Licht- und elektronenmikroskopische Untersuchungen an Blättern mehrerer Kartoffelsorten nach Salzgaben zu verschiedenen Entwicklungsstadien

Zusammenfassung

Veränderungen in der Blattfeinstruktur als Folge von in verschiedenen Entwicklungsstadien einsetzender Versalzung wurden bei den Kartoffelsorten Hansa und Clivia mehrmals im Vegetationsablauf untersucht. Die Chloroplasten reagierten am deutlichsten auf den Salzstre\: ein Abbau der Granastapel, Schwellungen der Thylakoide, mehr und grö\ere Plastoglobuli sowie Stärkeakkumulation wurden beobachtet.

‘Hansa’ schien zu Beginn der Vegetationsperiode salzempfindlicher zu sein, da sich hier stärkere strukturelle Veränderungen zeigten als bei der Sorte Clivia, deren Chloroplasten erst gegen Ende der Vegetationsperiode Beeinträchtigungen aufwiesen.

Summary

The leaves of the potato cultivars Hansa and Clivia were examined by light and electron microscopy after salt treatment. Salt was applied once: a week after emergence, at the beginning of tuber formation, or during tuber development. The salt solution (conductivity 12 mS/cm) contained NaCl and Na₂SO₄, and was administered to the water capacity of the pots. Leaf samples were taken at three different stages of vegetative development (Figure 1).

In leaf sections examined by light microscopy, salt stress resulted in a rounding off of cells, smaller intercellular spaces and a reduction in chloroplast number.

With the electron microscope salt-induced changes were more marked in the chloroplasts than other organelles. Salt reduced the numbers and depth of the granastacks and caused a swelling of the thylakoid. Changes in ultrastructure were already apparent before the occurrence of other symptoms in the leaf.

The observed changes in the chloroplasts of plants treated with salt were alwas greater in the palisade parenchyma than in the spongy parenchyma (Figure 3a, 3b).

The cultivars Hansa and Clivia reacted differently to salt. At the start of the vegetative period ‘Hansa’ (Figure 2b, d) appeared more sensitive than ‘Clivia’ (Figure 2c) with greater ultrastructural changes. By the last sampling date ‘Clivia’ was showing the greatest effects (Figure 4). Large starch grains in the chloroplasts indicated disturbed transport of assimilates. Often there were no grana, but severely swollen thylakoids, usually with disintegrating membranes.

Changes in the chloroplasts, especially in the thylakoids, as established by microscopy, presumably affected photosynthetic and assimilative performance.