اثرات متقابل اثر اسيد ساليسيليك و هورمون هاي گياهي بر رشد طولي ريشه هاي دانه رست هاي تربچه

The Interactions of Salicylic Acid and Plant Hormons on Root Elongation of Radish Seedlings

In this study, the effect of salicylic acid (SA) on seed germination and growth of radish seedlings (Raphanus sativus L.) and its interaction with plant hormones were investigated. The results of experiments showed that SA at high concentrations inhibited seed germination and at 4 mM reduced it to zero. Meanwhile, with increasing the SA concentration, root length, a- amylase activity reduced but auxin oxidase activity increased. In order to investigate, the reasons of root length reduction, the interactions of SA with IAA, GA, ABA and cytokinin were studied. GA alone was not limiting to root growth but showed synergism with SA and further reduced seedling root growth. IAA at 10-8, 10-7 and 10-6 mM concentrations promoted root growth and at 10-8 and 10-7 mM along with 0.5 and 1 mM SA increased root growth, but could not overcome to reducing effect of 2 mM SA. ABA alone was limiting to root growth and at 1 mM completely blocked seed germination. Interestingly, ABA at 10-6 and 10-4 mM showed antagonism with reducing effect of SA, and increased root growth. Cytokinin alone at 10-6 and 10-4 mM increased root growth but at 1 mM decreased it drastically. Cytokinin at 10-6 and 10-4 mM acted as antagonist with SA and increased root growth.