Influence of Geographic Position, Leaf Surface and Genetic Variability on Content of Total Essential Oils in 12 Distinct Populations of Bay Laurel (Laurus nobilis L.)
Summary
Within research project “Taxonomy, Ecology and Utilization of Carob tree (Ceratonia siliqua L.) and Bay Laurel (Laurus nobilis L.) in Croatia” (HRZZ-IP-11-2013-3304), a total of 1200 plant samples were collected from 12 distinct populations of bay laurel in Croatian Adriatic area. After morphometric analyses of leaves, AFLP analyses of genetic variability, and variability of total essential oils content in leaves of bay laurel populations, significant correlation between leaf surface and essential oils content (Spearman’s Rank Order Corr. Coeff. rs = 0.15 ns) was not found, while the correlation between latitude and essential oils content was strongly negative (Spearman’s Rank Order Corr. Coeff. rs = - 0.78; p<0.05). However, the correlation between longitude and essential oils content was strongly positive (Spearman’s Rank Order Corr. Coeff. rs = 0.73; p<0.05). On the other hand, the results of Mantel test showed low, but positive and highly significant correlation between AFLP variability of populations and essential oils content (r = 0.39; p<0.01), while the significant correlation between AFLP variability of populations and leaf lamina surface (i.e. expectedly the most influential factor on accumulation of essential oils) was not obtained. Obtained results of these matrix correlations (i.e. Spearman’s Rank Order Correlations and Mantel test) correspond with the results of Friedman’s ANOVA and Kendall’s Coeff. of Concordance for variability of total essential oils content between the populations (ANOVA Chi Square = 21.88; p = 0.025 and Kendall’s Coeff. of Concordance = 0.99; Aver. rank r = 0.98). According to these results, it is possible to conclude that the populations of bay laurel from locations of south-east Croatian Adriatic islands and coastal area accumulate higher quantity of essential oils in the comparison with the populations of north-west islands and coastal area.
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