The effects of salinity on pigments content and growth of two canola (Brassica napus) cultivars

Salinity is one of the most important factor that limits plant growth and production in the whole world. Identification of salt tolerant cultivars and improving tolerance of plants is the most effective method for increasing yield. To evaluate the response of growth and pigment contents in canola genotypes to salinity, a factorial complete randomized design with four replications was conducted. Sodium chloride salinity at three levels 0, 175 and 350 mM on two genotypes, Brassica napus L. cv.Sarigol and Brassica napus L. cv.Hyola308 was applied in stages 3-4 leaves. Dry weight of shoots and roots, chlorophyll a and b, carotenes and xanthophylls, anthocyanins, flavonoids and finally UV absorbing compounds contents were studied in the leaves. The results showed root dry weights reduced in both genotypes during high salinity conditions. The exposure of Sarigol plants to 175 mM NaCl induced a significant increase in shoot dry weight, but salinity had no significant effect on Hyola308 plants. Only in Sarigol cultivar Chlorophyll a contents increased during low salinity but Chlorophyll b contents decreased with high salinity. Increasing carotenoids in Hyola308 could be a reason of resistance to salinity and stability in photosynthetic structures. Under high salinity, there was not a significant trend in decreasing non-photosynthetic pigments in both genotypes. So it could be concluded that in canola plants, one of the most important factors for salinity tolerance could be unimpairing the main photosynthetic pigments.