
The Indian government recently allowed the commercial cultivation of two non-transgenic varieties of herbicide-tolerant (HT) basmati rice: Pusa Basmati 1979 and Pusa Basmati 1985.
- Developed by the Indian Council of Agricultural Research (ICAR), these varieties promote sustainable paddy cultivation practices that conserve water and reduce carbon emissions.
- Transgenic: Refers to a Genetically Modified Organism (GMO) or cell whose genome has been altered by the introduction of one or more foreign DNA sequences or genes from another species by artificial means.
- GMO: An organism that contains a genetically modified genome. All transgenic organisms are GMOs.
- Non-Transgenic: Does not involve inserting any foreign DNA.
Key Features of the New Varieties of Rice:
- Mutated ALS Gene: These new varieties contain a mutated AcetoLactate Synthase (ALS) gene, allowing farmers to spray Imazethapyr (a herbicide) to control weeds.
- Herbicide Tolerance: The mutated ALS gene prevents the ALS enzymes from having binding sites for Imazethapyr, ensuring that amino acid synthesis remains unaffected.
- Amino Acid Synthesis: The ALS gene in rice encodes an enzyme responsible for synthesizing amino acids essential for the crop's growth and development.
- Herbicide Impact: In normal rice plants, the herbicide binds to the ALS enzymes, inhibiting amino acid production.
- Weed Control: Imazethapyr effectively targets a variety of broadleaf, grassy, and sedge weeds but cannot distinguish between the crop and invasive plants.
- Non-GMO: Since no foreign genes are involved, herbicide tolerance is achieved through mutation breeding, making these plants non-Genetically Modified Organisms (non-GMOs).
Significance:
- Benefits: These HT rice varieties offer several benefits such as eliminating the need for nursery preparation, puddling, transplanting, and field flooding, reducing methane emissions, a major greenhouse gas by supporting Direct Seeding of Rice (DSR).
Concerns Regarding the Use of HT Variety of Rice:
- Super Weeds: Risk of developing "super weeds" that become resistant to herbicides through repeated use, making them harder to control.
- Herbicide Residue: Worries about potential herbicide residue accumulation in food products, despite developers' assurances that the grain is residue-free.
- International Trade: While India permits certain herbicides like imazethapyr, the European Union bans them, which could impact international trade and safety standards.
- Long-Term Sustainability: Questions arise about the long-term sustainability of HT crops, as increased herbicide use over time might lead to ecological concerns.
Paddy Transplantation vs Direct Seeding of Rice (DSR)
Paddy Transplantation
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DSR
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The field where the seedlings are transplanted has to be “puddled” or tilled in standing water.
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The pre-germinated seeds are directly drilled into the field by a tractor-powered machine.
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For the first three weeks or so after transplanting, the plants are irrigated almost daily to maintain a water depth of 4-5 cm.
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There is no nursery preparation or transplantation involved in this method.
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Farmers continue giving water every 2-3 days even for the next four-five weeks when the crop is in tillering (stem development) stage.
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Farmers have to only level their land and give one pre-sowing irrigation.
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Paddy transplantation is both labour- and water-intensive.
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It is water and labour efficient and reduces methane emissions due to a shorter flooding period and comparatively decreased soil disturbance.
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Rice Cultivation in India:
- Climatic Requirements: Rice is a kharif crop that requires high temperature (above 25°C) and high humidity with annual rainfall above 100 cm.
- Multiple Crops: In southern states and West Bengal, the climatic conditions allow the cultivation of two or three crops of rice in an agricultural year.
- Crop Names: In West Bengal, farmers grow three crops of rice called ‘aus’, ‘aman’, and ‘boro’.
- Cropped Area: About one-fourth of the total cropped area in India is under rice cultivation.
- Leading Producer States: West Bengal, Uttar Pradesh, and Punjab.
- High Yielding States: Punjab, Tamil Nadu, Haryana, Andhra Pradesh, Telangana, West Bengal, and Kerala.
- Global Ranking: India is the second-largest producer of rice after China.
- Export Significance: Basmati rice is India’s top agricultural-export produce. In 2022-23, India exported 4.56 million tonnes of basmati rice valued at USD 4.78 billion.
- Distinctive Fragrance: Basmati's distinctive fragrance is attributed to 2-acetyl-1-pyrroline (2-AP), an organic compound produced during maturation that gives this rice grain its nutty and fragrant aroma.
