Water Requirements of Drip Irrigated Cumin and Their Effects on Growth, Yield and Some Physiological As Well As Biochemical Parameters.

The effect of different irrigation levels on growth, yield, oil content and chemical constituents of cumin plant were investigated. The amount of applied irrigation water was added as 20, 40, 60, 80 and 100 % of the potential evapotranspiration (ETP) values based on class-A pan. Plant growth as well as fruit and oil yields were negatively affected by deficit irrigation. Relative water content, membrane stability index and soil water content were maintained higher than those obtained by deficit irrigation. Irrigation water use efficiency (IWUE) was increased by reducing the irrigation level. Increasing the irrigation level from 20 to 100 % ETP gradually decreased the volatile oil percentage. GC-MS analysis of volatile oil revealed that the main components were cumin aldehyde, cumin alcohol, p-cymene, alpha-pinene and beta-pinene. These components were slightly affected by deficit irrigation. Unlike carbohydrate percentages, chlorophyll content and N, P, K were increased with increasing irrigation level. Deficit irrigation increased fruit phenolic content as well as DPPH scavenging capacity. Applying 75 % ETP irrigation level was the optimum level and it can be recommended as a possible technique for saving water and maximizing the irrigation water use efficiency in cumin cultivation.