## 4 Discussion
### Further Understanding about the Relationship of F760 with Growth and Environmental Parameters
This has been partly explained by [PERSON] et al., who showed that LAI is not the main factor for driving F760 differences between species from different plant functional types [31]. In fact, biochemical properties may play an important role in driving F760 differences across plant functional types. The role of biochemical properties (e.g., fraction of functional reaction centers, maximum carboxylation capacity, and rate constant of sustained thermal dissipation) was more remarkable for SIF yield [47], which will be further discussed in Sections 4.2 and 4.3. Further Understanding about the Relationship of AF760 and Fy760 with Growth and Environmental Parameters  
Compared with F760, the dependences of AF760 and Fy760 on SWR were much smaller, which was deduced from their weaker relationships, especially for both seasonal and diurnal patterns of wheat and the diurnal pattern of maize (Figures 6 and 7). This was because of the removal of the SWR influence by means of F760/SWR and F760/L685. With less dependence of AF760 and Fy760 on SWR, both AF760 and Fy760 generally showed weaker relationships with VPD, Ta, and Rh relative to F760. This result is attributed to the fact that partial information of AF760 and Fy760 with Ta, Rh, and VPD were simultaneously removed by F760/SWR and F760/L685, since Ta, Rh, and VPD were covariant with SWR. When the impacts of air parameters (Ta, Rh, and VPD) on AF760 and Fy760 were partially removed, the influence of SM both on AF760 and Fy760 became larger, especially for wheat measurements, most of which may have suffered from water stress. After removing the influence of SWR by using F760/SWR, it was expected that AF760 at seasonal and diurnal scales would show an enhanced relationship with growth parameters. However, this assumption was only established for wheat LAI and RWC at the seasonal scale, which showed an enhanced impact on AF760 (Figure 6). Other growth parameters (e.g., Chl and MTA) did not show obviously enhanced effects in affecting AF760, both at seasonal and diurnal scales for wheat and for maize (Figures 6 and 8). This means that the impacts of LAI and RWC for AF760 at different time scales were more pronounced. Fy760 was more closely related to SIF yield than AF760 since it removed the partial influence of SWR on one hand and eliminates the canopy structure influence on the other hand [39]. Therefore, in the wheat plots, the influence of LAI, Chl, and MTA showed a reduced relationship with Fy760 compared with AF760. In maize plots, similar results were also found for the seasonal relationship of MTA and RWC in relating with Fy760. LAI and Chl in maize plots did not show consistent results, which might be attributed to the complicated canopy structure and close distance between the fiber and canopy. In our study, the greater influence of structural variables (e.g., LAI) on AF760 than F760 was also observed, which was not consistent with the findings by [PERSON] et al., who reported a lower sensitivity of SIF yield to structural variables. This was probably due to the SIF yield in [PERSON] et al. being calculated by using hemispherically integrated flux, which is much less influenced by these structural variables than the fluorescence in a single observation in our study.