Patent ID: 7199376

Claim:
A method of detecting the onset of an at least partially reversible stress condition in chlorophyll-containing matter caused by said chlorophyll-containing matter being exposed to a stress inducing environmental condition, the method comprising: (a) exposing the matter to light to cause chlorophyll in the matter to fluoresce and emit a fluorescence signal, (b) detecting the emitted fluorescence signal, (c) measuring the value of a parameter based on the detected fluorescence signal, (d) monitoring the value of said parameter, (e) detecting changes in the value of said parameter, (f) providing a threshold value of a predetermined level of change in said parameter which only if reached and exceeded signifies the onset of said at least partially reversible stress condition in the chlorophyll-containing matter caused by said stress inducing environmental condition, and (g) comparing changes in the value of said parameter with said threshold value, wherein a determination that the value of said parameter reaches and exceeds said threshold value signifies the onset of said at least partially reversible stress condition in the chlorophyll-containing matter caused by said stress inducing environmental condition.