The growth and development of plants is incremental and cumulative over seasonal timescales. Environmental conditions are continuously variable with plant responses occurring on sub-hour time scales. The cumulative metabolic activity in sub-hour increments over 100-day seasons results in agricultural productivity. It is now relatively simple to monitor canopy temperatures in the field on 15-minute intervals over 100-day periods at an appropriate temporal resolution for understanding plant/environment interactions. Crop water use, metabolic optimality and crop development can all be monitored under research and production conditions using commercially available infrared thermometry systems. Large numbers of observations can be made in an automated manner. Such fine-scale measurements provide a "seasonal narrative" of the plant's interaction with the environment. Interpretation of this narrative in terms of our traditional understanding of plant/environment interactions is the challenge. We need the equivalent of a Rosetta Stone to translate plant temperature into plant physiology. Examples relating to water use, metabolic optimality and crop development will be presented.
Dr Mahan is a research plant physiologist with the USDA/ARS (federal research organization) at the Plant Stress and Water Conservation Laboratory in Lubbock, TX (28 years). He received a BS in Biology from Southwestern Oklahoma State University and a MS and PhD in plant physiology from Texas A&M University.
Dr. Mahan's research has broadly considered the response of plants to water deficits and thermal stress under irrigated and rainfed conditions. The focus has been on the development of metabolic indicators of stress. As agricultural production transitions from water inputs designed to prevent water deficits to a future where water deficits will be unavoidable sustainability will be defined by our ability to identify, quantify and manage water deficits.
Previous work has focused on the linkage between biochemical optimality and environmental stresses. He has investigated the effects of water and temperature stress on: antioxidants (waste of time), herbicide efficacy (insightful), activity of specific enzymes (dodgy), gene expression (confusing) and currently metabolite response (last option so it better work).
His recent efforts have focused on the use of seasonal patterns of near-continuous canopy temperature measurements as an indicator of water use, water status and metabolic function in crops. Dr. Mahan has developed the first low cost wireless infrared thermometry system for irrigation management and research. This system is marketed in the US by Smartfield (smartfield.com).
While the primary focus has been on cotton, other crops investigated include: corn, sorghum, peanut, forage grasses, wheat, sesame, and palmer amaranth.
Mahan has ongoing collaborations with scientists and students from University of Sydney, University of Western Sydney and the Australian Cotton Research Institute in Narrabri.