Due to increased occurrence and intensity of agricultural droughts in humid Mediterranean regions, monitored irrigation is becoming an increasingly inevitable element of agricultural practice. To determine the impact of different irrigation regimes on olive tree (Olea europaea L.) growth and crop yield, and of the olive oil production and biophenol content, a 3-year study was conducted in an olive grove located in a relatively humid region of southwestern Slovenia. The mean olive production from trees under full irrigation (replacement of 100% crop evapotranspiration) was significantly higher than those that were only rain fed or were under deficit irrigation (replacement of 33 and 66% crop evapotranspiration). There were no significant differences in total biophenol contents of the olive oil across these irrigation treatments. These irrigation effects can be explained according to the levels of precipitation throughout the growing season. Despite the positive effects of rainfall on these parameters, the mean olive oil yield of the rain-fed olives was about 30% lower than that for the deficit irrigation treatments.
Potatoes are variably sensitive to water deficit. There are several studies in which the influence of controlled deficit irrigation has been studied on potato crop cultivated in arid and semi-arid zones, using drip irrigation. Several factors have been identified as important, namely growth stage, extent of water deficit, nutrient regime and irrigation strategy (such as partial root drying). Depending on the growth stage on which the water deficit was imposed variation in yield quantity and quality was recorded. Irrigated water increased yields not only by increasing tuber number, but also by increasing the mean weight of the tubers. In the presented study, factors influencing potential for deficit irrigation in potatoes crop production in humid climate for Slovenia were evaluated. Feasibility study considered standard potatoes growing practices and tillage as well as irrigation technique availability and know-how.
A review of hop irrigation scheduling in the period 1958?2017 reveals four basic principles to irrigation scheduling of hop that rely on (i) evapotranspiration and water balance, (ii) soil tension or soil moisture across the rooting depth, (iii) measurement of plant stress, and (iv) simulation methods. The methods (iii) and (iv) are more useful as research methods, while method (i) and (ii) are also suitable as a practical tool for irrigation scheduling.
Morphological and physiological traits of olive (Olea europaea L.) contribute to its high drought tolerance. Due to more extreme weather conditions, reduced and irregular precipitation, olives nevertheless frequently experience drought stress. In this paper we present physiological response of ‘Istrska belica’ olive to summer drought in 2015 evaluating the effects of deficit irrigation. Reduced water availability, decrease of water potential, contributed to strong stomatal inhibition of photosynthesis in non-irrigated plants, while this inhibition was much smaller in fully irrigated plants. Results suggest, that a substantial mitigation of water stress and shortening of its duration can be achieved by deficit irrigation.
Deficit irrigation technology was developed in the areas, where availability and the cost of water forced producers towards rational use of water. The principle of deficit irrigation is effecting plant fertility and yield potential by adding smaller amount of water than optimal, thus putting less pressure on natural resources. This technology is currently successfully tested in orchards on coastal karstic region in Slovenia. The paper addresses major challenges and possibilities for deficit irrigation in crop and vegetable production in Slovenia.