Sugarcane leaf photosynthetic light responses and their difference between varieties under high temperature stress

Abstract

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.