عنوان مقاله [English]
Effects of priming by different levels of salicylic acid (SA) on some characteristics of wheat, cv. Alvand, seedlings at two different sowing dates, conventional and late sowing dates, was investigated under field conditions in 2009-2010. The factors were seven levels of priming by SA, including control or untreated seeds, 400, 800, 1200, 1600, 2000 and 2400 µM SA and two sowing dates including conventional sowing date (23 October) and late sowing (22 November). Results showed that delayin sowing date leads to reduce emergence percent, seedling winter survival, leaf and tiller number, leaf area index, plant dry weight and leaf area ratio. Seed priming by SA improved traits such as leaf and tiller number, first leaf length, root length, fresh and dry weight of different parts of plant, soluble sugar and proline content and growth indexes Especially in conventional planting date. However, In late sowing priming only affected emergence percent, seedling survival percent, root length and proline and soluble carbohydrate content. In both planting dated, seed priming induced a reduction in S/R ratio. It seems that SA enhanced dry matter accumulation and distribution in roots than shoot. The highest number of leaf and tiller, fresh weight (total, root and crown) dry weight (total, foliage leaf sheath and crown) and S/R ratio were found in 2400 µM treatment. It seems that SA application by increment in germination rate and emergence percent and proline and soluble carbohydrate content in crown and leaf produced vigorous seedlings that had more potential to protect themselves from winter freezing compared to untreated seeds. Therefore, survived seedlings increased significantly.