The effects of foliar application of salicylic acid and potassium nitrate on chlorophyll content, electrolyte leakage and replacement corm growth of saffron in Birjand

Foliar application of phytohormones and nutrients can affect the saffron vegetative growth and its tolerance to environmental stress. In order to evaluate the role of salicylic acid and potassium nitrate foliar application on saffron growth, a two years' study (2014-16) was carried out based on a randomized complete block design with four replications at Sarayan faculty of agriculture, university of Birjand. In this study, different levels of salicylic acid (0.5, 1 and 2 mM) and potassium nitrate (250, 500 and 1000 mg L-1) plus control (distilled water) was sprayed twice during plant growth. Based on the results, the highest chlorophyll a (6.93 mg/g FW) and chlorophyll a/b obtained at plants treated with 1000 mg L-1 of potassium nitrate, which had no significant difference with level of 2 mM Salicylic acid. The highest chlorophyll b content was obtained at 0.5 mM salicylic acid (1.084 mg/g FW) that showed no significant different with 1 mM treatment. All levels of salicylic acid and potassium nitrate reduced the electrolyte leakage percentage. Moreover, the highest amounts of daughter corms fresh weight (3.9 g), number of leaves (8 leaf per plant), and leaf length (33.81 cm) were gained at concentration of 2 mM salicylic acid. Overall, it can be concluded that foliar application of salicylic acid and potassium nitrate is an appropriate strategy in saffron cultivation which can reduce the effects of thermal stress (reduce in electrolyte leakage) and increase replacement corm growth and leaf extension