<p><strong>ABSTRACT</strong></p> <p>As plants are sessile organisms, detecting the presence of neighboring plants and exhibiting competitive behavior to acquire limiting resources is crucial. One of the ways plants respond to belowground competition is by allocation to fine roots in order to acquire the limited resources. However, this phenotypic plasticity can be costly as it assigns resources away from reproduction. Being able to recognize the relatedness of one′s neighbours and preferentially compete with strangers is a beneficial trait that can minimize the costs of competition with relatives and increases inclusive fitness. Many studies have looked at the association between resource availability and competition in plants while others have observed kin recognition in several plants species. However, no one has yet studied the effect of resource availability on kin recognition in plants. Here, I looked at root architecture to test if there is an association between kin recognition and nutrient availability in <em>Cakile edentula</em>.</p> <p>I found that the root system architecture is highly plastic and complex, showing variable responses to neighbour identity signals and resource availability. The results from the four experiments demonstrate that the responses of <em>C. edentula </em>to neighbour relatedness are dependent on nutrient availability. Additionally, this study also indicates that kin recognition in <em>C. edentula</em> does not require root contact; instead it occurs through a signal found in soluble compounds excreted from plants, possibly root exudates, as observed in <em>Arabidopsis thaliana</em> <em>(</em>Biedrzycki et al. 2010).</p> <p>In conclusion, this study provides novel findings regarding the dynamics of root behavior in response to nutrient availability and the relatedness of neighbours.</p> / Master of Science (MSc)