Variation in ultrastructure of chloroplasts in needles of silver fir [Abies alba Mill.] saplings growing under the canopies of diverse tree species

Ultrastructural traits of chloroplasts in needles of Abies alba saplings growing under the canopy of Larix decidua Mill. and Picea abies Karst. were studied. An acclimation of chloroplast from the palisade parenchyma to different light conditions created by the principal species of the canopy was assessed using transmission electron microscope and light microscope. A comparison of such chloroplast patterns as: number of chloroplast per palisade parenchyma section unite, chloroplast section surface, number of thylakoids per granum, number of grana per section surface of chloroplast, thylakoids section surface to stroma section surface ratio, number of osmophilic granules, and size of starch granules allowed to determine plasticity of the ultrastructures in response to irradiance level under each canopy. There was, for example, evidence that the number of thylakoids per granum was lower, whereas chloroplast section surface inversely, was higher at greater canopy openness. The investigated patterns of chloroplasts, which reflect their biochemical adaptations, might significantly affect photosynthetic capacity of the young firs. Their variation reflected an ability of Abies alba photosynthetic apparatus to acclimate to canopy shading at the ultrastructural level.