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Enabling better global research outcomes in soil, plant & environmental monitoring.

Measurement of Water Relations Variables in Almonds

Mike Dixon and Alec Downey, March, 2017.

A trial of field equipment, including stem psychrometers for the measurement of total water potential and instruments to measure rates of sap flow in almond trees, has been underway in Hillston, NSW since July 2015.

Daryl Winter, Farm Manager for Rural Funds Management has been in charge of the trial in collaboration with Alec Downey, Head of Plant Science Applications and Research for ICT International Pty. Ltd.

Mr. Downey and Dr. Dixon travelled to Hillston on March 24-25. 2017 to meet with Mr. Winter and inspect the field site. We also engaged in extensive discussions on both days regarding the application of the data from the instruments and options for additional research in the future.

The activities related to almond harvest were demonstrated. (Figs 1-3) and the research field site was inspected (Figs 4-5). Application protocols were discussed and confirmed.

Upon viewing the historical data sets (see Alec Downey’s report for examples) from the trial it was clear that almonds were remarkably amenable to the application of these techniques. The longevity of installations, especially for psychrometers, is far longer (eg. Months) than most species tested to date (eg. Weeks) which lends itself to long term assessments of irrigation management strategies deployed for this commodity. Initial results have already indicated a variety specific response to irrigation which has implications for the long term variety selection program recently initiated at this farm with over 30 varieties (Fig 6).

Discussions with Mr. Winter confirmed the value of the instruments and data in the development of irrigation management strategies for his crops. He clearly appreciated both the interpretation of the data and the implications for his management of water throughout the season. His goal is to specify water application frequencies and durations for individual varieties as determined by their various physiological responses measured by the psychrometers and sap flow meters. The prospect of optimising water use while not compromising the production and quality of the almonds is clearly in sight.

Dr. Mike Dixon
Professor and Director
Controlled Environment Systems
University of Guelph, Canada

Mr. Alec Downey
Head of Plant Science Applications and Research
ICT International Pty. Ltd.
Armidale, NSW, Australia


Figure 1: Almonds ready for harvest


Figure 2: Almonds recently shaken from trees inspected by Daryl Winter


Figure 3: Almonds laid out in windrows for drying


Figure 4: Field equipment after > 1 year


Figure 5: Inspecting psychrometer installation


Figure 6: Experimental plot with > 30 varieties of almonds