Effect of irrigation regimes on yield and yield components of cumin

In order to evaluate the effect of irrigation regimes on yield and growth parameters of cumin (Cuminum cyminum) an experiment was conducted in Mashhad, Iran, during the years 1998-2000. Six irrigation treatments were used as:T1: No irrigation during growing period (rainfed).T2: One irrigation during flowering stage.T3: One irrigation during seed formation.T4: Two irrigations during growing season; one at flowering stage and one at seed formation. T5: Three irrigations during growing season; one after germination, one at flowering and one at seed formation stage.T6: Full irrigation during growing season.During the growing season, treatments of rainfed and full irrigation received 185 and 350 mm of water respectively. The results showed that by reducing numbers of irrigation at various treatments, plant water potential is also decreased. It reached to -30 bars without showing any sign of wilting at T1 as compared to -15 T6. Seed yield, number of umbels per plant and number of seeds per umbels were not significantly different at 5 percent level. However, treatment T6, showed to have least weight of 1000 seeds and harvest index and highest total biomass. Differences between weight of 1000 seeds of T1 and harvest index of T3, T4, T5 and total biomass of T1, T2, T3, T4 were significantly different with treatment 6 at 5 percent level. The overall results showed that in climatic condition of Mashhad, Cumin need not to be irrigated in years with rainfall close to average.