Résumé -On a étudié l'effet du stress hydrique osmotique sur la germination des graines chez les provenances de Cèdre du Liban. En utilisant le polyéthylène glycol (PEG-6000) pour préparer les niveaux différents de stress hydrique osmotique suivant les traitements envisagés (0, -2, -4, -6 bars) on a procédé à la comparaison expérimentale des facultés germinatives et des temps moyens de germination des graines de dix provenances. Les résultats essentiels obtenus sont les suivants : d'une façon générale, on n'a pas déter-miné de différences importantes entre les provenances correspondant au temps moyen de germination. Le taux de germination moyen pour toutes les provenances diminue de 48 % à -2 bars, de 61 % à -4 bars, et de 75 % à -6 bars par rapport au traitement témoin (0 bars). Des différences très nettes entre les provenances étudiées du point de vue des taux de germination relatif dans les niveaux différents de stress hydrique osmotique ont été mises en évidence. Bien que les données climatiques manquent, il y a des relations entre les facultés à germer des provenances étudiées face aux stress hydriques du substrat et les conditions écologiques de leurs milieux naturels. Il semble que ces différences entre les provenances procèdent de variations intraspécifiques produites sous les effets des sélections naturelles.Cèdre du liban / provenance / germination / stress hydrique / polyéthylène glycol Abstract -Effect of osmotic water stress on germination of Lebanon Cedar (Cedrus libani A. Rich.) seeds from the provenances of Turkey. Seeds from ten provenances of Cedrus libani were subjected to germination test on filter paper saturated with polyethylene glycol (PEG 6000) solutions made up to provide osmotic potentials of 0, -2, -4 and -6 bars. Mean germination percent for all provenances decreased about 48% in -2 bars, 61% in -4 bars and 75% in -6 bars treatments compared to control (0 bar) treatment. There were significant differences among the relative germination percent of the provenances in different treatments. In spite of climatic data, strong correlations were found between germination capabilities under different stress levels and the ecological conditions in the natural habitats of the provenances. Differences between the germination capabilities of the provenances under different stress conditions were interpreted as an intraspesific heritable variation constituted by natural selection.Lebanon cedar / provenance / germination / water stress / polyethylene glycol

Background Stone pine (Pinus pinea L.) is harvested for its edible kernels. It is an important forest tree species, and also plays an important role in afforestation. Successful afforestation activities strongly depend on the quality of seeds and seedlings. Five eastern native populations of stone pine were analyzed, in terms of their geographical and climatic parameters, in order to identify their cone, seed, pine nut, and seedling traits. With this regard, we aimed to contribute to the reforestation, yield, and breeding of this species. Results All native populations occur in the sub-humid bioclimatic zone, according to Emberger’s bioclimatic classification, ranging 74.7–63.2 of Emberger’s Q Index value (Q), which synthesizes humidity and temperature, with lower values indicating more arid conditions. With regard to geographical factors, altitude was found to have the greatest effect on cone diameter and seed weight, while there was a weak correlation of cone, seed, and pine nut dimension with longitude and latitude. In terms of climatic factors, Q and mean of the maximum temperature of June, July, and August (ME) were found to be the main drivers behind significant effects in cone, seed, and pine nut morphometric traits. The most negative effect on seed number cone−1 (r: − 0.897), pine nut number cone−1 (r: − 0.923), pine nut yield (r: − 0.903), and pine nut weight (r: − 0.878) was Q, whereas cone diameter, seed length, and seed weight were positively correlated with the ME (r: 0.939, r: 0.889, and r: 0.866, respectively). Cone and seed diameter and seed weight increased with decreasing summer drought index (r: − 0.806, r: − 0.846, and r: − 0.866, respectively). Rainfall in the June of the third year prior to harvest time (RJ) had a negative effect on the percentage of sound seeds per cone. Annual rainfall in the third year prior to harvest time (AR) significantly affected pine nut weight (r: 0.889), although rainfall during summer had a negative effect. The empty seed ratio of the different populations ranged from 20 to 68%, while considering all populations, the empty seed ratio was 46%. Conclusions The study suggests that the Q Index and ME should be taken into account to determine cone to pine nut yield. With this regard, plantations of stone pine should be established on sub-humid areas and Q values should not exceed 75.

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