The fertilization effect of global dimming on crop yields is not attributed to an improved light interception. (15th October 2019)

• Record Type: Journal Article
• Authors: Shao, Liping; Li, Gang; Zhao, Qiannan; Li, Yabing; Sun, Yutong; Wang, Weinan; Cai, Chuang; Chen, Weiping; Liu, Ronghua; Luo, Weihong; Yin, Xinyou; Lee, Xuhui
• Is Part Of: Global change biology. Volume 26:Number 3(2020)
• Page Start: 1697
• Page End: 1713
• Publication Date: 2019-10-15
• Subjects: acclimation -- diffuse radiation -- fertilization effect -- global dimming -- radiation use efficiency -- rice -- wheat -- yield; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.14822
• Languages: English
• ISSNs: 1354-1013

Abstract

Abstract: Global dimming, a decadal decrease in incident global radiation, is often accompanied with an increase in the diffuse radiation fraction, and, therefore, the impact of global dimming on crop production is hard to predict. A popular approach to quantify this impact is the statistical analysis of historical climate and crop data, or use of dynamic crop simulation modelling approach. Here, we show that statistical analysis of historical data did not provide plausible values for the effect of diffuse radiation versus direct radiation on rice or wheat yield. In contrast, our field experimental study of 3 years demonstrated a fertilization effect of increased diffuse radiation fraction, which partly offset yield losses caused by decreased global radiation, in both crops. The fertilization effect was not attributed to any improved canopy light interception but mainly to the increased radiation use efficiency (RUE). The increased RUE was explained not only by the saturating shape of photosynthetic light response curves but also by plant acclimation to dimming that gradually increased leaf nitrogen concentration. Crop harvest index slightly decreased under dimming, thereby discounting the fertilization effect on crop yields. These results challenge existing modelling paradigms, which assume that the fertilization effect on crop yields is mainly attributed to an improved light interception. Further studies on the physiological mechanism of plant acclimation are required to better quantify the global dimming impact on agroecosystem productivity under future climate change. Abstract : A popular approach to quantify global dimming impact is the statistical analysis of the historical data. Here, we show that experimental data are essential to reliably identify global dimming impact on crops, and that a diffuse radiation fertilization effect on wheat and rice yields was attributed to increased radiation use efficiency (RUE) rather than canopy light interception. The increased RUE was explained not only by nonlinearities of photosynthetic light response curves but also by plant acclimation to dimming. Moreover, harvest index often decreased, discounting the fertilization effect. These results challenge existing model prediction paradigms on global dimming impact on agroecosystem productivity.