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| Variations and driving factors of multi-scale light use efficiency in micro-irrigated kiwifruit orchards in Southwest China |
| YANG Binhuan1, CUI Ningbo1*, HE Qingyan2, JIANG Shouzheng1, ZHENG Shunsheng1, HUANG Yaowei1 |
| 1. State Key Laboratory of Hydraulics and Mountain River Engineering/College of Water Resource and Hydropower, Sichuan University, Chengdu, Sichuan 610065, China; 2. Sichuan Reseach & Design Institute of Agricultural Machinery, Chengdu, Sichuan 610066, China)〓 |
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Abstract To reveal the changing trends of light use efficiency of kiwifruit orchards at different scales in the humid regions of Southwest China and to explore the influence mechanism of physiological, environmental and vegetation factors on light use efficiency of kiwifruit orchards at different scales. The vorticity correlation system was used to conduct comprehensive observations of water, heat and carbon flux for three consecutive years from 2018 to 2020 in the kiwifruit orchards in Pujiang County, Sichuan Province. The regulations of light use efficiency at different scales in kiwifruit orchards were explored. The path analysis method was used to quantify the total effect of physiological factors, climatic factors, soil moisture factors, and vegetation factors on the light use efficiency of kiwifruit orchards at different scales. The results showed that kiwifruit′s leaf instantaneous light use efficiency(LUEi)decreased with increased photosynthetically active radiation(PAR), ranging from 0.006 to 0.026 μmol/μmol. The monthly average daily changes of canopy light use efficiency(cLUE)and ecosystem light use efficiency(eLUE)were U-shaped. The monthly cumulative cLUE and eLUE ranged between 0.77—2.67 and 0.58—1.63 g/MJ, respectively, and their trends are the same with no obvious seasonal change. LUEi is mainly affected by meteorological factors(PAR)and physiological factors(Pn)significantly, and PAR and Pn have significant direct(-0.99)and indirect(-0.81)effects on LUEi, respectively; cLUE and eLUE are significantly affected by meteorological factors(Rg, Ta and VPD)and vegetation factor(LAI). Rg and VPD mainly affected eLUE and cLUE by affecting the light absorption process, while Ta and LAI affected eLUE and cLUE through carbon assimilation.
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Received: 10 January 2022
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