Causal relationship between juvenile shoot growth characters in picea abies

The causal relationships between shoot growth variables were analysed on the basis of a study in the Phytotron where six full‐sib families of Picea abies L. (Karst.) were grown for six growth periods. Phenotypic correlations and path analysis were used for the analysis of causes. The phenotypic correlations were estimated in three different ways: 1) separate analyses within each growth period based on individual tree data, 2) based on family means at different growth periods (0, and 3) using differences in family means between two consecutive growth periods (dt). The two methods based on t or dt‐values gave different results in a number of cases. We argue that, because of the rapid concurrent changes that occurred between growth periods, we could not conclude that the correlations based on family means (t) reflected causal relations and, also, that the method based on dt‐values gives a better indication of causal relationships between different variables. Using dt‐values, the variation in shoot elongation period was mainly explained by the variation in free growth (82%) while the variation in shoot growth initiation only explained a minor fraction. Variation in leader length was mainly explained by growth rate and only to a minor extent by shoot elongation period, meaning that the observed decrease in shoot elongation period did not cause a corresponding changé in leader length. One conclusion from this finding is that we do not necessarily lose growth capacity if we breed for a better adapted growth rhythm (i.e. shorter shoot elongation period) of the seedlings.     

Estimated bud development period in Picea abies

The bud development period was estimated using shoot growth data from a Phytotron study in which six full‐sib families of Picea abies L. (Karst.) (Norway spruce) were grown for six growth periods. Simple algebraic relationships based on assumptions of the relationship between shoot growth and bud development were used. The estimated bud development period, defined as the period when the budscale and needle primordia were initiated, decreased as growth periods advanced. Furthermore, the relationship between the period of production of free growth needles and bud scales to that of predetermined needle primordia was surprisingly constant irrespective of the change in free growth. These results indicate that free growth during one year did not encroach on the period of predetermined growth, but instead increased the amount of predetermined growth.     

Environmental influences on juvenile shoot growth in Picea abies

Under certain environmental conditions, juvenile shoot growth characters might give early indications of adaptability and growth potential. Therefore, the reaction patterns of predetermined and free shoot growth were studied on Picea abies (L.) Karst, plants, which at different times during the growth period were treated by (1) application of nutrients, (2) defoliation, and (3) short days. Fertilization caused an increase in both predetermined and free growth, while defoliation and short day treatment caused a decrease in both forms of shoot growth and short days did not allow any free growth to occur. In the growth period following the treatments, fertilization caused more predetermined and less free growth to occur, while defoliation caused less predetermined and more free growth. Predetermined growth is explainable by the finite number of predetermined needle primordia. Free growth is initiated thereafter. It is influenced strongly by the environmental conditions and seems not to be influenced by the amount of preceding predetermined growth. Free growth enables young plants to utilize favourable growth conditions in summer for height growth precociously, which might increase their adaptability and competitive value. However, predetermined growth is the preferable mode of shoot growth because favourable conditions in successive growth periods induce more predetermined than free growth. Predetermined and free growth are well integrated forms of shoot growth giving no supporting evidence to the hypothesis that free and predetermined growth are inherited independently of each other. Rank changes in provenance development are probably not explainable by a loss in height growth when free growth occurs no more due to age, but by other causes.     

Genetic control and age‐related changes of juvenile growth characters in Picea abies

In full‐sib families of Picea abies (L.) Karst. (Norway spruce) the dynamics of juvenile growth and the inheritance of the most important growth characters were analysed in six growth periods in climate chambers followed by two additional growing seasons in a nursery. The full‐sib families were of French and North Swedish origin including both within and between provenance crosses. All growth rhythm characters changed over time. For instance, number of days to budbreak increased, whereas days to budset decreased, as growth periods advanced. Concurrent with the changes in growth rhythm, free growth decreased with increasing age. Half of the total variation for different growth rhythm characters within a growth period could in most cases be explained by provenance effects. Early selection is, therefore, meaningful to reduce damage by frost and mortality. Furthermore, the actual distances between family means decreased substantially with increasing age, and the actual length of the shoot elongation period decreased from 31 days during the second growth period to 16 days during the sixth. We suggest therefore that selection together with some treatment in the nursery that alters the growth rhythm of the seedlings are the best ways to increase frost resistance. Tree height was influenced by a set of complex gene actions that changed over time. Provenance effects were important during the first two growth periods. Subsequently, non‐accumulative within provenance family variance took over. If this pattern holds true in general, juvenile selection for height growth in Norway spruce cannot be made as early as that for growth rhythm.     

A selection experiment for height growth with cuttings of Picea abies (L.) Karst

Twenty sets, each consisting of a tall, a medium, and a small plant, were selected from a 2 by 2‐year‐old nursery crop. Selection differential was measured. Cutting propagation was undertaken and the subsequent clones were tested in a field experiment. Differences between groups at age 1, 2, 3, 6, 8, and 10 were calculated, and ortet/ramet regressions and age‐to‐age correlations were conducted. Selection of the tall plants gave a response of approximately 17% at age 10. Accumulated genetic gain at this age by a specified stepwise selection procedure is estimated to 36%. Step one is the early selection in the nursery, step two is a later selection amongst the early selected clones and performed after 7 years’ field testing. Ageing of clones, selection for other traits and application of the clones over a variety of sites will reduce these gains.     

Modelling incidence of root rot in picea abies plantations in Southern Sweden

An empirical model is presented to forecast the incidence of root rot at stand level. In addition, the impact of different thinning programmes on the incidence of root rot is evaluated. The model is based on data from 152 permanent forest research plots of pure Picea abies in southern Sweden, within which the incidence of root rot at stump height in thinned trees has been recorded after each thinning since 1950. In total, about 20 000 stumps have been studied. According to simulations with the model, areas previously used as fields or for grazing are particularly susceptible to root rot, while old hardwood sites are less susceptible. Furthermore, simulations with the model imply that the earlier, the harder or more often a stand is thinned, the faster will be the development of root rot.     

Genetic variation in nutrient utilization and growth traits in picea abies seedlings

Genetic variation in nitrogen (N) and phosphorus (P) utilization (amount of total biomass produced per unit nutrient in the needles) and growth traits in seedlings from 30 open‐pollinated families of Picea abies (L.) Karst. was estimated. Seedlings were grown under two nutrient regimens: free access to nutrients and restricted access. There was a strong treatment effect on most growth traits. With free access, families allocated relatively more biomass to the stem and less to the roots than they did with restricted access. Heritabilities for growth traits were higher with free access treatment (0.33–0.81) than with restricted access treatment (0.20–0.45). Family variance components for N and P utilization were significant (p < 0.05) with restricted access but not with free access. Genetic correlation between nutrient utilization and height traits with restricted access ranged from none to moderate ( — 0.31 to 0.56). Genetic correlations between the same trait assessed in the two treatments were strong for height and moderate for biomass.     

Stand volume functions for picea abies in western Norway

A material of 1156 observations was used to develop two Norway spruce (P. abies (L.) Karst.) stand volume functions for western Norway. An additive model initially based on a polynomial of second degree was found to be most suitable. The independent variables were stand basal area, Lorey's mean height, the product of basal area and mean height, and the square of the mean height.

In order to roughly reflect the different climatical conditions within western Norway, all municipalities were classified into the categories “inland” and “coast”. The individual observations were assigned the category of the municipality in which they were sited. The type of district was included in the selected additive model by means of a dummy variable approach. Testing showed that two individual regressions should be recommended for prediction purposes in the respective districts. R² was 0.998 and C.V. was less than 2.5%. The regressions fitted most parts of the material very well, with exception for low densities for inland districts. Testing by means of an independent data set indicated no systematic differences.     

Effects of growth regulators on germination of picea abies and Pinus sylvestris seeds

Nine seed lots each of Norway spruce (Picea abies L.), and Scots pine (Pinus sylvestris L.) were treated with combinations of the growth regulators: Indole‐3‐acetic acid, indole‐3‐butyric acid, etephone, kinetin, fusicoccin, and the gibberellins A₁ A₃ A_4/7, and A₉. GA₉ GA_4/7 and fusicoccin significantly promoted the germination of five Norway spruce, and three Scots pine, seed batches. Independent of species, the germinability of seeds treated with auxins, etephone, kinetin, GA₁ and GA₃ were unaffected or reduced. The rate of germination was stimulated for both species when treated with GA₉ or GA_4/7. The germination percentage for Scots pine seeds was enhanced by GA₉ but not by GA_4/7. Neither of the two GAs enhanced the germination percentage of Norway spruce seeds.     

Genetic variation and ortet/ramet relationships in a clonal test with Picea abies

Eight trees were selected at age eight years from seed in each of 52 full‐sib families of Picea abies and were propagated by rooted cuttings. The parents were both of Norwegian and German origin. Results are presented for the variation in height growth in the progeny test and in the clonal test, for rooting percentages, and for plagiotropic growth. More than 40% of the total variance of rooting percentages is of genetic origin. In the set of crosses between Norwegian and German parents 18% of the clones were classified as plagiotropic, while the same number was 27% in the crosses between Norwegian parents. The plagiotropic growth reduces the correlations between ortets and ramets both at the individual and at the family level. Family information is important in the selection of ortets, and a culling of plagiotropic clones seems necessary to obtain a substantial gain from selection.     

A comparison between three different methods of measuring knot parameters in picea abies

Both foresters and sawmillers are interested in the knot structure of trees; in particular, position and number of knots, knot diameter, knot length and dead knot border. For research purposes, it is possible today to carry out non‐destructive measurements using computer tomography (CT) and image analysis. The aim of this study was to measure knot parameters on Norway spruce (Picea abies (L.) Karst.) using a non‐destructive method developed for Scots pine (Pinus sylvestris L.), and to compare the results of this method with the results of two different destructive methods. In order to do this, two Norway spruce stems were scanned by CT. Then five logs from one stem were cut into flitches 20 mm thick and the defects on the sawn surfaces were scanned manually. The other stem was cut just above every whorl and then each knot was split through its centre and the knot parameters were measured manually. The study showed that the CT method compares well with the destructive methods. It is a reasonably fast, non‐destructive method which measures position and diameter of knots and detects larger knots with acceptable accuracy. The study also showed that a large number of smaller knots were not found by the CT method and that the CT method measured knot length and dead knot border with low accuracy. This means that the CT method has to be adjusted to Norway spruce in order to improve its ability to measure knot length and dead knot border and to detect smaller knots.     

Earliness and growth performance in clones of picea abies selected for late frost resistance

Four late frost reistant trees in a young plantation of Picea abies were selected and compared with 15 non‐resistant ones after they had been propagated as cuttings. Two cutting trials were established, one in a nursery and one at the original selection site. Flushing, growth rate and total growth were assessed during four years. Frost resistant clones were found to be delayed in their flushing and growth development in early summer as compared to non‐resistant clones but the differences were not statistically significant. Large block variance and errors reduced the power of the statistical tests. Clone, site and year were found to be significant sources of variation in ANOVA, but neither interaction between clone and site nor clone and year were statistically significant. It is concluded that differences in growth rhythm parameters cannot be established between resistant and non‐resistant clones in this experiment, but the results are encouraging for the deployment of clones in forest plantations, provided the clones are tested and their performance remain stable over several propagation cycles.     

Vitality rating of picea abies by defoliation class and other vigour indicators

The study was made to assess the relationship between visually estimated defoliation class and a number of other variables depicting the vitality of Norway spruce (n=50). Variables characterizing crown size and condition were determined on the standing trees. Electrical impedance (an indication of the physiological status of a tree) was measured in the inner bark tissue of the living trees. Shoot growth and needle variables were determined from the detached sample branches. Negative correlations were found between defoliation class and the growth parameters (5‐year height, radial and volume growth of the trunk). Positive correlations were observed between the needle loss class and the abundance of branch damage, secondary shoots and impedance values. 18 variables (defoliation excluded) describing tree size and vitality were summarized in a factor analysis incorporating 5 factors. These were interpreted as 1) vitality, 2) foliage discoloration, 3) tree size, 4) needle number and 5) needle size factors. The tree‐specific score values for the first factor were interpreted as “vitality indices”;. The rank correlation between these score values and defoliation degree was 0.835. This result suggests that the defoliation class and vitality parameters contributing to the first factor give a consistent estimate of the tree condition.     

Shape and distribution of knots in a sample of picea abies logs

In an attempt to develop a better understanding of the effect of knottiness on the yield of logs for sawn timber products, the present study examines the position and geometrical characteristics of 429 knots found in seven Norway spruce (Picea abies (L.) Karst) middle logs from southern Finland. The raw data used in this study were in the form of coordinates of points located on the knot surface recorded in a cylindrical (R, L, T) reference frame. The data were smoothed using a non linear three‐dimensional model. A curvature analysis of the knot pith was used to differentiate the curved and straight portions of the knots. This analysis made possible calculation of knot angles, symmetry, ovality and volume. The major finding of this study is the uneven distribution of knots around the log circumference. Nearly 50% of the total knot volume was concentrated in one‐third of the log facing the south‐east. Knots were also more prominent in higher portions of the logs studied. These observations support the argument that the uneven distribution of knots offers potential for improving the grade yield of timber sawn from trees harvested in high‐latitude countries.     

Variation in growth of Heterobasidion parviporum in a full-sib family of Picea abies

Abstract

Heterobasidion parviporum (Fr.) Niemelä & Korhonen and Heterobasidion annosum (Fr.) Bref. sensu lato are some of the major forest pathogens in the northern hemisphere causing root and butt rot to conifers. The relative susceptibility to H. parviporum was investigated in a full-sib family of Norway spruce [Picea abies (L.) Karst.] by inoculating a set of 252 cloned progenies from a controlled cross. Four ramets of each progeny were used and the 2-year-old rooted cuttings were incubated for 6 weeks under greenhouse conditions. The condition of the cuttings was assessed visually and all the plants were in excellent vigour with no mortality recorded during the experiment. To score the relative susceptibility, lesion length in the inner bark and fungal growth in the sapwood were measured. Among the progenies, significant differences were found for fungal growth in the sapwood (p<0.0005). There was no significant difference for lesion length; however, there was a significant positive correlation between fungal growth and lesion length. The broad-sense heritability was 0.11 for fungal growth. This shows that the genetic component for susceptibility to H. parviporum can be detected even within a full-sib family of Norway spruce and that there is a potential for mapping quantitative trait loci for this trait in Norway spruce.     

欧洲云杉苗期生长指标研究

以引进的欧洲云杉和乡土种青海云杉、粗枝云杉种子5年生苗的苗高、地径、当年新梢生长量、分枝数、总芽数及二次抽梢等6个生长指标,进行了差异显著性分析,结果表明,欧洲云杉较乡土种在苗期即具有显著的生长优势,在适生区选择欧洲云杉育苗,即可解决云杉育苗周期长的问题。     

A test of the accuracy of two individual tree growth functions for Picea abies

The accuracy of two distant‐independent diameter growth functions for individual trees of Picea abies L. (Karst.) are tested on plots older than 55 years b.h., and with relatively few trees per hectare. Both functions (I1 and I2) have site index, stand basal area, and individual tree basal area as explanatory variables; in addition age at breast height is used in Function I1. Relative to mean measured increment, Functions I1 and I2 underestimate the growth of the test plots by 4.4% and 10.9% respectively; Function I1 shows a root mean squared deviation of 29.2% for single plot predictions, and 5.4% for mean of all plots. Function II predicts the growth as well as some stand functions frequently in use in Norway. Function I2 is unacceptable because age is not an independent variable.     

Genotypic variation in natural infection frequency of Heterobasidion spp. in a Picea abies clone trial in southern Sweden

Abstract

Natural root and butt rot infection with Heterobasidion spp. was recorded on three occasions in trees from a 20-year-old Norway spruce [Picea abies (L.) Karst.] clone trial. In the first assessment, carried out when the trial had been running for 15 years, 29.5% of the trees felled were infected with Heterobasidion spp., but no statistically significant differences were found between the different clones. In the second assessment, also at 15 years, bore cores were taken from 595 trees. Of these cores, 16.5% were infected, but again no statistically significant differences were found between the different clones. Combining the two first assessments also revealed no significant differences. The discrepancy in rot incidence between the two assessments was explained by the inaccuracy of the bore core method. The third assessment was carried out after the trial had been running for 20 years. At that time, 424 trees of 50 clones were felled and sampled. Visible infection was recorded in 46.5% of the trees. The differences between clones were statistically significant and the broad-sense heritability estimate was 0.18. There were no significant genotypic correlations between tree size and rot infection; this is important for the Norway spruce breeding strategy. Calculations show that economic viability would increase by 0.28 SEK per plant for every 10% decrease in root rot frequency at final felling.     

Growth and survival of seedlings of various picea species under northern climatic conditions

The main purpose of these studies was to investigate the adaptation of young seedlings of various seed lots of Picea abies (L.) Karst., P. glauca (Moench) Voss, P. x lutzii Little and P. sitchensis (Bong.) Carr. to northern climatic conditions. Effects of temperature and photoperiod on elongation growth and growth cessation were studied under controlled conditions in a phytotron. In addition, growth and survival of the seedlings outdoors at 69°39’ N lat. were followed for two years. Seed lots of /’. abies originated from northern Norway (66° N lat.), those of the other species were from Alaska (between 57°.and 66° N lat.). The critical photoperiod for budset was 19–20 h for seed lots of P. abies. In general, the critical photoperiod for budset increased with increasing latitude of the seed source, but the results indicated a significantly shorter cirtical photoperiod for seed lots from about 60° N lat., <120 m a.s.l. of P. sitchensis (between 12 and 16 h) than for comparable seed lots of P x lutzii (17–18 h) or P. glauca (18 h). The time course of budset under natural light conditions, both in the phytotron and outdoors, generally followed the pattern predicted from the critical photoperiod. However, in P. glauca the budset occurred earlier than in P. abies although the latter had a longer critical photoperiod. Due to the short critical photoperiod and consequently delayed growth cessation and hardening, all seed lots of P. sitchensis (from 58° to 60° N lat.) were severely damaged during winter. Some damage was also observed in P. x lutzii and in P. abies. The optimum temperature for elongation growth was higher for P. sitchensis than for the other species. In the phytotron experiments, seedlings of P. sitchensis grew best at temperatures between 12 and 21°C, but at 9°C the best growth was obtained in some seed lots of P. abies. After two growth seasons outdoors, all seed lots of P. abies were taller than any seed lot of the other species. Also P. glauca seed lots and one seed lot of P. x lutzii showed good growth, and their growth rhythm seemed to be well adapted to the northern conditions.     

Application of growth regulators in aqueous media and organic solvents to seeds of Picea abies and Pinus sylvestris

Incubation with acetone and dichloromethane had little effect on the germination of different lots of Norway spruce seeds. This was not the case with Scots pine where almost half the seed lots tested were adversely affected by acetone and dichloromethane. The auxins indole‐3‐acetic acid (IAA) and indole‐3‐butyric acid (IBA) were applied to Scots pine seeds in acetone, dichloromethane and phosphate‐citrate buffer. The uptake of the two compounds was most rapid from acetone. Although the uptake from dichloromethane was slower than from acetone it reached the same level after 6 h. Uptake of the growth regulators from buffer was significantly lower than from the organic solvents. The accumulation of IAA and IBA into the seeds from both acetone and dichloromethane was linear between 0.5 and 10 mM, and between 0.5 and 15 mM from buffer. IAA and IBA levels in infused seeds declined over a 5‐day germination period, the former more rapidly than the latter. The metabolic activity of the IAA degradation system was as effective in seeds after immersion in the organic solvents as seeds immersed in buffer.