Articles
Pollen performance under heat temperatures in a promising olive clone (‘Leccino’)
Article number
1446_32
Pages
135 – 242
Language
English
Abstract
During the progamic phase of olive trees, unsuitable weather conditions may produce aberrations on anthesis and pollination processes.
In particular, the functionality of pollen grains, as well as being influenced by genetic factors, may be affected by abiotic factors such as heat waves, a worrying condition due to ongoing climate change.
In previous research work, floral quality parameters have been analysed in several ‘Leccino’ clones and notable performance of pollen grains has been observed for the clone L 1.4 under sub-optimal microclimatic conditions at the canopy level.
Considering these interesting preliminary results, new experimental trials were planned in order to evaluate a possible pollen ability to face heat stress around anthesis.
The study was conducted on potted olive trees that were subjected to the high temperature (HT) of 35°C (±0.5), according to daily cycles set up in growth chambers.
Germination ability and pollen tube growth, as a result of active self-and cross-pollinations, were assessed by in vivo fluorescent microscope observations, in comparison with control conditions (temperature regimes in open air). Moreover, the HT influence on pollen viability and germination power was determined by in vitro tests on an agar medium.
After 24-48 h at HT incubation, germination power of pollen grains was significantly reduced by about 40 and 50%, respectively, in comparison to control conditions.
The in vivo observations, after self- and cross-pollination, showed a regular growth of pollen tubes through the style up to ovary, in control pistils.
Although a tube elongation slowdown was observed, the HT cycles did not hinder the pollen tubes growth.
A good rate of pistils which did not evidence a stunting of pollen tube growth suggests L 1.4 as potentially suitable for target-oriented new olive plantations to face the current climate change.
In particular, the functionality of pollen grains, as well as being influenced by genetic factors, may be affected by abiotic factors such as heat waves, a worrying condition due to ongoing climate change.
In previous research work, floral quality parameters have been analysed in several ‘Leccino’ clones and notable performance of pollen grains has been observed for the clone L 1.4 under sub-optimal microclimatic conditions at the canopy level.
Considering these interesting preliminary results, new experimental trials were planned in order to evaluate a possible pollen ability to face heat stress around anthesis.
The study was conducted on potted olive trees that were subjected to the high temperature (HT) of 35°C (±0.5), according to daily cycles set up in growth chambers.
Germination ability and pollen tube growth, as a result of active self-and cross-pollinations, were assessed by in vivo fluorescent microscope observations, in comparison with control conditions (temperature regimes in open air). Moreover, the HT influence on pollen viability and germination power was determined by in vitro tests on an agar medium.
After 24-48 h at HT incubation, germination power of pollen grains was significantly reduced by about 40 and 50%, respectively, in comparison to control conditions.
The in vivo observations, after self- and cross-pollination, showed a regular growth of pollen tubes through the style up to ovary, in control pistils.
Although a tube elongation slowdown was observed, the HT cycles did not hinder the pollen tubes growth.
A good rate of pistils which did not evidence a stunting of pollen tube growth suggests L 1.4 as potentially suitable for target-oriented new olive plantations to face the current climate change.
Publication
Authors
S. Bartolini, L. Pappalettere
Keywords
Olea europaea L., viability, germination, tube growth, progamic phase, abiotic stress
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