Abstract Effects of temperature on the ionic relations and energy metabolism of Chara corallina were investigated. Measurements were made of the ionic content, tracer ion fluxes, and photosynthetic and dark CO2 fixation in isolated cells, and of O2 exchange in photosynthesis and respiration in isolated shoot apices.The total intracellular concentration of K+, Na+ and Cl− was the same in cells held for 5 days in non‐growing medium at 15°C (the growth temperature) as in those held at 25°C or 5°C. The tracer influx in the light of all ions tested (Rb+, Na+, CH3NH3+, Cl− and H2PO4−) was lower at 5°C than at 15°C in experiments in which cells were subjected to 5°C for less than 24 h in toto. The influx at 25°C was greater than that at 15°C for H2PO−4, there was no difference between the two temperatures for Na+, while the influx at 25°C was less than that at 15°C for Cl−, Rb+ and CH3NH3+ For Cl− and H2PO−4 similar results were found in later experiments with cells grown at 20—23°C. Photosynthetic CO2 fixation and O2 evolution, and respiratory O2 uptake, are greater at 25°C, and lower at 5°C, than they are at the growth temperature of 15°C. In longer‐term pretreatments at the different temperatures, tracer Cl− influx at 15°C and particularly at 25°C were lower than in short‐term experiments, while the influx at 5°C was higher.It was concluded from these experiments, and from previous data on H+ free energy differences across the plasmalemma, that (1) the maintenance of internal ion concentrations involves a close balancing of influx and efflux of K+, Na+ and Cl− at all experimental temperatures; (2) the regulation of the tracer fluxes of the ions is kinetic rather than thermodynamic and (3) that the tracer fluxes at low temperatures are not restricted by the rate at which respiration or photosynthesis can supply energy to them.

RAVEN, J. A., & SMITH, F. A. (1978). Effect of temperature on ion content, ion fluxes and energy metabolism in Chara corallina. Plant, Cell & Environment, 1(3), 231–238. Portico.