Olive Bud Dormancy Release Dynamics and Validation of Using Cuttings to Determine Chilling Requirement

Abstract

Dormancy release dynamics in olive tree (Olea europaea L.) reproductive buds as affected by cold accumulation, tree bearing status, and budburst temperature was studied under natural and controlled conditions, using both cuttings and container- and field-grown plants. The chilling necessary for dormancy release was acquired at different times within the bud population, presenting a progressive pattern of reproductive budburst. Once sufficient chilling is accumulated, 20 °C is a suitable temperature for reproductive budburst, although higher temperature, e.g., 30 °C, during dormancy release can inhibit budburst. While the bearing status of trees determined the amount of return bloom, dormancy release followed a similar pattern for previously bearing and non-bearing trees. Concurrent with investigating budburst factors, the use of shoot cuttings was tested as a method for olive dormancy release studies by contrasting with results from whole trees. It was found it to be valid for studying reproductive budburst, thus providing a useful method to screen chilling requirements in cultivar evaluation and the breeding programs currently ongoing in this species. However, the method was not valid for vegetative budburst, with varying results between cuttings and the whole plant.

Flowering Phenology of Olive Cultivars in Two Climate Zones with Contrasting Temperatures (Subtropical and Mediterranean)

“…Flowering was observed in all of Tenerife's environments and in all the cultivars tested. This happened despite the fact that the optimal chilling accumulation temperature previously established at 7-12 • C for olive crops [23][24][25] was rarely reached in winter in all three of Tenerife's environments.…”

“…In the only previous report of cultivar evaluation for FP in multiple Mediterranean environments, no significant differences among cultivars were observed [14]. Growth chamber experiments at constant temperatures have been also proposed to test the winter chilling needs of olive cultivars [25,30]. In those works, whenever not enough chilling was accumulated, flower bud burst was not observed.…”

Estimating Freezing Injury on Olive Trees: A Comparative Study of Computing Models Based on Electrolyte Leakage and Tetrazolium Tests

“…Furthermore, the values of these coefficients also differed across the three stages of dormancy (i.e., pre-, deep, and post-dormancy) within each olive cultivar. These differences can be attributed to variations in the response of different olive cultivars to freezing injury during each stage of dormancy [30]. To gain a deeper understanding of this issue, we conducted a sensitivity analysis of the TZ model's predictions for sub-zero temperatures by examining the impact of changes in the b 1 and b 2 regression coefficients.…”