Annual shoot-growth in Nothofagus antarctica (G. Forster) Oersted (Nothofagaceae) from northern Patagonia |
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Authors: | M Stecconi J Puntieri D Barthélémy |
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Institution: | (1) Departamento de Botánica Centro Regional Universitario Bariloche Universidad Nacional del Comahue, Quintral 1250 8400 San Carlos de Bariloche, Argentina Consejo Nacional de Investigaciones Científicas y Técnicas Argentina e-mail: stecconi@crub.uncoma.edu.ar Fax: +54-02944-422111, AR;(2) Programme modélisation des plantes du CIRADamis Unité associée INRA/CIRAD ”AMAP forêt”, France, FR |
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Abstract: | The growth dynamics of annual shoots of Nothofagus antarctica shrubs from northern Patagonia was studied. The pattern of extension of the shoots derived from the three most distal buds
of 100 parent shoots was registered. Weekly measurements and observations of extending shoots were carried out during the
1996–1997 growth season. The date of shoot extension initiation was less variable than the date of shoot extension cessation.
Extension curves had an asymmetrically sigmoid outline. Most extension took place uninterruptedly between mid-September 1996
and the end of January 1997. Extension rate reached its highest value in the second half of the extension period. Leaf unfolding
rate had a peak early in the extension period and fluctuated irregularly later on. The apical meristem of all shoots died
by the end of shoot extension. In general terms, shoot length, diameter, leaf number and extension duration decreased from
the first to the third position from the parent shoot’s apex, although exceptions to this pattern were found. Shoot extension
rate was affected by maximum and minimum daily temperatures but not by the amount of precipitation during the extension period.
The size of a bud was not related to the size of the shoot derived from it. The size of shoots in the third position from
the apex was related to parent shoot size; this was not the case for more distal shoots.
Received: 14 May 1999 / Accepted: 10 November 1999 |
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Keywords: | Extension period Extension rate Nothofagus Plant architecture Shoot growth |
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