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United States Department of Agriculture

Agricultural Research Service

Research Project: Strategies to Predict and Manipulate Responses of Crops and Crop Disease to Anticipated Changes of Carbon Dioxide, Ozone and Temperature

Location: Plant Science Research

Title: Quantifying plant age and available water effects on soybean leaf conductance

Authors
item Matthews, Jessica -
item Fiscus, Edwin
item Heitman, Joshua -
item Smith, Ralph -

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 1, 2012
Publication Date: January 12, 2013
Citation: Matthews, J., Fiscus, E.L., Heitman, J., Smith, R. 2013. Quantifying plant age and available water effects on soybean leaf conductance. Agronomy Journal. 105:28-36.

Interpretive Summary: Using an innovative technique for controlling soil moisture content in field plots, a statistical model was developed relating soybean leaf conductance to easily measured soil moisture content and to plant development under a range of soil moisture conditions. The resultant statistical model showed a surprising similarity to a physiological model invoking the influence of Abscisic Acid in plant responses to declining soil moisture.

Technical Abstract: In this study, we present data characterizing the effects of soil moisture levels on total leaf conductance for two distinct determinate soybean (Glycine max (L.) Merr.) genotypes and subsequently use these data to formulate and validate a model that characterizes total leaf conductance. Conductance data were collected for two soybean genotypes, Haskell and N01, grown in a controlled water stress field during 2008 and 2009 in North Carolina. An empirical model of leaf conductance based on plant age and soil moisture content was developed. As a function of plant age, conductance was well represented by a parabolic function increasing throughout the vegetative period, peaking at approximately the time of first flower, and decreasing throughout the reproductive period through senescence. A sigmoidal function explains the relation of soil moisture content to conductance. Conductance is lower under water stressed conditions and increases to a plateau as conditions are increasingly well-watered. This new empirical model effectively quantifies the response of total leaf conductance to soil moisture and plant age. It also relates soil moisture deficit to conductance via a functional form similar to the ABA-related mechanistic Tardieu-Davies model; however, soil moisture is a more easily accessible model input.

Last Modified: 9/2/2014
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