Effects of various winter chilling regimes on flowering quality indicatorsof Greek olive cultivars

Abstract

Aims of the present two-year study were to evaluate the feasibility and identify potential drawbacks of the greenhouse/ outdoors parallel plant growth methods for investigation of the effects of various winter chilling regimes on flowering quality indicators of four Greek olive cultivars, namely Mastoidis, Amfissis, and Lefkolia Serron (originating from mountainous and colder areas) compared to cv. Koroneiki (grown mainly in plain warm areas). Groups of potted olive plants were either grown outdoors under ambient temperature or transferred into a greenhouse for one, two, or three months during winter in Crete, Greece. During the first year, chilling accumulation deficit caused a marked decrease in the number of inflorescences per plant in all four olive cultivars. In the second year, chilling accumulation deficit had a negative effect on the number of inflorescences per plant in 'Mastoidis' at 3-month greenhouse treatment but not at all in 'Koroneiki'. Chilling deficit caused an overall decrease in the number of flowers per inflorescence in both 'Koroneiki' and 'Mastoidis' as well as in the percentage of morphologically perfect flowers. The width and length of inflorescences were not affected by chilling deficit in both the cultivars. In vitro pollen germination was reduced in all greenhouse treatments in 'Koroneiki'; however, this effect was significant only after 3 month, whereas no effect was observed in 'Mastoidis'. The results of the present study may contribute to understanding olive flowering biology and selecting appropriate cultivars for new plantations according to historical meteorological data and predicted climate change scenarios.

Climate change implications for olive flowering in Crete, Greece: projections based on historical data

“…This extremely low chill accumulation may not prove adequate for the induction of flowering in Koroneiki or other olive cultivars of similar temperature adaptations. Koroneiki olive cultivar has also been the subject of other research studies in relation to its suitability in projected climate scenarios (Gabaldón-Leal et al 2017;Koubouris et al 2019). In comparison, the present study appears to have a higher value as our analyses are based on field observations up to 31 years, whereas the above two studies consist of experimentation on potted plants, including outdoor and greenhouse treatments for a limited time.…”

“…Olive cultivar genotype and its local adaptation define thermal requisites whereas latitude, longitude, and elevation are among the most important factors that modulate the fulfillment of the thermal requisites of the olive tree (Aguilera et al 2014;Rojo et al 2020), although, so far, tree chill and heat needs generally have not been reliably quantified (Chuine et al 2016;Lorite et al 2020). A number of studies have linked changes in the chilling process with impacts on the quantity and quality of flowering that subsequently may affect olive production (Torres et al 2017;Koubouris et al 2019;Benlloch-González et al 2019).…”

Flowering Behavior of French Olive Cultivar ‘Picholine’ Under Syrian Coast Conditions

“…Olive cultivars differ in chilling requirements between low chilling requirements like 'Koroneiki' and high like 'Sevillano' (Aybar et al, 2015;Malik and Bradford, 2006). Koubouris et al (2019) reported a decrease in the number of flowers/inflorescences in Greek olive cultivars 'Koroneiki' and 'Mastoides' resulted from low chilling, while no effect was found on inflorescence length or width. Any way the threshold used in calculating chilling requirements differed among authors, where some used 7.2°C (Hartmann and Porlinglis, 1957;Zouari et al 2017), while others used 9, 10, 12.5, 15 and/ or 16°C (Alcalá and Barranco, 1992;Haberman et al, 2017;Selak et al, 2018;Koubouris et al, 2019).…”

“…Koubouris et al (2019) reported a decrease in the number of flowers/inflorescences in Greek olive cultivars 'Koroneiki' and 'Mastoides' resulted from low chilling, while no effect was found on inflorescence length or width. Any way the threshold used in calculating chilling requirements differed among authors, where some used 7.2°C (Hartmann and Porlinglis, 1957;Zouari et al 2017), while others used 9, 10, 12.5, 15 and/ or 16°C (Alcalá and Barranco, 1992;Haberman et al, 2017;Selak et al, 2018;Koubouris et al, 2019). Other studies reported different thresholds depending on latitude, so thresholds are lower in olive orchards located at higher latitudes (Aguilera et al, 2014).…”

The Effect of Low Temperature on Physiological, Biochemical and Flowering Functions of Olive Tree in Relation to Genotype

“…Climatic conditions, in general, play a decisive role in tree phenology and adaptation [29]. Temperature during spring is considered to have great effect on olive flower development [30], pollen germination [31], fruit set and development [5] as well as the number of flowers per panicle [32]. In addition, temperature levels as low as 0 • C may cause drastic damages on flower buds and flowers [33].…”