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Canopy transpiration obtained from leaf transpiration, sap flow and FAO‐56 dual crop coefficient method
Author(s) -
Zhao Liwen,
Zhao Wenzhi
Publication year - 2015
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.10417
Subject(s) - transpiration , crop coefficient , canopy , environmental science , sowing , irrigation , agronomy , crop , evapotranspiration , hydrology (agriculture) , mathematics , photosynthesis , botany , biology , ecology , geotechnical engineering , engineering
With a maize seed planting area of about 67 000 hm 2 , Zhangye city supplies the seeds for more than 40% of the maize planting area in China. Irrigation water is often overused to ensure the quality of the maize seeds, leading to serious water shortage problems in recent years. An accurate and convenient estimate of canopy transpiration is of particular importance to ease the problem. In this paper, leaf transpiration and sap flow in a maize field were measured in 2012 using a portable photosynthesis system and a heat balance sap flow system. Based on a large amount of meteorological data and relevant maize plant‐growing parameters, canopy transpiration was up‐scaled from both leaf transpiration ( T l ) and sap flow ( T f ), and also calculated by the FAO‐56 dual crop coefficient method ( T ). Comparing these three types of transpiration, T f was proved to be more reliable than T l . Taking T f as a benchmark, the basal crop coefficient ( K cb , the key parameter of FAO‐56 dual crop coefficient method) was further adjusted and verified for the maize plants in this region. In addition, the errors when using up‐scaling methods and FAO‐56 dual crop coefficient method are summarized. Copyright © 2014 John Wiley & Sons, Ltd.