Quantifying Plant Age and Available Water Effects on Soybean Leaf Conductance
2013
Matthews, Jessica L. | Fiscus, Edwin L. | Smith, Ralph C. | Heitman, Joshua L.
Given the ever-present threat of drought and the knowledge that water availability is the strongest limiting factor in vegetation growth, it is important to characterize the effect of water limitations on agricultural production. In this study, a small field plot technique for controlling soil moisture content suitable for physiological research in moist, humid areas was tested. We characterized the effect of water stress on total leaf conductance (gₗ) for two distinct determinate soybean [Glycine max (L.) Merr.] genotypes. Based on these findings, a model of gₗ as a function of plant age and soil moisture content was formulated and validated. The dependency of gₗ on plant age was well represented by a parabolic function that increased throughout the vegetative period, peaked around anthesis, and decreased throughout the reproductive period and senescence. A sigmoidal function explained the relation of gₗ to plant-available soil water content. This new empirical model effectively quantifies the response of gₗ to plant-available soil water and plant age with a functional form similar to the abscisic acid related Tardieu–Davies model.
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