An experiment was performed in order to study the applicability of light-response models for summer maize (Zea mays L.) by using rectangular hyperbola model, nonrectangular hyperbola model, exponential model, binomial regression model, and modified rectangular hyperbola model (Ye model), respectively. Our results showed that the fitted effect of Ye model was best and photosynthetic parameters were closest to the observation. The photoinhibition coefficient was significantly negatively correlated with the light-saturation point (Is), the light-saturation coefficient (γ), and maximum net photosynthetic rate at light-saturation point (PNmax), respectively. PNmax and Is, apparent quantum yield, and γ performed significantly positive relationship, respectively. When the soil volumetric water content varied from 13 to 21%, PNmax had significant positive correlation with the soil water content and stomatal conductance. Under water and temperature stress, the net photosynthetic rate decreased and photoinhibition occurred, which could be well simulated by the Ye model. It seems that Ye model would have more applications, especially for the regions with strong solar radiation.

Leaf photosynthetic light response (PLR) of six sugarcane (Saccharum officinarum L.) varieties with a high sugar content was measured in the field. PLR curves were fitted by the rectangular hyperbola (RH) model, the nonrectangular hyperbola (NRH) model, and the Ye model, respectively. Photoinhibition occurred under warm and humid environment for all tested sugarcane varieties except for GT02-467 with the photosynthetic rate reduced significantly. The Ye model was the best for PLR curve fitting, especially when photoinhibition occurred. Nearly all PLR parameters estimated by the Ye model were better than the other two models. Some PLR parameters correlated with each other. A significant negative correlation was found between the photoinhibition coefficient and the photosaturation coefficient. The varieties with high light-use efficiency (e.g., YZ99-91 and YZ01-1413) are suitable for dense planting under warming climate, while the varieties with strong ability for dim light use (e.g., GT02-467 and MT69-421) would be appropriate for planting at a high density under warming and dimming climate in the future.