اثر پرایمینگ بذر بر مؤلفه‌های جوانه‌زنی، تغییرات بیوشیمیایی و رشد اولیه گیاهچه کنجد (Sesamum indicum)

Extended abstract Introduction: Today, various technologies have been developed to improve seed quality with the aim of increasing the percentage, speed and uniformity of germination and better seedling establishment under different environmental conditions. One of these technologies is seed pre-treatment or seed priming. In this regard, some studies confirmed that pre-treatment of seeds with hormones and plant growth regulators improved germination behavior and its related indices, including average germination time, seed vigor, radicle length, plumule length, germination rate and seedling establishment in primed seeds of sesame. Considering the sensitivity of the germination process as the first plant developmental stage and also, the importance of improving germination indices and sesame seedling establishment, the aim of this study was to evaluate the seed priming efficiency using salicylic acid, methyl jasmonate and humic acid on the germination performance, biochemical changes and early seedling growth of two sesame cultivars including Yellow white and local cultivar of Dezful. Materials and Methods: This experiment was conducted as factorial based on completely randomized design with four replications in the seed technology Laboratory of Safi Abad Dezful Agricultural Research Center in the summer of 2015. The first factor was seed pre-treatment with distilled water (control), salicylic acid 0.1mM, methyl jasmonate 1µM, and humic acid 1.5% and the second factor was two varieties of sesame including Yellow white and and local cultivar of Dezful. Germination percentage, germination rate, seed vigor index, radicle length, plumule length, allometric coefficient, proline content, soluble proteins and catalase enzyme activity were determined to compare the treatments. Results: The results of the experiment showed that seeds priming had a significant effect on germination percentage, germination rate, seed vigor index, radicle length, plumule length, allometric coefficient and seedling biochemical changes, and improved them. The effect of cultivar on all studied traits, except mean daily germination and plumule length, was not significant. In this research, Dezful cultivar had an average of 13.52 seeds per day with higher germination rates than other cultivar (Yellow white). Also, the interaction of priming × cultivar was significant only on seed vigor index and allometric coefficient, where the comparison of the meanings indicated that the highest seed vigor was obtained by using humic acid 1.5% in Dezful cultivar (10.09), while the highest allometric coefficient in seed pre-treatment with methyl jasmonate was found in the Yellow white cultivar (1.57). Conclusions: In this study, the most effective seed priming treatments for improving germination, biochemical changes and seedling growth of sesame was humic acid 1.5%, recording in local cultivar of Dezful. Seed priming with humic acid 1.5% was significantly better than control and Dezful cultivar germination performance was better than that of Yellow white cultivar, therefore it can be stated that pre-treatment of seed with humic acid with more effect on germination characteristics of sesame can be more effective in establishment of seedlings. It is very useful to use this organic acid for better root system development and sesame seedlings establishment, which is a major problem at the beginning of the growing season.   Highlights: Humic acid was the most effective seed priming treatment on germination characteristics, biochemical changes and seedlings growth of sesame. The effect of seed priming treatments on the germination characteristics of Dezful cultivar was higher than that of Yellow white.