New Zealand Journal of Botany abstract

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B97049
Received 16 July 1997; accepted 12 March 1998

Inflorescence photosynthesis and investment in reproduction in the dioecious species Aciphylla glaucescens (Apiaceae)

K. P. HOGAN

Landcare Research
P.O. Box 69
Lincoln, New Zealand

M. B. GARCíA

Estación Biológica de Donñana (CSIC)
Apartado 1056
E-41080 Sevilla, Spain

J. M. CHEESEMAN

Department of Plant Biology
University of Illinois
505 S. Goodwin
Urbana
IL 61801, USA

M. D. LOVELESS

Department of Biology
College of Wooster
Wooster
OH 44691, USA

Abstract  The differences in the costs of reproduction between males and females of dioecious plants should lead to differences in life history evolution, but photosynthesis of reproductive structures can reduce the cost of these structures. We hypothesised that the greater costs of reproduction would select for greater photosynthetic capacity in reproductive structures of female plants of the dioecious species Aciphylla glaucescens. However, measurements of gas exchange using a portable infra-red gas analysis sytem showed that the photosynthetic capacity of male inflorescences is greater, and their total mass is half that of females. Thus, male inflorescences contribute more to their own carbon and energy costs. Estimates of the contribution of inflorescence photosynthesis suggest that much of the reproductive biomass is attributable to import of photosynthate from the leaves. Total nitrogen investment in reproductive structures was much greater in females. Life history differences between males and females may be driven by nitrogen or ecological factors rather than by carbon acquisition or energy requirements.

Keywords  dioecy; biomass; nitrogen; gender dimorphism; fruit photosynthesis

PDF file of entire paper: medium quality (581K); (scanned from paper original: notes about this process)

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