Pedro Valverde. Marche Politecnic University/UCO

The evolution of agriculture has been a continuous process throughout human history, marked by domestication and in recent centuries by significant advances in plant breeding. From early nomadic cultivation to sophisticated modern farming techniques, agriculture has undergone a radical transformation to feed an ever-growing population. However, it was not until more recent times that plant breeding began to be applied in order to obtain varieties that were resistant to pests and diseases, productive and without forgetting the nutritional value and quality of the product.

In crops such as wheat and rice, breeding through directed crosses can be considered to have started in the mid-19th century. Since then, the development of varieties has been carried out continuously due to its great importance as a crop for feeding the population and its status as an annual crop, which facilitates the breeding process. In the case of woody crops, crops such as almonds or peaches, in which genetic improvement began at the beginning of the 20th century and over the years began to be carried out in different countries, resulting in the development of a multitude of new varieties. On the other hand, we also find crops such as the olive tree, in which only 5 varieties had been registered 10 years ago.

In the olive tree, a very rustic crop with many varieties perfectly adapted to different areas, it was not until 1960 that the first steps were taken in genetic improvement in Italy and Israel, and subsequently improvement programmes were started in other countries such as Spain. These breeding programmes consist of carrying out the work that man has carried out for thousands of years in a reduced time by applying knowledge and using advanced tools. At the beginning, the objectives of genetic improvement were mainly the development of more productive varieties adapted to vase training. In the 1990s, the hedgerow cultivation system began to be developed, a system which in the first 15 years was questioned due to the radical change in the formation of the trees and the type of cultivation system, but which in the last 10 years has been consolidated to the point that today the majority of olive plantations are planted using this system in which the individual tree is no longer the productive unit but the linear metre of hedgerow. This system has its advantages, such as the reduced need for labour due to greater mechanisation and the high quality of the oils due to the speed of harvesting and the possibility of rapid transport of the fruit to the oil mill, and its disadvantages, such as the higher cost of implementation and the impossibility of harvesting in plantations with steep slopes. Another point to be taken into account and which is setting the direction of improvement programmes is the need to use less vigorous varieties which can be harvested with harvesters. Until a few years ago, and due to the fact that for thousands of years farmers have traditionally selected vigorous varieties with a high production capacity, only two traditional varieties were perfectly adapted to this harvesting system, 'Arbequina' and 'Arbosana'. Nowadays, these varieties occupy more than 80% of the world's hedgerow olive grove area, a sufficiently important reason to incorporate the development of new varieties with low vigour in the improvement programmes. As a result of this cultivation system and the need for new varieties, since 2008 some varieties have already been registered, such as 'Sikitita', 'Lecciana', 'i-15', 'Sikitita 2', 'Oliana', 'Sultana', etc. However, these new varieties must not only meet the requirement of low vigour, but they must also be early to enter into production, highly productive and with high quality oils. On the other hand, the olive tree improvement programmes that are being developed also seek to develop new varieties resistant to diseases such as Verticillium dahliae and Xylella fastidiosa. In addition, the search for new varieties with a certain tolerance to abiotic stresses such as frost or cold damage and low water requirements are being studied and will bear fruit in the coming years.

However, due to the importance of the quality of EVOOs, all these agronomic characteristics will not be of particular interest if the oils do not meet quality requirements. In this sense, the increase in polyphenols, oleic acid and other quality parameters will be differentiating characteristics of the new varieties. In particular, another point of special interest in the new oils is high stability, a characteristic that very few traditional varieties have in a very high degree, but which will be a differentiating point in the new varieties. Of course, the combination of several of these characteristics in the same variety is not an easy task and will require many years of effort and evaluations in different environments to characterise the behaviour of the varieties in order to be able to offer the farmer the best profitability for his farm and the consumer the best AOVES.