The story so far: M.S. Swaminathan, the agricultural scientist known as the father of the Green Revolution in India, died at his residence in Chennai on Thursday morning. He was 98.
Dr. Swaminathan played a pivotal role in defining India’s tryst with scientific agriculture. He helped develop high-yielding varieties of wheat and rice to counter back to back droughts in 1960s and save the country from famine.
What was the Green Revolution?
A period of rapid, scientific agricultural advancement in the mid-1960s that involved growing a high-yielding, disease-resistant variety of wheat, primarily in Punjab, was the beginning of India’s Green Revolution. Dr. Swaminathan was the key architect of this movement and worked in close collaboration with former Union Agriculture Ministers C. Subramaniam (1964-67) and Jagjivan Ram (1967-70 and 1974-77) towards safeguarding India’s food security. Short-straw or dwarf varieties of crops like rice and wheat formed the basis of India’s Green Revolution. Dwarf strains have a higher Harvest Index, which means that the plant puts more of its energy resources into seeds rather than leaves or other plant structures. Harvest Index quantifies the crop yield in comparison to the total biomass produced.
What are high-yielding varieties of crops?
High-yielding varieties of crops, or HYVs, produced a higher yield of crop per hectare in comparison to traditional variants. These variants are produced using a combination of traditional breeding steps and biotechnology, which includes genetic diversity. The resulting HYVs are usually disease-resistant and have a higher tolerance to conditions like drought.
IR8, a variety of rice developed by the International Rice Research Institute (IRRI) that could produce as much as seven tonnes of rice per hectare compared to traditional seeds that could produce only two tonnes per hectare, was one of the main HYVs grown during the Green Revolution. This “miracle rice” was first introduced in the Philippines and was produced by crossing a tall high-yielding strain from Indonesia called Peta with a sturdy dwarf variety from China called Dee-Geo-woo-gen.
Other HYVs grown during the Green Revolution in India included Kalyan Sona and Sonalika varieties of wheat which were considered to be of good “chapati-making” quality and had “amber grains and good yield potential” (a few varieties of Mexican dwarf wheat which were procured earlier were rejected because of their red colour).
Yield gap
The difference between the potential or maximum achievable yield of a crop and the actual realised yield for a given area is called the yield gap. During the Green Revolution, one of the main areas of focus was the increase productivity from existing farmlands using HYVs in order to tackle the threat of famine.
Cytogenetics
Cytogenetics is the study of chromosomes (DNA-carrying structures) and how they related to hereditary characteristics and traits. Identifying traits such as resistance to diseases, drought, and pests in crops are applications of cytogenetics.
Hexaploid wheat
Scientifically known as Triticum aestivum, hexaploid wheat contains six sets of chromosomes and is among the most widely cultivated cereal crops across the world. It is also called “bread wheat”. Dr. Swaminathan is associated with research on the cytogenetics of hexaploid wheat.
Carbon fixation
Carbon fixation is the process by which crops capture carbon dioxide from the atmosphere and convert it into organic compounds like sugars and starches, mostly through photosynthesis.
Grass species either use C3 or C4 classes of photosynthetic pathway for carbon fixation. The C3 pathway, also called the Calvin cycle, is slower in comparison to C4 – also called the Hatch and Slack pathway. C3 cycle of fixation occurs when the tiny pores of surface of leaves (in the mesophyll cells) are open, while C4 occurs in both mesophyll cells and bundle sheath cells (that surround the veins of the plant), making photosynthesis more efficient.
Research on the C4 rice plant was started at the IRRI when Dr. Swaminathan was the Director General of the organisation.
