Intraspecific variation in seed dormancy and germination among populations of Stellaria media and Galium aparine : a modelling approach to investigate the effects of environmental and management factors

• Main Author: Christal, Anna
• Published: University of Edinburgh 2000
• Subjects: 571.2
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.643152

This thesis aims to describe aspects of the ecology of two common winter annual weed species, <i>Stellaria media</i> and <i>Galium aparine</i>, in order to support the development of more sustainable weed control measures in arable crops. In arable crops, effective broad-leaved weed control tends to be associated with the early removal of weed seedlings and this may be facilitated by predictions of the timing and extent of weed seedling emergence. Seedling emergence can be divided into three stages: seed dormancy, seed germination and seedling pre-emergence growth. Seed dormancy and germination are particularly variable and this thesis therefore focuses on these key processes. Models for the timing and extent of germination for <i>S. media</i> and <i>G. aparine</i> are developed and variability is addressed by investigating the extent of intraspecific variation between populations and according to maternal effects. Intraspecific variation between populations was investigated using contrasting populations selected from a large-scale screening. The seed dormancy and germination models were developed following a review of existing models and identification of data requirements. This initiated field experiments to quantify seasonal changes in <i>S. media</i> seed dormancy and laboratory experiments to quantify the combined effects of temperature and water potential on seed germination for <i>S. media</i> and <i>G. aparine. </i>Also according to the data requirements identified by review, further laboratory experiments were conducted to analyse the effects of light and nitrate on <i>S. media </i>germination. For <i>G. aparine</i>, additional data were derived, as required, from published literature. For <i>S. media</i> significant variation between populations was recorded in initial and seasonal patterns of seed dormancy, and in the timing and extent of seed germination according to temperature, water potential and light. For <i>G. aparine</i> significant variation was recorded between populations for initial seed dormancy and seed germination according to temperature and water potential.