Premium
Lower responsiveness of canopy evapotranspiration rate than of leaf stomatal conductance to open‐air CO 2 elevation in rice
Author(s) -
Shimono Hiroyuki,
Nakamura Hirofumi,
Hasegawa Toshihiro,
Okada Masumi
Publication year - 2013
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.12214
Subject(s) - evapotranspiration , lysimeter , transpiration , stomatal conductance , vapour pressure deficit , canopy , environmental science , leaf area index , growing season , agronomy , atmospheric sciences , botany , photosynthesis , soil water , biology , soil science , ecology , geology
An elevated atmospheric CO 2 concentration ([ CO 2 ]) can reduce stomatal conductance of leaves for most plant species, including rice ( O ryza sativa L.). However, few studies have quantified seasonal changes in the effects of elevated [ CO 2 ] on canopy evapotranspiration, which integrates the response of stomatal conductance of individual leaves with other responses, such as leaf area expansion, changes in leaf surface temperature, and changes in developmental stages, in field conditions. We conducted a field experiment to measure seasonal changes in stomatal conductance of the uppermost leaves and in the evapotranspiration, transpiration, and evaporation rates using a lysimeter method. The study was conducted for flooded rice under open‐air CO 2 elevation. Stomatal conductance decreased by 27% under elevated [ CO 2 ], averaged throughout the growing season, and evapotranspiration decreased by an average of 5% during the same period. The decrease in daily evapotranspiration caused by elevated [ CO 2 ] was more significantly correlated with air temperature and leaf area index (LAI) rather than with other parameters of solar radiation, days after transplanting, vapor‐pressure deficit and FAO reference evapotranspiration. This indicates that higher air temperatures, within the range from 16 to 27 °C, and a larger LAI, within the range from 0 to 4 m 2 m −2 , can increase the magnitude of the decrease in evapotranspiration rate caused by elevated [ CO 2 ]. The crop coefficient (i.e. the evapotranspiration rate divided by the FAO reference evapotranspiration rate) was 1.24 at ambient [ CO 2 ] and 1.17 at elevated [ CO 2 ]. This study provides the first direct measurement of the effects of elevated [ CO 2 ] on rice canopy evapotranspiration under open‐air conditions using the lysimeter method, and the results will improve future predictions of water use in rice fields.