NEW DELHI: The Green Revolution that brought self-sufficiency in food grains production to India has a troubling downside. High-yielding wheat and rice strains over the last 50 years have steadily been losing nutrient and mineral content but adding toxic elements to themselves, the latest study has found.
The insertion of high-yielding dwarf genes during the Green Revolution reduced the capacity of the natural evolutionary process and further impaired the screening capacity of plants, altering the nutrition profile of grains. It led to the accretion of toxic elements and a reduction in the nutritional concentration of grains.
Notwithstanding modern-bred rice and wheat varieties introduced to kickstart the Green Revolution in the 1960s, India continues to be the global malnourishment capital. The country ranked 107th out of 121 on the Global Hunger Index in 2022. As many as 224.3 million people in India (out of 828 million globally) last year were undernourished.
The Green Revolution was biased towards increasing yield and building resistance to pest diseases. The nutrient and minerals angle was largely overlooked, the study found.
The research shows a decreasing trend of minerals like zinc and iron in grains in India, which are important for the body’s building blocks. In their absence, cases of cardiovascular, respiratory, and musculoskeletal diseases besides anemia due to iron deficiency could escalate among the Indian population in the coming decades, the report warns.
The study, ‘Historical shifting in grain mineral density of landmark rice and wheat cultivars released over the past 50 years’ in India was done by a batch of scientists led by Dr Biswapati Mandal at West Bengal’s Bidhan Chandra Krishi Viswavidyalaya. Published in the scientific journal Nature, the study analyzed the period from 1960 to 2010. It is noticed that there has been a significant depletion in the concentration of essentials like phosphorus, calcium, iron, zinc, and copper, and beneficial minerals like nickel and silicon. However, there is an accretion of toxins like arsenic, chromium, barium, strontium, and aluminum in rice cultivars.
Within a span of 50 years, the concentration of zinc and iron decreased by 33% and 27% in rice, respectively. In the same time period, in wheat, zinc and iron concentrations decreased by 30% and 19%, respectively, the study said.
The corresponding drop was seen in the mineral-diet quality index (M-DQI), which measures the intake profile of an individual or group. There was a significant decrease – 57% in rice and 36% in wheat – in the reported time span (1960-2010).
What happened to plants?
The study finds that high-yielding varieties of crops, which have been in use since the Green Revolution, are incapable of sequestering nutrients from the soil. Researchers concurred that the depleting trend in the grain nutrient concentration was caused by the plant rather than soil factors.
Insertion of a gibberellin-insensitive dwarfing gene in rice (sd-1 gene) and wheat (Rht gene) during the Green Revolution impacted crop physiology. It is responsible for the impairment of the screening capacity and regulatory mechanism of plants. It led to toxic accretion from the shoot to grains in high-yielding cereal cultivars - rice in particular.
“Possibly, it occurred due to a loss of natural evolutionary defense mechanisms of the landmark cultivars against the toxicants amid continuous genetic tampering under the modern breeding program,” says Dr Biswapati Mandal, Directorate of Research, Bidhan Chandra Krishi Viswavidyalaya, Kalyani, West Bengal who led a 12-member team of scientists for the study.
“Our observed depletion in the concentration of essential vis-à-vis accretion of toxic elements in grains of the cereal cultivars released over time may be a fallout of the above phenomena,” Mandal added.
The scientists warned that the Indian population will keep consuming mineral-deficient grains till 2040 as there will be no dramatic change in the philosophical approach to modern cereal breeding. Moreover, rising industrialization and urbanization would contaminate the soil with heavy metals and accrete grains amid India’s ambition to become a $40 trillion economy by 2047, it added.
They urged policymakers to improve the grain mineral density - at least essential nutrients - of these staples through genetic interventions for the sustenance of nutrition and human health. The favorable alleles (genes) that were ‘left behind’ during the modern breeding process may be bred back into the cultivars, the report suggested, adding the grain nutrient profile should mandatorily be evaluated before release of a cultivar in the future.
DEPLETION AND ACCRETION
1. Depletion of essential (phosphorus, calcium, iron, zinc, and copper) and beneficial (nickel and silicon) elements in wheat and rice
2. Accretion in toxic elements – arsenic, chromium, barium, strontium, and aluminum