Osmotische Verhältnisse und Zuckergehalte im Jahresgang bei Bäumen Ost-Afghanistans. 1, Quercus balout Griffith

Abstract

The two investigated localities of Quercus balout Griffith located near the western Iimit of the distributional area in the Eastern part of Afghanistan, are characterized in their climate by the meteorological dates of Kabul and Karizimir. The locality near Charikar is located within irrigation land. The other locality at the Latahband-pass is one of the last natural localities of this oak near Kabul. The annual curves of the potential osmotical pressure and of the refractive index of cell sap show, very clearly their highest values during winter time. The contents of sucrose and glucose in leaves and bark show distinct seasonal variations, which are similar to those of middleeuropeans species. The minimum of starch-contents and the maximum of sugars during winter are correlated with the occurence of raffinose in leaves and bark. The relationships in the changes of sugar contents and the osmotical behaviour are discussed. Near the western limit of the distributional area the frost conditions during winter time seem to be the most important ecological factor, more important than drought during summer.