Exploiting the potential of genotype microbiome interactions to promote sustainable soil health in southern Africa

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ContextMaize is the most important cereal crop in southern Africa but without new management practices in the face of increasing occurrence and severity of drought and low soil nutrient availability, yields which are already low are predicted to further decline. It is critical that new approaches are developed to ensure food security, and help alleviate poverty of smallholder farmers. Breeding for new maize cultivars with greater tolerance to drought and enhanced ability to take up nitrogen holds much promise to transform these cropping systems, but first we need to understand how these crop plants interact with the soil, the microorganisms in the soil, and with management to confer benefits for crop production, that will help ensure food security. Aims and objectivesOur research aims to address whether considering the nature of interactions between crop genetic make-up (genotype), soil microorganisms and the processes they undertake provides a viable approach for future maize breeding programmes to help ensure yield stability and resilience to low nutrient availability and drought in southern Africa. We will firstly undertake, under controlled environment conditions, a detailed screening of a wide range of maize genotypes from the CIMMYT germplasm collection to establish the extent of variation in influence on soil nitrogen and carbon processes. This screen will include varieties characterised by CIMMYT as being tolerant of low soil nitrogen or drought stress conditions. From this screen we will select lines to examine in more detail, and look at how they shape the microbial populations that undertake these processes, and gain understanding of plant-soil interactions underpinning sustainable production and soil health. We will then select six maize lines to establish consistency of interactions, established in controlled environments, under field conditions across CIMMYT farmer's network in Zimbabwe. Understanding these interactions will tell us if there is potential in using different maize genotypes to influence the soil microbial community, or future breeding for particular characteristics, to promote more effective nitrogen use and to confer greater resilience to drought. Potential applications and benefitsDemonstrating variation of maize for impacts on soil microbiota and processes is an essential step to developing strategies to exploit these traits for enhancing crop yields in combination with sustainable management practices. We anticipate that this foundation award will lead in the future to the development of a framework to inform future maize breeding initiatives or cultivar selection for southern Africa, that is based on the ability of crops to enhance and capitalise on soil health in terms of sustainable nutrient acquisition thereby helping ensure more reliable yields and greater resilience to changing environmental conditions.