Genetic progress battles climate variability: drivers of soybean yield gains in China from 2006 to 2020

While improvement of soybean productivity under a changing climate will be integral to ensuring sustainable food security, the relative importance of genetic progress attributed to historical yield gains remains uncertain. Here, we compiled 16,934 cultivar-site-year observations from experiments during the period of 2006-2020 to dissect effects of genetic progress and climate variability on China’s soybean yield gains over time. Over the past 15 years, mean yields in the Northeast China (NEC), Huang-Huai-Hai Plain (HHH) and Southern Multi-cropping Region (SMR) were 2,830, 2,852 and 2,554 kg ha-1, respectively. Our findings show that genetic progress contributed significantly to yield gains, although underpinning mechanisms varied regionally. Increased pod number per plant (PNPP) drove yield gains in the NEC, while both PNPP and 100-grain weight (100-GW) contributed to yield gains in the HHH. In all regions, incremental gains in the reproductive growing periods increased PNPP, 100-GW and yields. While heat stress in the reproductive period reduced average yields in all regions, superior yielding cultivars (top 25%) in the HHH and SMR were less sensitive to heat stress during the reproductive phases, indicating that the higher yielding cultivars benefited from genetic improvement in heat stress tolerance. Our results highlight the importance of genetic improvements in enabling sustainable food security under global warming and increasingly frequent heat stress.