Response of photosynthetic characteristics and accumulation and distribution of assimilation products in tobacco to different light environments

Abstract

In order to reveal the photosynthetic characteristics and the mechanism about accumulation and distribution of photosynthetic assimilation products under different light environments, potted tobacco was cultivated in a climate control chamber, there were three light intensity treatments (shading: (400±15)-(500±15) μmol·m-2·s-1; natural light: (800±15)-(1000±15) μmol·m-2·s-1; high light: (1500±15)-(1800±15) μmol·m-2·s-1). The results showed that with the decrease of light intensity, the biomass and root allocation, the net photosynthetic rate (Pn), stomata conductance (gs) and transpiration rate (Tr) were decreased, but the intercellular CO2 concentration (Ci) increased. The maximum net photosynthetic rate (Amax), light saturation point (LSP), light saturation point (LCP) and dark respiration rate (Rd) reached the maximum level under high light condition while the apparent quantum efficiency was higher in low light environment. The effects of light intensity on the absorption, accumulation and distribution of 13C in tobacco were significant, with a reduced proportion of enriched 13C distributed to the root under shading. The changes in the external light environment not only significantly affected the photosynthetic cha-racteristics and biomass accumulation of tobacco leaves, but also the distribution pattern of photosynthetic carbon in tobacco plant-soil system.