[Investigations of the needle foliage relations of spruce]

1. Previous studies of the needle foliage of spruces have mainly dealt with the question of the existence of a possible relation between needle volume and growth increment. The present paper addresses itself to the following points: a) What characters are important for the description of the needle foliage conditions of spruce ? b) What are the mean values of these characters and what are their standard deviations ? c) What influence have hereditary disposition and environmental factors respectively on the development of the characters ? d) What conclusions can be drawn for breeding purposes? The investigations are based on extensive material, composed of different provenience tests and evaluations of single trees. 2. For the character needle age class a relationship to the altitude of the locality of origin could not be shown. Environmental factors such as drought, nutritional difficulties, light conditions, effects of competition and exposure have such an influence that the needle age by itself cannot be used to characterize the condition of the needle foliage. 3. Differences in needle length are individually determined and therefore do not overlap the differences between the localities of origin. The absolute values are greatly influenced by environmental conditions. As a rule, shortened needles will develop in the growth period following a drought year. Although the genetical component will manifest itself very strongly, needle length cannot be used as a characteristic or serve as a basis to initiate selection. The average needle length of the test material was 15.18±2.46 mm. 4. The average surface area of a needle was found to be 36.61±8.34 mm(2). On the average 1211±443 stomata are arranged in 9.7 rows on this surface. Within a tree close correlations exist between needle length and needle surface, but if one compares several trees these correlations no longer hold. 5. A correlation of up to 90% was found between the "Thousand-needle-dry-weight" (TNG=3.30±0.95 g) and surface of the needles. This character may be used for the determination of the assimilation surface. Spruce trees from the same locality of origin may form greatly variable amounts of needles depending on the test sites. The differences increase with increasing ecological differences of the test locations. A very close correlation exists also between dry needle weight and altitude of the locality of origin on the one hand and dependence on the test site on the other hand, so that the adaptability of trees of different provenience to the new location may be estimated. 6. Comparisons of the needle foliage relations of several trees from several localities of origin on different soil locations may result in considerable shifts in the order of precedence and of other relationships. Conclusions as to the suitability for a certain site as well as an estimate of the genetical fixation of the potential efficiency up to an estimated maximum may be drawn. It may also be possible to determine an optimal range. These determinations are correlated with the question of the expediency of intensification measures, i.e. support by application of fertilizers. 7. The marked influence of the environment on the main characters under investigation prevents the selection of plus variants, whose superiority of performance would be based on characteristics of the needle foliage. Individuals which are to be tested, must therefore be propagated autovegetatively, and these clones must then be cultivated in different soil locations and be compared with regard to their needle characters. Experiments of this kind are now in progress.