CHARACTERIZATION OF APPLE TREE LIGHT CLIMATE WITH HEMISPHERICAL PHOTOGRAPHY

Hemispherical (fisheye) photography, first developed for cloud descriptions and then adapted for ecological exposure studies, was tested for use in characterizing the light climate and canopy architecture of apple trees.

The technique utilizes inexpensive film, is rapid for collecting many samples, and can be analyzed by several techniques.
Analysis of the negative directly by false colour densitometry is very rapid and accurate.
The % sky in the photographic image is correlated to light climate measurements of photosynthetically active radiation (PAR) at the site of the photograph.

In a range of tree types and sizes, the % sky of hemispherical photographs has been found to be well correlated to: available total PAR, available diffuse PAR, sunfleck %, and specific leaf weight.
Using the above correlations, the % available light to selected spurs in dwarf. semi-dwarf, and standard apple trees was estimated during canopy development by hemispherical photographs taken at 4–6 day intervals.

After calibration to light conditions within tree canopies, the hemispherical photographic technique can be used for rapid evaluation of light climate modification by pruning, training, or other practices.

Symposium on High Density Planting

A.N. Lakso

https://doi.org/10.17660/ActaHortic.1978.65.8