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Does morphology or the size of the internal nitrogen store determine how Vaccinium spp. respond to spring nitrogen supply?
Author(s) -
Grelet G.A.,
Alexander I. J.,
Millard P.,
Proe M. F.
Publication year - 2003
Publication title -
functional ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.272
H-Index - 154
eISSN - 1365-2435
pISSN - 0269-8463
DOI - 10.1046/j.1365-2435.2003.00776.x
Subject(s) - vaccinium myrtillus , evergreen , shoot , biology , deciduous , vaccinium , ericaceae , botany , herbaceous plant , nitrogen , chemistry , organic chemistry
Summary1 Vaccinium myrtillus (deciduous) and V. vitis‐idaea (evergreen) are ericaceous shrubs adapted to low‐nitrogen environments. Their comparative responsiveness to N supply was determined in relation to both N storage and developmental constraints. 2 Plants were grown with high or low N in sand culture to condition their N storage, and their growth measured during the first flush of a second year when plants from each treatment were again supplied either high or low N. 15 N‐labelling was used to quantify remobilization of N taken up in the first year for growth in the second. 3 In both species, the growth response to external N availability was mediated through a change in the number of buds, initially present, which produced shoots, with no alteration of the number of leaves per shoot; but the magnitude of the response was smaller in the evergreen species. The second flush of growth took place more rapidly in V. myrtillus than in V. vitis‐idaea , and depended on both external and internal N supply, in terms of the number of shoots produced and the number of leaves per shoot. 4 The amount of labelled N remobilized by both species depended on the level of N reserves, and on the number of initial buds which produced shoots. In V. myrtillus , the total amount of N remobilized to new growth was significantly affected by external N supply. Since the total amount of N remobilized is independent of external N availability during spring growth, this result implies that the age of the N remobilized depended on the number of buds that produced shoots. We explain this result by the perennial nature of N storage in V. myrtillus and the age range of the pool of buds coming into growth each year on an individual plant. 5 Nitrogen remobilization and the growth response to N supply were closely linked with the pattern of bud activation. Species‐specific growth responses to N supply in spring were better explained by developmental constraints on growth than by the ability to store and re‐use N.