Abstract
Cumin (Cuminum cyminum) is one of the most important medicinal plants in Iranian dry region. In order to study the effects of irrigation times and salinity stress on yield and yield components of cumin, an experiment was conducted at the Research Farm Ferdowsi University of Mashhad in 2009. Factors including irrigation times (1: one time irrigation, 2: two times irrigation 3: three times irrigation and 4: four times irrigation (control)) with two levels of salinity stress (irrigation with normal water and saline water of 5 dS/m) and two Cumin cultivars (Sarayan, Indian cultivar RZ 19) were compared in a split plot based on randomized complete block design with three replications per treatment. The results showed that two and three time irrigation with normal water produced the highest biological and seed yield and there was no significant difference at these traits. One time irrigation and two times irrigation treatments with saline water had lowest seed yield, biological yield and seed number per umber and umbers per plant. Salinity stress decreased significantly all parameters of cumin cultivars such as seed yield, biological yield, number of umbers per plant, number of seeds per umber, 1000 seeds weight. The Indian cultivar was less reduced on seed yield than Sarayan cultivar under salinity stress and also Sarayan cultivar was less affected on seed yield in drought stress than Indian cultivar, however, in overall, Sarayan cultivar had higher seed yield than Indian cultivar in all treatments. Based on the results of this experiment (two times irrigation with normal water for Cumin in Mashhad area) will be achieved as desirable seed yield. However, yield reduction of cumin under irrigation with saline water of 5 dS/m was less than 20% compared with control.

Keywords: Irrigation, Salinity stress, Cumin, Yield, Yield component