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Biology of the rangeland weed hoary alyssum (Berteroa incana (L.) DC.)

University of British Columbia

Hoary alyssum (Berteroa incana (L.) DC) has become a serious weed of rangelands, pastures, and forage crops in British Columbia. In order to develop effective management strategies for this weed, a sound knowledge of its biology and ecology is essential. The goal of this research is to improve our understanding of the biology of hoary alyssum and to identify vulnerable links in its persistence strategy that may be exploited to develop effective management strategies for this weed. The distribution of hoary alyssum seeds in the soil profile; the size and persistence of its seed bank; the effect of burial depth on the dynamics of seed dormancy and germination; the response to mechanical removal of flowering shoots (mowing); the potential allelopathic influence on seed germination and seedling growth of associated forage grasses; and the effect of nitrogen fertilization on the growth of hoary alyssum and associated forage grasses were investigated. Results show: (1) 93-95% of hoary alyssum seeds were present in the top 4 cm of the soil profile at infested sites in the Morrissey Creek, BC area; (2) the size of soil seed banks ranged between 0 to 132.4 million seeds ha₋¹; (3) seeds on the soil surface showed little primary dormancy, but buried seeds showed some enforced and some induced dormancy; (4) mowing of flowering shoots resulted in the release of apical dominance and the regeneration of shoots; (5) delaying mowing until later stages of flower and seed development increased plant mortality, but some plants were still able to reproduce shoots and seed; (6) leachates of hoary alyssum leaves strongly inhibited the seed germination and seedling growth of grassy species in Petri dish assays, but this allelopathic influence was not observed consistently in soil assays; (7) hoary alyssum biomass increased in response to nitrogen (urea) fertilization, but forage grasses showed no response due to leaching of this nutrient; and (8) nitrogen fertilization promoted bolting and flowering in hoary alyssum. These results improve our understanding of hoary alyssum biology, and may aid in the development of effective management strategies for this weed.

Text

2012-04-20

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/42131

Plant Science

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/