Rhizome

About: Rhizome is a research topic. Over the lifetime, 2556 publications have been published within this topic receiving 28597 citations. The topic is also known as: rhizomes & rootstalk.

Rhizome elongation and seagrass clonal growth

Abstract: A compilation of published and original data on rhizome morphometry, horizontal and vertical elongation rates and branching patterns for 27 seagrass species developing in 192 seagrass stands allowed an examination of the variability of seagrass rhizome and clonal growth programmes across and within species. Seagrass horizontal rhizomes extend at rates ranging between 1.2 and 574 cm yr(-1), develop a branch, with an angle from 19 to 72 degrees, for every 6 to 1800 horizontal internodes, and add a new shoot for every 1.1 to 7.5 cm of rhizome produced. Vertical rhizomes elongate at rates between 0.1 and 34 cm yr(-1) and the probability that they will branch varies over 3 orders of magnitude. Much (between 40 and 173%) of the variability of seagrass horizontal rhizome and clonal growth programmes is species-specific, largely (21 to 63% of the variance) associated with differences in size among species, although seagrasses also show important intraspecific variability. The broad repertoire of seagrass rhizome and clonal growth programmes explains the different rates and efficiency at which the species occupy space. The implications of specific growth programmes for space occupation were examined by simulating the development of seagrass rhizome networks of 3 seagrass species encompassing the range of horizontal rhizome growth (Halophila ovalis, Thalassodendron ciliatum, Posidonia oceanica). This exercice showed that small, fast-growing species achieve a much lower spread efficiency (m(2) of ground covered m(-1) of rhizome produced) than the large, slow-growing species. Differences in rhizome branching angles greatly constrained the form of rhizome networks. The results show that clonal growth patterns are a primary component of seagrass productivity and, therefore, the key to the development and maintenance of seagrass meadows. [KEYWORDS: seagrasses; clonal growth; plant allometry; rhizome diameter; spacer length; rhizome elongation; branching rate and angle Herb glechoma-hederacea; nodosa ucria ascherson; cymodocea- nodosa; thalassia-testudinum; posidonia-oceanica; syringodium- filiforme; population-dynamics; experimental burial; branching patterns; vertical growth]

Phragmites australis: Venturi- and humidity-induced pressure flows enhance rhizome aeration and rhizosphere oxidation

Abstract: SUMMARY A Venturi-induced convection of gases through the Phragmites rhizome system is reported and the effects of this, and a humidity-induced convection previously described, are quantified. The Venturi-convection is driven by a pressure differential created by wind blowing across tall dead culms which sucks air into the underground system via culms snapped off close to ground level. The results demonstrate how wind, by increasing Venturi-induced convection, and how radiant energy, by increasing humidity-induced convection, raise the oxygen concentrations in the rhizome system, thereby causing much greater fluxes of oxygen into root and rhizosphere than are achieved if rhizome aeration is by diffusion alone. In laboratory experiments convective flow rates of as low as 0 7-1 4 x 10-8 m3 s-' (approx. 20-40 mm min-1 in the rhizome) were sufficient to raise rhizome oxygen concentrations to 90 % of atmospheric. The significance of this is discussed in connexion with pollutioni control by constructed wetlands, and photographic evidence is provided of the rhizosphere oxidizing activities in soil and anaerobic solution. A mathematical model is derived to help to evaluate the contributions of convection and diffusion in rhizome aeration, and to assess the likely effects of root and rhizosphere oxygen demands.

Light‐enhanced convective throughflow increases oxygenation in rhizomes and rhizosphere of Phragmites australis (Cav.) Trin. ex Steud.

Abstract: Summary The convective throughflow of gases found recently in Phragmites australis increased with increasing fluxes of photosynthetically active radiation. Despite this, the oxygen in the venting gases remained lower than in air and the convection is thought to depend mainly on a humidity-induced diffusion of atmospheric gases across the leaf sheaths. When convection was prevented, and aeration was dependent entirely upon diffusion, no photosynthetic enhancement of rhizome and root aeration could be detected. In terms of oxygen transport, rapid rates of convection were much more effective than diffusion and substantially enhanced the entry of oxygen into the rhizome system. This resulted in large increases in the efflux of oxygen into the rhizospheres of basal laterals and apical and sub-apical regions of the adventitious roots. This effect was attributed to a greater diffusion of oxygen from rhizome to root. Substantial diurnal fluctuations in rhizome oxygen regimes and in root oxygen efflux occurred. It is estimated that because of convection and diffusion, up to 0.31 kg of oxygen d−1 m−1 may enter the rhizome system of vigorous stands of Phragmites during summer months. By comparison, diffusion alone could be expected to supply less than 0.01 kg d−1. Scanning electron micrographs of root-shoot junctions showed that the resistance to gaseous diffusion from rhizome to roots must be especially small in Phragmites.

In vitro clonal multiplication of turmeric (Curcuma spp.) and ginger (Zingiber officinale Rosc.).

Abstract: Rhizome buds, excised from threeCurcuma spp., and ginger, inoculated aseptically on MS medium with varying levels of BAP and kinetin, produced multiple shoots. For shoot multiplication, a concentration of 3.0 mg/l BAP was found to be optimum for all the species.In vitro plants were successfully established in the field and were morphologically uniform. A simple method to extend the subculture interval was used and its relevance to germplasm conservation is discussed.