Climate change impacts and potential benefits of heat-tolerant maize in South Asia

Abstract

Maize is grown by millions of smallholder farmers in South Asia (SA) under diverse environments. The crop is grown in different seasons in a year with varying exposure to weather extremes, including high temperatures at critical growth stages which are expected to increase with climate change. This study assesses the impact of current and future heat stress on maize and the benefit of heat-tolerant varieties in SA. Annual mean maximum temperatures may increase by 1.4-1.8°C in 2030 and 2.1-2.6°C in 2050, with large monthly, seasonal, and spatial variations across SA. The extent of heat stressed areas in SA could increase by up to 12 % in 2030 and 21 % in 2050 relative to the baseline. The impact of heat stress and the benefit from heat-tolerant varieties vary with the level of temperature increase and planting season. At a regional scale, climate change would reduce rainfed maize yield by an average of 3.3-6.4 % in 2030 and 5.2-12.2 % in 2050 and irrigated yield by 3-8 % in 2030 and 5-14 % in 2050 if current varieties were grown under the future climate. Under projected climate, heat-tolerant varieties could minimize yield loss (relative to current maize varieties) by up to 36 and 93 % in 2030 and 33 and 86 % in 2050 under rainfed and irrigated conditions, respectively. Heat-tolerant maize varieties, therefore, have the potential to shield maize farmers from severe yield loss due to heat stress and help them adapt to climate change impacts.

CGIAR modeling approaches for resource‐constrained scenarios: I. Accelerating crop breeding for a changing climate

“…Similarly, simulations by van Oort and Zwart (2018) showed that favoring varieties with greater thermal time can compensate for climate change-induced yield reductions in African rice systems. Similar findings have been reported for Asian rice (Li & Wassmann, 2010;Mottaleb et al, 2017), groundnut (Singh et al, 2012(Singh et al, , 2014b, sorghum (Singh et al, 2014c), pearl millet , chickpea (Singh et al, 2014a), maize (Tesfaye et al, 2017), and wheat in China (Challinor et al, 2010).…”

Optimizing sowing window and cultivar choice can boost China’s maize yield under 1.5 °C and 2 °C global warming

“…However, there were still some uncertainties in our study. We did not consider future cultivars, including rapidly updated higher heat-and droughtresistant cultivars, which may lead to increased adaptation (Singh et al 2014, Guan et al 2017, Tesfaye et al 2017. All simulation assumed under rainfed and no nitrogen stress conditions.…”

Climate change and agriculture in South Asia: adaptation options in smallholder production systems

“…Crop yield studies focusing on India have found that global warming has reduced wheat yield by 5.2% from 1981 to 2009, despite adaptation (Gupta et al 2017). It is projected that climate change would reduce rain-fed maize yield by an average of 3.3-6.4% in 2030 and 5.2-12.2% in 2050 and irrigated yield by 3-8% in 2030 and 5-14% in 2050 if current varieties were grown (Tesfaye et al 2017). Despite variability in input use and crop management, there is a negative effect of both season-long and terminal heat stress on rice and wheat, though wheat is considerably more sensitive than rice (Arshad et al 2017).…”