COMPARISON OF STRESS DETECTION GLASSES WITH OTHER SUNGLASSES

Though not part of the original project, the NASA stress detection glasses were compared to other readily available sunglasses. It has been noted that amber lenses can detect stress related changes in plants. Are these detectable changes comparable to the NASA glasses? Do other colors work?

Four pair of sunglasses were compared to the NASA glasses where the changes in the plant were already apparent. Colors evaluated were blue, green, amber and brown.

The colored glasses appear to enhance color differences that are the same color as the lenses. The blue and the green did not seem to do much to enhance visibility of changes in plants due to stress/mortality. The amber glasses did the best job of the sunglasses particularly where the foliage turned orange or brown. The brown glasses did amplify some changes but not to the degree of the amber glasses. Wade (1997) found that among the most effective glasses were those that block the blue and haze that comes from the scattering of blue light under hazy conditions. He also found that the inexpensive variety of blue-blocking glasses was as effective as the expensive one.

However, compared to the NASA stress detection glasses, none of the sunglasses detected as wide a variety of change nor did they adequately detect early changes like the NASA glasses did.

Schultz (2001) tested 19 lenses of various colors, including the stress detection glasses evaluated in the paper. His test used ponderosa pine. He found that the stress detection glasses showed no particular advantage at detecting off-color ponderosa pine. He also found that the stress detection glasses were too dark to conveniently or safely wear while driving or walking under forested conditions.