Improving production efficiency of African Eggplant (Solanum aethiopicum) for smallholder farmers in sub-Saharan Africa

Malnutrition affects one in three people on the planet, with 2 billion people being deficient in one or more micronutrients. In Sub-Saharan Africa malnutrition is a chronic problem. The sustainable production and consumption of biodiverse nutritious horticultural crops provide a key part of the solution to this problem. There are many indigenous vegetable species that are grown in Africa and sold in local markets, mainly by female producers, as a source of income to alleviate their poverty. However, many of these crops are under-researched and their full potential has not been realised. African eggplant, Solanum aethiopicum, is such a crop. It is widely consumed across both West and East Africa as a leafy vegetable and also as a fruit. Solanum aethiopicum is closely related to Solanum melongena, aubergine/eggplant, and to tomato, Solanum lycopersicum and potato, Solanum tuberosum. Similar to these Solanum species, the availability of soil water and the health of the soil, as defined by the presence or absence of diseases, will greatly affect productivity and nutritive content. There is therefore an immense potential to improve the production of African eggplant through better water management strategies, improving soil health and growing varieties that are more resilient to water stress. Here we will adopt two major approaches to maximise African eggplant production: 1) developing new plant and crop management strategies to improve production; 2) characterise the genetic diversity towards identifying more drought resilient accessions of African eggplant. To inform best practice for irrigating African eggplant we will characterise the current commercial varieties' responses to a range of soil water deficits. Under controlled conditions we will identify the range of soil matric potentials and volumetric water contents that support optimum yields and nutritive quality. We will test the potential of using hyperspectral imaging to identify the onset of plant water stress and its use as a tool to identify water resilient lines. Responses to soil water deficits will be further investigated in pot experiments in Africa prior to testing in the field. We will also determine if nursery plants can be primed for a greater resilience to soil water stress and soil health before planting in the field. This will be done by using a mild wilting stress and the use of arbuscular mycorrhiza to induce better plant performance. Our final plant management strategy is to improve soil health. First we will characterise the DNA present in the soil on African farms to gain understanding of the microbes present and thus soil health. This will inform which soil amendments will have greatest potential to improve soil health, and these will be tested on the farms. We will assess the effect of these management practices on African eggplant productivity and take into account the economic cost and farmer preference towards generating best practice guides. At the same time as improving crop management we will characterise the extensive germplasm in our collection. To gain understanding of the potential diversity we will resequence the genomes of 20 accessions and identify the variation. We will multiply the seed in our collection and evaluate, in association with farmers, 160 accessions in drought-prone areas and characterise which lines are more resilient to low soil water availability. Based on farmer feedback we will phenotypically characterise in more detail the preferred accessions and initiate crosses of the best performing lines to advance current breeding programmes. To help inform breeding efforts, we will characterise a population of African eggplants that segregate for their ability to grow under increasing soil water deficits. We will identify molecular markers that are linked to better drought resilience that can be deployed in the breeding programmes.