Initial selection steps in olive breeding programs

Abstract

Information on olive breeding is very scarce and particularly concerning selection strategies to obtain new olive cultivars, while for other fruit tree crops different possibilities of resources allocation have been reported regarding the number of selection steps, number of replications and number of characters under evaluation and phenotyping methodologies. In this work, we report the utility of an intermediate step in an olive breeding program in contrast with a previous strategy where the initial selection at the seedling stage was directly followed by the final step in different environments. Correlations between data recorded at seedling and intermediate steps indicate that selection for bearing earliness, fruit size and oil content can be efficiently performed at the seedling stage, whereas evaluation at the intermediate step would be necessary to select for yield and vigor. Similar conclusions were obtained from the analysis of heritability estimated for these characters at the intermediate step of selection. Additionally, genotypes evaluated at this intermediate step showed high variability for characters not previously considered at the seedling step such as pattern of oil accumulation and oil quality parameters as fatty acid composition, tocopherol and sterols content. Therefore, the intermediate step proposed seems an efficient strategy for accurate selection of genotypes for productivity, tree vigor, oil content and quality.

Early selection for oil quality components in olive breeding progenies

“…In most of the cases, this variability (both coefficient of variation and range of variability) was higher in the set of seedlings than in the cultivars used as female parents. Narrower range of values was found for most of the components in a previous evaluation of these quality traits in intermediate breeding selections of the same breeding program . This variability was also higher than the one found for agronomic traits measured on the same set of seedlings .…”

“…Selection process in olive is based on three main steps, i.e., the initial seedling population, an intermediate step of selection, and a final set of comparative trials in different environments . Due to the long juvenile phase and unproductive period of olive, this selection process can take 15–20 years .…”

“…However, little is known about the genetic control of this variability. In fact, there are only few attempts to determine the heritability of the traits under selection, and most of the works are related to fruit traits . But little information on the genetic control of the oil quality traits is available on olive, despite their importance on the selection of new cultivars.…”

Fruit Phenolic Profiling: A New Selection Criterion in Olive Breeding Programs

“…The selection process on the olive breeding program of Cordoba, (Spain) is divided in three steps, seedling stage, intermediate selection and final comparative trials (León et al, 2015 ). In each step, the number of genotypes is reduced and the number of replications per genotype increases (de la Rosa et al, 2016 ).…”

High-Resolution Airborne UAV Imagery to Assess Olive Tree Crown Parameters Using 3D Photo Reconstruction: Application in Breeding Trials

“…It consists of an intermediate breeding trial [35] arranged in a randomize design with four blocks and one tree per elementary plot. Trees were planted at 4 m × 2 m and trained as single trunk open vase at 1-m height to form a discontinuous canopy of scattered trees.…”