The Effect of Different Levels of Salinity (NaCl) on Germination and Seedling Growth of Safflower ( Carthamus tinctorius L.) Cultivars

Soil salinity is an increasing environmental stress on crops in most areas of Iran since farmers use underground saline water for irrigation. In order to investigate the effects of salt stress on germination and seedling growth of safflower (Carthamus tinctorius L.), an experiment was conducted at two stages (germination seedling growth), using four levels of NaCl salinity (0, 5, 10, 15 ds/m), and four cultivars of spiny and non-spiny safflower ( a landrace from Isfahan bred cultivars of IL, LRV and PI). The design was factorial and completely randomized based on 3- replicates (CRD). Germination percentage, germination velocity index, root and shoot length, root and shoot dry weight, root to shoot dry weight ratio and salt tolerance index were measured at germination stage. In seedling growth stage, traits such as, stem length, number of leaves, chlorophyll index, root and shoot dry weight, root to shoot dry weight ratio and salt tolerance index were also measured. Results for both growth stages showed that salt stress decreased all the above mentioned traits, significantly, in all cultivars. Salinity × variety interaction at germination stage was also significant, compared to seedling growth stage. Salt tolerance index decreased significantly with increasing salinity at both stages, but differences between cultivars were not significant. Cultivars PI and IL were characterized as the tolerant ones at germination and seedling growth stages, respectively. It could be concluded that safflower cultivars responded differently to salinity in germination phase compared to seedling growth phase, and that safflower suffers more from salinity during germination stage.