wide angle photo of small olive trees in the greenhouse on a sunny day

Aristotelis Azariadis is in the midst of an investigation of the effect of salinity and drought stress on four different olive cultivars, aiming to determine whether olive trees can be grown where we think they can’t survive. This is good to know in such places as Crete and North Africa, given a Cretan tradition of watering olive trees with sea water.

Equipped with a master’s degree in Agricultural Science and Biotechnology and finishing a second master’s at the Mediterranean Agronomic Institute of Chania (MAICh) in Crete with a thesis based on this experiment, Azariadis plans to continue for a PhD. He tells me that this experiment may be the first attempt to grow olive trees in pots in a controlled greenhouse environment without soil.

This project is supervised by Dr. Panagiotis Kalaitzis, the Studies/Research Coordinator of the Horticultural Genetics and Biotechnology Department at MAICh. MAICh is part of the International Centre for Advanced Mediterranean Agronomic Studies (CIHEAM). 

Since these olive trees are not growing in real soil, but in an inert substance (half river sand and half perlite), they are not part of a real ecosystem. With nothing to hurt these isolated plants, there is no need for herbicides or pesticides. Ventilation and temperature are controlled. That simplifies the situation in order to focus on drought and salinity, although it obviously differs from a real world experience for the trees. 

Because growing space is limited to 70 trees in the 300 square meter greenhouse at MAICh, four Greek olive varieties were chosen to test: the resilient Lefkolia and Arvanitolia, the more sensitive Gaidourolia (whose name is related to the Greek word for donkey), and the moderately salinity tolerant Koroneiki, which was also chosen for its high quality products and its commercial significance for Greek olive oil production.

For each cultivar, there are some trees in a control group, others in a drought group, and others in a salinity group. The control group is watered normally, the drought group gets too little water, and the salinity group is given water with a high concentration of sodium chloride (NaCl)—a concentration resembling that in the Dead Sea rather than the more moderately salty Mediterranean, where some Cretans get water for their trees.

A follow-up to a smaller experiment, this project started about a year ago, but it took some time to set up. There were problems to resolve, such as the lack of big enough pots for trees in Crete, which led to the use of food storage barrels as planters. Now the trees have been growing in the greenhouse for seven months, and have been treated for a few months. Azariadis expects to continue growing the trees under these conditions for approximately a year.

The plan is to collect leaves and root samples, as well as extracting genetic material, in order to consider potential differences between the control and treatment groups. Azariadis expects the trees to produce olives starting in 2017. He says the fruit will also be part of the study; their morphology (form and structure) and quality will be analyzed. He expects to wait another year for substantial results.

Azariadis adds that a similar experiment on a larger scale in a real-life ecosystem, to see how pests and other real world conditions might complicate the effects of salinity and drought, “would be ideal, but this will depend on the results of this experiment.” He will see if initial results encourage further research in real-world conditions. Watch for updates here later.

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