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The Reproductive Strategy of Higher Plants: I. The Concept of Strategy with Special Reference to Senecio Vulgaris L.

John L. Harper and John Ogden
Journal of Ecology
Vol. 58, No. 3 (Nov., 1970), pp. 681-698
DOI: 10.2307/2258529
Stable URL: http://www.jstor.org/stable/2258529
Page Count: 18
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The Reproductive Strategy of Higher Plants: I. The Concept of Strategy with Special Reference to Senecio Vulgaris L.
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Abstract

This paper is the first of a series in which the partitioning of dry matter and energy throughout the life cycle of different plant species will be described. The concepts of energy allocation, strategy and tactics, and the measurement of `reproductive effort' are considered, primarily in relation to annual composites. An experimental application of these concepts to the life cycle of Senecio vulgaris grown under different `stress' conditions is described. Three `stress' treatments were imposed by growing the plants from seed in pots of three different sizes, in a poor sandy soil. The smallest pots imposed the greatest `stress'. The distribution of dry matter to the different parts of the plant was followed throughout the life cycle. Calorie conversion factors were obtained for the different organs, so that dry weights could be converted into calories, and the net energy budget described. `Reproductive effort' defined as: (Total seed production)/(total net production) × 100 (with production expressed as total calories) was found to lie between 18 and 24% for S. vulgaris, except under extreme stress conditions, when the plants were depauperate and flowering was erratic. The `reproductive effort' estimated for S. vulgaris is very similar to estimates for other annual Compositae. Annual composites which have been cultivated as crop plants are apparently no more efficient (as seed producing machines) than weed species in the same family.

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