Effect of sulphur dioxide on the partitioning of assimilates in Scots pine (Pinus sylvestris L.) seedlings of different susceptibility to this gas.

A study was made of the influence of SO2 at concentrations 0.25, 0.50 and 0.75 ppm for 5 h on the 14CO2 assimilation and 14C transport in SO2-sensitive and SO2-tolerant seedlings of Scots pine and on the regeneration of the above mentioned processes depending on the duration of tune from the end of fumigation (i. e. after 24 h or 48 h). Immediately after treating the seedlings with SO2 or 24 h later they were exposed to an atmosphere with 14CO2 for 20 min and then after a further 24 h the incorporation of 14C into the general ethanol-soluble fraction, the total sugar fraction and its various components was investigated using ion-exchange, paper chromatography and radioautography. SO2 inhibited the 14C-translocation more than 14CO2 uptake. Also the regeneration of 14C-transport was slower than the regeneration of photosynthesis, which was particularly obvious in the SO2-sensitive plants. The inhibitive effect of SO2 on the transport of 14C-sugars was characterized by a significant lowering of the level of sugars exported from the needles to the roots but not by any qualitative changes. [ABSTRACT FROM AUTHOR]