Herbicide-Tolerant Mustard

Herbicide-tolerant mustard refers to genetically modified (GM) mustard varieties that are engineered to withstand the application of specific herbicides, particularly those that inhibit weed growth. In India, the development and debate around herbicide-tolerant mustard has been a significant part of discussions concerning agricultural biotechnology, food security, and biosafety. The most notable example is DMH-11, a hybrid mustard developed by the Centre for Genetic Manipulation of Crop Plants (CGMCP) at Delhi University, which employs transgenic technology.

Background and Development

Mustard (Brassica juncea) is one of the most widely cultivated oilseed crops in India, contributing significantly to edible oil production. Despite its economic importance, mustard yields have historically remained lower in India compared to other oilseed crops and global averages. Challenges such as weed infestation, limited hybridisation options, and agronomic stress have hindered productivity.
To address these issues, Indian scientists developed transgenic mustard hybrids that use the barnase-barstar-bar gene system. The hybrid DMH-11 (Dhara Mustard Hybrid-11) was created using genetic engineering to improve hybrid vigour and enhance yield potential. The herbicide tolerance trait is introduced to facilitate weed control, allowing farmers to apply specific herbicides without damaging the crop.

Genetic Mechanism

The development of herbicide-tolerant mustard involves the use of three key bacterial genes derived from Bacillus amyloliquefaciens:

• Barnase gene: Causes male sterility in mustard plants, enabling hybridisation.
• Barstar gene: Restores fertility in hybrid plants by blocking barnase activity.
• Bar gene: Provides tolerance to the herbicide phosphinothricin (commonly known as glufosinate ammonium), allowing selective weed management.

The barnase-barstar system facilitates the creation of hybrids, while the bar gene enables herbicide resistance. The combination of these traits helps in improving crop yields and reducing labour costs associated with manual weeding.

Regulatory Context in India

The Genetic Engineering Appraisal Committee (GEAC), functioning under the Ministry of Environment, Forest and Climate Change, is the apex regulatory authority for GM crops in India. In 2017 and again in 2022, GEAC recommended the environmental release of GM mustard (DMH-11) for seed production and testing. However, the decision has been subject to intense debate, legal interventions, and public protests.
Supporters argue that GM mustard can help India reduce its dependence on imported edible oils and enhance domestic oilseed productivity. Critics, however, raise concerns about biosafety, environmental risks, and corporate control over seeds.

Potential Benefits

The introduction of herbicide-tolerant mustard is associated with several claimed advantages:

• Yield improvement: Hybrid mustard varieties such as DMH-11 are projected to deliver higher yields compared to traditional cultivars.
• Weed management: Herbicide tolerance allows efficient and cost-effective weed control, reducing the reliance on manual labour.
• Oil security: Enhancing mustard production could reduce India’s heavy dependence on edible oil imports.
• Technological progress: Adoption of GM mustard may pave the way for more biotechnology-based solutions in agriculture.

Concerns and Criticism

The development and proposed release of herbicide-tolerant mustard has faced significant opposition from farmers’ groups, environmental activists, and sections of the scientific community. Major concerns include:

• Biosafety risks: Potential impacts on non-target organisms, pollinators, and biodiversity remain under scrutiny.
• Herbicide use: Critics argue that herbicide-tolerant crops may lead to increased chemical use, environmental pollution, and herbicide-resistant weeds.
• Seed sovereignty: Concerns have been raised about farmers’ dependence on commercial seed suppliers, undermining traditional seed-saving practices.
• Health concerns: Public apprehension persists about possible long-term health impacts of GM food crops, although no conclusive evidence has been presented.
• Socio-economic implications: Small and marginal farmers may find it difficult to bear the cost of GM seeds and associated herbicide inputs.

Global Context

Globally, herbicide-tolerant crops such as soybean, maize, and canola have been widely adopted, especially in countries like the United States, Canada, Brazil, and Argentina. These crops have significantly altered weed management practices and agricultural productivity. However, they have also generated debates regarding herbicide resistance, environmental sustainability, and corporate monopolies in the seed sector.
India’s decision on GM mustard is seen as a critical test case for the acceptance of GM food crops, as the country has so far permitted only one GM crop—Bt cotton—for commercial cultivation.

Significance for Indian Agriculture

Herbicide-tolerant mustard represents a potential technological intervention aimed at bridging India’s oilseed productivity gap. If widely adopted, it could reduce edible oil imports, enhance food security, and contribute to agricultural modernisation. At the same time, its adoption depends heavily on regulatory decisions, judicial oversight, and public acceptance.
The debate around herbicide-tolerant mustard underscores the broader tension between technological innovation and ecological, social, and ethical considerations in Indian agriculture. Its outcome is likely to shape the trajectory of biotechnology adoption in India for years to come.