In: Phyton, 52 Fasc. 2 (2012), S. 245-262, with 9 figures

Key words: Vaccinium myrtillus, Ericaceae. – Extrinsic ice nucleation, leaf angle, supercooling, stomatal density, water repellence and retention.

Summary

Aryal B. & Neuner G. 2012. Leaf wettability in bilberry Vaccinium myrtillus L. as affected by altitude and openness of the growing site. – Phyton (Horn, Austria 52 (2): 245–262, with 9 figures.

Leaf wettability of Vaccinium myrtillus L. (Ericaceae) leaves was investigated on plants naturally growing along an altitudinal gradient from 690 m to 2030 m a.s.l. and in open and understorey habitats in the Tyrolean Central Alps of Austria in order to investigate the role of environmental factors for the development of highly non-wettable or wettable leaf surfaces. Leaf wettability was assessed by measurement of the water droplet contact angle, ?. ? was positively related with increasing altitudes, i.e. leaves from subalpine individuals were non-wettable (?>110°) and that from montane sites were highly wettable (?<90°). Analysis of variance also indicated that leaf wettability was significantly different along increasing elevation. Leaf surfaces of plants from open habitats were more water repellent, than that from leaves grown in the adjacent understorey. In the understorey, droplet retention was much higher as compared to open places. Steep angled leaves from the subalpine region had also a low leaf wettability, which repels water droplets away from the leaf surface immediately after contact. Stomatal density increased from lowland (99.7 ± 3.6) to highland (153.4 ± 5.1) and from the understorey to open growing places. Leaves were amphistomatous but had much more stomata on abaxial than adaxial leaf surfaces. Leaf surface wettability of V. myrtillus decreases with increasing altitude and with increasing openness of the habitat. In both gradients the probability of wetting events increases having major effects on gas exchange but additionally promotes infection and formation of diseases that in turn can increase leaf surface wettability.