Seasonal Changes in Efficiency of Solar Energy Utilization and Solar Energy Conversion in Two-rowed Barley of Warm Regions in Japan

Abstract

Efficiency of solar energy utilizatiion (Eu, %), efficiency of solar energy conversion (Ec, %) and conversion efficiency were determined for two-rowed barley (cv. Nishinochikara) plant grown in warm regions in Japan. Absorbed solar radiation during the stage from internode elongation to heading was about 56% of the total supplied solar radiation, and that in the ripening stage was about 70%. Absorbed solar radiation (SR_α) in the growing period was 865.02 MJ m^-2, equivalent to about 40% of the total solar radiation. Ec at the internode elongation to heading stage was 3.94%. Eu and Ec were 1.47% and 2.13% in the ripening period, both of which accounted for 1.09% and 2.71% in the whole growing period, respectively. These values were equal to those of rice grown in the same regions in Japan. Top dry weight was variable in proportion to SR_α, and Cs (Conversion efficiency) was 2.32g MJ^-1, The value of Cs determined in the early and middle ripening stages were 1.79g MJ^-1 and 1.17g MJ^-1, respectively.