Evaluación agronómica de genotipos seleccionados en un programa de mejora genética de olivo

Olive growing techniques have changed considerably in the last decades, which have promoted the development of breeding and selection programs in order to obtain new cultivars able to face the new challenges. In this work, different trials including selections obtained in the cooperative olive breeding program carried out by the Institute of Agricultural and Fishery Research and Training (IFAPA) and the University of Cordoba, Spain, have been evaluated. Particularly, two trials corresponding to two possible breeding schemes were evaluated: a comparative trial with 10 selections and an intermediate trial with 77 selections (including those of the previous trial). The general aim was to complete the agronomic evaluation of these trials in order to select the most interesting genotypes for future stages of breeding selection. Moreover, the intention was also to compare the efficiency of the two alternative breeding schemes. The genotypes evaluated were initially selected in progenies from crosses and open pollination carried out in 1998/99. The evaluation included different traits of selection (earliness of bearing, fruit weight, oil content, vigour, fruit removal force, fatty acid composition, etc.) on four different dates (September, October, November and December). A high degree of variability and significant differences between genotypes were obtained for all the fruit characteristics analyzed. Moreover, some of the selections tested showed better or similar values than the genitors used as controls for these characters. On the other hand, a high correlation was obtained between the data for the characteristics evaluated at different sampling dates, which indicates that data obtained on a common date may be sufficient for the selection of genotypes according to their level of maturity and, therefore, to significantly simplify the evaluation process. The determination of the optimal harvesting date based on the evaluated characteristics has shown that this date is independent of ripeness index measured by fruit colour. The results obtained allow to identify the selections UC-I 36-41, UC-I 36-43 AND UC-I 42-48 as the most potentially interesting to become new cultivar with good productivity characteristics. However, intermediate trial results allowed to select a higher number of potentially interesting genotypes not previously identified in the initial population of seedlings and therefore discarded for a pre-selection trial. This indicates the importance of the intermediate trial here proposed in order to increase the efficiency of the breeding programs.