Morpho-physiological parameters of Cedrus atlantica Manetti pollen discriminate genetically distinct populations of climatically different regions in the Moroccan Atlas

In North Africa’s forests of Cedrus atlantica many tree stands perished in the last 130 years due to environmental changes. Variations in some morpho-physiological characters of cedar pollens were studied in three populations localized in Azrou and Midelt regions of  Moroccan Atlas having different local environmental conditions and levels of genetic diversity. Results of Spearman nonparametric coefficient of correlation showed significant correlations ( -0.726 ≤ r ≤ 0.812) (p < 0.01). Corpus length (Lc) and volume (Vc), balloon volume (Vb) and the volume total of pollen (Vtp) were negatively related to annual mean precipitation (P) and positively to longitude (Long) and altitude (Alt). Lc and Vc were also negatively correlated with latitude (Lat) while positively with annual mean temperature (T) for Vc. Balloon height (Hb), number of germinated pollen (NGP) and germination frequency of pollen (GFP) were positively linked to Alt. Pollen starch content (Starch) was negatively correlated to T and Long and positively to P and Lat. Production of pollen (NTP) was positively correlated with P and negatively with Long and Alt. The PCA analysis showed that Lc, Vc, Lg, Hb, Vb, Vtp, NGP, GFP, NTP were influenced by climatic conditions and geographic location. The ascending hierarchical classification showed that  populations of Ait Oufella and Ait Ayach are separated from the Seheb population. Tukey’s test showed that at least five morpho-physiological characters separated significantly the populations. The structuration of morphological traits of Atlas cedar pollen of the populations was discussed in relation to physiological traits and local environmental conditions.