Abstract

Samples of 66 autochthonous and 42 introduced provenances of Larix decidua were selected in respect of filled, empty and insect-attacked seeds vith the help of x-ray radiography. Thousand Grain Weight (TGW) was determined for each of the abore seed types within a sample. Seed was uniformly dewinged before weighing. Both these methodical aspects, namlely, the exact determination of the seed quality and the uniform dewinging of the material, are basic requirements for obtaining correct TGW values. In order to study the relationships between TGW and seed origin,the localities of the autochthonous provenances were divided into seven geographical regions: 1. Polish, 2. Sudetian, 3. Slovakian, 4. Rumanian, 5. Eastern Alpine, 6. Central Alpine, and 7. Western Alpine. The first four regions lie isolated from one another, whereas the remaining three form a continuous area of the Alpine larch. The average altitude of the regions 1-7 increases from east to west (excluding Rumanian larch). For TGW of larch, the following relationships have been found: (1) TGW values of filled seed lie between 3.73-10.81 grams. There is a direct relationship between the TGW and the average altitude of a region. The differences among the regions are gradual, i.e. the greater the difference betmeen the average altitutdes of two geographic regions, the farther apart lie the TGW values. The TGW for a particular altitude was found to be greater the higher the mountain massif in a region. (2) The TGW of empty seeds is about 70 per cent of that of filled ones. There was a tendency that with increasing altitude of the provenances, the relatire weight of the empty seeds also increased. (3) The TGW value of insect-attacked seeds was about 74.4 per cent of that of filled oncs. The insect-attacked seeds occurred chiefly in the provenances from low elevations. (4) The TGW values do not change even after the provenances have been introduced into other localities. Thus, TGW is genetically strongly fixed and only slightly modified by external factors. The following conclusions can be drawn from the results: The effectiveness of the various methods for separating the empty and the insect-attacked seeds from the filled ones can easily he checked by x-ray radiography. Of course, for practical purpose it is not necessary to remove empty seeds from the sample, if the density of sowing is estimated on the number of filled seeds. In view of the fact that TGW values of larch seed from different geographical regions are constant and specific, they could be used as a criterion for the identification of the origin of larch. However, the TGW variation among the regions has a c1inal character. which makes it difficult or impossible to determine the origin of provenance material lying on the boundary of two neighbouring regions. Chiefly in addition to other characters (e.g. form and size of cones, colour of flowers, etc. ), TGW can be useful for the identification of the origin of larch. For carrying out the identification test with the help of TGW, it is necessary to construct a standard TGW-frame for each region, based on a large and autochthonous seed material.

Keywords

seed weight; Larix; provenances; x-ray; Thousand Grain Weight

Published in

Studia Forestalia Suecica
1967,
Publisher: Skogshögskolan

Permanent link to this page (URI)

https://res.slu.se/id/publ/125287