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Variation in seed traits among Mediterranean oaks in Tunisia and their ecological significance.
Ann Bot 2020AB

Abstract

BACKGROUND AND AIMS

Oaks are the foundation and dominant tree species of most Mediterranean forests. As climate models predict dramatic changes in the Mediterranean basin, a better understanding of the ecophysiology of seed persistence and germination in oaks could help define their regeneration niches. Tunisian oaks occupy distinct geographical areas, which differ in their rainfall and temperature regimes, and are thus a valuable model to investigate relationships between seed traits and species ecological requirements.

METHODS

Seed morphological traits, desiccation sensitivity level, lethal freezing temperature, embryonic axis and cotyledon sugar and lipid composition, and seed and acorn germination rates at various constant temperatures were measured in Quercus canariensis, Q. coccifera, Q. ilex and Q. suber, using seeds sampled in 22 Tunisian woodlands.

KEY RESULTS

Only faint differences were observed for desiccation sensitivity in the oak species studied. By contrast, the species differed significantly in sensitivity to freezing, germination rates at low temperature and base temperature. Q. ilex and Q. canariensis, which occur at high elevations where frost events are frequent, showed the lowest freezing sensitivity. A significant correlation was found between hexose contents in the embryonic axis and freezing tolerance. Significant interspecific differences in the time for seeds to germinate and the time for the radicle to pierce the pericarp were observed. The ratio of pericarp mass to acorn mass differed significantly among the species and was negatively correlated with the acorn germination rate. Q. coccifera, which is frequent in warm and arid environments, showed the highest acorn germination rate and synchrony.

CONCLUSIONS

Seed lethal temperature, seed germination time at low temperatures, the ratio of pericarp mass to acorn mass, and the embryonic axis hexose content appeared to be key functional traits that may influence the geographical ranges and ecological requirements of Mediterranean oaks in Tunisia.

Authors+Show Affiliations

Laboratoire d'Ecologie Forestière, INRGREF Tunis, Rue Hédi EL Karray El Menzah IV, Ariana, Tunisia. Faculté des Sciences de Bizerte, Université de Carthage, Jarzouna, Tunisia.IRD, Université Montpellier, UMR DIADE, Montpellier, France.IRD, Université Montpellier, UMR DIADE, Montpellier, France.Faculté des Sciences de Bizerte, Université de Carthage, Jarzouna, Tunisia.IRD, Université Montpellier, UMR DIADE, Montpellier, France.IRD, CNRS, Université Montpellier, MIVEGEC, Montpellier, France.Laboratoire d'Ecologie Forestière, INRGREF Tunis, Rue Hédi EL Karray El Menzah IV, Ariana, Tunisia.IRD, Université Montpellier, UMR DIADE, Montpellier, France.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31904087

Citation

Amimi, Nabil, et al. "Variation in Seed Traits Among Mediterranean Oaks in Tunisia and Their Ecological Significance." Annals of Botany, 2020.
Amimi N, Dussert S, Vaissayre V, et al. Variation in seed traits among Mediterranean oaks in Tunisia and their ecological significance. Ann Bot. 2020.
Amimi, N., Dussert, S., Vaissayre, V., Ghouil, H., Doulbeau, S., Costantini, C., ... Joët, T. (2020). Variation in seed traits among Mediterranean oaks in Tunisia and their ecological significance. Annals of Botany, doi:10.1093/aob/mcz211.
Amimi N, et al. Variation in Seed Traits Among Mediterranean Oaks in Tunisia and Their Ecological Significance. Ann Bot. 2020 Jan 6; PubMed PMID: 31904087.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Variation in seed traits among Mediterranean oaks in Tunisia and their ecological significance. AU - Amimi,Nabil, AU - Dussert,Stéphane, AU - Vaissayre,Virginie, AU - Ghouil,Hana, AU - Doulbeau,Sylvie, AU - Costantini,Carlo, AU - Ammari,Youssef, AU - Joët,Thierry, Y1 - 2020/01/06/ PY - 2019/09/20/received PY - 2020/1/7/entrez KW - Quercus canariensis KW - Quercus coccifera KW - Quercus ilex KW - Quercus suber KW - Mediterranean climate KW - desiccation-sensitive seeds KW - drought KW - freezing tolerance KW - germination KW - oak acorn KW - recalcitrant seeds KW - seed functional traits JF - Annals of botany JO - Ann. Bot. N2 - BACKGROUND AND AIMS: Oaks are the foundation and dominant tree species of most Mediterranean forests. As climate models predict dramatic changes in the Mediterranean basin, a better understanding of the ecophysiology of seed persistence and germination in oaks could help define their regeneration niches. Tunisian oaks occupy distinct geographical areas, which differ in their rainfall and temperature regimes, and are thus a valuable model to investigate relationships between seed traits and species ecological requirements. METHODS: Seed morphological traits, desiccation sensitivity level, lethal freezing temperature, embryonic axis and cotyledon sugar and lipid composition, and seed and acorn germination rates at various constant temperatures were measured in Quercus canariensis, Q. coccifera, Q. ilex and Q. suber, using seeds sampled in 22 Tunisian woodlands. KEY RESULTS: Only faint differences were observed for desiccation sensitivity in the oak species studied. By contrast, the species differed significantly in sensitivity to freezing, germination rates at low temperature and base temperature. Q. ilex and Q. canariensis, which occur at high elevations where frost events are frequent, showed the lowest freezing sensitivity. A significant correlation was found between hexose contents in the embryonic axis and freezing tolerance. Significant interspecific differences in the time for seeds to germinate and the time for the radicle to pierce the pericarp were observed. The ratio of pericarp mass to acorn mass differed significantly among the species and was negatively correlated with the acorn germination rate. Q. coccifera, which is frequent in warm and arid environments, showed the highest acorn germination rate and synchrony. CONCLUSIONS: Seed lethal temperature, seed germination time at low temperatures, the ratio of pericarp mass to acorn mass, and the embryonic axis hexose content appeared to be key functional traits that may influence the geographical ranges and ecological requirements of Mediterranean oaks in Tunisia. SN - 1095-8290 UR - https://www.unboundmedicine.com/medline/citation/31904087/Variation_in_seed_traits_among_Mediterranean_oaks_in_Tunisia_and_their_ecological_significance L2 - https://academic.oup.com/aob/article-lookup/doi/10.1093/aob/mcz211 DB - PRIME DP - Unbound Medicine ER -