Effect of salinity on germination characteristics and early seedling growth of canola cultivars (Brassica napus L.)

Germination response and early seedling growth of canola cultivars (Okapy, Zarfam, Talayeh, Hayola, RGS003, SLM046) to different salinity levels (0, 5, 10, 15 and 20 ds.m-1) were investigated in a randomized complete block design (RCBD) with three replications in the laboratory. The experiment was conducted in the research laboratory of the Faculty of Agriculture, the University of Birjand, during 2007. Increasing salinity level caused a significant reduction in final germination percentage, germination rate, root and shoot length, and fresh weight. The response rate, however, was different depending on the tested cultivar, and cultivar × salinity interaction was significant in the analysis of variance of all measured parameters. The functional three- parameter logistic model provided a successful estimation of the relationship between salinity and final germination response of Canola Cultivars. The highest and the lowest model slopes were observed in RGS003 and SLM046, respectively, which, in turn, indicates the highest and the lowest salt sensitivity. The fitted model showed that the salinity level that causes 50% reduction in final germination percentage was 14.5 dS.m-1 for RGS003 and 26.8 dS.m-1 for SLM046. In general, results showed the following order in salinity resistance during germination and early seedling growth: SLM046> Zarfam> Talayeh> Okapy> Hayola> RGS003. This classification depicts the salt tolerance of canola cultivars during early stages of plant growth; therefore it is essential to conduct further research for assessing this tolerance during later plant growth stages.