FROST-RESISTANCE AND PH OF CELL EFFUSATE IN NEEDLES OF ARTIFICIALLY DEACCLIMATED SCOTS PINE (PINUS-SYLVESTRIS)

Provenances of seedlings of Scots pine (Pinus sylvestris L.) from nort hern Finland (65 degrees N) and cuttings from trees of the same specie s about 30 to 40 years in age were studied in 3 artificial deacclimati on experiments during the winter and spring of 1994. The deacclimation conditions varied in terms of temperature rise and photoperiods. Fros t resistance and the pH of the cell effusate were studied in order to investigate the possibility of a connection between them. Complete dea cclimation was achieved, as shown by a frost resistance of -60 degrees C to -65 degrees C in the seedlings and -80 degrees C in the cuttings at the beginning of the experiment and decreased to above -10 degrees C by the end. The frost resistance and pH of the cell effusate respon ded significantly to the increase in temperature that marked the onset of the deacclimation process, whereas the response to different photo periods was only slight. A highly significant correlation was found be tween frost resistance and the pH of the cell effusate. These variable s were also significantly correlated with the freezing test temperatur e, indicating the condition of plasmalemma and tonoplast; and with sam pling day, indicating the response to deacclimation. In the light of t hese findings, it is concluded that the pH of the cell effusate with c ertain reservations, can be used as a time saving, alternative viabili ty test when determining frost resistance.