An assessment of genetic and environmental effects on sporangial development in bracken [Pteridium aquilinum (L.) Kuhn] using a novel quantitative method

A scheme for quantifying sporangial development on Pteridium fronds was con structed. Five stages of development were identified, and the percentage co ver of each stage was estimated on one pinna of the frond in question. A we ighted sum was calculated to give a single quantitative result. The scheme was used to identify developmental differences in bracken plants of four ge notypes grown in factorial combinations of two light and two temperature re gimes. Both increased temperature and increased light significantly increas ed the rate of sporangial development. Genotypes were significantly differe nt from each other, and showed significant differences in response to their environment. (C) 2000 Annals of Botany Company.