Interaction effects of irrigation regime and salinity on flower yield and growth of saffron

SummarySaffron (Crocus sativus L.) is the most important export crop in the Islamic Republic of Iran. Water scarcity and salinity are important limitations for saffron production in arid and semi-arid regions. The objective of the present study was to determine the interaction effects of salinity and irrigation regime on flower yield and growth of saffron in a pot experiment under a transparent shelter. Irrigation treatments consisted of four irrigation intervals (i.e., 2, 4, 6, and 8 d between successive irrigation events). Salinity treatments in the irrigation water had EC values of 0.5 (tap water), 1.7, 2.9, and 4.0 dS m–1. The results indicated that saffron flower and corm yields were the most and the least sensitive to soil water depletion, respectively; and that leaf and root sensitivities lay between those of flowers and corms. Furthermore, we concluded that corm and root growth were inhibited at field-capacity soil water content and that deficit irrigation was necessary for optimum growth. Dry weight (DW) reductions per unit increase in the salinity of the drainage water were 14.2, 10.8, 9.1, and 2.9% for saffron flowers, corms, roots, and leaves, respectively. Threshold values for the EC of the drainage water ranged between 0.08 and 0.67 dS m–1 for flowers and roots, respectively. Furthermore, DW reductions per unit increase in salinity of the irrigation water for saffron flowers, corms, roots, and leaves were 28.3, 25.0, 21.1, and 7.0%, respectively. The threshold EC values of the irrigation water ranged between 0.13 and 0.48 dS m–1 for flowers and roots, respectively. When saline water was used to irrigate saffron, the irrigation interval needed to be more frequent (i.e., at 2-d intervals) to avoid severe water stress.