EFFECT OF WATER STRESS AND POTASSIUM HUMATE ON THE PRODUCTIVITY OF ORGANO PLANT USING SALINE AND FRESH WATER IRRIGATION

Abstract

To study the response of oregano (Origanum vulgare L.) plants to soil moisture regimes using fresh and saline water irrigation and potassium humate fertilization, a pot experiment was conducted during two successive seasons (2007/2008 and 2008/2009) under the natural conditions of the greenhouse of the National Research Center, Dokki, Giza, Egypt. Herb fresh weight g plant -1 and the content and yield ml plant -1 of essential oil were decreased significantly by using saline water irrigation compared to fresh water irrigation. Herb fresh weight g plant -1 and essential oil yield ml plant -1 of Origanum vulgare L were significantly decreased with the rise in water stress levels. Whereas, there was significant increase in essential oil % by using lower level of available soil moisture (30% ASM) followed by 90% ASM and then 60% ASM contained the highest values of essential oil %. Fresh herb and essential oil production increased significantly with K-humate application. The maximum of herb fresh and essential oil yields were obtained from plants irrigated with 90% available soil moisture fresh water combined with k-humate fertilizer 1.5 g pot -1 . Essential oil % recorded their maximum value from plants irrigated with 60% ASM fresh water combined with 1.5 g pot -1 K-hum ate. Totally, 20 compounds were identified in essential oils of three populations by means of GLC. Carvacrol was the dominant compound (46.44-77.96%) for all essential oil samples, followed by p-cymene (5.31-19.30%) and γ-terpinene (3.38-16.42%). The composition of essential oil of oregano was affected by soil moisture regimes using fresh and saline water irrigation and potassium humate fertilization.