Context

Micronutrient malnutrition (“hidden hunger”) remains a persistent agrifood and public health challenge in South Asia. Although cereal-based diets ensure calorie sufficiency, they frequently fail to meet essential micronutrient requirements, particularly zinc and iron. In the eastern Indo-Gangetic Plains (EIGP) of India, Bihar exhibits a high prevalence of anemia, stunting, and underweight populations. Addressing these challenges requires scalable, food-based nutritional interventions that enhance dietary quality without compromising crop productivity, climatic resilience, or farmer incomes.

Objective

This study tested the hypothesis that zinc-biofortified wheat varieties can simultaneously deliver stable grain yield, enhanced grain zinc and iron concentrations, and broad agro-ecological adaptability under farmer-managed conditions in Bihar.

Methods

Multi-location field evaluations were conducted over five consecutive wheat-growing seasons (2018–19–2022–23) across all 14 districts of Bihar, covering diverse agro-climatic sub-zones. Two zinc-biofortified wheat varieties (BHU-25 and BHU-31) were compared with a widely cultivated commercial variety (HD-2967). The dataset comprised more than 11,000 plot-level observations generated through HarvestPlus yield trials, strip trials, and farmer-led demonstrations conducted under real-world management practices.

Results

Across locations and seasons, both biofortified varieties produced grain yields comparable to, or numerically higher than, the commercial check (HD-2967), with mean yields ranging from 3.9 to 4.2 Mg ha⁻¹ . Although BHU-31 recorded a numerically higher mean yield (3.6 %) and BHU-25 a marginal advantage (0.5 %) over HD-2967, these differences were not statistically significant (P > 0.05), indicating the absence of a yield penalty associated with biofortification. Grain zinc concentrations consistently met or exceeded the biofortification target of 38 mg kg⁻¹ and remained stable across environments, with district means ranging from 26.4 to 40.1 mg kg⁻¹ . Grain iron concentrations showed moderate but significant spatial variation across environments (33.2–40.5 mg kg⁻¹). Importantly, during climatically adverse seasons characterized by excessive rainfall and heat stress, both biofortified varieties maintained yields above 3.0 Mg ha⁻¹ , comparable to the commercial check.

Conclusions

Zinc-biofortified wheat varieties demonstrated a rare combination of high yield potential, enhanced micronutrient density, and climatic resilience under farmer-managed conditions, with no evidence of a yield penalty.

Implications and limitations

The findings provide robust field-scale evidence that zinc-biofortified wheat is a cost-effective, climate-resilient, and nutrition-sensitive intervention for cereal-based food systems. Integration of these varieties into public procurement, school feeding programs, and decentralized seed systems offers a scalable pathway to improve dietary zinc intake while sustaining wheat productivity in Bihar and similar agro-ecosystems of South Asia. While the study captures extensive spatial and temporal variability, direct assessments of household consumption and nutritional outcomes were beyond its scope.