灌漑・排水システム工学

Lemongrass (Cymbopogoncitratus(DC.)Stapf) Response for Supplementary Irrigation in Rain-fed Agriculture at Wondo Genet, South Ethiopia

Abstract

Elias Meskelu*, Mulugeta Mohammed and Henok Tesfaye

The study was conducted at Wondo Genet Agricultural Research Center, SNNP Region, Ethiopia, 7°05’ N latitude, 38°37’ E longitude and 1785 m.a.s.l for two years (2013/14 to 2014/15) based on the objective to evaluate the response of lemongrass (Cymbopogoncitratus (DC) Stapf) to supplementary irrigation (SI) at different levels and different growth stages. Five levels of SI (100, 75, 50, 25% and no SI) and three supplementary irrigation at growth stages (one SI at mid-season, one SI at maturity and two SI at mid-season and maturity stages) with three replications were used in randomized complete block design. Application of supplementary irrigation to lemongrass had a highly significant (p<0.01) effect on fresh biomass, essential oil content and water use efficiency during the first year. Significant (p<0.05) effect was also observed in dry biomass and essential oil yield. However, no significant (p>0.05) effect was observed on number of tiller per hill. Highly significant (p<0.01) influence was observed on fresh biomass, dry biomass and water use efficiency during the second year. Though essential oil content affected significantly (p<0.05), no significant (p>0.05) variation was observed in essential oil yield due to supplementary irrigation during the second year. Maximum (43.4 and 60.1 t/ha) and minimum (29.7 and 51.1 t/ha) annual fresh biomass production were recorded at 100% ETC SI and rain-fed treatment both years, respectively. Similarly, maximum (9.15 and 13.8 t/ha) and minimum (5.74 and 11.4 t/ha) annual dry biomass production were recorded at 100% ETC SI and rain-fed treatments both years, respectively. Maximum (0.55 and 0.64%) essential oil content was observed at application of two SI at mid-season and late season stage and rainfed treatment during the first and the second year, respectively. Conversely, minimum (0.44 and 0.55%) essential oil content was observed at 100% ETC SI both years. Maximum annual essential oil production of 219.8 and 219.7 kg/ha were recorded at 75% ETC and two SI at mid-season and maturity stage during the first year. Minimum annual essential oil production of 152.2 kg/ha was recorded at rain-fed (no supplemental irrigation) treatment during the first year. The maximum (0.59 and 1.47 kg/mm) and minimum (0.19 and 0.28 kg/mm) water use efficiency was recorded at rain-fed treatment and 100% ETC SI during both years, respectively.