The Sahel region is a semiarid climate zone that stretches from the east to the west of Africa and separates the Sahara Desert to the north and the tropical savannas to the south. During the second half of the 20th century, the Sahel region experienced a major climate shift – from a relatively wetter period in the 1950s and 1960s to a dryer climate in the 1970s and 1980s. This dry period led to major episodes of drought, food shortages, and dramatic environmental and societal effects (Tomalka et al., 2021). Although, the levels of rainfall have increased, they are lower than those in the 1940s and 1950s, with high year-to-year variability and increased unpredictability.
In the Sahel, agriculture is the main pillar of the countries’ economy. In this region, 80–90 % of the population is engaged in agriculture, on which they depend for both food and income. Therefore, even minor perturbations could threaten people’s livelihoods and food security. Unfortunately, in the Sahel, agricultural production is primarily subsistence-based and rainfed, which makes the region highly dependent on rainfall patterns and thus vulnerable to climate change. Climate change projections indicate that the Sahel will gradually become hotter, with some areas experiencing increased, but erratic rainfall (Tomalka et al., 2021). In this context, droughts and floods are expected to intensify (i.e., become stronger and more frequent), hence the emergency for appropriate adaptation measures to reduce the insecurity and vulnerability in the region.
Sahelian droughts and their effects have been studied extensively since the 1970s. CERAAS, the lead organization behind this book project, is a full-fledged Senegalese research center entirely dedicated to studying drought adaptation and its improvement. It does so through genetic crop improvement in association with other disciplines since its creation 40 years ago. Sound expertise on drought research has earned CERAAS a renowned reputation, which was strengthened by its recognition as a Regional Center of Excellence on dry cereals and associated crops with the mandate to lead research and development on pearl millet, sorghum, fonio, peanut, cowpea, and sesame in West and Central Africa.
Over the years, CERAAS has accumulated a wealth of knowledge and experience on dryland crops improvement, with the collaboration of numerous regional and international partners. This book pays tribute to the excellent work done by dedicated research teams on crop improvement and adaptation to drought-prone environments in West Africa. Rather than compiling 40 years of research on this topic, we opted to share the latest developments relevant to concepts, methods, and technologies associated with dry cereals and legume crops’ production in the semiarid West Africa. More specifically, this book highlights key results from both applied and basic research undertaken in West Africa towards the development and deployment of climate-smart technologies, especially drought-adapted varieties. These tools include advanced analysis tools and methods used to characterize drought-prone environments and understand crops adaptation to drought and decision support tools designed to guide a better targeting of necessary technologies to the right environments. This book project was also an opportunity to strengthen young scientists’ writing skills and self-confidence as some of them embraced lead author roles. Although, most of the contributors are francophone, to broaden the spectrum of readership, we have undertaken the task of writing and publishing the book in English.
The book encompasses 19 chapters and is organized into three parts – socioeconomic analysis of dryland crop production, advanced phenotyping and crop modelling for adaptation to drylands, and genetic diversity and improvement of dryland crops.
Part 1: Socioeconomic Analysis of Dryland Crop Production illustrates the socioeconomic factors that affect the food systems for these crops. It contains six chapters that provide an overview of crop production and consumption in the region (Chapter 1). Then, important inputs that affect system productivity are presented: preferences for new seed varieties (Chapter 2), yield response to fertilizer (Chapter 3), counterfeit herbicides (Chapter 4), and the way farmers develop expectations about the weather events that shape cropping outcomes (Chapter 5). Chapter 6 is dedicated to understanding urban consumer preferences for processed food products derived from pearl millet.
Part 2: Advanced Phenotyping and Crop Modelling for Adaption to Drylands addresses the state of the art of plant phenotyping and the modeling of crop adaptation to dryland cropping systems. The first three chapters focus on drone-based high throughput phenotyping in field situations. Chapter 1 describes an automated data pipeline to fast-track image data processing and analysis. Using sorghum as a test case, Chapter 2 provides evidence of the effectiveness and accuracy of drones for drought phenotyping. Chapter 3 outlines the prospect of a regional network for phenotyping to mutualize investment. Chapters 4 and 5 focus on root traits and their use in crop improvement programs, while Chapters 6 presents crop ideotypes to guide genetic improvement and variety recommendations.
Lastly, Part 3 investigates the genetic diversity and improvement of dryland crops. The seven chapters in this section focus on biodiversity and agricultural systems sustainability, orphan crops, such as fonio, and the utilization of a regional germplasm collection in the improvement of cowpea, groundnut, pearl millet, and sorghum. Opportunities offered by advances in genetics and genomics for more effective use of genetic resources for varietal development are also highlighted.
The richness of this book lies in the multidisciplinary expertise mobilized by CERAAS through its partnerships, but unfortunately, not all chapters received could be included in this book. To maintain the standards of scientific quality and thematic relevance, some chapters were excluded. However, throughout the review process, which involved both internal and external steps, authors were guided with constructive feedback. In addition, research related to dryland crop management, crop protection, nutrition, as well as technology diffusion pathways, and gender and youth inclusion were deliberately not addressed in this book to keep this first edition concise and focused on CERAAS’ core discipline – genetic improvement.
Overall, it has been a long journey since the time the call for chapters was launched in 2020, to the identification of an appropriate publisher in 2021, and the publication of the book in 2022. A lot of time and energy has been spent to compile the information contained in this book. It was a very demanding experience but also very rewarding and satisfying, and a lot has been learned through the process.
We hope that all the parties involved in this project are proud of the outcome of this journey.
We hope that readers will find informative and useful answers herein and better understand the kind of research that is being undertaken to improve crops’ adaptation to drought and how the findings can contribute to increasing crop productivity and building more climate resilient cropping and food systems.
We wish you all a happy reading!
Tomalka, J., Birner, J., Dieye, A. M., Gleixner, S., Harper, A., Hauf, Y., Hippe, F., Jansen, L., Lange, S., Laudien, R., Rheinbay, J., Vinke, K., von Loeben, S. C., Wesch, S., Zvolsky, A., Gornott, C. (2021). Climate risk profile: Sahel. A joint publication by the Potsdam Institute for Climate Impact Research (PIK) and the United Nations High Commissioner for Refugees (UNHCR) under the Predictive Analytics project in support of the United Nations Integrated Strategy for the Sahel (UNISS), Potsdam: Potsdam Institute for Climate Impact Research (PIK) and the United Nations High Commissioner for Refugees (UNHCR). https://publications.pik-potsdam.de/pubman/item/item_26168