Female genitor effect on the juvenile period of olive seedlings

Abstract

Shortening the juvenile period (JP) is one of the main strategies to increase the efficiency of olive breeding programs due to the long generation time of this species. Seedling vigor has been reported to be negatively associated to the length of the JP. In the present work we analyzed the influence of the female genitor on the length of the JP of olive seedlings, their vigor (plant height and trunk diameter), and the relationship between seedling vigor and JP using 3650 seedlings from 10 female genitors evaluated over 14 years. Overall, the length of the JP significantly varied for the female genitor and year of germination. Female genitors evaluated were classified into three groups according to the length of the JP of their progeny, as follows: short (‘Arbequina’ and ‘UCI 7-34’); medium (‘Lechín de Sevilla’, ‘Manzanilla de Sevilla’, ‘Picual’, ‘UCI 11-28’ and ‘Zaity’); and long JP (‘Frantoio’, ‘Memecik’ and ‘UCI 10-30’). Vigor, measured as the height of the seedling at planting, was significantly correlated (P<0.001) with the length of the JP for all progenies except for those of ‘Lechín de Sevilla’, ‘Memecik’ and ‘UCI 10-30’ because most of their seedlings did not flower during the studied period. The highest proportion of flowering plants was obtained when the height of the plants was from 126 to 150cm at planting. In addition, flowering, measured as presence or absence of flowers, was significantly related to the plant height according to a logistic regression. Nevertheless, for each female genitor, the inflection point of the curve (height at which 50% of the seedlings flowered) presented different values, suggesting that height selection thresholds should be specific for each female genitor.