Investigating physiological and biochemical

2.5. Linseed and Salinity
Linseed (Linum usitatissimum L.) is an economically important dual purpose 
medicinal crop. It gives fiber (flax) from stem and oil (linseed) from seed. It is grown 
as minor crop in a large number of countries for different types of products (Ebtihal et 
al., 2012). Linseed has great adaptability and product diversity and researchers of 
Australia, North America, Europe and Asia are conducting research for producing its 
bio-products.
Linseed has significant variations for salinity tolerance and its salt tolerance 
ability does not change with the stage of plant growth and development (Ashraf and 
Fatima, 1994). Biochemical markers for salt tolerance in linseed were evaluated by 
El-Beltagi et al. (2008) in linseed cultivars and they established that the relative salt 
tolerance of tolerant cultivars was linked with high activity of SOD, POD and APX 
enzymes and low MDA concentration. It was also noted that low Na
+
/K
+
ratio was an 
indicator of salt tolerance in linseed cultivars. In another experiment, Emam and Helal 
(2008) investigated that flax seeds tolerated NaCl stress up to 200 mM NaCl at 
germination stage and germination was completely inhibited at 300 mM NaCl. In 

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addition, it was recorded that salt stress significantly increased soluble carbohydrates, 
MDA contents, reduced glutathione and proline contents but reduced the total phenols, 
ascorbic acid and total free amino acid contents. They also observed an increased 
activity of antioxidant enzymes like SOD, APX, ASO (ascorbate oxidase), phenol 
peroxidase, GPX and polyphenol oxidase, POX in linseed seedlings.
Linseed growth has been studied on salt-affected soils and different physiological 
and biochemical traits have been indicated which grant salt tolerance in linseed. But 
little work is done on native linseed genotypes and controversial claims regarding salt 
tolerance in linseed are reported. For instance, Ashraf and Fatima (1994) reported that 
degree of salt tolerance of linseed does not vary with growth stage and Na
+
inclusion 
in the shoot is the physiological trait of salt tolerance in this crop. Similarly, 
Muhammad and Hussain (2010) studied physiological growth responses of some 
medicinal plants including linseed and reported that test species were tolerant to 
moderate salinity and can be grown on saline soils to obtain some biomass. These 
controversial results encouraged us to conduct comprehensive study of linseed 
regarding its various aspects from germination to maturity under saline conditions. 
Thus current study was designed to know the germination response of linseed under 
salt stress and its growth and yield attributes were recorded to assess the salt tolerant 
traits in native linseed germplasm.

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