Efficient tree diagnosis methods have been required for the improvement of maintenance techniques in indoor plants. Laser induced chlorophyll fluorescence induction kinetics have been shown to be one of the possible techniques to detect indoor tree conditions. In this study, changes in induction kinetics and leaf sugar content with the dark treatment were investigated using <i>Myrica rubra</i> and <i>Ternstroemia gymnanthera</i>. Measurements conducted during July and September (Japan) showed good correlation between the period of dark treatment and the induction kinetics/leaf sugar content, regardless of the kind of trees tested. Effects of the dark treatment were detected in the second time derivatives of the induction kinetics curves between 5-24s. However, results in the early spring and late fall did not show such correlation. These results showed that LIF application to detect low irradiance stress of indoor plants has high potential, but that its application season is restricted.