Needles Of Damaged Trees Research Articles

Changes in Levels of a-Tocopherol and Ascorbate in Spruce Needles at Three Low Mountain Sites Exposed to Mg2+-Deficiency and Ozone

The main objective of this study was the com parison of changes in levels of α-tocopherol and ascorbate in needles of spruce trees with various degrees of damage at three low mountain sites. The ascorbate content in needles of spruce trees with various degrees of dam age differs in the course of seasons as well as in the absolute level. The antioxidant status was affected mainly during summer. The content of ascorbate in needles of dam aged trees was significantly increased compared to that of undamaged trees. Despite seasonal and daily fluctuations, the level of ascorbate seems to be a good indicator for the degree of dam age in the case of symptoms described as montane yellowing. Together with an increasing content of α-tocopherol per chlorophyll, a rise of ascorbate content indicates enhanced oxidative stress in the needles of damaged trees, particularly in summer. Asc/αToc ratios were increased in needles of damaged trees. At the studied sites enhanced oxidative stress could be caused by the com bined action of Mg2+-deficiency, high ozone concentrations and high-light intensity, all inducing an increased production of radicals in combination with a reduced photosynthetic capacity

Investigations on the content indole-3-acetic spruce needles of healthy and damaged trees of various sites

Summary Surveys were made on the concentration of indole-3-acetic acid (IAA) in spruce trees of various sites. The concentrations of the hormone were specified with a radioimmunoassay after the needle extract had been purified in several steps. The content of IAA in needles of damaged trees was distinctly lower than the content in needles of healthy trees. Another feature was the annual rythm of the IAA content with the maximum of concentration in June. A distinct diurnal course with highest level of concentration during the early afternoon hours was also observed. The diurnal rhythm of the damaged trees was clearly lower. The supposition is that the lower IAA content is responsible for a premature needle abscission.