Introduction

Mustard is India’s largest indigenous edible oil source, cultivated across nearly nine million hectares, primarily in Rajasthan, Uttar Pradesh, Madhya Pradesh, Haryana, and West Bengal. The crop is increasingly threatened by Orobanche aegyptiaca, a root-parasitic weed that attaches to mustard roots and extracts nutrients, water, and carbon. The infestation has led to severe yield losses, stagnation in productivity, and renewed dependence on edible oil imports despite policy emphasis on self-reliance.

Why in the News

Orobanche has emerged as the number one “hidden threat” to mustard in major producing states, particularly Haryana and Rajasthan. The infestation has intensified uniformly across fields, even where no visible weed shoots appear initially. Yield losses have become severe, with farmers reporting declines from 9 quintals per acre to 6 quintals, despite normal weather and irrigation. This represents a sharp contrast to earlier years when mustard yields remained stable under similar conditions. The problem directly affects India’s strategy to curb edible oil imports, which stood at $15.9 billion in 2023-24 and $18.3 billion in 2024-25, making the issue macro-economically significant.

Why is mustard critical to India’s edible oil economy?

1. Dominant Indigenous Crop: Accounts for over 40 million tonnes of indigenous edible oil output in 2023-24 and 2024-25, the highest among domestic oilseeds.
2. Import Substitution Role: Identified as the primary crop for yield improvement to reduce 16 million tonnes of annual edible oil imports.
3. Farmer Dependence: Traditionally grown on three-fourths of irrigated land in parts of Haryana due to low input requirements.

What is Orobanche aegyptiaca and why is it dangerous?

1. Parasitic Nature: Attaches underground to mustard roots, extracting nutrients and water, causing wilting and stunted growth.
2. Hidden Infestation: Damage occurs before shoots appear above ground, delaying farmer response.
3. Seed Proliferation: A single plant produces 40-45 flowers, each bearing 4,000-5,000 seeds, viable for up to 20 years in soil.
4. Rapid Spread: Disperses through wind, water, and irrigation channels, creating dense seed banks.

Why has the infestation intensified in recent years?

1. Cropping Pattern Rigidity: Repeated cultivation of mustard on the same land enhances parasite density.
2. Irrigation Practices: First irrigation at 25-30 days after sowing creates ideal soil moisture for Orobanche germination.
3. Climate Suitability: Moist soils followed by underground establishment accelerate attachment to roots.
4. Delayed Visibility: By the time shoots emerge, yield damage is irreversible.

Why are existing herbicide options ineffective?

1. Non-Selective Action: Glyphosate inhibits EPSPS enzyme in both crops and weeds, preventing selective control.
2. Dosage Constraints: Recommended spray levels are too low for absorption by Orobanche.
3. Crop Damage Risk: Stronger herbicides like glufosinate, paraquat, imazapyr cannot be used on normal mustard.
4. Control Failure: Current chemical strategies fail to distinguish between host and parasite.

How can herbicide-resistant mustard hybrids change outcomes?

1. Technological Breakthrough: Introduction of imidazolinone-resistant mustard hybrid ‘Pioneer 45S42CL’.
2. Selective Weed Control: Enables use of imazapyr and imazapic to kill Orobanche without harming mustard.
3. Field Evidence: Two sprays covering two acres cost ₹3,150, significantly lower than yield losses.
4. Farmer Adoption: Hybrid sold in 700-gram packs with bundled herbicide, showing positive early results.

What are the long-term scientific and policy responses underway

1. Genetic Solutions: Development of GM mustard lines containing ‘cp4 epsps’ and double-mutant ‘als’ genes.
2. Resistance Spectrum: Enables tolerance to glyphosate, imidazolinones, and sulfonylureas.
3. Seed Bank Management: Emphasis on preventing early emergence to reduce soil seed viability.
4. Institutional Research: Ongoing work at the Centre for Genetic Manipulation of Crop Plants, Delhi University.

Conclusion

The Orobanche infestation has transformed mustard cultivation from a low-risk crop into a high-uncertainty enterprise. Addressing this challenge is essential not only for farmer incomes but also for India’s edible oil security strategy. Herbicide-resistant hybrids and genetic interventions represent critical pathways to restoring productivity and reducing import dependence.

PYQ Relevance

[UPSC 2017] What are the major reasons for declining rice and wheat yield in the cropping system? How crop diversification is helpful to stabilise the yield of the crops in the system?

Linkage: The rice-wheat system question reflects UPSC’s focus on yield stagnation due to monocropping and biological stress. This pattern is equally visible in mustard through Orobanche infestation. Mustard, like rice-wheat, shows that repeated cropping without diversification increases pest and weed pressure, making crop diversification critical.