Evaluation of potential deer browsing impact on sunflower (<Emphasis Type="Italic">Helianthus annus</Emphasis>)

Large herbivores are the key species for game management in the Central Europe. Analyses of factors affecting the feeding behaviour of herbivores and consequences of their browsing are therefore highly important both for farmers and for game managers as the protective measurements should be focused on the most threatened fields. The influence of fallow (Dama dama) and roe deer (Capreolus capreolus) browsing during vegetation period on sunflower production was studied. The experiment was carried out in 2006 on a field located near a forest complex. We marked out pairs of paired permanent plots and monitored deer impact regularly from the emergence of plants until the harvest. Herbivores damaged the sunflower intensively immediately after the emergence at the height of 1 to 2 cm above the ground. When the plants had reached approximately 15-40 cm in height, deer browsed the top shoots and as the plants grew higher the browsing was restricted to leaves or to substitute stems of the previously browsed plants. Sunflower ceased to attract big herbivores in flowering stage. Browsing significantly affected the yield of seeds. Approximately one half of the plants that had been damaged in early stage died as well as 12.5% of plants that had been damaged at second term; the rest produced substitute stems. Almost 33% of the substitute stems did not form disc florets; the second third of them formed disc florets with a diameter of 6-8 cm, and the last third set disc florets with a diameter of 8-10 cm.     

Induction and Inducers of the Pectolytic System in Aureobasidium pullulans

The strain of Aureobasidium pullulans NRRL Y-2311 (CCY 27-1-98), known as a hyperproducer of endo-1,4-β-xylanase, exhibited good growth on pectin or pectate. Growth on these carbon sources is associated with an inducible production of significant amounts of pectolytic enzymes, of which exopolygalacturonase (EC 3.2.1.67) and endopolygalacturonase (EC 3.2.1.15) were identified. The two enzymes are not produced on D-glucose or under carbon starvation conditions. The enzymes can be induced in glucose-grown cells by D-galacturonic acid and its oligomers. Thus, D-galacturonic acid, the monomer derived from the polysaccharide, appears to be the natural inducer or a precursor of an inducer of pectolytic enzymes in the studied yeast. Received: 4 November 1995 / Accepted: 11 December 1995