A study has warned that the dry-season irrigated rice in West Africa’s Sahel region has reached the critical threshold of 37 degrees Celcius – the tipping point.
It added that further temperature rise could devastate rice yields in the region due to decreasing photosynthesis at high temperatures.
According to the Inter-governmental Panel on Climate Change (IPCC), the Sahel will experience higher average temperatures as well as changes in rainfall patterns over the course of the 21st century. These changes threaten food security and the livelihoods of the region’s predominantly rural population.
“Our model shows that without adaptation, irrigated rice yields in West Africa’s Sahel region in the dry season would decrease by about 45 per cent, but with adaptation, they would decrease significantly less – by about 15 per cent,” explained the lead author Dr Pepijn van Oort, a Crop Modeler at Africa Rice Centre (AfricaRice).
Oort clarified that it was important to keep in mind that this is a West Africa average, and that there are big differences within West Africa. “Things are better in the cooler coastal regions and a lot worse in the hotter inland sites,” he added.
“Also, more investigation is needed to understand clearly photosynthesis processes at extreme temperatures, as there has been almost no research conducted on rice at such high temperatures,” Dr van Oort cautioned.
In addition, he said there is need to explore further adaptation options, such as shifting sowing dates more into the cold dry season.
Although rice thrives well in hot and warm climates, high temperatures of more than 35 degrees Celcius can damage plant processes and lead to lower yields. Rice is also vulnerable to cold temperatures, which can slow growth.
The study forecasts that in East Africa, rising temperatures will create new opportunities for rice. In East Africa rice is grown mostly in the highlands, which are often too cold for the crop, and this will improve with higher temperatures. Also, rice could benefit from increased CO2.
However, improved water and nutrient management will be needed to have the maximum benefit, the study added.