Seed yield and essential oil responses of Cumin to different irrigation regimes and super absorbent levels in Urmia climatic conditions

In order to evaluate the seed and essential oil yield and harvest index of cumin, a factorial experiment based on randomized complete blocks design was conducted with three replications, at the research farm of the faculty of agriculture of Urmia University in 2010. Treatments were four irrigation regimes (irrigation after 50, 100, 150 and 200 mm of evaporation from a class A pan) and different amounts of superabsorbent polymer (0, 60, 120, 180, 240 and 300 kg/ha). The highest biomass yield (3640 kg/ha), seed yield (1226 kg/ha) and essential oil (36.5 kg/ha) belonged to irrigation after 50 mm of evaporation and 60 kg/ha superabsorbent polymer application. Increasing in irrigation distances to 100, 150 and 200 mm of evaporation needs to 180 and 120 kg/ha polymer to produce maximum yield (biomass and seed), but they were 60 and 300 kg/ha polymer for essential oil yield and harvest index, respectively. The maximum harvest index of seed for irrigation after 100, 150 and 200 mm of evaporation belonged to 180 kg/ha superabsorbent treatment. Application of superabsorbent at irrigation after 50 mm of evaporation (non-stress condition) does not have efficiency for essential oil production compared with the control (without polymer in this irrigation). In conclusion, increasing irrigation intervals from 50 to 200 mm of evaporation from pan lead to reduce the yield (biomass, seed and essential oil), that application of superabsorbent polymer A200 compensate part of this reduction.