Abstract
Efficient irrigation scheduling in orchards requires effective tools to understand water status in the soil-plant system. Home-made Arduino-monitored tensiometers (range 0 to -80 kPa), capable of digitally and continuously recording soil water potential (SWP), were used in this study. They were installed in a mature apple orchard (‘Nicoter’ aka ‘Kanzi®’ grafted on ‘M9’ rootstock) at a soil depth of 25 and 10 cm from the drippers. We tested four treatments differing in terms of SWP threshold used to trigger the irrigation (-30 or -60 kPa = regulated deficit irrigation, RDI) and irrigation volumes (1=partial root drying, PRD, 2, and 4 drippers per tree). The tensiometers demonstrated a fast and reliable response to the changes in soil water availability and maintained SWP in the desired range between field capacity (around -16 kPa) and the threshold fixed for each treatment, triggering irrigation accordingly. Tree water status measured by midday stem water potential, yields, fruit growth, and quality did not differ among treatments. Lowering SWP threshold from -30 to -60 kPa using either RDI or PRD (wetting only half of the root apparatus) led to irrigation water saving in the range of 65-70% without affecting tree performances. These findings may encourage farmers to implement such techniques for more efficient irrigation scheduling.