Field phenotyping for African crops: overview and perspectives

Abstract

Improvements in crop productivity are required to meet the dietary demands of the rapidly-increasing African population. The development of key staple crop cultivars that are high-yielding and resilient to biotic and abiotic stresses is essential. To contribute to this objective, high-throughput plant phenotyping approaches are important enablers for the African plant science community to measure complex quantitative phenotypes and to establish the genetic basis of agriculturally relevant traits. These advances will facilitate the screening of germplasm for optimum performance and adaptation to low-input agriculture and resource-constrained environments. Increasing the capacity to investigate plant function and structure through non-invasive technologies is an effective strategy to aid plant breeding and additionally may contribute to precision agriculture. However, despite the significant global advances in basic knowledge and sensor technology for plant phenotyping, Africa still lags behind in the development and implementation of these systems due to several practical, financial, geographical and political barriers. Currently, field phenotyping is mostly carried out by manual methods that are prone to error, costly, labor-intensive and may come with adverse economic implications. Therefore, improvements in advanced field phenotyping capabilities and appropriate implementation are key factors for success in modern breeding and agricultural monitoring. In this review, we provide an overview of the current state of field phenotyping and the challenges limiting its implementation in some African countries. We suggest that the lack of appropriate field phenotyping infrastructures is impeding the development of improved crop cultivars and will have a detrimental impact on the agricultural sector and on food security. We highlight the prospects for integrating emerging and advanced low-cost phenotyping technologies into breeding protocols and characterizing crop responses to environmental challenges in field experimentation. Finally, we explore strategies for overcoming the barriers and maximizing the full potential of emerging field phenotyping technologies in African agriculture. This review paper will open new windows and provide new perspectives for breeders and the entire plant science community in Africa.

Keywords: African agriculture; African crops; field phenotyping; high-throughput phenotyping; low-cost phenotyping; phenotypes; phenotyping infrastructures; precision agriculture.

Figure 1

Major crop distribution in Sub-Saharan African region based on average production values between 2011-13. Adapted from FAOSTAT (2016). FAO, http://faostat3.fao.org/.

Figure 2

Overview of the most common field phenotyping systems and approaches at proximal and remote sensing scales. The proximal sensing approach is based on ground-based platforms such as handheld spectrometers, hand-pushed carts equipped with sensors, tractor-based platforms fitted with multiple cameras and gantry scanalyzer systems that collect spectral information of crops in close range or contact. On the other hand, the remote sensing technique is based on aerial platforms including unmanned aerial vehicles (i.e., drones), manned aircraft and satellites that acquire spectral imagery of crops without making physical contact but at a distance. Figure 2 was modified from (Pineda et al., 2021).

Figure 3

The ICARDA's precision field phenotyping platforms installed at Sidi el Aidi (Settat) in Morocco. Images are in courtesy of Andrea Visioni of ICARDA-Morocco.