Investigating physiological and biochemical

3.3.2.3 Relative growth rate (RGR) 
 
For the determination of relative growth rate (RGR, g g
-1
d
-1
), plant dry weights 
of the two successive harvests were used. Three plants from each tub were harvested 
at two week interval. Relative growth rate was determined by the following formula: 
(Ashraf and Fatima, 1994) 
Where W = dry weight of the plants at first harvest; dW = difference in dry weights of 
plants at two harvests and dt = time interval between the two successive harvests. 
3.2.2.4 Determination of Na
+
 and K
+
 contents
After 30 days of salt stress, three plants from each treatment were harvested, 
washed thoroughly with distilled water and dried using blotting paper. The root, shoot 
and leaves were separated at harvesting time and dried at 65±2℃ for 2 days in a 
forced air-driven oven to determine Na
+
and K
+
. For the analysis of Na
+
and K
+
, 50 
mg of well ground dry material of each of root, shoot and leaves was digested 

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71 
separately in 10 ml of di-acids (HNO
3
:HClO
4
) mixture. The filtrate was filtered 
through whatman No. 1 filter paper and Na
+
and K
+
contents in the filtrate were 
determined with a flame photometer (Jenway PFP7). 
3.2.2.5 Seed germination
For the determination of seed germination of linseed under salt stress conditions, 
a separate experiment was conducted at Saline Agriculture Research Centre. Four
replicates of 50 seeds were germinated in covered, sterilized, disposable petri dishes 
containing whatman No. 3 filter paper moistened with either distilled water (control) 
or 100 or 200 mM of NaCl solutions. Petri dishes were sealed with parafilm to 
prevent evaporation, to minimize changes in the concentration of solutions. Seeds 
were incubated in a growth chamber at 20 ±1 ºC and were considered germinated with 
the emergence of radical. Germinated seeds were counted every day until the end of 
germination period of 10 days. Every three days, germinated seeds were removed 
from the petri dishes. To maintain adequate moisture, 5 ml of original salt solutions 
were added to each petri dish every three days