journal of forest science

1989 – deionised water; MCKAY 1998 – distilled water;
SMIT-SPINKS et al. 1985 – solution of CaSO 4 ). Moreover
there were different ways of autoclaving and measurement.
The objective of this study was to find the influence of
different duration of autoclaving on the rate of electrolyte
leakage from oak tap root and changes of EL rate
measured in different time intervals after stress treatments.
Specific aim was to test changes of electrolyte
leakage rate from tap root after same intensive stress factors
on different dates.
MATERIALS AND METHODS
Two-years old bare-rooted seedlings of pendunculate
oak (Quercus robur L.) which had been growing in
a nursery of Lower Saxon orestry Institute (360 m a.s.l.,
annual precipitation 800 mm, in vegetation period
400 mm, mean of annual temperature 7.6°C) were used
in this study. The biometrical characteristics and age of
tested planting stock are given in Table 1.
According to the modified method described by MC-
KAY (1992) the electrolyte leakage from tap root (samples
were taken directly under root collar) was measured
in three different time intervals after stress treatments.
The root system was washed in cold tap water to remove
soil and rinsed in deionised water to remove surface ions.
The sample length from tap root was 2 cm. Individual
samp- les were put to 40ml universal glass bottles containing
30 ml deionized water of conductivity < 3 µS/cm.
The bottles were capped and left at room temperature for
24 h. The bottles were shaken (5×) and the conductivity
of bathing solution was measured using the conductivity
meter L 320 with built in temperature compensation
25°C. Then the samples were killed through autoclaving
at 110°C for three different time intervals (10, 20, and
40 min). The second conductivity measurement was
made 24, 48, and 72 h after the autoclaving. The total
conductivity was:
conductivity after 24 h
EL (%) = ————————————————— ·100
conductivity 24, 48 or 72 h after autoclaving
The electrolyte leakage was measured from 20 plants
per variant.
Electrolyte leakage at different intervals after stress
treatments
On 17. 11. 1999, there were realized two frost tests to
determine the influence of different time period after
Table 1. Age and morphological traits of planting stock
Age
Oak
2 + 0
Height (cm) ±sx 21 ± 7.5
Root length (cm) ±sx 19 ± 3.4
Stem diameter (mm) ±sx 4.5 ± 1.9
Root diameter (mm) ±s x
7.2 ± 2.2
stress factor on the rate of electrolyte leakage. The plants
were placed to climatic rooms directly after lifting. The
plants were kept in these rooms 6h/–3°C and 8h/–5°C.
Next, electrolyte leakage was measured for 20 plants and
60 oak seedlings were placed to cold storage. During cold
storage the root system was in polyethene bags (temperature
1–2°C, air humidity 90–92%). The rate of electrolyte
leakage was measured in three different terms after
frost tests.
A desiccation test was carried out with plants from the
same seed plots on 2. 2. 1998. After the test, 60 plants
were placed to cold storage (the same cold storage conditions
as in frost tests) and in an interval of 3 weeks,
5 weeks and 2 months after the test electrolyte leakage
was measured.
The influence different ways of autoclaving and interval
of second measurement on electrolyte leakage
There was a different time of autoclaving used (10, 20,
and 40 min) and different intervals of second measurement
(24, 48, and 72 h after autoclaving) for finding its
sensitivity. The longest time interval of second measurement
was not used because there was a risk of contamination
of samples due to microbial activity. The test was
realized on 15. 10. 1997. The measurement of electrolyte
leakage was carried out in unstressed planting stock directly
after lifting.
Electrolyte leakage after stress treatment of same intensity
on different dates
On three different dates, the cold test (2h/0°C) was realized
with bare-rooted oak planting stock. Similarly,
a desiccation test was carried out (4h – 15% air humidity/25°C)
and following directly the stress treatments electrolyte
leakage was measured.
RESULTS
Electrolyte leakage at different intervals after stress
treatments
In this test, the influence of different intervals of measurement
after stress factors on the rate of electrolyte
Table 2. The electrolyte leakage from tap root at different intervals
after frost stress
Time interval after REL (%)
frost test 6 h/–3°C Duncan 8 h/–5°C Duncan
Directly after stress 22 A 37 A
1 week after stress 15 B 29 B
1 month after stress 11 C 16 C
2 months after stress 10 C 16 C
α *** ***
R2 0.67 0.63
***P < 0.001 (means followed by the same letter are not significantly
different)
302 J. FOR. SCI., 47, 2001 (7): 301–306