Evaluation of vegetative growth traits and their relation to time to first flowering of olive seedlings

The aim of this work was to assess growth traits during the initial developmental stages of olive seedlings, which could be correlated to time to first flowering, facilitating fast selection in olive breeding programs. The experimental material consisted of 232 olive seedlings derived from controlled crosses of ʹKalamonʹ with self (KA × KA), with ʹAmphissisʹ (KA × AM), and with ʹKoroneikiʹ (KA × KO) and from open pollination of ʹKalamonʹ, ʹAmphissisʹ, ʹKoroneikiʹ, ʹChalkidikisʹ, and ʹManzanilloʹ. Vegetative traits of the seedlings, including canopy height and diameter, length of lateral vegetation, number of leaves, mean and total leaf area per plant, leaf shape characteristics, and specific leaf area (SLA), were recorded until 15 months after sowing. The first seedlings to initiate flowers, 4 years after sowing, were also recorded. The existence of correlations between the above growth traits and time to first flowering was investigated. In singlebranched seedlings 6 months after sowing, height measured at this stage was significantly correlated with the mean and total leaf area per plant, specific leaf area, and other vegetative traits measured 15 months after sowing. Seedlings with high values of these parameters were the first to initiate flowers 33 months later. Our results indicated that preselection of olive seedlings for earliness of first flowering is possible, based on vegetative characteristics assessed very early in their development.