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Seasonal pattern of dry matter allocation in Dactylorhiza lapponica (Orchidaceae) and the relation between tuber size and flowering
Author(s) -
Øien DagInge,
Pedersen Bård
Publication year - 2003
Publication title -
nordic journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.333
H-Index - 33
eISSN - 1756-1051
pISSN - 0107-055X
DOI - 10.1111/j.1756-1051.2003.tb00418.x
Subject(s) - biology , biomass (ecology) , botany , population , primordium , vegetative reproduction , orchidaceae , shoot , dry season , dry matter , horticulture , agronomy , ecology , biochemistry , demography , sociology , gene
A population of the tuberous orchid Dactylorhiza lapponica was sampled from June 2000 to June 2001 in the Sølendet Nature Reserve, Central Norway. Dry matter of aerial shoots, old tubers and new (replacement) tubers was measured, as well as reproductive status during 1999–2001. The biomass of the new tuber was found to continue to increase after the assimilation from photosynthesis had ceased in August. It is suggested that the increase is caused by mycotrophic activity and reallocation of nutrients from the aerial shoots. There was a clear relationship between tuber size and flowering behaviour. Individuals with flower primordia had the largest replacement tuber, whereas those that flowered in the sampling season or remained vegetative throughout 1999–2001 had the smallest. Individuals that flowered in the sampling season had the largest old tuber. Those, which had not flowered for at least two years, but had developed flower primordia, had the second largest, and those that remained vegetative throughout 1999–2001 had the smallest one. Individuals with a replacement tuber less than 0.22 g in October, have a very low probability of flowering the following season. Flowering entails a cost in terms of reduced biomass of the replacement tuber compared to vegetative individuals with old tubers of similar size. Allometric analyses revealed that above‐ground biomass and biomass of replacement tubers increased with the biomass of old tubers in vegetative individuals. For generative individuals, however, above‐ground biomass was only weakly related to below‐ground biomass.