In this section

4.1.1. Fatty Acids

4.1.2. Phenols

4.1.3. Volatiles

Temperature plays multiple roles in the survival, vegetative growth, flowering and fruit production of olive trees. Before establishing a new plantation, we should study the meteorological history of the area to ensure that there is no frequent temperature drop below 0ºC. This condition will minimise the risk of frost damage to our plants and fruit. An upper temperature limit that we should consider when selecting the planting site would be roughly 40ºC. An area with frequent incidents of higher temperature would make an olive plantation prone to several problems. 

Olive trees need a certain amount of mildly low temperature hours during winter to induce bud dormancy break and produce satisfactory flowering in the subsequent spring. The effective temperature range is 5-12ºC and the number of these chilling hours varies among olive varieties and should be checked for the specific one we intend to plant. In general, olive varieties grown in cold climates and known for their cold tolerance require a greater accumulation of chilling for decent flowering. On the other hand, varieties grown in hot environments have minimal chilling needs and can have a satisfactory flowering even after very mild winters. For example, Koroneiki and Arbequina have low chilling requirements and can produce decent flowering even in warm winter areas. Similarly, the olive varieties originating from North African countries and the Middle East are considered to have low chilling requirements. 

Olive trees are well-suited to warm Mediterranean climates but are susceptible to low temperatures, especially when they occur unexpectedly and out of season, potentially causing irreversible damage. Cold stress is a natural factor that restricts the growth, productivity and survival of plants, and determines their geographic distribution. Low temperatures inhibit plant growth while freezing temperatures below 0°C damage cell membranes and lead to cell death. Plants from regions with a natural habitat for cold acclimation can adapt fully, whereas those from warmer climates often struggle to withstand winter due to inadequate cold acclimation. The genetic diversity of plants is essential for global sustainability as it provides the foundation for adapting to climate change and promoting sustainable development, benefiting human populations in numerous ways.

In the context of climate change, simulation models have projected a steady rise in global average temperatures, accompanied by irregular and short-period cold spells. For instance, frost events in 2008, 2014 and 2016, over periods of up to three days, caused extensive damage to olive trees in northern parts of Iran, resulting in significant economic losses for the olive industry. Generally, frost events are highly unpredictable in terms of frequency and timing, occurring unexpectedly in late autumn or mid-winter. Symptoms of frost damage vary depending on factors such as canopy temperature, frost duration, olive tree variety, age, acclimatisation, previous crop load, water status of the soil, and plant and agricultural practices, including irrigation and pruning.

1 Estación Experimental Agropecuaria San Juan, Instituto Nacional de Tecnología Agropecuaria (INTA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Juan, Argentina. 2 Ingeniería Agronómica, Facultad de Ingeniería, Universidad Nacional de San Juan. 3 Instituto Multidisciplinario de Biología Vegetal (IMBIV), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad Nacional de Córdoba (UNC), Córdoba, Argentina.

The production potential of olive trees is determined by numerous genetically based characteristics, such as chilling requirements, pollen-pistil incompatibility, ovary abortion and fruit size, among others. The expression of these characteristics is significantly influenced by external factors, such as site location and year of cultivation, planting density and orchard management practices (irrigation, fertilisation, pruning, diseases and pests, etc.). Thus, the productive efficiency of an olive orchard depends on the interaction between the cultivar and these environmental and management factors. Consequently, the range of the olive’s productive potential is very broad, with average yields ranging between 2,000 and 20,000 kg ha⁻¹, depending on the selected cultivar, the site and climatic conditions, age, orchard design and management practices.

When determining the productive potential of varieties, several indices are considered (León et al., 2007): 

Mariela Torres: Estación Experimental Agropecuaria San Juan, Instituto Nacional de Tecnología Agropecuaria (INTA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Juan, Argentina. Pierluigi Pierantozzi, Mariela Torres: Ingeniería Agronómica, Facultad de Ingeniería, Universidad Nacional de San Juan. Damián Maestri: Instituto Multidisciplinario de Biología Vegetal (IMBIV), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad Nacional de Córdoba (UNC), Córdoba, Argentina.

One of the first questions asked by people who want to establish an olive grove is: how much olive oil can I get from my trees? There is no simple answer to this question as many factors interact and affect oil yield. Another common question is: how many olives are needed to produce one litre of olive oil? This depends on the fruit oil content of the particular olive variety -there are hundreds of them with different oil synthesis capacities. In some varieties, oil accumulation in the fruit is low (these are usually intended for table olive production). By contrast, other varieties accumulate high percentages of oil. Most olive varieties have intermediate oil contents (Figure 1).

Although the maximum amount of oil that an olive variety can produce is genetically determined, it may be influenced by several factors. These can be grouped into five dimensions which also have sub-components: 1) Olive cultivars; 2) Growing environments; 3) Climate and weather; 4) Agronomic management; 5) Orchard design (Figure 2).