventions on root and tuber crops. It remains an underexploited food resource (Falade & Okafor, 2013; Onyeka, 2014), with a reported decline of production levels in Ghana and Cameroon (Onokpise et al., 1999; Onyeka, 2014).

The challenge of underutilization is exacerbated by the existing confusion in taxonomy and nomenclature which limits researchers in exploiting data from one area of indigene to another (CABI 2014; Crop Trust 2010; Osuji & Nwala, 2015; Vaneker & Slaats, 2013). This makes it essential to provide an overview of the taxonomic reference and employed nomenclature in every scientific study for accurate information dissemination and use.

A comprehensive insight into existing indigenous varieties and the potential utilization of these varieties, as well as adaptable modern analytical methods for research in sub-Saharan Africa, would facilitate efforts to enhance the utilization of these indigenous varieties for sustained food and nutrition security.

1.2 Problem statement

Cocoyam is one of the most important traditional tropical root crops, being the fifth most produced tuber crop in the world with over 12 million metric tons annually (Taylor et al., 2019). Cocoyam is a staple crop in Cameroon which constitutes an important component for subsistence agriculture, which provide nutrition and income to the population. With the increasing demand for this staple tuber, cocoyam is exposed to disorders like shrinkage, sprouting and rot disease, different botanicals will be used to improve on the shelf life of cocoyam.

1.3 Objectives

1.3.1Main objective

The main objective of this study is to evaluate the effect of botanicals on the shelf life of Cocoyam in the Buea municipal area.

1.3.2 Specific objectives

1. To evaluate the effect of botanicals on the shelf life of Cocoyam.
2. To identify weight loss, sprouting, shrinkage and rot infecting Cocoyam
3. To determine the performance of botanicals on the shelf life of Cocoyam under different treatment dates.

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