Tracer studies of gas circulation in Nuphar: 18O2 and 14CO2 transport

Abstract

A flow‐through ventilation system operates in the yellow waterlily (Nuphar luteum ssp. macrophylla Beal). The flow of air into the youngest emergent leaves and down their petioles to the rhizome is confirmed by 18O2 and 2H2 tracer experiments conducted in the field, showing that most of the O2 in the rhizome originated in the atmosphere. This flow of air into the rhizome forces a simultaneous gas flow from the rhizome up the petioles of the older emergent leaves to the atmosphere. Radiolabelled CO2 was used to demonstrate that CO2 present in the gas moving up these petioles was fixed before reaching the atmosphere.