Büchler, W.

RERO DOC Digital Library

Proceeding of the Royal Society of Edinburgh, 98B, 235-249,1992ABSTRACTS OF POSTERSWaterlogging effects on Salix viminalisPaul A. Attwood1'2, Edward I. Newman1 and Michael B. Jackson2Department of Botany1 and Agricultural Science2, University of Bristol, U.K.Willow is common in riparian zones that are frequently waterlogged. There isinterest in fast-growing willow for biomass, and land that is subject to flooding maybe suitable for this purpose. Accordingly, we have studied the ability of willow towithstand poorly aerated root environments under controlled conditions.Rooted cuttings of Salix viminalis L. cv. Bowles Hybrid were grown in aerated ordeoxygenated nutrient solution. They showed considerably reduced root growthwhen dissolved oxygen partial pressures were reduced from 21 kPa to 0-2 kPa. Atbelow 1 kPa, adventitious roots extended at about one third the rate of aerated roots.Growth in dry mass was also curtailed. Root growth under these conditions couldhave been sustained either by oxygen transported to the roots internally from theshoot or by the root's ability to respire and grow without oxygen. These possibilitiesare being examined further.Aerenchyma (internally interconnected gas-filled space) is the most likely path-way for oxygen transport to the roots, from aerial parts. Therefore roots wereinvestigated for the presence or absence of aerenchyma. Roots of all treatments hadsimilar amounts of aerenchyma (20-30% of the cortex). Aerenchyma formation inSalix viminalis therefore appears to be constitutive and is not induced by poorlyaerated conditions, as happens in cereal roots such as wheat and maize. In the latterspecies, ethylene (ethene) is thought to be responsible for inducing aerenchyma bypromoting lytic breakdown of cortical cells. To test whether ethylene is active inwillow, silver nitrate, a well-known inhibitor of ethylene action was applied. Silvernitrate was toxic at concentrations of 0.05 mg I"1 and above but did not inhibitaerenchyma formation at lower non-toxic concentrations. Ethylene therefore isunlikely to be involved in aerenchyma development.A preliminary account of chromosome numbers in the Salix - sectionRetusaeW. BiichlerFlurystrasse 12, CH-8620 Wetzikon, SwitzerlandSalix serpyllifolia Scop., 5. retusa L. and 5. kitaibeliana Willd. differ almost only byquantitative features. The dwarf of the three, 5. serpyllifolia has long been regardedavailable at https:/www.cambridge.org/core/terms. https://doi.org/10.1017/S026972700000765XDownloaded from https:/www.cambridge.org/core. University of Basel Library, on 11 Jul 2017 at 11:39:06, subject to the Cambridge Core terms of use,236 Abstracts of Postersas a subspecies or variety of 5. retusa, which arose under the hard climatic conditionsof the high mountains. Rechinger (1938) first proposed that 5. retusa and S. kitaibe-liana could be polyploid descendants of S. serpyllifolia. Recent chromosome countsmade by several authors seem to confirm this but suggest that the situation mighteven be more complex (Table 1).At first sight, there doesn't seem to be a simple coherence between species andpolyploidy level. In each taxon we find two or even three different chromosomenumbers. This might be because the species are primarily defined by their morpho-logical (in this case quantitative) characters and not necessarily according to theirsterility barriers (e.g. different polyploidy levels) to other species. Quantitativefeatures may overlap between neighbouring polyploidy levels from genetic varia-bility and response to environmental influences. It is concluded that both 5. retusaand 5. kitaibeliana do not contain the diploid level.The situation becomes somewhat clearer when considering the geographical distri-bution of the polyploidy levels. The diploid 5. serpyllifolia appears to be restricted tothe central part of the Alps. Tetraploid plants of all three species are reported eitherfrom the Tatra mountains (Poland and C.S.F.R.) or at least from authors of thesecountries. Plants of the highest polyploidy levels (2n = 114... 152) were found in theAlps, the Tatra- and the Pirin-mountains (Bulgaria). They often show more or lessserious irregularities with losses of chromosomes during meiosis (Biichler 1986).Some of them were found to be aneuploid, with an outset point at 2n = 152. Others,like the hybrids of 5. retusa with 5. nigricans Sm. and S. bicolor Ehrh. started atIn = 7 x 133 (resulting from a combination of hexaploid and octoploid parents).Descendants of these plants may have chromosome numbers floating between2n = 114... 152, in the long-term probably with a downward trend.ReferencesBiichler, W. 1985. Neue Chromosomenzahlungen in der Gattung Salix. Botanica Helvetica 95, 165-75.Buchler, W. 1986. Neue Chromosomenzahlungen in der Gattung Salix. 2. Teil. Botanica Helvetica 96/2,135-43.Chmelaf, J. 1979. The Taxonomic Importance of Chromosome Numbers in the Genus Salix L. Lesnictvi25,411-15.Izmaitow, R. 1980. Cytological studies in Salix L. I. Ada Biol. Cracov 22, 101-11.Rechinger, fil. K.H. 1938. Salicologische Fragmente 1-4. Feddes Repertonium, 45, 87-94.Love, A. & Love, D. 1961. Chromosome numbers of central and northwest European plant species.Opera Botanica 5, 118-21.Salix acmophylla Boiss. - another Salix species with two loose budscales?W. BuchlerFlurystrasse 12, Ch-8620, Wetzikon, SwitzerlandIn most willow species axillary buds have a single bud scale formed by the fusion oftwo prophylls on both abaxial and adaxial side (see Figs 1 and 2). The first twocataphylls appear usually in the transversal plain while the following pass over in thespiral fashion of about 2/5 divergence (Kimura & Sugaya 1965).available at https:/www.cambridge.org/core/terms. https://doi.org/10.1017/S026972700000765XDownloaded from https:/www.cambridge.org/core. University of Basel Library, on 11 Jul 2017 at 11:39:06, subject to the Cambridge Core terms of use,

A preliminary account of chromosome numbers in the Salix - section Retusae

Abstract

Similar works

Full text

Available Versions

RERO DOC Digital Library