Biomass partitioning and its effect on reproduction in a monocarpic perennial (Anthriscus sylvestris). Response to nitrogen and light supply

Plants of Anthriscus sylvestris (L.) Hoffm. originating from seed were grown from April 1989 to June 1990 in a factorial pot experiment to study the effects of light and nitrogen over time on biomass allocation to different plant parts and their relation to reproduction and reproductive effort. For a species depending on resources stored in a taproot for flowering, it was expected that environmental conditions promoting allocation to roots would lead to a high reproductive output and/or reproductive effort. In this context the relation between growth of the resource-storing taproot and the resource-capturing side-roots was studied. The first year, during the vegetative stage, the root/shoot ratio was influenced by an interaction between light and nitrogen, and within the root fractions the two components were equally affected. During the flowering stage, the variation in partition pattern was mainly time related. It was found that sexual reproductive output varied in direct proportion to the amount of resources stored in the taproot during the vegative phase of the plant. Despite the large variation in root/shoot ratio during the first growing season, this factor had no influence on the reproductive effort, i.e. seed production was determined by plant size, which depended on resources stored in the taproot at the end of the first growing season and on the availability of nitrogen in the second growing season.