We researched the cambial zone and phloem in 6 beech trees (Fagus sylvatica L.) from the site near Šentjur during a period of winter dormancy, from 20th November 2009 until 25th April 2010. Intact tissue samples of wood, cambium and bark were taken in 1 or 2 week intervals. We embedded tissues in paraffin and used a rotary microtome to cut 8-10 ßm thick microscopic slides, which we stained with safranine and astra blue, and embedded in euparal. To analyse starch, we cut the slides using a sliding microtome and stained them with iodine. We used a light microscope and an image analysis system for the analysis. We observed the dormant cambial zone and the adjacent undifferentiated phloem and xylem cells. On average, the dormant cambial zone contained 4 to 5 layers of cells, after 18th April 2010, the number of cells increased. The number of undifferentiated sieve cells varied during the period of dormancy between 1 and 2 layers per radial row, and the first newly formed phloem cells appeared on 18th April 2010. At that time we recorded on average 4 layers of newly formed cells. The first newly formed xylem cells appeared one week later, on 25th April 2010. In our analysis of starch, we determined the surface portion of darker starch grains in parenchyma cells of the wood. Compared to the radial section, these grains were more clearly visible in the transversal section. It was shown that we should analyse a greater number of slides to obtain more reliable results on starch portions.
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