Seasonal Variation of Organelle Numbers in Sections of Fusiform Cambium Cells ofPinus radiataD.Don

Abstract

A method has been devised for estimating variation in numbers of organelle profiles in sections of fusiform cambial cells of Pinus radiata D.Don. The method was applied to mitochondria, plastids, spherosomes, and dictyosomes in samples taken at intervals during the year. The most informative study was that of mitochondria. Mitochondrial profiles are most abundant in sections of fusiform cells when the activity of the cambium is at a minimum; i.e., during winter, during “false ring” formation induced by drought, or in trees whose growth is suppressed. Results for the other organelles were less informative. The possibility of using this method of estimating mitochondrial profile frequency as a guide to, or even as an assay of, cambial activity is discussed.