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 (SRα) 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 SRα, 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.