EFFECT OF DEFICIT IRRIGATION LEVELS ON YIELD AND YIELD COMPONENTS OF SESAME (Sesamum indicum L.) IN BENA TSEMAY WOREDA, SOUTH OMO ZONE, ETHIOPIA

Abstract

Scarcity of water is one of the major constraints for the development of agriculture in arid and semi-arid regions. Hence, the effective use of available water by deficit irrigation is an alternative means to alleviate the problem and optimize the water productivity of crop in the region. The objective of this study was to determine the effect of deficit irrigation levels applied on yield, yield components and water productivity of sesame (Sesamum indicum L.). The field experiment was carried out at Bena Tsemay Woreda, Southern Ethiopia. The experiment was laid out in randomized complete block design with six irrigation treatments and three replications. The treatments were five water deficit irrigation levels (85%ETc, 75%ETc, 65%ETc, 55%ETc and 45%ETc) and full (100%ETc) as a control treatment. The result of analysis of variance showed that the different deficit irrigation levels applied had statistically significant (p < 0.01) effect on yield and yield component of sesame. Significant delay in flowering and maturity was observed as the water deficit level increased. The highest plant height, number of branch per plant, number of capsules per plant, number of seed per capsule, 1000-seed weight, aboveground biomass, harvest index and straw yield were observed under control treatment (100%ETc), while the lowest observed in 45%ETc treatment respectively. The maximum grain yield (2164.56 kg/ha) was observed under control (100%ETc), while the minimum (1377.37 kg/ha) was obtained from 45%ETc treatment level. From the mean result of grain yield it was observed that control treatment (100%ETc) significantly different from all treatments except treatment under 85%ETc. The highest water productivity (0.55kg/m3 ) was observed under 45%ETc, while the lowest (0.39 kg/m3 ) was at control treatment. From the result of study it was observed that the obtained yield response factor (Ky) was less than unity (Ky < 1), this indicates that sesame is tolerant to water stress. From the result of study it was observed that deficit irrigation under 75%ETc resulted in significant water saving and improved water productivity with insignificant yield reduction; therefore, sesame could be irrigated at 75%ETc in region with limited water resource condition