Determination of the dynamic viscosity of vascular saps (η)
The measuring instruction of the dynamic viscosity was described in Adam
et al. (2009). The dynamic viscosity of the phloem sap was
quantified with 0.5 µl glass capillaries (CAMAG®, Muttenz, Switzerland).
The calibration required the determination of the specific viscometer
constant (κ = mPa l g-1) by using H2O
as reference solution with known dynamic viscosity (η0 =
1.0087 mPa s) and density (ρ0 = 997.9 g
l-1) for 20 °C. Following the measurement of elapsed
time (t0), the specific viscometer constant was
calculated:
\begin{equation}
\kappa\ =\ \frac{\eta_{0}}{\rho_{0}\ t_{0}\ }\ (\frac{\text{mPa\ l}}{g})\nonumber \\
\end{equation}The dynamic viscosity of the phloem sap was calculated after the
measurement of elapsed time (t) and determination of density (ρ):
η = κ * ρ * t (mPa s)