Table 1 presents aggregate measurements from the harvest of the 2018–2022 vintages for the experimental vineyard at Omala.

Table 1. Harvest measurements from 480 experimental vines from the Omala vineyard.

According to Table 1, after repeated fertilizer applications, grape yield rose substantially in 2022. Still, the per hectare yield remained low compared to what is customary for the viticultural zone. The vines were nutritionally deficient to begin with, due to a lack of funding during the critical years 2014–2017. Nevertheless, grape quality seems excellent, which results in the harvest of the entire vineyard being vinified as Thymari Petras, a limited edition of approximately 1200 bottles produced by the Petrakopoulos winery. The wine retails for around €45 per bottle.

As far as the Robola experimental vineyard in the Omala region, the main findings are:

• In terms of ampelographic descriptors, it seems that the four Robola biotypes V₁–V₄are more similar to each other than to the typical Robola preserved at the national germplasm collection in Athens. We recommend further analysis of their genetic affinity with molecular methods.
• The highest yielding combinations of rootstock and scion are 1103P-V₂, 1103P-V₁ and R110-V₁. Biotype V₁ seems indifferent to rootstock as it performed similarly on both 1103P and R110 rootstocks.
• Ongoing research at our lab examines more ampelographic descriptors related to mature leaf and berry characteristics.

As far as the experimental vineyard at the Ionian University in Argostoli, the main findings are:

• After 10 years of No till treatment, several soil properties improved—albeit marginally—relative to the Till or “conventional” treatment. Specifically, in the No till treatment, organic matter is marginally higher for both soil depths examined.
• The No till treatment holds an advantage as far as nutrients: Exchangeable potassium, plant available phosphorus, and total nitrogen. This advantage is consistent for both depths examined.
• The No till treatment holds an advantage as far as microbial biomass nitrogen and phosphorus in the surface layer.
• The activities of enzymes β-glucosidase and L-asparaginase are higher in the surface layer of the Till treatment, possibly due to the incorporation of fresh organic residue.

The detailed results from both experimental vineyards were presented at the 2022 meeting of the Soil Science Society of America and the American Society of Agronomy:

Katsalirou, E., A. Gerakis, and V. A. Groubos. 2022. Evaluating combinations of biotypes of Robola grape on different rootstocks. [Online]. In 2022 Agronomy abstracts. ASA, Madison, WI. Available at https://scisoc.confex.com/data/handout/crops/2022am/Paper_144398_handout_6747_0.pdf (accessed 3 Jul. 2024).

Katsalirou, E. and A. Gerakis. 2022. Ten years of no till result in unimpressive advantage over till in a vineyard soil. [Online]. In 2022 Agronomy abstracts. ASA, Madison, WI. Available at https://scisoc.confex.com/data/handout/crops/2022am/Paper_144397_handout_6759_0.pdf (accessed 3 Jul. 2024).