In a game-changing development for Indian agriculture, the Indian Agricultural Research Institute (IARI) has created the nation’s first non-GM (genetically modified) herbicide-tolerant rice varieties – Pusa Basmati 1979 and Pusa Basmati 1985. These new strains are capable of direct seeding, which can save significant amounts of water and labor compared to the conventional transplantation technique routinely used.
Understanding the New Rice Varieties
The breakthrough of these new rice varieties primarily lies in their altered AcetoLactate Synthase (ALS) gene, which allows farmers to employ Imazethapyr, a broad-spectrum herbicide, for weed control with no damage to the rice crop.
In normal rice plants, this herbicide would bind to the ALS enzymes, disrupting their ability to produce essential amino acids necessary for crop growth. However, due to chemical mutation using ethyl methanesulfonate, the new Basmati varieties carry a uniquely mutated ALS gene that does not bind with the herbicide, thus ensuring uninterrupted amino acid synthesis. This attribute makes the plant “tolerant” to the herbicide, which now kills only the undesired weeds. Since there is no foreign gene involved, the modification is accomplished via mutation breeding and not genetic modification.
Benefits of the New Varieties
The most significant advantage of these new varieties revolves around a major shift in cultivation practice: from paddy transplantation to Direct Seeding of Rice (DSR).
DSR eliminates the need for nursery, puddling, transplanting, and flooding of fields, which are generally required in the conventional cultivation method. The new varieties replace water with Imazethapyr as a natural herbicide, leading to savings in water and labor.
Economic and Safety Benefits
From an economic standpoint, DSR is beneficial as it reduces the costs associated with alternative herbicides such as Pendimethalin and Bispyribac-sodium; Imazethapyr is a more affordable option. It also exhibits a broader weed-control spectrum and is safer as the ALS gene is absent in humans and mammals.
Comparison: Paddy Transplantation and Direct Seeding of Rice
Traditional paddy transplantation is a labor- and water-intensive process that involves puddling, constant irrigation, and frequent watering to maintain water depth. On the other hand, DSR allows pre-germinated seeds to be drilled directly into the field using a machine, eliminating the need for nursery preparation and transplantation.
Pros of Direct Seeding of Rice
DSR offers several advantages, such as water savings, reduced labor costs, and decreased methane emissions due to shorter flooding periods and less soil disturbance.
Constraints of Direct Seeding of Rice
Despite its advantages, DSR has some constraints. The seed requirement is higher (8-10 kg/acre compared to 4-5 kg/acre in transplanting), and timely sowing is essential to ensure proper plant growth before the monsoon season. Furthermore, laser land leveling is mandatory in DSR, which is not required in traditional transplanting.
This breakthrough in rice cultivation led by the Indian Agricultural Research Institute represents a significant stride towards more sustainable and cost-effective agricultural practices in India.
