Submitted to: Remote Sensing and Modeling Applications for Natural Resource Management
Publication Type: Abstract Only
Publication Acceptance Date: March 3, 2002
Publication Date: March 23, 2002
Citation: Ephrath, J., Timlin, D.J., Baker, J.T., Reddy, V. 2002. Effects of elevated co2 concentration and water stress on leaf water potential, water use and root growth of cotton [abstract]. Remote Sensing and Modeling Applications for Natural Resource Management. Technical Abstract: In GLYCIM and GOSSYM increased root growth is triggered by leaf water potential under water stress. There is limited quantitative data to evaluate this mechanism. The purpose of this study was to investigate the effects of two water stress levels under ambient (350 ppm) and enriched (700 ppm) CO2 concentrations on the above and below ground development, and don the water use of cotton plants. Whole canopy photosynthetic and transpiration rates, and soil water content were measured continuously. Pre-dawn and midday leaf water potential were measured during the water-stress and the recovery periods. Root development and above ground plant growth were measured twice weekly throughout the growing period. Root growth was monitored using a minirhizotron system and by counting roots visible in digitized pictures taken with a miniature video camera inserted into the soil through a transparent tubes. Soil cores were collected for root length measurements at the end of the experiment. Leaf water potentia was higher in the high CO2 treatment both under well watered and the stressed conditions. During the stress period, the minimum soil water content for the ambient CO2 plants was significantly lower than for the high CO2 plants. The data suggested that lower leaf water potentials in the ambient CO2 treatments were associated with greater soil water extraction and lower minimum soil water contents. The relationship between root length and root dry weight was found to be linear: Y = 403 + 2624.1*DW (r2 = 0.84) where Y is root length in cm and DW is root dry weight in gr. Results indicate that root growth was enhanced in the water stressed compared to the well-irrigated treatments.