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Aspects of the Comparative Physiology of Ranunculus bulbosus L. and Ranunculus repens L.: II. Carbon Dioxide Assimilation and Distribution of Photosynthates

H. D. GINZO and P. H. LOVELL
Annals of Botany
New Series, Vol. 37, No. 152 (September 1973), pp. 765-776
Published by: Oxford University Press
Stable URL: http://www.jstor.org/stable/42752154
Page Count: 14
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Aspects of the Comparative Physiology of Ranunculus bulbosus L. and Ranunculus repens L.: II. Carbon Dioxide Assimilation and Distribution of Photosynthates
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Abstract

Detailed analysis of the interrelationships between sources of photosynthate production and sites of utilization in the taxonomically closely related species Ranunculus bulbosus L. and R. repens L. showed that leaves whether present on rosette, stem, or stolon had similar levels of ¹⁴CO₂-fixation but the pattern of distribution of radiocarbon to the rest of the plant differed. Fruits of R. bulbosus had a lower fixation rate than leaves but were characterized by total retention of the fixed radiocarbon. Rosette leaves of R. bulbosus supplied the young leaves, developing apices in the rosette, roots, and corms, whereas the labelled assimilates from cauline leaves were evenly distributed between reproductive and vegetative parts. The corm was the major sink both at the flowering and fruiting stages. When plants were treated with ¹⁴CO₂ in the field even higher levels of radiocarbon moved into the corm than in comparable experiments under greenhouse conditions. The rosette leaf of R. repens exported mainly to actively growing stolons in plants with many stolons bearing rooted ramets although growth of a stolon was also substantially supported by photosynthates produced by its own ramets. A proportion of the radiocarbon fixed by leaves of mature ramets was exported and moved in a predominantly acropetal direction into the stolon apex, stolon axis, and young ramets of the same stolon. The stock in R. repens had a much lower demand for assimilates than the corm in R. bulbosus. The results are consistent with the concept that R. bulbosus operates a conservative policy involving the replacement of the parent in situ by a daughter from the corm, coupled with extensive fruit production. In R. repens the emphasis is on lateral spread and exploitation of substantial areas of ground by vegetative spread and replacement of the parent by daughters many of which may occupy sites some distance from the parent.

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