APPLICATIONS OF PHYSIOLOGICAL ECOLOGY TO WEED SCIENCE

Weed scientists are trained broadly in agronomy, botany, chemistry, soils, and other agricultural disciplines. The study of weeds, rather than the techniques used or the questions asked, unifies weed scientists around a common focus. It is often difficult for weed scientists to identify closely with any one scientific discipline, since the techniques and questions of many disciplines are needed to address problems posed by weeds. One discipline with relevance and potential for addressing weed science problems is physiological ecology. The study of the functioning or adaptation of plants in relation to environmental influences has its roots in both classical ecology and experimental physiology. Application of this discipline to weed science may take an environmental approach (e.g., studying limiting factors in the environment), a physiological approach (e.g., studying the responses of critical plant processes to environmental stress), or a more autecological approach (e.g., studying the physiological basis for the adaptation of a particular weed to a particular habitat). Many methodologies and technologies are available for both field and laboratory investigations. For example, photosynthesis, a major determinant of plant growth, can be investigated in the field at the leaf, plant, or canopy level using plant growth analysis or a portable infrared gas analyzer (IRGA) and appropriate assimilation chambers. Investigations of photosynthesis in the laboratory can focus on the plant, leaf, chloroplast, or thylakoid level using an IRGA or the techniques of polarography (measurement of evolved oxygen) or fluorometry. Application of such approaches to weed science should improve our understanding of the basis for particular weed problems and thus broaden our options for management.