Articles

Influence of x-rays on the fresh weight and the chlorophyll synthesis of spruce seedlings

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Abstract

Since  a few years, many X-ray techniques have been used for the control of forest  tree seeds. The influence of high quantities of X-rays and the enduring  character of these irradiations have been examined. After an imbibition time  of 24 h selected seeds of Picea abies KARST. (provenance Bodensee) were irradiated during different  periods, corresponding with 0 r, 690 r, 1.380 r, 2.590 r, 3.880 r, 5.175 r  and 10.350 r. Determinations of the fresh weight and the chlorophyll content  in different levels of the primary shoot have been done on nine weeks old  seedlings.        1. Influence of X-rays on the fresh weight    a. An irradiation time of 30 min (2.590 r) has a positive influence on the  fresh weight of each considered primary shoot level.    b. The irradiation effect disappears   as the seedlings grow up and the slightest influence has been observed  in the lowest levels of the primary shoot.    c. The influence of the irradiation is not so strongly marked in the  cotyledons because these needles are already present in the seed at the  moment of the applied irradiations.    2. Influence of X-rays on the chlorophyll synthesis    a. An irradiation time of 30 min (2.950 r) has a negative influence on the  chlorophyll synthesis. This quantity of X-rays probably brakes high energetic  reactions, necessary for the formation of chlorophyll. Irradiation times of 8  min (690 r) and 120 min (10.350 r) have a positive influence.    b. This X-ray effect is lost  as the  needles become older and is replaced by a 'formation' effect. This influence  is nothing else than a chlorophyll synthesis taking place in proportion to  the fresh weight.    c. The cotyledons must be considered separately. They are only liable to  the 'formation' effect because a great part of the precursors, necessary for  the formation of chlorophyll, exists before the X-ray treatment.    The influence of the used irradiations (0 r ~ 10.350 r) is in the beginning  of the development of the seedling very high, but disappears when the plant  grows up. It can be expected that on one year old seedlings the consequences  of a X-ray treatment can hardly be discovered anymore.     On the other hand it must be mentioned that an irradiation time of 120 min  (10.350 r) brings on a reduction of the germination percentage. Probably  10.000 r is the lethal limit dose.

How to Cite:

Thas, J., (1967) “Influence of x-rays on the fresh weight and the chlorophyll synthesis of spruce seedlings”, Silva Gandavensis 4. doi: https://doi.org/10.21825/sg.v4i0.1017