The effect of salinity of irrigation water on some physiological characteristics and dry mass of linseed at vegetative stage

Soil and water salinity is a major constraint in arid and semi-arid regions. In order to study the impact of water salinity on physiological characteristics and dry matter production of six linseed genotypes، a 4-replicate factorial randomized complete block pot experiment was conducted. Salinity consisted of four levels: 0 (control)، 35 (low salinity)، 70 (intermediate salinity) and 105 mM (severe salinity) of NaCl and genotypes consisted of C1، C2، C3، B، 33 and Khorasan. Severe salinity led to 37، 33، 36، 3، and 61% decreases in chlorophyll a (chl a)، chl b، chl total، chl a/chl b and carotenoids contents، respectively. Mean proline content of plant leaf and root increased by 6. 35- and 1. 54-fold under 105 mM، compared to the control، respectively. Genotypes C3 and 33 indicated the greatest (6. 4-fold) and smallest (2. 8-fold) increases in leaf proline content، respectively. Khorasan indicated the greatest increases (3. 81-fold) and C3 the smallest (1. 97-fold) increase in leaf soluble carbohydrate content. While mean antioxidant activities increased with salinity، the greatest mean enzymes activities were detected with the intermediate level of salinity. In contrast to the rest of genotypes، Khorasan and 33 indicated increases in their catalase، ascorbate peroxidase and glutation peroxidase activities when subjected to the severe salinity، compared to the intermediate salinity. Mean plant dry mass decreased with increase in salinity، with Khorasan indicating the smallest decrease. It could be concluded that physiological attributes، growth and dry mass production in linseed is negatively affected by NaCl، even with intermediate water salinity. Genotypes Khorasan and C3 seemed to be more resistant to the NaCl salinity due، at least in part، to maintaining or increasing the level of antioxidants activity.