WHAT LIMITS AND HOW TO IMPROVE WATER USE EFFICIENCY IN OUTDOOR CONTAINER CULTIVATION OF ORNAMENTAL NURSERY STOCKS

Abstract

Around the town of Pistoia (Tuscany, Italy) there is the most important centre in Europe for the cultivation of landscaping ornamentals, which typically require plenty of nutrients and water. Unfortunately, in these crops water use efficiency (WUE) is low as a consequence of over-irrigation, also due to the practice to place different plant species in the same cultivation plot, which results in the tendency to regulate irrigation on the basis of the most water demanding crop. This paper discusses how to improve WUE in outdoor container crops on the basis of an experiment conducted by simulating the cultivation of different ornamental species (Forsythia intermedia, Photinia × fraseri, Prunus laurocerasus and Viburnum tinus) in the same irrigation plot with the objective of: i) estimating the intra- and inter-specific variability in crop evapotranspiration (ET); ii) assessing water use and runoff in plot with irrigation controlled by a tensiometer placed in a reference plant (Prunus); iii) developing a simple model for ET based on plant height and reference ET. The main conclusion is that, compared to the traditional timer-based irrigation scheduling, substrate moisture sensor (SMS) can improve WUE of container crops even in nurseries characterized by a large inter-pot variability in ET as a consequence of the accustomed practice to place different crops in the same irrigation sectors. Due to the high number of irrigation plots in commercial nurseries, plenty of sensors must be installed and therefore it is crucial to design a cheap and low-maintenance SMS and a user-friendly irrigation control system based on a network of wireless sensors.