Studies have showed that rice grown at concentrations of atmospheric CO2 expected by the end of this century will have lower levels of energy,protein, four key B vitamins and key micro nutrients such as zinc and iron.This study was published in May 2018 in a top international journal, “Science Advances” by an international team, including a Sri Lankan scientist, Professor Saman Seneweera, Director of National Institute of Fundamental Studies. This trend has been identified for the first time in the world.
Rice is the primary food source for more than 2 billion people in the world. Decreases in the nutritional value of rice will have a major impact on the health and nutritional status of most of the Asian and African people living in countries where rice is the staple food.Rice not only provides energy, but also proteins, minerals and vitamins, especially for poorer communities in developing countries.
The research team investigated rice cultivation under higher carbon dioxide concentrations expected in the second half of this century (568 to 590 parts per million).
Rice was grown at research sites in China and Japan utilising a state of art experimental technique, Free Air Carbon Dioxide Enrichment Facility (FACE). Researchers then analysed a total of 18 different varieties of rice for protein, iron,vitamins and zinc levels.
They reported an average 10 % reduction in protein, 8% reduction in iron and 5% reduction in zinc, when compared with rice grown under current CO2 concentrations. Also, average vitamin B1 (thiamine) levels decreased by 17%, average vitamin B2 (riboflavin) by 17%, average vitamin B5 (pantothenic acid) by 13%, and average vitamin B9 (folate) by 30 %. No change in levels of vitamin B6 or calcium, were reported.
Though several small scale experiments have been conducted to investigate rice’ responses to future climate, hardly, any experimental data on the nutritional value of rice cultivars originating from Sri Lanka is available. Similar to rising CO2 levels in the atmosphere, temperature is also exponentially increasing.
As Sri Lanka is located in the tropics, our rice industry is largely threatened by climate change. Therefore, we need to develop new breeding strategies to mitigate climate stress, particularly the yield and quality traits of rice.
Newly released demographic and health survey emphasises that stunting, wasting and underweight among children under 5 is still a public health problem in Sri Lanka. The Food & Agriculture Organisation of WHO reported that 42 % of the total energy and 39% of total protein intake of Sri Lankans is from rice.
It may be a real challenge for Sri Lankans to have an adequate dietary intake of energy and protein from their diet in the future. If the findings of the above research on rice has a similar pattern for Sri Lankan rice varieties as well, we will face another new challenge.