Non-limiting Resource Mechanisms of Plant Competition

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Plant competition has been viewed traditionally as the negative effects which one plant has on another by being more successful at consuming or controlling access to resources such as light water and nutrients. While there is no doubt that resource limitation is a major factor in plant competition, other non-limiting resource mechanisms such as hormonal and light signalling have been shown to play important roles in plant competition. Most competition studies have been limited to descriptive outcomes of competition such as changes in biomass or yield loss, with little or no understanding of the actual molecular and physiological changes that have occurred within the plant. The results of my previous research suggest that crop/ weed competition is not driven initially by limiting resources, but rather by molecular, physiological and morphological changes that occur initially in crop plants in response to changes in the Red to Far Red ratio reflected from the vegetative tissue of above ground neighbouring weeds. There is an emerging body of evidence to suggest that these molecular and physiological changes may directly alter yield potential and/or pre-condition the crop plant to be more susceptible to subsequent stresses caused by biotic or abiotic variables such as limiting resources. In order to advance our knowledge of these fundamental mechanisms of plant competition I propose an experimental plan to test several hypotheses designed to determine how changes in the Red to Far Red ratio can alter the molecular expression and subsequent physiology of a corn or soybean plant. Experiments will be designed to study the effect of the Red to Far Red ratio reflected from both above ground neighbouring weeds and a non-biological Far Red filter on the molecular and physiological changes that occur in the cells and organelles of maize and soybean plants. This research will contribute new knowledge to our understanding of the underlying mechanisms of plant competition as well as provide novel information which may be used in maize and soybean breeding programs to enhance stress tolerance.