Underutilized Bambara groundnuts in a red basket with winged beans hanging above

November 2, 2022, by Lexi Earl

Underutilized crops and their future potentials

The importance of crop diversification, for biodiversity and to cope with extreme weathers brought on by climate change, has never been more important. At the University of Nottingham, we have set up a Crop Diversification Unit, led by Dr Sean Mayes, to examine traditionally underutilized crops and their potentials as alternative sources of food for communities over the next decades. In this first blog post, we explore some of the varieties of crops that might become part of our diets in the next few years.

This post is written by Dr Alberto Tanzi, with contributions from Dr Alexandra Burgess and Dr Sean Mayes.

Our food environments – understood as where we can access, choose, and consume food – have seen a consistent decline in diversity over the last century. In fact, in the whole of the natural world, the number of species we cultivate has decreased dramatically, to the point where up to 90% of our food energy intake comes from 15 to 20 species. This translates into diets that offer fewer sources of nutrients, contributing to malnutrition. Furthermore, when one of these crops fails or becomes inaccessible, it leaves our food systems vulnerable and affects the global food market. (Think for example, of the war in Ukraine, and its effects on global wheat availability.) If you are thinking that the solution to the latter is to simply grow the same crops everywhere, think again. Crops do not grow or yield the same in different environments – changes in weather, pests and soil conditions all affect plant physiology. While breeding can be used to adapt some plants to yield, others may never be suited to a particular environment. This gap is even more predominant in countries where access to machineries, fertilisers, irrigation, or quality seeds may be limited. Therefore, it is difficult to diminish the dependence for imports of the staple crops that cannot be grown everywhere.

Luckily, there are many more edible species out there, which are adapted to specific local conditions, show good nutritional profiles, and have been grown in low-input environments, often for thousands of years. They go by many names: underutilized, neglected, orphan, ancient, forgotten, minor or undervalued crops. However, what they all share is untapped potential, a lack of research and breeding investment, or a proper market for their products. Think of lupin, haricot bean, kamut, senatore Cappelli, teff, fonio, cassava, taro, mustard green, bitter gourd, jackfruit and so on. While you might have come across some of them, especially in countries where they have been traditionally grown, these have been largely neglected by research, markets and the policymakers who are needed to support their development and potential.

Bringing crops like these ‘into the light’, as it were, is the goal of the Crop Diversification Unit (CDU) at UoN. Stemming from experience on a range of underutilized crops, and from the wealth of research capital developed through the Future Food Beacon, the CDU is well positioned to carry out analysis on these plants’ potentialities. The CDU capitalises on cutting-edge techniques and approaches for whole plant analysis (above and below ground), backed up by genetic studies and germplasm resources, whilst nutritional analyses provide a detailed understanding of their potential contribution to human or animal diets. Giving farmers a wider choice of crops is the first step in building more resilient, sustainable and complex agricultural systems. Working alongside partner institutes and farmers worldwide, the CDU will support and promote the wider utilization of neglected crops. Below we discuss some examples of the different types of crops with the potential to become part of our diets.

Bambara groundnut (Vigna subterranea)

Bambara groundnut is perhaps the underutilized crop that UoN, together with collaborators in Africa, Asia, and Australia, have investigated the most so far. Originating from Africa, Bambara groundnut is a legume grown in different climatic regions (from Senegal to Kenya and South Africa), and is able to produce yield in soils where other crops may struggle. While it has seen increasing cultivation, it still has to reach its full potential and access to a wider market, even in the sub-Saharan areas where it is typically – but not exclusively – cultivated.

Bambara groundnut shown in various forms: growing in a field, unearthed with pods exposed, and the different colours of seeds. Bambara is an underutilized crop

(left) Bambara groundnut grown in ridges, during a research trial in Malaysia (image: Crops For the Future); (centre) in Tanzania, once uprooted for harvesting, Bambara shows its pods, each containing one to two seeds (image: Tanzania Agricultural Research Institute); (right) a sample showing some of the variation in seed colour observed in Bambara (image: Crops For the Future).

Bambara’s potential lies in its ability to perform well under drought conditions and to not rely on large quantities of fertilizer, as it fixes nitrogen from the air. This has contributed to its success in providing nutrition and additional income to many smallholder farmers. More recent studies at UoN have looked into root architecture, and how individuals adapt to different environments through soil exploration for water. Photoperiod (the day length required to induce flowering, or pod development) and drought tolerance have also been key traits investigated in order to expand the geographical areas in which Bambara can be grown. We have also started to look at its cookability, and how to develop products from its seeds, while conducting international trials with institutes in Africa and Indonesia.

A recent entrepreneurial effort has demonstrated the possibility of producing value-added products like noodles and plant-based milk from Bambara, which are expanding into new markets and supporting demand for Bambara groundnut. Demand is a crucial bottleneck for underutilized crops, and this example shows how the struggle to bring these crops to wider markets is not always linked to the plant itself, but rather to the barriers in generating market opportunities.

Winged bean (Psophocarpus tetragonolobus)

Winged bean embodies past efforts in bringing mainstream agriculture to an underutilized crop. Labelled the “soybean for the tropics”, Winged bean drew international efforts to support its development culminating in a dedicated research centre (the International Council for Development of Underutilized Plants), promoted by none other than Nobel Laureate Dr Borlaug and research institutes across all continents.

This legume is cultivated primarily for its green pods, leaves, and tuberous roots, with culinary preferences varying across South Asia and the Pacific area. If you get an opportunity to visit our campus in Malaysia, you will find stir fried kacang botol in the food stalls. Travel slightly further afield and you will find boiled roots dressed with one sauce or the other. If you’d rather skip the flight, winged bean can be spotted in Asian grocery shops in the UK as well, and has also been grown outside of its original geographical zone including in areas such as North and South America, and Africa.

Winged beans in various states: growing on string in Malaysia, in a UK store, and the seeds in test tubes. Winged bean is an underutilized crop.

(left) field trial of Winged bean grown on a vertical string, in Malaysia (image: UoN Malaysia); (centre) an unexpected journey: winged bean pods found at a local store in Nottingham, UK(image: Alberto Tanzi); (right) ground winged bean seeds, ready for protein content analysis at UoN-UK.

Grown as a pulse, mature seeds have shown promising nutritional values for protein content and for the possibility to develop value added products. Tofu, tempeh, and raw ingredients like flour and oil have been produced from the plant products. Research efforts across UoN campuses have focused on how to cultivate Winged bean in the field, and further improve its nutritional value. Taming its vigorous growth for large-scale cultivation and stabilising its pod/seed productivity are crucial aspects to ongoing work. At the same time, in the Future Food Beacon, research on how seeds accumulate proteins, and how to improve their availability during digestion can help transform this crop to be a main source of plant protein – and, perhaps, introduce it to the growing market of plant-based products as well. As with Bambara, research across UoN campuses has looked into the development of molecular tools for Winged bean, not least the sequencing of its genome and the generation of molecular markers for genetic analysis and breeding.

Foxtail millet (Setaria italica) and Pearl Millet (Pennisetum glaucum)

Millets can be considered the underdogs of the cereal world, despite their vast geographical distribution, history, and contribution to human nutrition. For example, Foxtail millet was originally from the Yellow River areas in Northern China, while Pearl millet comes from the hot and arid regions of West Africa. Despite this geographical distance, these crops share some common features. They both can be grown on marginal soils (where other crops struggle), are drought tolerant and are a staple food for millions, in particular across China, India, and Africa. Millets are also excellent sources of micronutrients (e.g., iron, zinc) and possess relatively high levels of proteins, making them a critical, well-rounded source of nutrition.

Foxtail millets showing the variation in panicles, growing outside and growing in a glasshouse. Foxtail millet is an underutilized crop

(left) a sample showing some of the variation observed in Foxtail millet panicles (the structure carrying seeds); (centre) foxtail millet growing outside; (right) a few Foxtail millet plants in Future Crops Glasshouses at UoN-UK.

A key factor for promoting millets wider cultivation, is their ability to withstand environmental stresses better than other cereals, an aspect linked also to their own biological mechanisms. Most plants lose water through pores on their leaf surface called stomata (known as transpiration) in exchange for carbon dioxide from the atmosphere during the process of photosynthesis. Therefore, the presence of water in the soil is crucial to replenish the water lost through this process resulting in susceptibility to drought. However, both millets possess a type of photosynthesis called “C4” – that allows them to capture and use carbon dioxide whilst limiting water loss via transpiration. This means that they are well adapted to hot and dry environments, keeping high growth and grain yield where other key cereals such as wheat and rice may struggle. Foxtail millet has even been brought forward as a model species for studying such a trait.

So far at UoN, research has focused on generating value-added products from pearl millet; in assessing the diversity in its grain (structure, composition, and functionality); and in studying its root architecture. These efforts aim to support the creation of products that could increase demand, similar to the example we saw earlier in Bambara, changing millet from being an underutilized crop, and to improve even further drought tolerance characteristics. In both millets, we have also invested in generating molecular tools that will support genetic analysis for creating improved varieties.

Crop diversity for the future

The CDU at UoN is continuously involved in collecting and characterising plant samples, performing genetic analyses, generating data to assess and promote the potential of underutilized crops, and in overcoming some of the bottlenecks that once limited their development. While only four underutilized crops were presented here, there is ongoing work on African rice (Oryza glaberrima), giant taro (Alocasia macrorrhizos), amaranth (Amaranthussp.), moth bean (Vigna aconitifolia), quinoa (Chenopodium quinoa) and others.

Increasing these crops’ utilisation in our agricultural systems is still a long and winding road. The twists and turns are made harder by the very same thing we are trying to harness: the diversity of the crop species out there, and the different environments in which we grow our food. Each combination of these two could lead to different outcomes, and the contribution of each crop to an agricultural system requires its assessment. While demanding, collaborations and the advancements made in tools and analysis methods – linked to molecular biology, phenotyping, and bioinformatics among others – make it possible to overcome limitations that hampered past endeavors.

Finally, it might be worth keeping in mind that these crops go beyond what we serve at our dinner table. For many people a crop is part of their cultural heritage, just as important as a building, an archeological site, a painting, or a book is for others. Recognising this cultural value, like the agronomic potential, will be crucial not just for the sake of historical appreciation, but in supporting those farmers who continue to grow these crops, and for the entrepreneurial efforts of those who wish to create and expand business opportunities. For these reasons, the CDU promotes a comprehensive vision for these crops, which will be key for fulfilling their potential.

Posted in Food Research