Hidrológiai Közlöny, 2015 (95. évfolyam)
2015 / 5-6. különszám - LVI. Hidrobiológus Napok előadásai
BO HIDROLÓGIAI KÖZLÖNY 2015. 95. ÉVF. 5-6. SZ. Irodalom Barkó, J.W. & Smart, R.M. (1985) Laboratory culture of submerged freshwater macrophytes on natural sediments. Aquatic Botany, 21: 251-263. Forchhammer, N. C. (1999) Production potential of aquatic plants in systems mixing floating and submerged macrophythes. Freshwater Biology, 41: 183-191. McLay, C.L. (1974) The distribution of duckweed Lemna perpusilla in a small southern California lake: an experimental approach. Ecology, 55, 262-276. McLay, C.L. (1976) The effect of pH on the population growth of three species of duckweed: Spirodela oligorrhiza, Lemna minor and Wol- ffia arrhiza. Freshwater Biology, 6, 125-136. Morris, K., P.C.E. Bailey, P.I. Boon & L. Hughes (2003) Alternative stable states in the aquatic vegetation of shallow urban lakes. II. Catastrophic loss of aquatic plants consequent to nutrient enrichment. Marine and Freshwater Reseach, 54, 201-215. Portielje, R. & R.M.M. Roijackers (1995) Primary succession of aquatic macrophytes in experimental ditches in relation to nutrient input. Aquatic Botany, 50, 127-140. Roijackers, R. M. M., Szabó, S. & Scheffer, M. (2004) Experimental a- nalysis of the competition between algae and duckweed -. Arch. Hydrobiol. 160:401-412. Survival strategies of two Elodea species Szabó S', Nagy 2 and Marten S3 'College of Nyíregyháza Institute of Environmental Sciences, Nyíregyháza, Hungary szabos@nvf.hu 2College of Nyíregyháza, Tuzson János Botanical Garden, Nyíregyháza, Hungary 3Wageningen University, Department of Environmental Sciences, Wageningen, The Netherlands. Abstract: he combined effect of nitrogen and light on the submerged macrophytes Elodea canadensis and E. nuttallii was investigated. In a factorial experiment, the plants were grown in aquaria containing five different N concentrations and incubated at five different light intensities. With decreasing nitrogen concentrations, relative growth rate (RGR), shoot elongation, relative elongation, number of side shoots, chlorophyll concentration and photosynthetic yield of the plants decreased, however, more roots were formed. Lowering the light intensity, the RGR, shoot elongation and number of side shoots decreased. The plants formed less roots and their nutrient uptake rate slowed down. However, with reduced light intensity, the relative shoot elongation, chlorophyll concentration in the leaves, and photosynthetic yield increased. The main difference between both species lies in the fact that E. canadensis formed side shoots already at shady and low nitrogen levels, whereas E. nuttallii needed high light levels together with higher nitrogen levels. Therefore, E. nuttallii will reach the water surface sooner and outcompete all other plants. Scheffer, M. (1998) Ecology of Shallow Lakes. Chapman and Hall. London. Scheffer, M., S. Szabó, A. Gragnani, E.H. Van Nes, S. Rinaldi, N. Ka- utsky, J. Norberg, R.M.M. Roijackers & R. Franken (2003) Floating plant dominance as a stable state. Proceedings of the National Academy of Science of the USA, 100,4040-4045. Szabó, S., Braun, M. & Borics, G. (1999) Elemental flux between algae and duckweeds (Lemna gibba) during competition. Archiv fur Hydrobiologie, 146: 355-367. Szabó, S., Roijackers, R. M. M. & Scheffer, M. (2003) A simple method for analysing the effects of algae on the growth of Lemna and preventing the algal growth in duckweed bioassays. Archiv fur Hydrobiologie, 157: 567-575. Szabó, S., R.M.M. Roijackers M., Scheffer & G. Borics (2005) The strength of limiting factors for duckweed during algal competition. Archiv für Hydrobiologie, 164, 127-140. Szabó, S., Scheffer, M., Roijackers, R., Waluto, B., Braun, M., Nagy, P, Borics, G.& Zambrano, L. (2010) Strong growth limitation of a floating plant (Lemna gibba) by submerged macrophyte (Elodea nuttallii) under laboratory conditions. Freshwater Biology, 55: 681 - 690
