The soil must be well drained. Olives are generally shallow-rooted plants. Most olives are cultivated varieties, so seeds from these cultivars will revert to the original variety. That means hardwood cuttings are the preferred method of propagation. Use 2-year-old hardwood shoots taken in winter or semi-ripe cutting taken in spring or summer.
Cuttings usually require four years to begin fruiting. Olives are self-fruitful. Climate and the tendency of olives—like other fruits—to bear more heavily every other year are the likely reasons for a small crop. Young olives will become established more quickly if they receive regular water. Mature olives generally are drought tolerant, but water during flowering and fruit formation will enhance the harvest. Olives are best fed with an annual application of garden compost or well-rotted manure around their trunks.
Avoid nitrogen-rich amendments which boost green growth, not fruit growth. Olives that are regularly pruned will perform the best. Prune out sucker and lower branches to encourage a vase-shaped, open-centered tree. Three to five main scaffold branches work best. Olives produce fruit on 1-year-oild branches so clip out stem tips to encourage the number of fruiting laterals.
Keep olives pruned to a manageable harvest height. Pests and diseases. Olives have few pest and disease problems apart from birds that eat ripe fruit. Keeping trees healthy and pruned will reduce risk of disease and insects. Olives come to harvest in late autumn and winter about six months after flowering. Olives can be harvest green, unripe, or black, ripe. Olives can not be eaten directly from the tree; they contain a bitter alkaloid.
This could indicate that the enzymatic activities of fatty acid desaturation metabolism are influenced by genotype x environment interactions. Correlation studies of olive oils from the warm valleys of NW Argentina suggest that temperature during the oil synthesis period could be the main environmental factor affecting fatty acid composition of VOOs. In this region, negative relationships between oleic acid concentrations at final harvest and seasonal mean temperatures during oil synthesis have been found for the cv.
Arbequina Rondanini et al. These authors found that fruits cv. Across the whole range of temperature explored, the oleic acid concentration decreased linearly 0.
In other words, oleic acid content increased with temperature in the seed, but it decreased in the mesocarp. The increase of oleic acid in the seed of olive fruit is consistent with the response observed in oil-seed crops, such as sunflower and soybean Rondanini et al. Detailed biochemical and molecular research is needed to understand why oleic acid content in the mesocarp decreases with temperature under field conditions.
The response of fatty acid composition to temperature has not been a subject of major concern in the Mediterranean Basin. However, it may become of interest with global warming. At the very least, this issue presents a drawback for commercial olive oil production in areas that already have high temperatures. Similar to Argentina, the wide variations in Australian olive crop environments sometimes result in oils with chemical and sensory attributes being more variable than those observed in oils produced in Mediterranean countries Ayton et al.
Variations in oleic acid content in other olive cultivars grown in Australia are also significant and follow the same tendency, i. The concentrations of the different fatty acids generally fall within the IOOC acceptable limits, but this is not always the case.
Under these mild temperature conditions, the oleic acid content of olive oils from 11 cultivars with different origins was found to be in the range In addition, the reductions in oleic acid appear to be cultivar-specific. This suggests that a genotype x environment interaction is likely important in olive oil quality responses to temperature. Attempts to modify oleic acid content with agricultural practices such as irrigation management have so far been unsuccessful e.
Only very subtle responses to irrigation level have been observed. This suggests that cultivar selection and potentially breeding will be of significant importance in obtaining olive oil with high oleic acid content in warm areas. Increasing global demand for olive oil has expanded olive cultivation to new growing areas in the southern hemisphere. These new crop environments often do not have typical Mediterranean climates, and some of them are in the subtropics where the response of the crop is relatively unknown.
With respect to selecting specific cultivars for new southern hemisphere environments, the cv. Arbequina, which is the most common cultivar worldwide in modern super-high density orchards, has been shown to flower consistently even in warm subtropical regions, but its oil concentration and oleic acid content are often much lower than when grown in the Mediterranean. Other cultivars have also been shown to have positive and negative attributes in these new environments.
Nevertheless, cultivar-specific simulation models are recommended as approximate tools to predict whether individual cultivars will likely flower in proposed new growing areas. Temperature has emerged as a key variable considering the geographic variability found in the southern hemisphere.
A critical aspect of future research may be the response of olive trees to temperature from the biochemical-molecular level to the whole-plant level. It will be important to take into account the considerable genetic variability in olive trees and the apparent genotype x environment interactions that exist for some aspects of olive quality.
Thus, the use of many cultivars in studies would be desirable when practical. Lastly, basic studies are not yet available for many growing regions in the southern hemisphere.
Such information would enhance our overall understanding of olive cultivation, and reduce the necessity to extrapolate from only a few regions. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Responses of several soil and plant indicators to post-harvest regulated deficit irrigation in olive trees and their potential for irrigation scheduling.
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Opposite oleic acid responses to temperature in oils from the seed and mesocarp of the olive fruit. Girona, J. Water function determination. CrossRef Full Text. Goldhamer, D. Irrigation requirements of olive trees and responses to sustained deficit irrigation. Olivae , 23— Effect of varied summer deficit irrigation on components of olive fruit growth and development. Water Manage. Greven, M. The effects of drought on the water use, fruit development and oil yield from young olive trees.
Gucci, R. Environmental stresses and sustainable olive growing. Water deficit induced changes in mesocarp cellular processes and the relationship between mesocarp and endocarp during olive fruit development. Tree Physiol. Hartmann, H. Unripe olives : the olives are still growing at this point. The flesh is very hard and is not suitable for use yet. Green olives : the skin of the olives is green and the fruits are rich in anti-oxidants.
These olives are harvested around late September and early October. Veraison olives : at this stage, the color of the olives is turning from green to purple. The olives are harvested at this point when the aim is to produce an oil with the best possible qualities in terms of aroma and flavor. This is also the ideal stage of ripening for table olives. Fully ripened olives : the skin of the fruit is almost entirely black. Over-ripened olives : at this point, the olives begin to fall off the tree to the ground and are at risk of being attacked by insects and mold.
These olives produce oils of inferior quality, with greater acidity and a less intense flavor. The end product may take on different organoleptic characteristics based on the method chosen. Stripping : the oldest method, whereby the fruit is harvested manually, directly from the tree. It has the advantage of not damaging the olives and avoiding fermentation processes, which can increase the level of acidity in the oil produced.
Abbacchiatura : this is the most widely used traditional method. The olives are made to fall from the trees into netting by hitting the branches with sticks.
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