Comparison between modified exponential model and common models of light-response curve

Abstract

Aims Our primary aim was to compare the differences and accuracies of light-response curves between C3 and C4 plants as described by five light-response curve models:modified exponential(a new model),rectangular hyperbola,modified rectangular hyperbola,non-rectangular hyperbola and exponential.Methods Light-response curves of Xizang hulless barley(Hordeum vulgare),grain sorghum(Sorghum bicolor),amaranth(Amarantus mangestbus) and Pinellia ternate were measured by a portable photosynthetic gas analysis system with a LED radiation source(LI-6400).The collected data were used to fit and test the five light-response curve models,and photosynthetic parameters,such as light saturation point and maximum net photosynthetic rate,were compared with the measured values.Important findings The results show that the light-response curves of the four plants described by the modified exponential and modified rectangular hyperbola models are better than the rectangular hyperbola,non-rectangular hyperbola and exponential models,especially when light intensity is beyond the light saturation point.The results also indicate that the modified exponential and modified rectangular hyperbola models also describe the light-response curves characteristics of C4 plants,although the two models were established based on C3 plants.Therefore,these two models provide a reference for the application of light-response curve models in plants with different photosynthetic pathways including C3 and C4.