Growth and carbon economy of a fast‐growing and a slow‐growing grass species as dependent on ontogeny

Abstract

In previous experiments systematic differences have been found in the morphology, carbon economy and chemical composition of seedlings of inherently fast‐ and slow‐growing plant species. The present experiment was to investigate whether these differences persist when plants become larger. Plants of the inherently fast‐growing Holcus Lanatus L. and the inherently slow‐growing Deschampsia flexuosa (L.) Trin. were grown under standardized conditions and growth, photosynthesis, respiration and carbon and nitrogen content were followed over a period of 4 to 7 weeks. Differences in relative growth rate were mainly due to the higher leaf area ratio (leaf area; plant weight) of the fast‐growing species. Rates of photosynthesis differed substantially when expressed on a leaf weight basis, but only slightly when expressed per unit leaf area. Although most parameters showed some ontogenetic drift, differences found for young seedlings persisted at least until plants reached a dry weight of circa 3 g. Therefore, at least for these two species, the conclusions based on interspecific variation relative growth rate of young seedlings apply to larger plants as well. Copyright © 1992, Wiley Blackwell. All rights reserved