THE INTERRELATIONSHIP BETWEEN TILLERS AND RHIZOMES OF POA PRATENSIS L.—AN AUTORADIOGRAPHIC STUDY

Abstract

The main shoot or selected tillers of seedling plants of Poa praUnsis I,, were sujjplicd with '•'CO; :>'id the diHtribuiion of '"'C-assimilalo.s wa.s followed hy autoradiognipliy. The pi^iiiiary tillers were inilially .supplied with '"'C-assimilatcs from the main shoot bul, once cslablisht-d, became independent of the parental shoot for carhoh yd rates. Similarly, tlcveloping rhizonic-trllcrs were supported by the main shoot and established jiriniary tillers but soon became setf-supporling. Defoliation of all the lillen of the plant htit one led to the dcfollaled primary and rhizome tillers being supplied with radiocarbon from the remaining intact shoot. Thus, allhough the primary tillers and rhizome-tillers in the intact plant appear to be physiologically independent, the entire liilcr-rhizome system may be re-integrated after defoliation, allowing assimilate rcdistributinn. I', (iratensls may be regarded as a convenient link between the non-weedy herbage grasses which generally lack rhizomes atul ihr weedy rhizoniatous grasses typified by i rvpen.^ (L.) Beauv. Eint des relations eiitre Irs taltes et les rhizomes de Poa pratensis /,. Etude auloradiographique Resume. La tige princrpale ou des talles choisies sur des plantules de Poa pratensis L. ont ete mises eii presence tie '"'COi ct la distribution des metabolites marques par le '"'CI ai^tc suivic par autoradiographie. Les talles primaires ont re^u au dt^but des mtHabolites au '••C; provcnant de la tige jjrincipale, mais une fois Otablies, elles sont dcvenues Indt?pendaruw c)e la tige-mere pour les hydrates de carbone. Ue la meme fa^on, les talles provenant de rhizomes en voie de dcvetoppement otit etc alimentecs par la tige principale alors ([ue le.s talles primairrs etabliesdevenaient rapidement Indepenclantes. La defoliation tk' touies les talles de la plaiite, saulune, provoqua la ftiurniture, aux talles primaires et aux talles de rhizonies, de radiocarbone ]jrovenant de !a lige restee intacte. Ainsi, hien que les lalles priniaires et les tatles de rhizomes semblent ctre physiologiquement ind<3pcndaiites dans la piarite intacle, I'ensemble du .^ysteme des talles de rhizomes peut etre r<'integre apres defoliation, ce qui permet la re<Iisiribution des melabohles. P. pmleiisl.t peut etre considere comme tni intermcdiaire vi'aisemblable cntre les gramini^es non nuisihles des herbages, c[iii sont gc^nei a lenient d<^pQurvues de rhizomes, et les graniinees rhizomaleuses, qui sont des mauvaises hcrbes, et dont le lype est VAgropyron repens L. (Ueauv.).

Physiological integration among tillers of Holcus lanatus: age‐dependence and responses to clipping and competition

“…This is often reported along with a decrease in support as tillers age (Forde 1966o, b;Ryle & Powdl, 1972;Nyahoza, Marshall & Sagar, 1973, 1974Ong & Marshall 1979;Colvitl & Marshall 1981;Alpert & Mooney 1986). This decreased support is brought about by increased tiller size and thus larger leaf and root areas.…”

Sectoriality and physiological organisation in herbaceous plants: an overview

“…In addition to the support of newly-produced ramets, quite widespread patterns of JaC-assimilate distribution appear to be sustained to varying degrees in diverse species such as Trifolium repens (Chapman et al 1991(Chapman et al , 1992Kemball & Marshall 1995), Podophyllum peltatum (Landa et al 1992) and Carex bigelowii (Jonsdottir & Callaghan, 1988). In other cases, where the clone tends to be composed of more functionally independent ramets, local shading or defoliation often results in the physiological re-integration of ramets as resources are translocated from unaffected ramets to those that have become resource-stressed (Nyahoza et al 1973;Mattheis et al 1976;Alpert & Mooney 1986). Functional vascular connections, without imposing any major sectorial constraint on the flow of resources, thus persist in a large number of stoloniferous and rhizomatous plants and allow resources to be readily translocated throughout much of the clonal system.…”

Adaptive architecture in rhizomatous plants

“…I t is difficult to determine how much the process 'costs', since branching is normally an integral part of ramet development. Undoubtedly the process is most efficient because directions and distances can be predetermined while large food reserves and a water supply are often maintained in the mature parental axis (Yin, Shen & Shen, 1958;Giddens, Perkins &Walker, 1962; de Byle, 1964; Qureshi & Spanner, 1971; Clifford, Marshall & Sagar, 1973; Nyahoza, Marshall & Sagar, 1973. There is the further possibility of feedback mechanisms which may be important in generalized flowering responses.…”