In this article:

This paper examines grapevines subjected to salt stress and shows that the response of leaf fluorescence depends upon maintenance of turgor pressure and osmotic adjustment.

Grapevine leaves subjected to salt stress showed an immediate reduction in variable fluorescence only where the osmotic potential of the watering solution exceeded cell turgor.

However the leaves rapidly osmotically adjusted to this salinity which led to a recovery of turgor and variable fluorescence by the next day. No decline in fluorescence was then recorded until excessive concentrations of chloride accumulated in leaves and they began to lose turgor.

It is apparent that short-term salt stress does not lead to an inactivation of photosystem ll activity in grapevine leaves provided turgor pressure remains positive or is restored through osmotic adjustment. However, the accumulation of excessive levels of chloride by the grapevine eventually causes cellular damage and a loss of turgor pressure.

Only at this stage does variable fluorescence decline to be followed by desiccation and leaf ‘bum ‘ symptom. Consequently the changes in chlorophyll α fluorescence in grapevine leaves subjected to salt stress are closely tied to plant water relations.

Turgor Maintenance during Salt Stress prevents loss of Variable Fluorescent in Grapevine Leaves

1983, Plant Science Letters, vol 31, pages 1-7

csiro 654

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