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.     

Dynamics of indole-3-acetic acid during germination of Picea abies seeds

High performance liquid chromatography and combined gas chromatography-mass spectrometry were used to identify indole-3-acetic acid (IAA) and indole-3-ethanol as endogenous constituents of germinating Norway spruce (Picea abies (L.) Karst.) seeds. Indole-3-methanol was tentatively identified by multiple ion monitoring. The free IAA content of the seeds rose from about 20 ng g(-1) to about 60 ng g(-1) (dry weight) during the first five days of germination and thereafter declined to around 20 ng g(-1). Indole-3-acetic acid released by alkaline hydrolysis, which was initially present at about 110 ng g(-1), decreased to 5-10 ng g(-1) during the first week of germination. The IAA content of seed lots differing in germination behavior was investigated. The findings are discussed in relation to the metabolism of IAA in conifer seeds.     

Autumn freeze testing of one‐year reciprocal families of Pinus sylvestris (L.)

Reciprocal families of Scots pine, Pinus sylvestris (L.), from a Swedish seed orchard were artificially freeze tested to ‐10°C at the end of the first growth period. The degree of freezing damage was used as an indication of the cold acclimatization achieved at the time of freeze testing. Both one‐year cold acclimatization and one‐year height were mainly additively inherited. Specific combining ability, reciprocal and maternal effects were small. On the family level, freezing damage was non‐significantly correlated with field survival and field height after ten years. One‐year height was positively correlated with 10‐year field height and negatively correlated with field survival on the family level. Within families, plants from early germinated seeds cold acclimated earlier and were higher at the end of the first growth period than plants from lately germinated seeds. The results indicate that conclusions made from first‐year cold acclimatization studies can be influenced by variation in the rate of seed germination and seedling/germinant development.     

Ectomycorrhizal fungi and exogenous auxins influence root and mycorrhiza formation of Scots pine hypocotyl cuttings in vitro

We studied the ability of the ectomycorrhizal (ECM) fungi, Pisolithus tinctorius (Pers.) Coker and Couch and Paxillus involutus (Batsch) Fr. (Strain H), to produce indole-3-acetic acid (IAA) and to affect the formation and growth of roots on Scots pine (Pinus sylvestris L.) hypocotyl cuttings in vitro. Effects of indole-3-butyric acid (IBA) and the auxin transport inhibitor, 2,3,5-triiodobenzoic acid (TIBA), on rooting and the cutting-fungus interaction were also studied. Both fungi produced IAA in the absence of exogenous tryptophan, but the mycelium and culture filtrate of Pisolithus tinctorius contained higher concentrations of free and conjugated IAA than the mycelium and culture filtrate of Paxillus involutus. Inoculation with either fungus or short-term application of culture filtrate of either fungus to the base of hypocotyl cuttings enhanced root formation. Inoculation with either fungus was even more effective in enhancing root formation than treatment of the hypocotyl bases with IBA. Fungal IAA production was not directly correlated with root formation, because rooting was enhanced more by Paxillus involutus than by Pisolithus tinctorius. This suggests that, in addition to IAA, other fungal components play an important role in root formation. Treatment with 5 microM TIBA increased the rooting percentage of non-inoculated cuttings, as well as of cuttings inoculated with Pisolithus tinctorius, perhaps as a result of accumulation of IAA at the cutting base. However, the marked reduction in growth of Pisolithus tinctorius in the presence of TIBA suggests that the effects of TIBA on rooting are complicated and not solely related to IAA metabolism. The high IAA-producer, Pisolithus tinctorius, formed mycorrhizas, and the IBA treatment increased mycorrhizal frequency in this species, whereas TIBA decreased it. Paxillus involutus did not form mycorrhizas, indicating that a low concentration of IAA together with other fungal components were sufficient to stimulate formation and growth of the roots, but not the formation of ECM symbiosis.     

3种植物生长调节剂对紫叶稠李扦插生根的影响

试验研究不同质量浓度（50、100、200 mg/L）的植物生长调节剂吲哚乙酸（IAA）和吲哚丁酸（IBA）、萘乙酸（NAA）和不同处理时间（30 min、60 min）对紫叶稠李扦插生根的影响。结果表明：30 min、60 min不同质量浓度IAA和NAA均未显著促进紫叶稠李扦插生根,而与CK相比,30 min、60 min IBA处理50、200 mg/L显著促进了紫叶稠李的生根率、根长及根数,且60 min IBA处理50 mg/L效果显著。表明植物生长调节剂IBA对紫叶稠李扦插生根的效果优于IAA和NAA,且60 min IBA处理50 mg/L是最佳组合。     

Using synergistic exogenous phytohormones to enhance somatic embryogenesis from leaf explants of a Eucalyptus grandis clone

Somatic embryogenesis (SE) in Eucalyptus spp. has been limited to germinated seeds, flowers, lignotubers or zygotic embryos. The low yield of somatic embryos from leaf explants has hampered progress, even though leaves offer a more viable source of clonal explants from superior selected genotypes. It was hypothesised that SE from leaf explants could be enhanced through pairing of synergistic exogenous plant growth regulators, such as natural auxins with natural cytokinins. Callus and embryo induction using 2,4-dichlorophenoxyacetic acid (2,4-D), α-naphthalene acetic acid (NAA), indole acetic acid (IAA), and indole butyric acid (IBA), each at either 1.0 or 3.0?mg L^?1, indicated that IAA and IBA favoured significantly higher numbers of embryos compared with 2,4-D or NAA. Hence, IAA and IBA were used for subsequent experiments, combining them (at 1.0?mg L^?1) with either the synthetic cytokinin, kinetin, or the natural cytokinin, trans-zeatin, both at 0.1?mg L?1. The combination of trans-zeatin and either IAA or IBA resulted in a significant increase in SE (e.g. 86 ± 17.2% and 23 ± 3.2% for IAA with trans-zeatin and kinetin, respectively), compared with kinetin, or with these auxins alone. Embryo maturation and plantlet regeneration was highest in those calli that were induced with IAA and trans-zeatin, indicating that maturation was dependent on auxin depletion, based on the stability of the analogue used for induction. For the E. grandis clone under study, the use of synergistic plant growth regulators significantly enhanced SE from leaf explants, thus presenting the opportunity to benefit from the advantages that SE offers over conventional organogenesis.     

Long-term variation in Scots pine seed crop size and quality in northern Finland

Abstract

Quantitatively and qualitatively good Scots pine (Pinus sylvestris L.) seed years are rare in northern areas because of the short growing seasons. The seed crop size was studied in four natural pine forests in northern Finland during 1960–2004. Data on seed crop quality were collected during 1986–2004 and quality was determined by X-ray radiography. The long-term average annual seed crop of pine was 77 seeds m^?2, varying from 5 to 225 seeds m^?2. The expected average annual germination percentage of the seed crop was 61%, varying from 7 to 81%. General linear models were used to analyse the size and quality of the seed crop. Independent variables explained 52% of the variation in annual seed crop quality, and no proper model was found for determining the size of the seed crop; the coefficient of determination was only 5%. A combination of more than 100 seeds m^?2 and an expected germination percentage of over 50% was observed once during the years 1986–2004. In most years, natural regeneration in northern Finland is difficult and often limited by the seed crop's quality as well as quantity. These results confirm the importance of seed tree cutting in abundant seed crop years to enable the natural regeneration of pine.     

Effects of Seedbed Substrate on Moisture Conditions and Germination of Pinus sylvestris Seeds in a Clearcut

The objective of the investigation was to describe moisture conditions and germination of Scots pine (Pinus sylvestris L.) seeds in different seedbed substrates (feather mosses, mineral soil, humus and ground organic material) with and without irrigation during 2 weeks, in a clearcut in northern Sweden. Without irrigation no seeds germinated, which could be explained as an effect of the low moisture conditions of the seedbed substrates. This was shown in the seeds' low moisture content, with highest values in mineral soil, 10-20%, and for the other seedbed substrates 5-15%. The moisture conditions were highest during the night and lowest in the afternoon. With irrigation, moisture conditions improved (seed moisture content 20-50%) and diurnal changes were moderated. Seeds germinated in all substrates with most seedlings in mineral soil (60% of sown germinable seeds). The moisture conditions of the seedbed substrates proved to be in poor agreement with the seeds' requirement for germination, especially during warm weather with no precipitation.     

Influence of environmental conditions on germinant survival and diversity of Scots pine (<Emphasis Type="Italic">Pinus sylvestris</Emphasis> L.) in central Spain

The aim of the study was to investigate dynamics and pattern of natural regeneration and the influence of seedbed and light on germination and initial seedling survival of Scots pine (Pinus sylvestris L.) during three growing seasons. Four 5-m² plots in a natural Scots pine forest in central Spain were randomly established at the beginning of the regeneration process. Germination and seedling survival were recorded in 100 regeneration sampling subplots (0.25 m²) per plot, while seedbed type and the relative light intensity reaching the forest floor was characterised in 1-m² subplots. The spatial correlations between survival, light conditions and organic matter depth were analysed through cross-variograms. Germination and survival were highly variable both within and between plots (ranging from 0 to 89%) and affected by high summer temperatures (33–35°C) in 2003. The spatial pattern characterisation of survival by Ripley’s K function showed a dominant cluster distribution. Occurrence tended to be clumped when abundance was greater than 15 seedlings, whereas for lower densities, seedlings were randomly distributed. Seedlings and herbs occupied the same sites where environmental conditions were appropriate for them to live. Spatial association occurred frequently for light and organic matter depth. Results suggested that the Scots pine seedlings in our study in central Spain preferred moderate light conditions (Global Site Factor <0.40). Thus, if this forest is to be naturally regenerated with Scots pine, the shelterwood system (whereby some mother trees are left to provide shelter for at least 5 years), along with mechanical disturbance of the seedbeds, would promote seed germination, as long as a seed source is present. However, regeneration success is affected by year-to-year conditions.     

Effects of artificial environmental conditions on anatomical and physiological ripening of Pinus sylvestris L. seeds

To determine suitable conditions for artificial ripening of Scots pine seeds, cones collected on seven occasions between August 6 and November 26, 1990, in northern Sweden, were subjected to artificial ripening at different temperatures (+5°–+15°C) and cone moisture contents for 3–9 weeks. Complete physiological ripening and improved seed vigour were attained after artificial ripening if collection occurred no earlier than the beginning of September. The highest germination percentage after artificial ripening, ca 90%, was achieved for seeds collected after the anatomical ripening in nature had ceased and was at least as high as for seeds ripened in nature. Temperature did not influence ripening, whereas a low cone moisture content impaired ripening of those seeds collected earliest. The germination percentage was not influenced by 2–6 months of cone storage subsequent to artificial ripening, but seed vigour was impaired. Anatomical ripening during artificial ripening was very limited.     

Seedling shoot,needle and bud development in three provenances of Pinus sylvestris and Pinus contorta cultivated in northern Sweden

The patterns of current‐year shoot, needle and terminal bud elongation in seedlings of three Scots pine (Pinus sylvestris L.) and three lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) provenances were compared during the third and fourth growing seasons after planting. Lodgepole pine produced longer shoots and buds than did Scots pine, mainly because lodgepole pine formed more stem units and elongated at a faster rate. Stem unit length and the duration of shoot and bud elongation differed relatively little between species and provenances. Lammas or polycyclic growth occurred in some lodgepole pine provenances, but not in any Scots pine provenance, and was associated with enhanced shoot elongation. Needle elongation commenced earlier, proceeded at a faster rate, and was greater in lodgepole pine than in Scots pine, but ceased about the same time in all species and provenances. The heat sum required to attain 50% of final length was lower for shoots and needles in lodgepole pine than in Scots pine, and for shoots in northern provenances than in southern ones. Mitotic activity in the apical meristem of the terminal bud, which occurred less than one week after the seedlings were free from snow, started and ceased about the same time in each species, but was higher in lodgepole pine than in Scots pine early in the shoot elongation period.     

Interference of bracken (Pteridium aquilinum L. Kuhn) with Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L. Karst.) seedling establishment

The nature of interference of bracken with Scots pine and Norway spruce seedling establishment was considered in three field experiments. In a seeding experiment, it was found that Scots pine germination was highest on exposed mineral soil and lowest when intact bracken litter and humus were present, suggesting adverse effects of litter and humus on pine regeneration probably due to phytotoxicity. In a second experiment, smothering by bracken caused high mortality of Scots pine seedlings while Norway spruce seedlings were relatively unaffected. Mortality for both Scots pine and Norway spruce seedlings was low when planted in a adjacent Scots pine-bilberry stand with no bracken. Annual shoot growth of Norway spruce was higher in bracken than in Scots pine-bilberry vegetation while no differences in shoot growth between these two vegetation types occurred for Scots pine. In a third experiment, activated carbon was added to the ground under Norway spruce seedlings planted in bracken to adsorb possible phytotoxic compounds released by bracken. The addition of carbon had no effect on seedling mortality or growth rate, indicating that the seedlings were not susceptible to allelochemicals released by bracken. Since large Norway spruce seedlings were relatively unaffected by bracken interference in this study, artificial regeneration with containerized Norway spruce seedlings is suggested to achieve an acceptable conifer tree establishment on clear-cuts invaded by bracken.     

Tap root formation and early root/shoot ratio of Pinus Contorts and Pinus sylvestris

Scots pine and different provenances of lodgepole pine were compared in regard to root characteristics and the distribution of biomass within individual trees. Tap root formation was more frequent and the root/shoot ratio was higher on Scots pine than on lodgepole pine but significant variation of these traits was found between provenances of planted lodgepole pine. A non‐destructive method for estimation of root biomass was developed.     

Effects of seedbed substrate on moisture conditions and germination of Scots pine (Pinus sylvestris) seeds in a mixed conifer stand

The objective of this investigation was to comparemoisture conditions and Scots pine (Pinussylvestris L.) seed germination percentages in fourtypes of seedbed substrates, (i.e., feather mosses,mineral soil, humus, and ground organic material). Twoexperiments were conducted, with and withoutirrigation, in the summer of 1996 in a stand innorthern Sweden. The moisture conditions weredetermined by periodically weighing seedsamples. When plots were not irrigated, no seedsgerminated, probably because conditions were too dryin the seedbeds, as indicated by the low seed moisturecontent (under 15%). However, during rainy days, seedmoisture contents were relatively high (20–45%). Onthe irrigated plots the seeds germinated on allseedbed substrates, with the best germinationoccurring in humus (about 40%). Seed moisturecontents were high and relatively consistent in allirrigated seedbed substrates (35–55%). Inirrigated plots temperature rather than moisture, wasa limiting factor, and germination was highest in thewarmest seedbed types which are generally regarded aspoor germination substrates. We suggest that seedbedsin areas scheduled for harvesting be prepared in thestand before clear-cutting, and that the preparationshould enhance not only the substrates's water-holdingcapacity, but its thermal conductivity as well.     

基于GC-MS流苏树种子挥发性成分分析

为研究流苏树种子的成分,探讨不同溶剂提取流苏树种子成分的差异。本研究分别采用石油醚、二氯甲烷和丙酮提取流苏树种子成分,以GC-MS联用技术对其化学成分进行分析。结果显示:石油醚提取物含有10种烷烃类、16种酯类和1种酰胺类化合物,占色谱总流出峰面积的91.36%,其中十六烷酸甲酯(10.83%)、反式-13-十八碳烯酸甲酯(60.67%)和6-十八碳烯酸甲酯(11.29%)含量较高;二氯甲烷提取物含有10种烷烃类、4种酯类、2种酸类和3种烯烃类化合物,占色谱总流出峰面积的80.85%,其中1,2-二甲基环戊烷(8.21%)、十六烷酸(14.51%)、(Z,Z)-9,12-十八碳二烯酸(35.93%)等化合物含量较高;丙酮提取物含有10种烷烃类、11种酯类和2种烯烃类化合物,占色谱总流出峰面积的98.23%,其中十六烷酸甲酯(14.07%)、(Z,Z)-9,12-十八碳二烯酸甲酯(44.65%)、(E)-9-十八碳烯酸甲酯(12.27%)和十八酸甲酯(15.62%)含量较高。石油醚和丙酮提取酯类的效果优于二氯甲烷,在提取酸类和烷烃类化合物时,二氯甲烷效果更佳。不同的溶剂提取流苏树种子成分的组成和含量存在一定的差异。     

Damage by pathogens and insects to Scots pine and lodgepole pine 25 years after reciprocal plantings in Canada and Sweden

A combined species – provenance – family experiment with Scots pine and lodgepole pine was planted in Canada and Sweden. One aim of the experiment was to evaluate the two species’ sensitivities to pathogens and insects 25 years after establishment in their non-native continents. In Canada, Scots pine had better average survival than lodgepole pine, but survival rates among trees from the best seed-lots were equal. In Canada only western gall rust infected Scots pine to some extent, and mountain pine beetles attacked and killed Scots pine more frequently than lodgepole pine. At one site in Sweden, lodgepole pine had higher survival rates than Scots pine, whether evaluated as an overall average or with data from only the best surviving seed-lots. At the other Swedish site, the species’ survival rates were equal, largely since moose damage was much more frequent on lodgepole pine than on Scots pine. Adaptation to local conditions seemed to be important in the resistance of stem breakage caused by heavy snowfalls. The exotic species generally seemed to resist the new threats, but more serious damage by mountain pine beetle on Scots pine than on lodgepole pine in Canada demonstrates possible drawbacks when using exotic species which are phylogenetically similar to native.     

Effects of Fencing and Ground Preparation on Natural Regeneration of Native Pinewood over 12 years in Glen Tanar, Aberdeenshire

An enumeration was carried out in 1989 to assess the effectsof fencing and ground treatment 11 years previously on survivaland growth of naturally disseminated Scots pine seedlings inthe native pinewood at Glen Tanar, Aberdeenshire. Results showeda significant difference between unfenced and fenced plots onpine seedling density and height in 1989. Initial effects ofseedbed treatment on Scots pine seedling density, 2 years afterthe experiment began had largely disappeared by 1989. If removalof ground cover is used to enhance pine seed germination, theexposed seedlings may need to be protected from browsing byfencing. Received 19 March 1990.     

Effects of drought stresses induced by polyethylene glycol on germination of Pinus sylvestris var. mongolica seeds from natural and plantation forests on sandy land

Effects of drought stresses induced by polyethylene glycol (PEG) (0.0%, 10%, 15%, 20%, 25%, and 30%, with four replicates) on germination of Mongolian pine (Pinus sylvestris var. mongolica) seeds produced in plantations (southern Keerqin sandy land) and natural forests (Hulunbeier sandy plain) were observed. The results indicated that the seeds from both provenances did not germinate when PEG concentration was more than 25%. The time of initial germination and that of its completion of stressed seeds from both provenances were delayed when compared with the unstressed seeds. The germination capacity and germination rate of natural seeds were significantly higher than those of plantation seeds for all treatment levels (P < 0.05). The mean growth rates of radicle and hypocotyl from natural seeds were significantly higher than those from plantation seeds at all treatment levels below 20% PEG treatment (P < 0.05). The ratios of radicle to hypocotyl of 20% PEG treatment were significant higher than those of the corresponding controls for both provenances (P < 0.05). These results suggested that Mongolian pine seeds/seedlings had stronger resistance to PEG drought stresses; 10% PGE stress did not significantly influence germination. Natural seeds exhibited more resistance to PEG stress than plantation seeds. It was concluded that drought stress on seed germination might be one cause of obstructed natural regeneration of Mongolian pine plantations on sandy land. It is recommended that natural seeds be used for afforestation, and light drought stress (e.g., 10% PEG stress) may be useful in improving seed germination and the growth of radicles and hypocotyls.     

A mycobacterium isolated from tissue cultures of mature Pinus sylvestris interferes with growth of Scots pine seedlings

We isolated a rapidly growing, pigment-producing mycobacterium from senescent tissue cultures derived from mature Scots pine (Pinus sylvestris L.). The bacterium was found in three senescent suspension cultures and in a senescent protoplast culture. Growth of Scots pine cells had ceased in all of these cultures. Exogenous contamination was eliminated by rigorous surface sterilization of the buds with hypochlorite before aseptic removal of the bud scales. Based on biochemical and physiological properties and DNA sequence comparisons, the isolated mycobacterium did not belong to any known species. Its sequence most closely resembled those of Mycobacterium obuense (97%) and M. aichiense (96%). Tissue browning was frequently observed in callus or suspension culture of Scots pine. Because the effect of the mycobacterium on growth of undifferentiated tissues that were browning was difficult to evaluate, we applied the bacterium to Scots pine seeds in aseptic conditions. Seedlings grown in the presence of the mycobacterium had shorter hypocotyls than control seedlings and seedlings cocultivated with a Pseudomonas strain known to be harmless to plants. However, hypocotyl growth of seedlings cocultivated with another mycobacterium, M. chlorophenolicum, was similar to that observed in the presence of the isolated mycobacterium. Phenylalanine ammonia-lyase activity of seedlings cocultivated with the mycobacterium isolate was significantly higher than that of control seedlings or seedlings cocultivated with M. chlorophenolicum or Pseudomotnas fluorescens. We believe that this is the first report of the isolation of mycobacteria from tissue cultures of a tree. Our finding that the mycobacterium may interfere with the growth of Scots pine in vitro warrants further study.     

Structure and abundance of arachnid communities in Scots and lodgepole pine plantations

Between April and September 1994, six plots within Aberfoyle Forest in Scotland, three of Scots (Pinus sylvestris) and three of lodgepole pine (Pinus contorta), were surveyed for spiders and harvestmen, as these are predators of several forest invertebrate pests.A total of 64 species of spider were trapped in Scots and lodgepole pine; 56 in Scots pine and 32 in Lodgepole pine. The most abundant spiders, both in Scots and Lodgepole pine, were Linyphiidae.Scots pine plots were floristically more diverse and structurally more complex than lodgepole pine plots. More species of spiders and harvestmen (midsummer only) were found at ground level in Scots pine than lodgepole pine plots. More species and a greater numbers of spiders were found in the canopy of Scots pine than in that of lodgepole pine. However, no differences in the abundance of harvestmen were found between the canopies of Scots and lodgepole pine. Spider species diversity was greatest in Scots pine.