Eclipse effects on CO2 profile within and above sorghum canopy

Tominaga, Jun and Kawasaki, Syunichiro and Yabuta, Shin and Fukuzawa, Yasunori and Suwa, Ryuichi and Kawamitsu, Yoshinobu (2010) Eclipse effects on CO2 profile within and above sorghum canopy. Plant Production Science, 13 (4). pp. 338-346.

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We analyzed the effects of a partial solar eclipse (22 July 2009) on microclimate including vertical gradients of CO2 concentrations ([CO2]), so called [CO2] profile, in a mature sorghum canopy. Together with CO2 measurement, major photosynthetic drivers of microclimate, light intensity, temperature and atmospheric H2O concentration ([H2O]) were also measured simultaneously at the same place and height. [CO2] at 6.0, 3.2, 2.1, 1.4, 0.7, 0 m above the ground (canopy height was 3.2 m) increased by 5.8, 4.8, 9.0, 7.8, 6.4, 7.6μmol mol-1, respectively, from 1 hour before the eclipse maximum to the eclipse maximum, during which the incident solar radiation above the canopy dropped by 1473 μmol photons m-2 s-1. However, it declined by 3.4, 10.6, 10.8, 6.0, 5.4, and 5.8μmol mol-1, respectively, from the eclipse to 1 hour later, during which the incident radiation increased by 1350μmol photons m-2 s-1. The [CO2] profi le during the eclipse was uniform except for higher [CO2] near the ground. Comparative analysis of the effect of light intensity on the microclimate during the eclipse-induced light decreasing phase (ELDP) and eclipse-induced light increasing phase (ELIP) revealed that [CO2], [H2O], temperature and relative humidity (RH) are significantly correlated with the light intensity above the canopy in a nearly linear fashion. Furthermore it indicated that detected less light-reacted canopy photosynthesis at a higher layer within the canopy during ELIP might be due to slower response of stomatal opening (than closing) to the light intensity above the canopy.

Item Type: Article
Author Affiliation: Faculty of Agriculture, University of the Ryukyus, Okinawa 903-0213, Japan
Subjects: Environmental Science > Environment
Divisions: Sorghum
Depositing User: Mr T L Gautham
Date Deposited: 18 Nov 2010 17:01
Last Modified: 29 Dec 2010 20:28
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