Compartmentation and fluxes of carbon in leaf blades and leaf sheaths ofPoa annuaL. andPoa x jemtlandica(Almq.) Richt

AbstractThe allocation of photosynthetically fixed carbon in the leaf blades and sheaths ofPoa annua(a ruderal grass) andPoa x jemtlandica(a sub‐arctic grass) was followed over a light‐dark cycle. Labelling with14Carbon and gas exchange measurements provide data for an eight‐compartment model describing the partitioning of carbon between spatially and chemically separated pools and their rates of turnover. Soluble sugars and fructans were turned over rapidly in the leaf blades of both species. The flux of carbon through pools of storage carbohydrates was higher in the leaves ofP. x jemtlandicathan inP. annua.The exchange of carbon between pools was slower in the sheath than the blade. Carbohydrates stored in the sheath appeared to have no significant role in metabolism over the light‐dark cycle studied here.