Global solar radiation has exhibited complicated changes with significant temporal and regional variations, while greater crop light utilization efficiency (LUE) was reported due to the increased yield. Based on daily meteorological data collected at 207 weather stations in the irrigated maize area of Northwest China (IMA) and the spring maize area in Northeast China (SMA), the spatiotemporal characteristics of regional photosynthetically active radiation (PAR) during the maize growing season and LUE are analyzed. Additionally, the probable reasons causing the changes in these variables are discussed from 1961 to 2014. Large regional differences of PAR during the maize growing season were found in the study area ranging from 4107.2 to 5937.3 mol center dot m(-2), which gradually decreased from west to east. Compared to the SMA, the IMA exhibited 12.7% greater PAR during the past 54 years, while IMA showed lower LUE in 1961 - 1999 and 28.9% higher than SMA since the 2000s. Both SMA the IMA have experienced a continuous dimming trend in the maize growing season as the total PAR has decreased by 4.63%, with an average change rate of - 36.04 mol center dot m(-2)center dot 10a(-1). However, a significant increasing trend for the maize LUE at the farmer's level was found in 1961-2014, which has changed from 0.39 to 2.90% in IMA and 0.39 to 2.19% in SMA, respectively. Furthermore, large LUE gaps exist between farmer's level and high record level, as the highest LUE has reached 6.74% in the study area. The inconsistent changes between the PAR and the LUE resulted from the increased yield. The positive effect of agricultural technology and crop varieties' improvement on maize yield compensated for the negative impact of PAR reduction. In summary, asymmetry dynamic change trends between the PAR and the LUE were found during the maize growing season in North China, and the IMA showed higher maize yield, PAR, and LUE. Making full use of radiation resources may be one of the effective ways to improve the maize yield in the SMA, which could help maize production better adapt to climate change.
He, HY; Hu, Q; Wang, J; Xing, MY; Liu, YY; Wang, XC; Li, R; Pan, XB; Pan, ZH; Huang, BX; He, QJ
Asymmetric changes of photosynthetically active radiation and light utilization efficiency during the maize growing season in North China
Theoretical And Applied Climatology