Evaluation of Variability in Tunisian Olea europaea L. Accessions using Morphological Characters and Computational Approaches

The olive trees (Olea europaea L.) have been cultivated for millennia in the Mediterranean basin and its oil has been an important part of human nutrition in the region. In order to distinguish between olive accessions, morphological and biological characters have been widely and commonly used for descriptive purposes and have been used to characterize olive accessions. A comparative study of morphological characters of olive accessions grown in Tunisia was carried out and analyzed using Bayesian Networks (BN) and Principal Components Analysis (PCA). The obtained results showed that averages of fruit and kernel weights were 2.27 grams and 0.41 grams, respectively. Besides, a relatively moderate level of variation (51.22%) being explained by four Principal components. BN revealed that geographical localisation plays a role in the increase of tree habit, size of lenticels and leaf shape. A dendrogram has been carried out in the aim to classify studied olive accessions. We proposed a novel method of analysis based on the three-step scheme, in which first the data set is clustered, then olive tree features are evaluated. The studied accessions can be divided into four main groups by cutting the dendrogram at a similarity value of 0.645. Different relationships are studied and highlighted, and finally the collected features are subjected to a global principal component analysis. Obtained results confirmed that core surface was negatively correlated with geographical location (r = -0.52, p<0.05) and maturation period r = -0.539, p<0.05). Number of lenticels was positively correlated to lenticels size (r = 0.632, p<0.05). Core shape had a negative correlation with fruit shape (r = -0.759, p<0.05). On the basis of these findings, this research confirmed that morphological markers are a preliminary tool to characterize olive oil accessions.

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CHANGES IN FRUIT YIELD AND PHOTOSYNTHESIS PARAMETERS IN DIFFERENT OLIVE CULTIVARS (Olea europaea L.) UNDER CON-TRASTING WATER REGIMES

Acta Scientiarum Polonorum Hortorum Cultus ◽

10.24326/asphc.2020.3.12 ◽

2020 ◽

Vol 19 (3) ◽

pp. 135-147

Author(s):

Majid Golmohammadi ◽

Omid Sofalian ◽

Mehdi Taheri ◽

Alireza Ghanbari ◽

Valiollah Rasoli

Keyword(s):

Drought Stress ◽

Olea Europaea ◽

Principal Component ◽

Fruit Yield ◽

Photosynthetic Parameters ◽

Olive Cultivar ◽

Drought Treatment ◽

Olea Europaea L ◽

Olive Cultivars ◽

Olea Europaéa

The evergreen tree olive (Olea europaea L.) is the only species of the genus Olea that produces edible fruits with high ecological and economic value. This tree species has developed a series of physiochemical mechanisms to tolerate drought stress and grow under adverse climatic environments. One of these mechanisms is photosynthesis activities, so that as yet little information achieved about the relations between olive production and photosynthetic parameters under drought conditions. An experiment was carried out during two consecutive years (2015–2017) to study the response of 20 different olive tree cultivars (Olea europaea L.) to drought stress. Several parameters like net photosynthetic rate (PN), stomatal conductance (GS), transpiration rate (TE), photosynthetic pigments (total chlorophyll, chlorophyll a, b and carotenoid) and fruit yield were measured. The results of combined analysis of variance for fruit yield and other measured traits showed that year, drought treatment, cultivar main effects and their interactions were highly significant. The results indicated that drought stress reduced all traits, however GS (42.80%), PN (37.21%) and TE (37.17%) significantly affected by drought. Lower reduction in photosynthetic performance (PN, GS and TE) in the cultivar T7 compared to other olive cultivars allowed them to maintain better fruit yield. Principal component analysis (PCA) identified two PCs that accounted for 82.04 and 83.27% of the total variation in photosynthetic parameters under optimal and drought stress conditions, respectively. Taken together, mean comparison, relative changes due to drought and biplot analysis revealed that cultivars ‘T7’, ‘Roghani’, ‘Koroneiki’, ‘Korfolia’ and ‘Abou-satl’ displayed better response against drought stress. According to our results, one olive cultivar namely ‘T7’, could be used in olive breeding programs to improve new high yielding cultivars with drought tolerance for use in the drought-prone environments.

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Reliability of Morphological Characters in Identification of Olive (Olea europaea L.) Varieties in Ex-Situ Conditions

Current Research in Agricultural Sciences ◽

10.18488/journal.68.2021.82.56.64 ◽

2021 ◽

Vol 8 (2) ◽

pp. 56-64

Author(s):

Fathi Ben Amar ◽

Hana Souabni ◽

Olfa Saddoud-Debbabi ◽

Mohamed Ali Triki

Keyword(s):

Olea Europaea ◽

Morphological Characters ◽

Ex Situ ◽

Olea Europaea L ◽

Olea Europaéa

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Physiological and biochemical responses of young olive trees (Olea europaea L.) to water stress during flowering

Archives of Biological Sciences ◽

10.2298/abs181001054e ◽

2019 ◽

Vol 71 (1) ◽

pp. 123-132 ◽

Cited By ~ 3

Author(s):

Yamani El ◽

El Sakar ◽

Abdelali Boussakouran ◽

Yahia Rharrabti

Keyword(s):

Olea Europaea ◽

Water Regime ◽

Soluble Sugars ◽

Principal Component ◽

Growing Season ◽

Olea Europaea L ◽

Growing Seasons ◽

Olive Trees ◽

Physiological And Biochemical ◽

Olea Europaéa

This study examines physiological and biochemical changes in three Moroccan varieties of young olive trees (Olea europaea L.) grown under three different water regimes (control, moderate stress and severe stress). Leaf relative water content (RWC), water potential (yw), transpiration rate (E), stomatal conductance (gs), maximum quantum efficiency of PSII (Fv/Fm), the contents of total chlorophyll (TCC), proline (ProC) and soluble sugars (SSC) were measured at the flowering stage during three growing seasons (2015, 2016 and 2017). ANOVA analyses showed that the effect of the water regime was predominant in all of the examined parameters, except for Fv/Fm, which was under the effect of both water regime and growing season. Impacts of variety and interactions were of lesser magnitude. Water deficit reduced E, yw and gs by 25%, while its effect on RWC and Fv/Fm was a decrease of about 7%; however, increases in SSC and ProC were more than 10%. Among the growing seasons, 2015 flowering displayed the lowest values for RWC, yw, E, gs, TCC and Fv/Fm, and the highest for ProC and SSC. Among plant varieties, no significant differences were observed. The three principal component (PC) axes accounted for 91% of total variance. PC1 was better explained by the water regime, while the growing season fitted PC3 variability. Correlation studies highlighted significant associations between most parameters. Positive relationships were found between RWC, yw, E, gs, Fv/Fm and TCC, while all of these parameters were negatively linked to ProC and SSC.

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