Page 154 - FRUTAS DEL TRÓPICO
P. 154
154 Frutas del trópico
Figura. 6. Typical pattern of chlorophyll fluorescence after leaf is illuminated Fo = initial fluorescence,
Fm = maximal fluorescence, Fv = variable fluorescence (Fm – Fo).
Plant Water Relations
Stem water potential (Ψ), a measure of the free energy of water, provides a good indication of
the water status in plants. Water moves to a more negative water potential. The components
of stem water potential are solute potential (Ψπ), matric potential (Ψm) and pressure poten-
tials (Ψp).
Ψ= Ψπ + Ψm+ Ψp
In xylem, solute and matric potentials are very low, so pressure potential is closely related
to stem water potential. Stem water potential is an indicator of plant water stress. A common
method of measuring xylem water potential is with a Scholander pressure chamber (Figure 7).
Universidad Autónoma de Chiapas
