The 2009 ASHS Annual Conference

Objective(s):
A variety of methods can be used to create environmental stresses for plant research. Some methods of inducing drought, salinity, and cold stress will be discussed with an emphasis on the implications of the methodology.

Using soil moisture sensors for controlled drought stress experiments.
Dr. Marc van Iersel, University of Georgia
Plant responses to drought stress not only depend on the severity of drought, but also on the rate at which the drought stress develops.  However, in many experiments, plants are exposed to drought by simply reducing the amount of water provided to the plants, or even by withholding water altogether.  In containerized plants, this may result in a very rapid imposition of drought, that is not representative of how drought stress is likely to develop under field conditions.   Using soil moisture sensors and a datalogger, it is possible to control both the rate of imposition, as well as the severity of drought stress, thus mimicking ‘real-world’ drought conditions.

Salinity stress in horticultural crops: Essential concepts and considerations to sound experimental details and procedures.
Dr. Raul Cabrera, Texas A&M
Besides quantity, water quality is one of the most significant factors affecting productivity and quality of horticultural crops, many of which are considered salt-sensitive. As horticulturists we all are familiar with the basic concept and measurement of salinity, almost invariable reported in the lumped parameter of electrical conductivity (EC), and experimentation with NaCl as the primary or sole salinizing agent. In this presentation the essential definition(s) and concepts of salinity will be discussed in light of its dynamic nature in the rootzone, the chemistry of the soil solution and its role in salinity stress.

Methods for evaluating whole-plant freezing tolerance:  silver birch (Betula pendula) as a model to determine the effect of regulated deficit irrigation or exogenous Abscisic Acid (ABA) on whole plant freezing tolerance.

Brent J. Markus, Nina L. Bassuk, Timothy L. Setter and Harold M. Van Es, Cornell University
Approximately 1200 silver birch (Betula pendula) were established in standard nursery trade size #3 containers (11.4 liters) and irrigated with microspray sprinklers.  Controlled deficit irrigation was managed and abscisic acid was applied to the root zone using the irrigation system.  Proportional injectors (Dosmatic MiniDos 2.5%) controlled the application of abscisic acid at four concentrations (0.01, 0.1, 1.0 and 10.0 μmol ABA).    Levels of plant ABA are being analyzed using ELISA.  A standard marine low temperature refrigerated container was modified for large scale hardiness and freezing tolerance evaluations to determine the effect of exogenous ABA or controlled deficit irrigation on whole plant freezing tolerance.