Current knowledge on Amaranthus spp.: research avenues for improved nutritional value and yield in leafy amaranths in sub-Saharan AfricaEuphytica

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Authors
Enoch G. Achigan-Dako, Olga E. D. Sogbohossou, Patrick Maundu
Year
2014
DOI
10.1007/s10681-014-1081-9
Subject
Agronomy and Crop Science / Horticulture / Plant Science / Genetics

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Text

REVIEW

Current knowledge on Amaranthus spp.: research avenues for improved nutritional value and yield in leafy amaranths in sub-Saharan Africa

Enoch G. Achigan-Dako • Olga E. D. Sogbohossou •

Patrick Maundu

Received: 2 December 2013 / Accepted: 14 February 2014 / Published online: 13 April 2014  Springer Science+Business Media Dordrecht 2014

Abstract In the past 20 years, very little progress has been achieved in reducing food insecurity, child malnutrition and hunger in Africa. Under-nutrition and micronutrients deficiencies are widespread and affect mainly women and children. To address these problems, increased consumption of African leafy vegetables is promoted as sources of both micronutrients and bio-active compounds. Widely promoted

African leafy vegetables include Amaranthus spp., a taxonomic group cultivated worldwide. Species of this genus are used as pseudo-cereals in Europe and

America, and are mostly planted as vegetables in

Africa. Amaranthus has been rediscovered as a promising food crop mainly due to its resistance to heat, drought, diseases and pests, and the high nutritional value of both seeds and leaves. Leaves are rich in proteins and micronutrients such as iron, calcium, zinc, vitamin C and vitamin A. All parts of the plant are used as medicine to heal many diseases in African communities. This paper focuses on leafy amaranths traditionally utilized on the continent. It briefly reviews the current knowledge on taxonomy, ecology, nutritional and nutraceutical value, production and cultivation systems, reproductive biology, genetic resources and breeding of amaranths. Species of interest include: A. blitum, A. caudatus, A. cruentus, A. dubius, A. hypochondriacus, A. spinosus, A. thunbergii, A. tricolor, and A. viridis. Research and development opportunities on nutritive and nutraceutical properties, production and commercialization, taxonomic evaluation and breeding perspectives were explored.

Keywords Amaranthus  Leafy vegetables 

Nutrients  Nutraceutical properties 

Genetic resources

Introduction

Africa has experienced mixed progress in reducing food insecurity and child malnutrition in the past 20 years (Garcia 2012). Approximately, one third of children under 5 years of age in Africa are stunted and more than a quarter are underweight. Micronutrient deficiencies affect mainly women and children and contributes significantly to the global disease burden of children by limiting proper cognitive development, impairing physical development, and increasing susceptibility to infectious diseases (Asare-Marfo et al. 2013). Most countries in Africa are still struggling to address problems of under-nutrition and micronutrient deficiencies (Lopriore and Muehlhoff 2003).

E. G. Achigan-Dako (&)  O. E. D. Sogbohossou

Horticulture and Genetics Unit, Faculty of Agronomic

Sciences, University of Abomey-Calavi, 01 BP 526 Tri Postal, Cotonou, Republic of Benin e-mail: enoch.achigandako@gmail.com

P. Maundu

Kenya Resource Centre for Indigenous Knowledge (KENRIK), National Museums of Kenya,

P.O. Box 40658, Nairobi 00100, Kenya 123

Euphytica (2014) 197:303–317

DOI 10.1007/s10681-014-1081-9

African leafy vegetables are increasingly recognized as possible contributors of both micronutrients and bioactive compounds to the diets of populations in

Africa (Smith and Eyzaguirre 2007). The continent is rich of vegetable species including amaranths which are among the most popular leafy vegetables on the continent (Maundu et al. 2009). Amaranths consist of 60–70 species (Xu and Sun 2001) and include at least 17 species with edible leaves and three grain amaranths grown for their seeds (Grubben and Denton 2004). Although several species are often considered weeds, people around the world value amaranths as leafy vegetables, cereals and ornamentals (Trucco and

Tranel 2011).

Most of the amaranth species are harvested in the wild as food resource. Only a few are grown and are among the leafy types most common in markets in tropical Africa. Amaranths can also be grown for their seeds. This is the case of some introduced varieties of

American origin (Wu et al. 2000). Grain amaranth is not commonly cultivated in Africa (Grubben and

Denton 2004). More recently however, a few farmers have taken the growing of grain amaranth more seriously and are supplying millers and supermarkets in Zimbabwe, Kenya, Uganda and Ethiopia. Since about 1980, Amaranthus has been rediscovered as a promising food crop mainly due to its resistance to heat, drought, diseases and pests, and the high nutritional value of both seeds and leaves (Wu et al. 2000). According to Onyango (2010), improvement of amaranths through research and development could produce an easy and cost-effective way of eliminating malnutrition and promoting people’s health as well as achieving food security. Unfortunately, there are still gaps in knowledge of some popular amaranths of

Africa and there are confusions in the nomenclature of species, for instance, of the hybridus complex while comprehensive nutritional profiles are yet to be compiled (Grubben and Denton 2004). Moreover, little is known on the breeding potentials particularly of wild relatives that can be promoted for sustainable utilization.

Some interventions were carried out thanks to partnerships between research institutions and local

NGOs and to promote indigenous vegetables including amaranths. For example, the Promotion of

Neglected Indigenous Vegetable Crops (IV) for

Nutritional and Health in Eastern and Southern Africa (ProNIVA) project led by the World Vegetable Center (AVRDC) have contributed to provide seeds of superior micro-nutrient rich amaranth (Amaranthus cruentus) cultuvars and increase production and consumption of leafy vegetables in Rwanda, Uganda,

Malawi and Tanzania (AVRDC 2008). Another important project was the Bioversity International’s

African leafy vegetables programme conducted in

Botswana, Cameroon, Kenya, Senegal and Zimbabwe which induced notable positive changes in growing, consumption, marketing and nutritional awareness of