engleski

In vitro pollen germination and pollen tube growth differences among Quercus robur L. clones in response to meteorological conditions

The paper deals with the impact of meteorological conditions on in vitro pollen germination and pollen tube growth during the initial phases of male flowers development of pedunculate oak. Phenological observations of male flowers and pollen sampling were performed on the field trial established with grafted pedunculate oak clones. During the investigation, weather conditions (absolute minimum and maximum daily air temperature, minimum absolute relative humidity of air and amount of precipitation) were recorded by an automatic meteorological station installed at the field trial. Influence of meteorological conditions on pollen germination and pollen tube growth was studied in the following stages of male flower: (i) during the last ten days of flower buds dormancy, (ii) during their swelling, (iii) during the bud burst and beginning of male catkins elongation, (iv) during the final stage of male catkins elongation. Pollen germination after incubation times of 2, 4, 6 and 24 hours ranged from 0, 0 to 8, 9 % ; from 0, 0 to 55, 6 % ; from 0, 0 to 59, 3 % and from 5, 9 to 90, 7 %, respectively. Pollen tube lengths after the same incubation times ranged from 15, 3 to 45, 0 μm, from 17, 0 to 88, 3 μm, from 20, 9 to 101, 9 μm and from 39, 9 to 241, 1 μm, respectively. High temperatures and low relative air humidity during the bud burst and beginning of male catkins elongation reduced pollen germination and pollen tube growth. Weather conditions did not significantly affected pollen germination and pollen tube growth during the swelling of flower buds, as well as in the final stage of male catkins elongation.

phenophases; bud burst; male flowers; air temperature; relative air humidity

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