Radiation use efficiency of maize under high-density optimal growth conditions in Jilin Province, China

1. During the entire growth period, maize radiation use efficiency (RUE) averaged 5.71 g MJ -1 APAR (absorbed photosynthetically active radiation) under high-density optimal growth conditions. 2. Within the vegetative and reproductive growth periods, maize RUE averaged 6.85 and 5.64 g MJ -1 APAR, respectively. 3. RUE, 5.07-5.85 g MJ -1 APAR, should be used to derive the optimal potential yield in maize simulation model. The study's framework and highlights To evaluate the impact of climate change on maize production, it is critical to accurately measure the radiation use efficiency (RUE) for maize. In this study, we focused on three maize cultivars in Jilin Province, China: Zhengdan 958 (ZD958), Xianyu 335 (XY335), and Liangyu 99 (LY99). Under the optimal growing conditions for high density (9 plants m -2 ), we investigated the maize RUE during the vegetative and reproductive phases, and the entire growth period. The results showed that the canopy light interception for maize peaked during anthesis. After anthesis, maize plant biomass continued to accumulate. Based on the absorbed photosynthetically active radiation (APAR), we calculated maize RUE. During the entire growth period, maize RUE averaged 5.71 g MJ -1 APAR among the three cultivars, with a high-to-low order of ZD958 (5.85 g MJ -1 APAR)>XY335 (5.64 g MJ -1 APAR)>LY99 (5.07 g MJ -1 APAR). Within the vegetative and reproductive growth periods, maize RUE averaged 6.85 and 5.64 g MJ -1 APAR, respectively. When utilizing maize models, such as APSIM, that depend on radiation use efficiency (RUE) to predict aboveground biomass accumulation, we observed that the current RUE value of 3.6 g MJ -1 APAR is considerably lower than the measured value obtained under high-density optimal growing conditions. Consequently, to derive the optimal potential yield for maize in such planting conditions, we recommend adjusting the RUE to a range of 5.07-5.85 g MJ -1 APAR.