Investigation of Altitudinal and Longitudinal Variations of Pollen Grains of the Oak Species (The Genus Quercus L.) in Duhok Province Iraq

Abstract

Pollen grains of 3 Iraqian oak (Quercus) species belongmg to section Quercus and section cerris growing naturally in Duhok province Iraq. Three altitudinal zones (500-1000 m, 1000-1500 m, 1500-2000 m) were examined by light microscope (LM) and scanning electron microscope (SEM). The main issue focused on in this study is to determine whether oak pollens have changed dimensionally and structurally according to both different latitudes and longitudes. Based on the averages obtained from seven variables, it has been demonstrated comparative data. The mean value, range (min.-max.), and standard deviation (SD) were calculated for polar axis(P), equatorial diameter (E), polar/equatorial ratio (P/E), apocolpium (AP), mesocolpiuin (ME), colpus length (CL) and exine (wall) thickness (ET). Mean values were assessed by the stattsticnl tests to compare the mean values for each variable. Pollen grains of all species are in monad, isopolar, radially symmetrical, their apertures are mostly tricolpate. Rarely 4-colporate as in Q.brantii and Q.libant, Overall mean polar length of Q.brantii, Q.infectoria subsp. Veneri and Q.libani were 24.34, 24.29, and 27.92 µm respectively. Pollen shape classes range from probate-spheroidal to sub-prolate at varying proportions for the species; Quercus brantii (P/E; 1.07 µm), Quercus infectoria (P/E;1.06 µm) and Quercus libani (P/E; 1.14 µm) According to pollen size classes, pollen grains of Q. brantii and Q. infectoria were 67% minute and 33% mediate, while in Q.libani are 100% mediate. Exine sculpturing pattern is gemmate-verrucate for all taxa