The aim of this work was to evaluate the effect of different irrigation depths on biomass production, yield and composition of lemongrass (Cymbopogon citratus)essential oil, because of poor information on cultivation practices. The experiment was set up in a protected environment to control irrigation and also to evaluate situations in which the normal climatic conditions are inadequate. A complete randomized block design was incorporated with five treatments and three replications, and averages were compared using the Tukey's test at 5% probability. In phase one, the treatments consisted of irrigation depths relating to 50%, 75%, 100%, 125% of crop evapotranspiration (ETc), irrigating twice a week, and irrigating only once a week for a sample supplied with 100% of the crop evapotranspiration (ETc); these were labeled T1, T2, T3, T4 and T5, respectively. In phase two, the treatments consisted of depths of 50%, 75%, 100%, 125% of the ETc, irrigating once a week, and another with 100% of the ETc, irrigating every 14 days, which were denominated T6, T7, T8, T9 and T10, respectively. Harvest of the lemon grass was done after 60 days of treatment. Plant height, number of tillers per plant, dry mass of the shoots, yield and composition of essential oil were evaluated. Treatment T5, characterized by water stress and a moderate irrigation interval, presented the highest dry matter production, lemongrass productivity, estimate of essential oil productivity and concentration of citral in the first phase. In phase two of this work, T6,characterized by a sharp increaseof water stress, presented the greatest estimate of essential oil productivity. According to the results observed, we could not define an optimal irrigation depth; however, we concluded that a single irrigation per week for the conditions of this experiment provided the best result.
lemongrass; irrigation; essential oil
