Photosynthesis and transpiration are important factors for improving crop yield. We examined the leaf and canopy transpiration rates of GP2, a heading gene mutant of hd3a, a rice orthologue of Flowering Locus T (FT) which promotes stomatal aperture in Arabidopsis FT in comparison with those of its wild type Gimbozu. Measurements were conducted with LI-6400 in 2012 and 2013. In addition, we measured and canopy surface temperature with a thermography camera at the experimental field in Kyoto University in 2013. The ratio of canopy transpiration between GP2 and its wild type Gimbozu was quantitatively analyzed using micro-weather data and canopy temperature. The photosynthesis measurements showed that GP2 had lower stomatal conductance (gs) than its wild type Gimbozu. Furthermore, the canopy temperature was higher and transpiration rate was lower in GP2 than in Gimbozu in the afternoon toward the end of July. These results indicated that Hd3a controls the transpiration in rice. Although there was no significant difference in the plant biomass and yield between GP2 and Gimbozu, these findings contribute to our understanding of water use efficiency in rice production.
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