A unified strategy for West African pearl millet hybrid and heterotic group development

Abstract

Smallholder farmers in Sahelian West Africa (WA) grow pearl millet [Pennisetum glaucum (L.) R. Br.] as a staple cereal in harsh and highly variable environments, predominantly relying on landraces or open-pollinated varieties (OPVs) with an average grain yield of 648 kg ha−1 (2017). Encouraging initial results with experimental pearl millet population or topcross hybrids and the available diversity in its WA center of origin offer a great opportunity for a regionally coordinated hybrid breeding approach. This review is therefore meant to summarize information on pearl millet hybrid breeding with emphasis on WA and to suggest a unified strategy as a way forward. Observed average better-parent heterosis ranged from 4–18% and 0–88% in population and topcross hybrids, respectively, across several studies, and the yield stability was comparable with or better than the parental OPVs. Diversity and combining ability studies pointed at eastern and western WA as promising starting points for systematic development of heterotic groups. Building on respective groups, reciprocal recurrent selection in combination with integration of further adapted genetic resources is recommended to systematically diversify and build up the heterotic parental pools, increase combining ability to the opposite group, and create a continuous output of OPV and hybrid varieties. Molecular markers supporting cytoplasmic male sterility (CMS) introgression are available, and genomic tools can improve hybrid prediction. Regarding the unpredictability and intensity of biotic and abiotic stresses, heterogeneous population and topcross hybrids appear most suitable to sustainably increase pearl millet yields and give maximal benefits to WA farmers.