Jill Elizabeth Cairns

Stress-tolerant crop varieties are widely promoted to enhance the resilience of smallholder farming systems under increasing climate variability. By stabilizing production under adverse conditions, such varieties may contribute to improved food security. However, evidence on realized benefits among resource-poor and women farmers remains limited. This study examines the associations between stress-tolerant maize (STM) adoption, yield, and household food security during the El Niño-induced drought of 2023/24 in Zimbabwe. Using survey data from 435 households and 542 plots, we assess STM performance across smallholder production contexts. Results show that STM adoption is associated with positive mean effects on maize yields and moderate but consistent reductions in food insecurity. Yield gains are concentrated around the median of the distribution, suggesting that STM primarily stabilizes production under intermediate stress conditions rather than preventing crop failure under extreme drought. Associations between STM adoption and food security are strongest among households cultivating small maize areas close to the homestead, where management intensity is higher. We do not find differential effects in households where women are the primary decision-makers in maize production. Women’s decision-making over maize use is positively associated with dietary diversity, indicating that such roles may influence food consumption outcomes through channels not directly linked to STM adoption. Overall, STM can contribute to more stable production and improved food security, but realized benefits are associated with farm context and agronomic management. Targeted promotion of STM in suitable agroecological zones, combined with complementary agronomic practices can enhance its contribution to inclusive and sustainable agricultural development.

Developing breakthrough products that deliver a minimum 25% productivity improvement in farmers’ fields requires that breeding pipelines more closely align with farmer and end-user needs and the target population of environments (TPEs). In the case of maize (Zea mays), climate change is accelerating climatic shifts within the TPE, potentially limiting future realized genetic gain. On-farm breeding approaches can play a valuable role in supporting breeding programs transitioning toward breakthrough products. Increased sampling of the TPE by moving selection into farmers’ fields can overcome the challenges of climatic changes within the TPE and extensive farmer diversity, whilst providing information to refine managed environment trials designed to sample the TPE. This review highlights advances in inclusive host farmer sampling, sparse testing strategies and phenotyping to facilitate scaling of on-farm testing within breeding pipelines.

Transitioning to sustainable agrifood systems requires innovations in the reduction in greenhouse gas (GHG) emissions without compromising productivity. Biological nitrification inhibition (BNI), a plant trait that suppresses soil nitrification through root-exuded inhibitory compounds, offers a novel pathway for reducing nitrogen (N) losses and associated emissions. In this study, a spatially explicit, ex ante assessment of the potential environmental benefits of BNI maize under three global fertilizer management scenarios is conducted using a partial life cycle assessment. Two BNI-enabled maize scenarios with 20% (BNI_20) and 30% (BNI_30) nitrification inhibition (projected for adoption by 2030 and 2050) are compared with a business-as-usual (BAU) baseline (BNI_0). In countries with limited N use, fertilizer rates were increased to 50 kg N ha⁻¹, reflecting regional policy targets, whereas in high-use countries, N application was proportionally reduced to modelled BNI-driven reductions in N losses. The results show that the adoption of BNI_20 and BNI_30 could reduce global fertilizer demand by 1.4% and 3.9%, respectively, and GHG emissions by 11.2% and 18.2%, respectively, relative to those in the BAU scenario. In contrast, conventional maize production under similar nutrient management conditions should increase fertilizer demand and GHG emissions by 3.5% and 3.4% in 2030, respectively, and by 3.2% and 3.1% in 2050, respectively. Relative to conventional maize, BNI_20 and BNI_30 could reduce N demand by 4.9% and 7.2%, respectively, and GHG emissions by 14.5% and 21.4%, respectively. These findings highlight the potential of BNI-enabled maize to significantly contribute to climate change mitigation in agriculture, particularly when it is integrated with national fertilizer policies that manage N use, food security, soil health, and environmental protection. To promote the effective implementation of this technology, developing deployment pathways for BNI traits in maize should be prioritized as part of broader strategies for sustainable intensification and low-emission farming.

Societal Impact Statement: Gender responsive and more socially inclusive breeding strategies are needed to ensure new crop varieties, which offer greater yields in an increasingly variable climate, meet the needs of a diverse range of smallholder farmers. Participatory varietal selection actively involves farmers in testing and selecting new varieties at the end of the breeding process. We evaluated the inclusivity of a participatory maize breeding program in Zimbabwe. Our analysis found that setting targets for women farmer participation ensured adequate representation, but participatory research should move beyond simple targets and ensure the inclusion of different types of women and men farmers. Summary: There is growing interest in participatory varietal selection and gender‐responsive breeding in research and development initiatives. On‐farm testing is increasingly used to ensure that new varieties perform within the target environments. However, there are few established approaches for selecting host women and men farmers who reflect the diversity of the overall target population of smallholder farmers. This study sought to evaluate ex‐post if recruited farmers within a participatory breeding network in Zimbabwe were representative of the surveyed population and pilot an approach to developing comprehensive farm typologies to ensure more gender‐responsive and socially inclusive breeding. A sample of over 2,000 randomly selected women and men farmers, including those hosting breeding trials, were surveyed. A typology was constructed to group farms with similar characteristics associated with household demographics, maize production and resource endowments. This facilitated the subsample of trial‐hosting farmers characteristics to be compared with the broader typology. The distribution of farm types selected by extension agents to host trials closely reflected the distribution of farm types within the surveyed population. Two farm types associated with women household heads and three types associated with men‐headed households were identified, highlighting the heterogeneity within these groups. Other important factors of differentiation included farm assets, livestock ownership and maize production features. Sampling strategies that explicitly incorporate agronomic and socio‐economic diversity within the target population should be used in the selection of host women and men farmers for participatory research to ensure appropriate gender and social inclusion.

Hybrid maize seed production in Africa is dependent upon manual detasseling of the female parental lines, often resulting in plant damage that can lead to reduced seed yields on those detasseled lines. Additionally, incomplete detasseling can result in hybrid purity issues that can lead to production fields being rejected. A unique nuclear genetic male sterility seed production technology, referred to as Ms44-SPT, was developed to avoid hybrid seed loss and to improve the purity and quality of hybrid maize production. Hybrid seed yield reduction following detasseling can be attributed to leaf loss. Our analyses showed an average 2.9 leaves are lost during the detasseling process, resulting in a seed yield reduction of 14.0%. These findings suggest that deploying the Ms44-SPT technology would avoid this seed yield loss. By simplifying hybrid production and increasing seed yields, Ms44-SPT could help drive hybrid replacement, providing smallholder farmers with better access to improved hybrids.

Societal Impact Statement: A hybrid maize seed production technology has the potential to reduce the complexity of hybrid seed production and increase seed quality. Here, we investigate the potential impact of this technology on yields when hybrid maize is recycled. Hybrid maize recycling is a practice used by resource‐poor farmers as a coping mechanism during drought years. Recycling hybrid maize produced using this technology could provide a small yet significant yield benefit to resource‐poor farmers when they chose to recycle. This study provides an example of how social considerations can be incorporated into testing strategies of new technologies to ensure equitable benefits.Summary: Understanding the performance of new genetic technologies in farmers' real‐world realities, especially those relevant to resource‐poor farmers, is often overlooked but is essential to ensure equitable benefits. A new genetic technology was developed to simplify hybrid maize seed production in sub‐Saharan Africa, thereby improving farmers' access to high‐quality hybrid seed. Hybrids produced with this technology segregate 50:50 for pollen‐producing and non‐pollen producing and are designated 50% non‐pollen producing (FNP). FNP maize has higher yields in low‐input environments. As recycling hybrid maize seed remains a common practice in Zimbabwe, including among resource‐poor households, it is important to understand the impact of recycling FNP seed on the yield gains from the FNP technology. The potential impact of recycling FNP hybrid seed was assessed by testing three seed recycling scenarios on‐station and on‐farm. The extent of hybrid seed recycling and the types of households recycling hybrid maize seed over a 3‐year period were also investigated. Hybrid maize seed recycling was associated with resource‐poor farmers, although it was not continually practiced across years. Yield gains associated with FNP were retained under recycling practices, albeit reduced. The greatest yield benefit was when seed from only non‐pollen‐producing plants was used. Yield gains were associated with longer ears and more kernels per ear. While recycling hybrid maize seed reduces potential yields due to inbreeding depression, in the years when farmers cannot afford to plant hybrid maize only, recycling non‐pollen‐producing hybrid maize seed conferred a yield benefit of 116 kg ha⁻¹.

This perspective describes the opportunities and challenges of data-driven approaches for crop diversity management (genebanks and breeding) in the context of agricultural research for sustainable development in the Global South. Data-driven approaches build on larger volumes of data and flexible analyses that link different datasets across domains and disciplines. This can lead to more information-rich management of crop diversity, which can address the complex interactions between crop diversity, production environments, and socioeconomic heterogeneity and help to deliver more suitable portfolios of crop diversity to users with highly diverse demands. We describe recent efforts that illustrate the potential of data-driven approaches for crop diversity management. A continued investment in this area should fill remaining gaps and seize opportunities, including i) supporting genebanks to play a more active role in linking with farmers using data-driven approaches; ii) designing low-cost, appropriate technologies for phenotyping; iii) generating more and better gender and socioeconomic data; iv) designing information products to facilitate decision-making; and v) building more capacity in data science. Broad, well-coordinated policies and investments are needed to avoid fragmentation of such capacities and achieve coherence between domains and disciplines so that crop diversity management systems can become more effective in delivering benefits to farmers, consumers, and other users of crop diversity.

The negative impacts of zinc (Zn) and iron (Fe) deficiency due to over-reliance on monotonous cereal-based diets are well-documented. Increasing micronutrient densities in maize is currently among top breeders’ priorities. Here, 77 single-cross Zn-enhanced hybrids with normal, provitamin A and quality protein maize genetic backgrounds were evaluated together with seven checks for grain Zn and Fe concentration and agronomic traits under optimum, low nitrogen (N) and managed drought conditions. Results showed a fairly wide variability for grain Zn (10.7–57.8 mg kg⁻¹) and Fe (7.1–58.4 mg kg⁻¹) concentration amongst the hybrids, across management conditions. Notable differences in Zn concentration were observed between the Zn-enhanced quality protein maize (QPM) (31.5 mg kg⁻¹), Zn-enhanced provitamin A maize (28.5 mg kg⁻¹), Zn-enhanced normal maize (26.0 mg kg⁻¹) and checks (22.9 mg kg⁻¹). Although checks showed the lowest micronutrient concentration, they were superior in grain yield (GY) performance, followed by Zn-enhanced normal hybrids. Genotypes grown optimally had higher micronutrient concentrations than those grown under stress. Genotype × environment interaction (G × E) was significant (p ≤ 0.01) for GY, grain Zn and Fe concentration, hence micronutrient-rich varieties could be developed for specific environments. Furthermore, correlation between grain Zn and Fe was positive and highly significant (r = 0.97; p ≤ 0.01) suggesting the possibility of improving these traits simultaneously. However, the negative correlation between GY and grain Zn (r = −0.44; p ≤ 0.01) and between GY and grain Fe concentration (r = −0.43; p ≤ 0.01) was significant but of moderate magnitude, suggesting slight dilution effects. Therefore, development of high yielding and micronutrient-dense maize cultivars is possible, which could reduce the highly prevalent micronutrient deficiency in sub-Saharan Africa (SSA).