Effect of irrigation frequency and amount on water use efficiency and yield of sesame (Sesamum indicum L.) under field conditions

The water-use characteristics of sesame (Sesamum indicum L.) were studied in the field under furrow irrigation. Irrigation water quantities were based on pan evaporation (E_pan) from a screened class-A pan. Treatments consisted of three irrigation intervals (I₁: 7 days; I₂: 14 days, I₃: 21 days), and four pan coefficients (K_cp 1: 0.60; K_cp 2: 0.80, K_cp 3: 1.00 and K_cp 4: 1.20). Average irrigation values for each treatment varied from 467 to 857 mm in 2003 and 398 to 654 mm in 2004. The highest seasonal evapotranspiration was obtained from the I₃K_cp 4 treatment in 2004 (1019 mm); the lowest value was observed in the I₁K_cp 1 treatment in the same year (598.0 mm). Data collected in 2003 and 2004 showed that the amount of irrigation water applied significantly the affected seed yield. However, the effects of irrigation interval on yield were not significant. On average, the K_cp 3 treatment gave the highest seed yield (1.915 t ha⁻¹), whereas K_cp 1 treatment gave the lowest (1.538 t ha⁻¹). Seasonal yield response factors (k_y) were 1.01 and 0.54 in 2003 and 2004, respectively. ET/E_pan ratios for each treatment varied from 0.3 to 1.3 in 2003 and from 0.1 to 1.1 in 2004. In conclusion, the K_cp 3 plant-pan coefficient is recommended for sesame grown under field conditions in order to maximise yield.