At 20.0 °C, the SGR exhibited similar
tendencies under three irradiance levels, and small difference
was observed at 22.5, 25.0 ,and 30.0 °C. At 27.5 °C, the SGR
reached the maximum at 40 μmol photons m−2 s−1 and was
nearly 1.5 times that at 20 or 100 μmol photons m−2 s−1.