Maturation, topophysis and other factors in relation to rooting in Larix

We examined effects of mist quantity, topophysis (origin of cutting in the crown of 6-year-old trees), maturation state of the donor stock, and time of sticking on rooting and root system quality of cuttings representing five full-sib hybrid larch families obtained with Larix decidua Mill., L. laricina (du Roi) K. Koch, and L. kaempferi (Lamb.) Sarg. (Sieb. and Zucc.) Gord., as parents. Mist frequency, supplemental watering and family all had highly significant effects on percentage of cuttings rooting and root system quality. The high-frequency misting regime yielded both higher rooting percentages and higher quality root systems than the low-frequency regime without supplemental watering. Supplemental watering of the rooting medium in the low-frequency misting regime increased both percent rooting and root system quality to values comparable with those obtained by cuttings in the high-frequency misting regime. Rooting of cuttings from the top, middle and bottom whorls of 5-year-old plantation grown trees tended to decline with increasing height for three of the five families. Overall, height of cutting origin did not significantly affect rooting, but when analyzed separately, two families exhibited a significant decline in rooting toward the top of the trees. Age of donor ortet (ranging from 1 to 7 years) significantly affected both percent rooting and root system quality. Rooting percentages declined linearly with age, and root system quality declined more sharply than percent rooting. The relatively poor root system quality of cuttings from ortets older than 1 year was closely associated with plagiotropic growth. Softwood cuttings (stuck in mid-July) rooted better than hardwood cuttings (stuck in early September) across all families.     

扦插过程中秤锤树插穗内激素含量的变化

采用酶联免疫法测定了秤锤树扦插过程中插穗的内源激素含量的变化。结果表明,2年生母树插穗内的IAA、ZR含量大于10年生母树插穗,利于生根;10年生母树的插穗内ABA含量大于2年生母树的,表现出对生根的抑制作用;在春夏季扦插IAA/ABA呈下降趋势,在生根关键阶段,处理大于对照,表现出促进生根,而ZR/IAA值是对照大于处理,表现出抑制生根的作用。     

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.     

杂种落叶松连续繁殖与插穗生根关系的生理研究

观察了日×长杂种落叶松连续繁殖插穗不定根发育进程,研究了连续繁殖对插穗生根力衰退的阻滞效应,并分析了一轮采穗圃与原株采穗圃插穗不定根发育期内源激素含量的动态变化。结果表明:扦插后13 31 d是愈伤组织形成和不定根原始体分化发育的关键期,此时一轮分生株愈伤组织形成和不定根发育均优于原株。连续繁殖对插穗生根性状有显著作用,尤其是生根率很低的原株,经过一轮繁殖后,生根性状有极显著提高。连续繁殖影响插穗自身激素含量,尤其是IAA,经过一轮繁殖后,含量明显高于原株。从不定根发育过程中激素的动态变化看,一轮分生株插穗(IAA+GA3+ZR)/ABA比值在不定根发育前期明显高于原株,与生根率的变化一致,可用来衡量不同繁殖次数插穗生根性状的优劣。     

Morphology and rooting of shoots developing in response to decapitation and pruning of Caribbean pine

The effects of decapitation at various levels, combined with heavy pruning of remaining branches, were examined for Caribbean pine. This treatment stimulated the development of shoots with long primary needles at all levels in the crown of trees aged one, four and eight years. Although a significant positive relationship between primary needle length and rooting was demonstrated, the very juvenile appearance of these shoots was not a reliable guide to rooting. There was an over-riding effect on rooting of the ortet age × level in crown × decapitation height treatment. Decapitated trees provided shoots of higher rooting capacity than intact trees for the one and four, but not the eight year old trees. Shoots developing in the lower crown in response to decapitation and heavy pruning of four year old trees displayed a high level of rooting-equivalent to that of shoots from the decapitated and pruned one year old trees.     

Rooting Success of Cuttings from Young Picea abies in Transition to Flowering Competent Phase

Abstract

Abundant flowering occurred in a central Swedish trial with 10-yr-old Picea abies L. (Karst.) cuttings, taken on 4-yr-old seedlings. Large deviations in cone-set between clones were assumed to reflect different stages in transition from juvenile to flowering competent phase. Rooting success and first-yr growth performance (leader length, leader origin and plagiotropic growth) were studied on cuttings originating from the upper and lower parts of the crown in 15 clones with heavy cone-set and 15 clones without cones. Twigs from the lower part of the crown had a significantly higher rooting percentage. Cone-set did not have an effect on any of the variables analysed. The results suggest that flowering ability and rooting capacity are independent age-related processes, implying that selection for high rooting capacity in clonal forestry does not reduce flowering competence. The results will have a great impact on breeding of P. abies, since both early flowering and high rooting ability are important traits for reducing the turnover time of the breeding cycle.     

Rejuvenation of juvenile growth characters in picea abies

Cuttings were made from six‐year‐old seedlings of Picea abies L. (Karst.) that had been studied in the Stockholm phytotron. The seedlings belonged to four full‐sib families, one being of French origin, one of North‐Swedish origin and two being hybrids between parents of North‐Swedish and French origin. Nine clones from each family were included. After the rooting phase, the cuttings were exposed to the same cultivation regimes as the seedling ortets. Characteristics of growth rhythm, percentage free growth and leader length were recorded during the 2nd to the 5th growth period (GP). Plagiotropic growth habit was recorded in the 3rd to the 5th growth period, and, characteristics of the rooting phase were studied. A juvenile behaviour very similar to that characterizing growth periods 2–3 of the seedlings was observed for growth rhythm characteristics and for free growth capacity during GP2 of the cuttings. The absolute value of the differences between each observation of the seedling ortets in GP6 and the means of the cuttings in GP2 produced a new variable that quantified the degree of rejuvenation. This new variable was meaningfully calculated only for growth rhythm and growth pattern variables. A gradual reversion of the growth rhythm occurred for the cuttings, which corresponded to the change with increasing age for the seedlings. The capacity for free growth, on the contrary, disappeared already in GP3 for the cuttings, except for the French family. A large variation in the rejuvenation ability between families was observed. Furthermore, the rejuvenation ability was negatively correlated with the ability to grow plagiotropically.     

不同穗条类型、长度的欧洲云杉扦插苗质量评价

[目的]为欧洲云杉扦插穗条选择和扦插苗培育提供依据。[方法]采用完全随机区组试验设计,研究了2种穗条类型(嫩枝基部带1.5年生硬枝、嫩枝)、3种穗条长度(5 10、10 15、15 20 cm)的嫩枝扦插苗从移植当年到第3年的成活率、保存率和生长情况。[结果]2种穗条类型扦插苗间的移植成活率和保存率差异不显著,但移植后嫩枝基部带1.5年生硬枝扦插苗的苗高、新梢生长量、地径、侧枝数、冠幅、鲜质量、干质量差异显著,都是嫩枝基部带1.5年生硬枝扦插苗大于嫩枝扦插苗。3种长度扦插苗的移植成活率、保存率的差异均显著;其中,15 20 cm长度穗条扦插苗移植成活率和保存率最高,分别是98.00%和86.00%,不同长度穗条扦插苗移植成苗率逐年下降,而且与穗条长度有关,弱小穗条获得的扦插苗成苗率低;5 10 cm的扦插苗移植成活率为46.00%,到第3年时保存率仅为23.33%,且移植后苗高、新梢生长量、地径、侧枝数、冠幅、鲜质量、干质量的差异也显著,且都以15 20cm穗条的扦插苗值最高,10 15 cm穗条的扦插苗次之,5 10 cm的扦插苗最小。嫩枝带硬枝扦插苗的苗木质量指数(QI)是嫩枝的7.74倍,15 20 cm穗条的扦插苗质量指数(QI)是5 10、10 15 cm扦插苗的5.47、5.23倍。扦插苗地径初始值与移植当年地径、苗高初始值与移植当年苗高间呈极显著正相关关系。[结论]扦插苗最初的生根状况和穗条质量影响后期培育过程中的存活和生长,嫩枝基部带1.5年生硬枝扦插苗和15 20 cm穗条的扦插苗不仅移植成活率、保存率高,而且生长量、生物量、质量指数都比短而弱小穗条的扦插苗高。     

Rooting and early shoot characteristics of Picea abies (L.) karst. cuttings originating from shoots with enforced vertical growth

Picea abies mother‐plants from 10 serially propagated clones (14 years old, chronologically) were treated in four different ways: (1) control with intact, non‐manipulated plants; (2) like (1) but with the leader cut off; (3) intact plants but with all branches of the upper two whorls forced to grow in a vertical way; and (4) like (3) but with the leader cut off. Cuttings from four positions (cutting‐types) on the mother‐plants were collected, rooted and evaluated for rooting %, number of main roots, number of lateral roots, plagiotrophy, needle symmetry on leader and growth of leader. Treatments 3 and 4 resulted in cuttings with more plagiotropic growth but with better rooting, more lateral roots and better growth than did cuttings from treatments 1 and 2. The genotype had a significant influence on rooting. Number of main roots was significantly influenced by the genotype and the cutting‐type, but not of the mother‐plant treatment. Symmetry of needles on the leader was fairly weakly influenced by genotype and cutting‐type yet not influenced by mother‐plant treatment. Clone effect was significant for leader growth.     

杨树新无性系扦插生根特性的研究

以杨树新无性系ＮＬ－８０１０６、ＮＬ－８０１２１和ＮＬ－８０３５１为材料，从解剖学角度研究其插插生根的机理。结果表明，无性系ＮＬ－８０１０６的生根能力较ＮＬ－８０３５１强；插穗的不定根原基在母株生长早期形成，起源于射线与形成层交叉处；不定根原基的数量随着苗高的增长而增多；但插穗的生根能力与不定根原基的数量关系不大。     

Growth and branching habit of rooted cuttings collected from epicormic shoots of Betula pendula Roth

Patterns of shoot growth and branching were studied over two growing seasons in rooted cuttings collected from both epicormic shoots and seedlings of Betula pendula Roth. Epicormic shoots were induced to sprout on stumps and small logs of 5-, 10- and 30-year-old trees. The use of epicormic shoots enhanced the rooting capacity of stem cuttings collected from these shoots but did not appear to reverse the process of maturation. In this study, maturation was based on characteristics typical of mature trees but not necessarily those of the mother plant, because it was not possible to root cuttings, for comparison, from 5-, 10- and 30-year-old ortets, other than from epicormic shoots. There was evidence of the persistence of mature characteristics through an increase in shoot plagiotropism with increasing ortet age. Rooted cuttings from both seedlings and epicormic shoots, however, assumed an increasingly orthotropic habit with a smaller shoot angle at the end of the first growing season than at the beginning and this continued into the second growing season. Other indications of maturation, such as delayed bud flushing and the incidence of flowering with increasing ortet age, were also evident in rooted cuttings from epicormic shoots. There was a clear difference in branching habit depending on cutting source. Rooted cuttings derived from epicormic shoots produced nearly twice as many lateral branches compared with rooted cuttings collected from seedlings, but this was not an effect of maturation. There was some evidence that rooted cuttings derived from seedlings grew taller than rooted cuttings from epicormic shoots.     

Vegetative propagation studies of gum arabic trees. 2. The vegetative propagation of adult Acacia senegal

Vegetative propagation of Acacia senegal is possible from branch fragments taken from the crown of mature trees (13 years old), without causing ortet destruction.The most responsive planting stock is taken from cuttings 15 cm long (with 12 to 15 nodes) and a diameter of 10 ± 6 mm (wood of 2 to 4 years old). With this material, the ablation of the leaves prior to planting is a factor which furthers development of the cutting's root system.The development of the root system is also highly influenced by the time at which the cutting is taken: results vary from 10% during the dry season to more than 70% during the rainy season (June—October).Cuttings can be taken from branches 50 cm long. It is thus possible to preserve the planting stock for 8 days in a continually humidified jute cloth and then to make the cuttings at the time of establishment in a nursery, without changing their rhizogenic aptitude.The cuttings show characteristics of maturity (slow growth, plagiotropy, fructification). It is nevertheless possible to preserve the collected genotypes in the field, or better, in planting pots in the nursery, so as to further the process of physiologic rejuvenation with the aim of in vitro cloning.researcher at CIRAD/C.T.F.T., detached to ISRA/D.R.P.F.     

Temporal changes in functional diversity of culturable bacteria populations in Sitka spruce stumps

Changes in culturable aerobic bacterial communities of Sitka spruce stumps between 1 and 10 years old were investigated by isolating from the top 55 mm of the stumps. High numbers of bacteria were recovered from 15 mm below the surface of 1‐ and 2‐year‐old stumps, particularly in the sapwood, after which numbers dropped by an order of magnitude. Proportions of colony‐forming units (cfu) capable of degrading cellulose and chitin increased with stump age, whereas siderophore producers decreased. Colony‐forming units were grouped on the basis of 13 phenotypic characteristics, including colony form and colour, Gram stain, heat tolerance, siderophore production and production of various enzymes. Four groups of bacteria were identified; the proportions of the three Gram‐negative groups varied with stump age. A quadratic relationship between bacterial diversity and stump age was detected using the Shannon–Weaver diversity index. Bacterial diversity was higher 15 mm below the stump surface than in deeper sampling points. The results are discussed in terms of the possible influence of prokaryotic organisms on the development of decay communities in Sitka spruce stumps.     

Damages and growth effects after selective mechanical cleaning

An annual survey of damages and growth was conducted two and three years after selective mechanical cleaning in two Norway spruce plantations‐7 and 11–16 years old—and one 11‐year‐old lodgepole pine plantation. The base machine was a modified Bruunett Mini with a rotating disc with two short steel flails, mounted at the tip of the crane. The results show that very few damages were caused by the cleaning device. 5–8% of the seedlings were driven over or otherwise damaged by the wheels and these seedlings show high mortality and great growth reduction. In stands with 1.5–4 m high trees, the trees are often damaged when they are straddled by the machine, which causes growth and quality losses. 14–25% of the undamaged seedlings in Norway spruce stands showed a 25 % annual height growth reduction the first two years after cleaning due to soil compaction and to possible root damage.     

Effect of Reforestation Methods on Pine Weevil (Hylobius abietis) Damage and Seedling Survival

Örlander, G.1 and Nilsson, U. (Swedish University of Agricultural Sciences, The Southern Swedish Forest Research Centre, Asa Forest Research Station, S-360 30 Lammhult, Sweden and Swedish University of Agricultural Sciences, The Southern Swedish Forest Research Centre, Box 49, S-230 53 Alnarp, Sweden). Effect of reforestation methods on pine weevil (Hylobius abietis) damage and seedling survival. Received Feb. 16, 1998. Accepted Sept. 15, 1998. Scand. J. For. Res. 00: 000-000, 199X. Damage to Norway spruce (Picea abies (L.) Karst.) seedlings by the large pine weevil, Hylobius abietis (L.) (Coleoptera: Curculionidae), was monitored in relation to clear - cutting age and silvicultural treatments in southern Sweden. New clear - cuttings were established on four sites during five consecutive years, and seedlings were planted on them from 1989 through 1993. In total, 31 774 seedlings were planted on 20 clear - cuttings. The measures evaluated were seedling insecticide treatment, application of herbicide to ground vegetation, scarification (mound) and planting late in the season. In addition, the effects of slash removal and seedling type were studied. The pine weevil was, by far, the dominant damaging agent. Planting without insecticide or soil treatment on fresh, one- or two - year - old clear - cuttings resulted in a mean level of weevil - caused mortality exceeding 60%. The results indicate that the risk of serious damage by pine weevils remains high until the clear - cuttings reach four or five years of age. Killing the vegetation with herbicide had no effect on pine weevil damage. Slash removal decreased damage on older clear - cuttings, but the effect was small. Scarification (mounding) strongly reduced damage. On fresh clear - cuttings the mean mortality caused by pine weevils in mounded plots was 13%, whereas it was 77% in the controls. The mounding effect varied between sites and clear - cuttings of different ages. Late planting (10 June instead of 1 May) reduced damage on two- and three - year - old clear - cuttings. Three - year - old, bare - rooted seedlings were not damaged as seriously as two - year - old, containerized ones, but the effect was probably due to the larger size of the bare - rooted seedlings. Non - lethal injury resulted in reduced seedling growth. Damage by pine weevils varied between years and within growing seasons. However, on fresh, one- and two - year - old clear - cuttings, damage was severe enough to cause high mortality during all studied years.     

Softwood cuttings for propagation of red alder

Tests were conducted to assess rootability of red alder softwood cuttings from shoots of young trees and epicormic sprouts of mature individuals. Ortets were 3 to 34 years old, and treatments with and without indole-3-butyric acid (IBA) were compared. The extent of rooting and root vigor on the cuttings varied greatly among ortets and treatments. Among nonterminal cuttings, the best overall rooting success, with and without IBA, was obtained with cuttings of the youngest ortet. Average rooting of terminal and nonterminal cuttings of one clone were 100% and 64%, respectively. Although cuttings of some trees rooted well without IBA, the IBA treatment appeared to be generally beneficial. For all nonterminal cuttings of all clones, best results (80.0%/x) were obtained with a 10-sec dip in 2,000 or 4,000 ppm IBA. Vigorous planting stock was obtained from the rooted cuttings of all clones. Using epicormic sprouts from mature trees of proven performance will presumably allow propagation of superior trees and establishment of new plantations with improved stock.     

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.     

Infection of Norway spruce container seedlings by Gremmeniella abietina

First‐ and second‐year containerized Norway spruce seedlings were inoculated with conidia of type A (large tree type) and type B (small tree type) of Gremmeniella abietina var. abietina at different times during the summer. The appearance of symptoms after artificial inoculation and natural infection on spruce seedlings were recorded the following spring and compared with the disease symptoms on Scots pine seedlings. The proportion of diseased seedlings after inoculation reached as high as 80%. The susceptible period during the summer began later on the first‐year seedlings than on the second‐year seedlings, and was similar for the pine seedlings. Susceptibility of first‐year seedlings was highest in August and on second‐year seedlings in July. The accumulated temperature sum, relative humidity and height growth for first‐ and second‐year seedlings was assessed. Natural infection in 2002 caused more disease on pine than on spruce seedlings. Experimental thinning of seedlings had no effect on disease incidence. In a preliminary comparison between the ability of A and B types to cause disease in Norway spruce seedlings, type B caused more damage than type A after inoculation. However, type A caused a high disease frequency in other experiments in this study. Symptoms on Norway spruce seedlings often first occurred in the mid‐section of the shoot, and were similar to those observed on pine seedlings: needles turned brown, starting at the needle base, in the spring following inoculation. On first‐year spruce, diseased needles were shed rapidly, in contrast to a slower rate of shedding on first‐year pine seedlings. Pycnidia developed about 2 years after inoculation (on pine 1 year after inoculation). On Norway spruce seedlings the lower part of the shoot, including the lateral shoots, often remained alive. The experiments show that G. abietina can cause disease on containerized Norway spruce seedlings under nursery conditions in Finland. The coincidence of spore dispersal, seedling susceptibility and predisposing factors are important in disease development.     

Spatial distribution and persistence of Heterobasidion parviporum genets on a Norway spruce site

Spatial distribution of Heterobasidion genets over a period of ca 50 years in two successive generations of Norway spruce (Picea abies) was unravelled. The genets were first identified in 1993 in a naturally regenerated 43‐year‐old spruce stand that had been thinned the previous winter. Heterobasidion parviporum was found in 17.5% of the old stumps of the previous spruce generation. Nine genets were identified on the study plot; seven of them were present in old stumps of the previous tree generation and two only in the new spruce generation. Eighteen spruce trees of the new generation were infected, 15 of them by vegetative growth of genets originating from the old stumps. The study plot was investigated again in 2005. No new genets had been established after thinning, and three old genets had died out. The remaining genets had infected five new trees, most likely from the thinning stumps of diseased trees. At the age of 56 years, 16.1% of the residual spruces were infected by Heterobasidion. The results of this study suggest that if spore infection to stumps of spruce can be prevented, the decay frequency caused by H. parviporum will not necessarily increase in successive generations.     

母株年龄和插穗基部切削方式对日本落叶松生根的影响*

在无激素处理的条件下，１．５年生幼龄母株的插穗易于生根，平均生根率达９６．０％以上，且发根最大，偏根率低；４．５年生时，插穗生根率极显著低于１．５年生母株，而与８．５年生母株无显著差异；１２．５年生母株插穗生根率又极显著低于８．５年生母株。母株年龄与插穗生根率和偏根率分别呈显著的负相关（ｒ＝－０．９６５２）和极显著正相关（ｒ＝０．９９９３），但与生根量和平均最长根长度无显著相关。插穗基部切削方式不