Influence of saffron corm soaking in salicylic acid and potassium nitrate on vegetative and reproductive growth and its chlorophyll fluorescence indices

Saffron that is an important medicinal plant of Iran is influenced by several environmental stresses. Therefore, the consumption of appropriate hormonal and nutritional compounds can reduce the negative impacts of stresses on it and improve the growth and yield of the plant. For this purposes, an experiment was carried out based on a Randomized Complete Block Design with four replications to study the effect of Salicylic acid (0, 0.5, 1 and 2 mM) and Potassium Nitrate (0, 250,500 and 1000 ml.g-1), in the research field station of the College of Agriculture, the University of Birjand, Iran, in the growing season of 2015. The indices evaluated included flower and corolla fresh weight, stigma weight and length, leaf length, corm and cormel weights and diameter, chlorophyll florescence parameters and total chlorophyll content. The results showed that the highest amounts of Fv, Fv/Fm, Fv/Fm (117, 0.27 and 0.44, respectively), total chlorophyll (0.85 µg.g fresh weight), flower and corolla fresh weight (36.9 and 32.1 g.m-2, respectively), stigma weight (4.2 g.m-2) and length (29.6 mm) and leaf length (37.7 cm) were obtained at 2 mM level of salicylic acid, while the highest Fm was recorded at 0.5 mM salicylic acid. In addition, pretreatment with 1000 mg.l-1 potassium nitrate increased the amounts of cormel weight and diameter by 30% and 19% compared with the control, respectively. Generally, the results of this experiment indicated an enhancement in saffron growth and yield, affected by corms soaking in salicylic acid and potassium nitrate.