Manal M. Tantawy, Samiha. A. Ouda, Fouad. A. Khalil( 2007). Irrigation Optimization for Different Sesame Varieties Grown under Water Stress ConditionsJournal of Applied Sciences Research, 3(1): 7-12, 2007
Abstract: Two field experiments were conducted at Shandaweel Agriculture Research Station, Egypt to study the effect of number of applied irrigation on sesame yield and water consumptive use. Yield-Stress model was used in irrigation optimization to maintain high yield. Four sesame varieties were used i.e. Giza 32, Toshky 1, Shandaweel 3 and Sohag 3 with two different number of applied irrigations i.e. seven irrigations and five irrigations. Furthermore, drought sensitivity of each variety was estimated. The accuracy of the model was tested by calculating percent difference between actual and predicted yield, root mean
square error (RMSE) and Willmott index of agreement. Results indicated that sesame yield was reduced to by up to 6.42 % when number of irrigation was reduced from seven to five irrigations. The most sensitive variety to water stress was Giza 32, where relative yield reduction, yield response factor and drought
susceptibility index were the highest. Yield-Stress model predictions gave a good agreement with actual yield and water consumptive use under the application of seven and five irrigations. Graphing readily available water depletion from root zone with days after planting for seven irrigations treatment showed that
irrigation was always applied before the depletion of all readily available water at root zone. Whereas, under five irrigations treatment, readily available water was not completely depleted from root zone after the 1st irrigation. However, it was completely depleted from root zone after the 2n d , 3rd and 4th irrigation, where
water stress was prevailed for several days between these irrigations. Therefore, a 10 % increase in the total amount of the five irrigations treatment was used to run the model. The results showed that yield losses were reduced to less than 2 %. Therefore, it is recommended to apply five irrigations to sesame with total amounts between 4367 and 4728 m3/ha, which could save up to 1027 m3/ha, with yield losses less than 2 %.
Keywords: (Irrigation Optimization Sesame Varieties Water Stress Conditions)
