Wheat cultivar mixtures increase grain yield under varied climate conditions

Abstract

Scaling current cereal production to meet the globally increasing food demand will be a challenge under climate change. Previous studies have shown that crop diversification, such as intercropping, can increase crop yield, stability, resource-use efficiency and resistance to both biotic and abiotic stresses in agroecosystems. However, more evidence is needed to explain the influence of inter-annual climate variations on crop yield in the context of genetic diversity. Here, we conducted a field experiment over four years in the North China Plain to test the effect of genetic diversity on yield under varied climate conditions. We compared the performance of eight winter wheat cultivars in monocropping with that of mixed cropping of two (mixture-2), four (mixture-4), and eight (mixture-8) cultivars. Our results showed that the yields of all cultivar mixtures were higher than those of their component cultivars in monocropping from 2017 to 2020. In particular, the grain yields of mixture-4 and mixture-8 were significantly increased by 7.37% and 5.94% in the drier years (2017 and 2019), compared with that of the highest yield of local cultivar (LY502). From 2017 to 2020, yield components in wheat mixed cropping had synergetic effects that could offset the tradeoffs among them and obtained an optimized combination at population level. Moreover, the yield stability of all mixtures was higher than the weighted means of monocultures averaged across the four years. The cultivation of mixtures of wheat cultivars effectively alleviated the negative effect of high temperature stress on 1000-grain weight, and improved grain water use efficiency in the drier years. Our findings showed that enhancing wheat genetic diversity at population level can effectively promote grain yield under drought and high temperature, which can be considered as an ecological approach to cope with global climate change towards food security.