Seed dispersal and seedling establishment of Linaria vulgaris Mill.

Abstract

The importance of seeds to the establishment and spread of Linaria vulgaris infestations in Alberta was assessed in 1988 and 1989. Stands were established on 17 May 1988. One 10-cm-long root piece with a 10-cm-tall shoot was planted in the centre of each of nine plots on fallow land and of nine plots in a barley crop. Over 90% of seeds in 1988, and over 80% in 1989 fell within a 0.5-m radius of the parent plants with very few seeds falling outside a 1.5-m radius. Seed deposition vs. distance followed a negative polynomial function. It was estimated that over 210 000 seeds m−2 fell less than 0.5 m away from the parent plant over the 1988 growing season. The presence of Gymnaetron sp. and Brachypterolus sp. in 1989 reduced seed deposition to a total of 1410 seeds m−2 within 0.5 m of the parent plant. The few seedlings that were established occurred in clumps, with densities varying from 1.3 to 7.0 seedlings cm−2 in May and from 0.8 to 7.8 seedlings cm−2 in June 1989. In 1988, total seedling emergence per plot varied between 0.13 and 0.23%. Seed viability and dormancy were major factors influencing seedling establishment. Seed viability was as low as 40% (tetrazolium test), and germination was maximized in the laboratory following a wet stratification at 5 °C for a period of at least 8 wk. Key words: Toadflax, Linaria vulgaris, seed dispersal, seedling establishment, seedling distribution