Enset‐based agricultural systems in Ethiopia: A systematic review of production trends, agronomy, processing and the wider food security applications of a neglected banana relative

Enset (Ensete ventricosum (Welw.) Cheesman) is the major starch staple of the Ethiopian Highlands, where its unique attributes enhance the food security of approximately 20 million people and have earned it the title “The Tree Against Hunger”. Yet enset‐based agriculture is virtually unknown outside of its narrow zone of cultivation, despite growing wild across much of East and Southern Africa. Here, we review historical production data to show that the area of land under enset production in Ethiopia has reportedly increased 46% in two decades, whilst yield increased 12‐fold over the same period, making enset the second most produced crop species in Ethiopia—though we critically evaluate potential issues with these data. Furthermore, we address a major challenge in the development and wider cultivation of enset, by reviewing and synthesizing the complex and fragmented agronomic and ethnobotanic knowledge associated with this species; including farming systems, processing methods, products, medicinal uses and cultural importance. Finally, we provide a framework to improve the quality, consistency and comparability of data collected across culturally diverse enset‐based agricultural systems to enhanced sustainable use of this neglected starch staple. In conclusion, we discuss the challenges and opportunities for enset cultivation beyond its restricted distribution, and the regional food security potential it could afford smallholders elsewhere in Southern and East Africa

Indigenous crop diversity maintained despite the introduction of major global crops in an African centre of agrobiodiversity

Societal Impact Statement The global success and expansion of a small pool of major crops, including rice, wheat and maize, risks homogenising global agriculture. Focusing on the agriculturally diverse Ethiopian Highlands, this study tested whether farm diversity tends to be lower among farmers who grow more introduced crops. Surprisingly, it was found that farmers have successfully integrated introduced crops, resulting in more diverse and heterogenous farms without negatively impacting indigenous crop diversity. This is encouraging because diverse farms, comprising indigenous agricultural systems supplemented by introduced crops, may help address global challenges such as food insecurity. Summary The global expansion of a handful of major crops risks eroding indigenous crop diversity and homogenising agroecosystems, with significant consequences for sustainable and resilient food systems. Here, we investigate the farm-scale impact of introduced crops on indigenous agroecosystems. We surveyed 1369 subsistence farms stratified across climate gradients in the Ethiopian Highlands, a hotspot of agrobiodiversity, to characterise the richness and cultivated area of the 83 edible crops they contained. We further categorise these crops as being indigenous to Ethiopia, or introduced across three different eras. We apply non-metric multidimensional scaling and mixed effects modelling to characterise agroecosystem composition across farms with different proportions of introduced crops. Crops from different periods do not differ significantly in frequency or abundance across farms. Among geographically matched pairs of farms, those with higher proportions of modern introduced crops had significantly higher overall crop richness. Furthermore, farms with a high proportion of modern introduced crops showed higher heterogeneity in crop composition. An analysis of socio-economic drivers indicated that poverty is negatively associated with the cultivated area of introduced crops. In our Ethiopian case study, global patterns of major crop expansion are not necessarily associated with agrobiodiversity loss at the farm scale or higher homogeneity across indigenous agricultural systems. Importantly, socioeconomic factors may influence farmers' propensity to adopt novel species, suggesting targets for agricultural extension policies. Given the rapid climatic, economic and demographic changes impacting global food systems and the threats to food security these entail, robust indigenous agricultural systems enriched with diverse introduced crops may help maintain resilience

Enset in Ethiopia: a poorly characterized but resilient starch staple

BACKGROUND: Enset (Ensete ventricosum, Musaceae) is an African crop that currently provides the staple food for approx. 20 million Ethiopians. Whilst wild enset grows over much of East and Southern Africa and the genus extends across Asia to China, it has only ever been domesticated in the Ethiopian Highlands. Here, smallholder farmers cultivate hundreds of landraces across diverse climatic and agroecological systems. SCOPE: Enset has several important food security traits. It grows over a relatively wide range of conditions, is somewhat drought-tolerant, and can be harvested at any time of the year, over several years. It provides an important dietary starch source, as well as fibres, medicines, animal fodder, roofing and packaging. It stabilizes soils and microclimates and has significant cultural importance. In contrast to the other cultivated species in the family Musaceae (banana), enset has received relatively little research attention. Here, we review and critically evaluate existing research, outline available genomic and germplasm resources, aspects of pathology, and explore avenues for crop development. CONCLUSION: Enset is an underexploited starch crop with significant potential in Ethiopia and beyond. Research is lacking in several key areas: empirical studies on the efficacy of current agronomic practices, the genetic diversity of landraces, approaches to systematic breeding, characterization of existing and emerging diseases, adaptability to new ranges and land-use change, the projected impact of climate change, conservation of crop wild relatives, by-products or co-products or non-starch uses, and the enset microbiome. We also highlight the limited availability of enset germplasm in living collections and seedbanks, and the lack of knowledge of reproductive and germination biology needed to underpin future breeding. By reviewing the current state of the art in enset research and identifying gaps and opportunities, we hope to catalyse the development and sustainable exploitation of this neglected starch crop.status: publishe

Maintenance and expansion of genetic and trait variation following domestication in a clonal crop

Clonal propagation enables favourable crop genotypes to be rapidly selected and multiplied. However, the absence of sexual propagation can lead to low genetic diversity and accumulation of deleterious mutations, which may eventually render crops less resilient to pathogens or environmental change. To better understand this trade‐off, we characterize the domestication and contemporary genetic diversity of Enset (Ensete ventricosum), an indigenous African relative of bananas (Musa) and a principal starch staple for 20 million Ethiopians. Wild enset reproduction occurs strictly by sexual outcrossing, but for cultivation, it is propagated clonally and associated with diversification and specialization into hundreds of named landraces. We applied tGBS sequencing to generate genome‐wide genotypes for 192 accessions from across enset's cultivated distribution, and surveyed 1340 farmers on enset agronomic traits. Overall, reduced heterozygosity in the domesticated lineage was consistent with a domestication bottleneck that retained 37% of wild diversity. However, an excess of putatively deleterious missense mutations at low frequency present as heterozygotes suggested an accumulation of mutational load in clonal domesticated lineages. Our evidence indicates that the major domesticated lineages initially arose through historic sexual recombination associated with a domestication bottleneck, followed by the amplification of favourable genotypes through an extended period of clonal propagation. Among domesticated lineages, we found a significant phylogenetic signal for multiple farmer‐identified food, nutrition and disease resistance traits and little evidence of contemporary recombination. The development of future‐climate adapted genotypes may require crop breeding, but outcrossing risks exposing deleterious alleles as homozygotes. This trade‐off may partly explain the ubiquity and persistence of clonal propagation over recent centuries of comparative climate stability.</p