Transforming a humble legume into a nutritional powerhouse with 77% yield increases and improved food security
In the heart of agricultural research centers across India and Africa, a quiet revolution is unfolding in the fields of a humble crop—pigeonpea. This protein-rich legume, known as toor dal in many households, sustains millions of smallholder farmers and their families across the tropics.
Yet, despite its nutritional value, pigeonpea faces a hidden enemy: micronutrient deficiency that stunts both crops and human health. As climate change intensifies, with rising temperatures threatening traditional growing seasons, scientists are pioneering an innovative solution—biofortification with zinc and iron—that promises to transform pigeonpea into a powerhouse of nutrition while boosting farmer incomes.
Recent research reveals that through strategic application of these vital micronutrients, pigeonpea yields can surge by up to 77%, creating what experts call a "win-win" scenario for both food security and economic prosperity 1 2 .
Pigeonpea (Cajanus cajan) stands as the fifth most important pulse crop globally, with India serving as the world's second-largest producer. This drought-resistant legume plays a dual role in sustainable agriculture: it provides protein-rich grains for human consumption while simultaneously enriching soils through natural nitrogen fixation.
For the vegetarian population of India and many African nations, pigeonpea represents a crucial protein source, offering high levels of fiber, vitamins, and potassium while being low in fat and sodium 4 .
Unfortunately, this nutritional powerhouse is struggling to reach its potential. According to agricultural scientists, approximately 40% of Indian soils are deficient in zinc, while 12.6% lack sufficient iron—a problem that reverberates throughout the food chain 4 .
5th most important pulse crop worldwide
Biofortification represents a groundbreaking approach to combating dietary micronutrient deficiencies. Unlike conventional fortification which adds nutrients during food processing, biofortification enhances the nutrient content of crops as they grow.
Strategic application of zinc and iron fertilizers through soil, foliar sprays, or seed treatments
Selecting and developing varieties that naturally accumulate higher mineral levels
Directly modifying plants to enhance nutrient uptake and storage
For pigeonpea, the focus has primarily been on agronomic biofortification—the application of specialized fertilizer formulations that boost the crop's zinc and iron content while simultaneously improving yields 5 . This dual benefit makes agronomic biofortification particularly attractive for resource-constrained farmers who cannot choose between productivity and nutrition.
In a landmark study published in Scientific Reports in 2025, researchers conducted comprehensive laboratory and field experiments to compare the effectiveness of green-synthesized nanoparticles versus commercial alternatives for pigeonpea biofortification 2 .
The research team employed an innovative approach to nanoparticle creation, using plant extracts from Terminalia catappa for iron nanoparticles and Tridax procumbens for zinc nanoparticles—a sustainable alternative to conventional chemical synthesis methods.
The experiment tested these nanoparticles through two primary application methods:
These treatments were evaluated against control groups and conventional fertilization methods to quantify their impact on germination, plant growth, and ultimate yield.
The findings demonstrated substantial advantages for the green-synthesized nanoparticles across all measured parameters:
| Parameter | Control Group | Nano-Primed Seeds | % Improvement |
|---|---|---|---|
| Germination Rate | Baseline | Significantly Higher | +15-20% |
| Seedling Vigor | Baseline | Enhanced | +25-30% |
| Root Development | Baseline | Substantially Improved | +35-40% |
The most dramatic results emerged from field trials that combined both seed priming and foliar application of the nano-formulations:
| Yield Parameter | Control Yield (kg/ha) | Nano-Treatment Yield (kg/ha) | % Increase |
|---|---|---|---|
| Seed Yield | 974 | 1,728 | 77.41% |
| Stalk Yield | 2,417 | 4,285 | 77.35% |
| Husk Yield | 544 | 828 | 52.20% |
SPAD values indicating better chlorophyll content
NDVI values indicating overall plant health
Beyond sheer productivity, the biofortification approach significantly enhanced the crop's physiological health and nutritional value. The researchers reported 27.82% higher SPAD values (indicating better chlorophyll content) and 54.38% improvement in NDVI values (indicating overall plant health) compared to control groups 2 . Perhaps most importantly, the zinc and iron concentrations in the harvested grains increased substantially, transforming the pigeonpea into a more potent source of these essential micronutrients.
The remarkable advances in pigeonpea biofortification rely on carefully selected research reagents and methodologies. The table below outlines key components of the biofortification toolkit as identified from multiple research studies:
| Reagent/Material | Function in Research | Notable Examples |
|---|---|---|
| Zinc Sulfate (ZnSO₄·7H₂O) | Standard zinc source for soil application (20-25 kg/ha) and foliar sprays (0.5%) | "Naya Zinc" (98% pure, 21% Zn) 8 |
| Iron Sulfate (FeSO₄) | Primary iron source for soil application (5 kg/ha) | Commercial grade FeSO₄ 4 |
| Green-Synthesized Nanoparticles | Sustainable nutrient delivery with enhanced efficiency | Terminalia catappa-synthesized Fe NPs; Tridax procumbens-synthesized Zn NPs 2 |
| Zinc Oxide Nanoparticles | Alternative nanoscale zinc source with controlled release | ZnO nanoparticles (135-197 nm size) 9 |
| Chelated Forms (Zn-EDTA) | Improved zinc availability in alkaline soils | Zn-EDTA (14% chelated Zn) 5 |
| Plant Growth-Promoting Rhizobacteria | Enhanced nutrient solubilization and root uptake | Bacterial strains (AW5) with siderophore production 9 |
These reagents enable multiple application strategies, each with distinct advantages. Soil application provides a steady nutrient reservoir, while foliar spraying ensures direct nutrient absorption during critical growth stages. The emerging approach of seed nutri-priming—soaking seeds in nutrient solutions before planting—offers a resource-efficient method that enhances early growth and establishes a foundation for improved nutrient uptake throughout the plant's lifecycle 5 .
Steady nutrient reservoir
Direct nutrient absorption
Resource-efficient method
Research indicates that pigeonpea genotypes vary significantly in their response to zinc and iron application. A 2020 study classified twenty different genotypes into four categories based on their efficiency in utilizing soil zinc and responding to fertilization 6 :
Ideal for cultivation as they perform well under low soil zinc and respond strongly to fertilization (e.g., Virsa Arhar-1, BDN-2)
Grow well in deficient soils but don't significantly benefit from added zinc (e.g., ICPL 87119)
Struggle in deficient soils but improve dramatically with fertilization (e.g., AKT 8811)
Poor performers regardless of soil zinc status
This classification provides farmers with tailored guidance for variety selection based on their specific soil conditions and capacity for fertilizer investment.
The economic case for biofortification continues to strengthen as new technologies emerge. Meanwhile, breeding programs are developing climate-resilient varieties like ICRISAT's ICPV 25444—the world's first heat-tolerant pigeonpea capable of withstanding temperatures up to 45°C during summer growth .
"What we have here is a variety that is designed to thrive in a warming planet... It is a step forward in building climate-smart, resilient agriculture that serves both people and the planet"
This 120-125 day variety represents a breakthrough in expanding pigeonpea cultivation beyond traditional seasons, potentially enabling double cropping and significantly boosting farmer incomes.
The combination of heat-tolerant varieties and targeted micronutrient application creates a powerful synergy. As Dr. Himanshu Pathak, Director General of ICRISAT, notes:
World's first pigeonpea variety resistant to 45°C temperatures
The biofortification of pigeonpea with zinc and iron represents more than just an agricultural advancement—it embodies a transformative approach to addressing intertwined challenges of malnutrition, poverty, and climate change. By applying innovative scientific solutions ranging from green-synthesized nanoparticles to strategic fertilizer management, researchers have demonstrated that we can significantly enhance both the quantity and quality of this vital pulse crop.
The impressive 77% yield increases coupled with improved nutritional profiles create what agricultural economists call a "win-win scenario"—farmers benefit from higher productivity and incomes, while consumers access more nutritious food. As these technologies continue to evolve and reach more smallholder farmers, the vision of nutrition-sensitive agriculture becomes increasingly attainable.
"Resolving this scientific challenge could have far-reaching implications. In the long term, the work could make an important contribution to safeguarding food security, reducing poverty, and promoting sustainable agricultural practices, particularly for vulnerable populations in low-and middle-income countries"
The journey of pigeonpea biofortification serves as an inspiring model for how targeted scientific innovation can cultivate a healthier, more food-secure future for all.