Assessment of Myrtus communis L. water status and water requirements

Myrtle (Myrtus communis L.) is a naturally occurring, highly drought-tolerant, evergreen shrub or small tree that is widely distributed within the Mediterranean basin. It is classified as an aromatic species because of the essential oil compounds of the leaves and fruits. Myrtle is commercially used for liquor production and perfume, and the harvest comes mainly from wild plants. Currently, there is insufficient wild-plant production to meet the demand for myrtle leaves and berries which has led to increasing interest to cultivate the plants to increase production. To assess the water requirements and water use efficiency, research was conducted on the ecophysiological responses of commercially grown myrtle plants to different soil-moisture conditions using stem water potential measurements. Data were collected in an eight-year-old myrtle orchard located near Alghero (Italy) during two consecutive summers. Plants showed higher values of net photosynthesis and water use efficiency under moderate stress than in well watered conditions. Severe stress symptoms appeared only with low soil moisture content. These results showed that optimal myrtle production will likely occur using regulated deficit irrigation. Crop evapotranspiration was determined using the surface renewal method, and the crop coefficient (K-c, relative to short-canopy standardized reference evapotranspiration (ETo) ranged between 0.7 and 1.2.