Investigating physiological and biochemical

3.1.2.2. Salinity treatments 
After one week of transplanting, salt (NaCl) was added to the nutrient solution 
and required levels of salinity (control, 100 and 200 mM NaCl) were developed in 
three increments, whereas no salt was added in control. Salinity was maintained 
continuously until final harvest. Electrical conductivities (EC
w
) of nutrient solutions 
were measured with an electrical conductivity meter on alternate days. Over the 
duration of stress, the first salt level (designated as low salinity level) of 100 mM 
NaCl and the second salt level (designated as high salinity level) of 200 mM NaCl 
were maintained during the experiment. The control, i.e., nutrient solution without 
added salts, had an EC
w
of 1.71 dS m
-1
. 
3.1.2.3. Plant harvest
 
After four weeks of salt stress, plants were harvested and washed thoroughly and 
root and shoot lengths were recorded. The young fully expanded leaves were 
separated at harvesting time and were dried at 65±5 
º
C to constant weight in a forced 
air-driven oven (Jones and Case, 1990). 

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55 
3.1.2.4. Measurements 
The data regarding growth parameters like plant height root/ shoot lengths, 
root/shoot fresh and dry weights, number of tillers per plant and ion contents (Na
+
K
+
and Na
+
/K
+ 
ratio) of the plant leaves were recorded for each genotype tested in the 
experiment. Root and shoot lengths and fresh weights were recorded just after 
harvesting while dry weights of roots and shoots were recorded after oven drying. For 
the analysis of Na
+
and K
+
, 50 mg of well ground dry material of leaves were digested 
in 10 ml of di-acids (HNO
3
:HClO
4
) (Jones and Case, 1990). The filtrate was filtered 
with Whattman No. 1 filter paper and Na
+
and K
+
contents in the digests were 
determined with a flame photometer (Jenway PFP7).