Some characters of the pollen of spring and summer flowering common oak (Quercus robur L.)

Branislava Batos,Danijela Miljkovic,M Bobinac

doi:10.2298/abs1201085b

Branislava Batos, Danijela Miljkovic + Show 1 more

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https://doi.org/10.2298/abs1201085b

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Abstract

Summer flowering of the common oak is a natural rarity, considering the large area of the species natural distribution. This phenomenon can be classified as an ancestral (atavistic) property. Pollen morphological and physiological characters from spring flowering male inflorescences collected over the period 2004 - 2007 and summer flowering male inflorescences collected in 1999 were compared. The analysis included the pollen of a tree with frequent summer flowering and a control tree with spring flowering only. The size and form of summer pollen differed from the spring flowering pollen. The germination percentage and germination energy depended on the pollen growing medium (0, 5, 10, 15, 20, 25% sucrose solution), year of collection (2004 - 2007), temperature (+5?C and -20?C) and storage period (1 to 24 months). The study results are significant for the explanation of common oak phylogenetic development, and they contribute to the knowledge of pollen characters under the effects of different factors.

Highlights

The Common Oak (Quercus robur L.) occupies the largest area of distribution in Europe of all Quercus L
Common oak pollen was collected from a tree observed for summer flowering and a neighboring control tree, in which summer flowering had not been detected to date
There are differences in pollen morphology depending on the year of collection

Summary

Introduction

The Common Oak (Quercus robur L.) occupies the largest area of distribution in Europe of all Quercus L., Quercus species are characterized by a complex annual shoot (Gruber, 1992). Common oak growth is manifested in different phases of ontogenetic development (Bobinac, 1994). There are significant differences between the growth phases in leaf and shoot morphology, anatomy and physiology (Masarovicova, 1991; Borzan, 1993; Ponton et al, 2004; Broshtilov, 2006). Polyphase growth can be induced by mechanical injuries, changeable conditions of environmental factors, primarily climate, and their synergistic effect with biotic factors (Sabatier et al, 2003; Girard et al, 2010; Bobinac, 2011). It is supposed that this process is based on the interaction of genotype and environmental factors, i.e. the capacity

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