Proso millet was the earliest domesticated millet. It dates to the Neolithic Age, about 7,000 years ago and originated in China around 4,000 to 3,000 BCE. By the time of the Zhou dynasty it was prevalent in northern China and was dominant in other regions too, writes Srividhya S, a scientist at the Indian Institute of Millet Research, Hyderabad, in the Times of India of 11 March.
The foxtail millet followed, she says. Its cultivation can be traced to 6,000 BCE. The early Egyptians were cultivating it around 3,000 BCE. Foxtail millet was also grown in Japan and Korea during Japan’s Jamon period around 4,000 BCE.
In India too, proso millet was the earliest crop, said to date back to the pre-Harappan period , around the first half of the second millennium BC, and grown widely in present-day Gujarat.
Millets were grown extensively from China to Eurasia and Egypt, Japan, Korea, India and the United States. They were part of the Roman diet too.
The domestication of major millets – sorghum, pearl and finger millets – started in Africa about 5,000-6,000 years ago. Kodo, little and browntop millets originated in India and are the heritage crops of India.
Srividhya says millet physiology evolved over the centuries. They have become climate-resilient and can well tolerate biotic and abiotic stresses. The plants belong to the C4 group unlike rice and wheat which are C3 crops. In C3 plants, Srividhya says, there are only mesophyll cells, which are the site of photosynthesis; the choloplasts for absorption of light are only found here. But C4 crops evolved to have two compartments – mesophyll cells and bundle sheath cells. These make the plants photosynthetically efficient. Their anatomy is also superior to C3 plants, she says. Millets do not have photorespiratory loss – they only have photosynthetic gain.
In 2009, the International Rice Research Institute tried to transfer genes from C4 millets into rice crops for superior photosynthesis. The carbon dioxide acceptance of millets is much more efficient than C3 crops as is their water-use efficiency. They produce more biomass per unit of water. They don’t need much fertiliser or rainfall. One or two irrigations are enough. Evolution gave their pollen fertility and reproductive structure the ability to withstand high temperatures. They have a mechanism called rapid drought escape. As soon as they sense that drought is likely, their life cycle quickens, and they yield better compared to other crops which become chaffy instead.
But we need to enhance their productivity, Srividhya writes. Traditional cultivars provided enough for the farmers’ own use. For better yield, we need varieties with altered seeds.
(Top photo of foxtail millet biryani, courtesy of Odisha Millet Mission)