Mitigating shading-induced yield penalty of maize via improving radiation utilization

Increasing radiation utilization efficiency can mitigate the negative effects of low light stress. The decrease in global solar radiation and population light competition due to continuously increasing planting density pose a considerable risk to maize yields. It is imperative to understand why certain hybrids, which are well-adapted to low-light conditions, can still realize high yields despite these conditions. In this study, we investigated the effects of different light levels (CK, nature light; S, 30% of nature light) and planting densities (D1, 7.5×10 4 plants ha -1 ; D2, 12×10 4 plants ha -1 ) on the yield and radiation utilization of 14 maize hybrids, on field experiments conducted at Qitai Farm, Xinjiang in 2020 and 2021. The results showed that when classifying all hybrids based on their average yields under both CK and S treatments, the hybrids were mainly distributed in type I (high yields under both CK and S treatments) and type III (low yields under both CK and S treatments). The yield of type I hybrids was 20.8% higher than that of type III hybrids. As solar radiation decreased, the yields of type I and type III hybrids decreased by 23.0 and 29.4%, respectively. The low light tolerance index of type I hybrids was 37.4% higher than that of type III hybrids. The higher yield of type I hybrids can be attributed to their higher pre-silking dry weight, post-silking dry weight, leaf area duration, photosynthetic rate, and radiation use efficiency, which exceeded those of type III hybrids by 8.3, 9.1, 15.3, 12.7, and 18.2%, respectively. Therefore, our findings emphasized that maintaining high photosynthetic performance under low light conditions, improving radiation use efficiency, and increasing post-silking biomass accumulation can effectively mitigate the yield penalties caused by decreased solar radiation.