Root growth capacity and field performance of Pinus sylvestris and Picea abies seedlings

Correlations between root growth capacity (RGC), at the time of planting, and field performance were studied for Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) seedlings. Before planting a gradient in seedling viability was generated through exposure to low root temperatures and different winter storage regimes. The hypothesis that high RGC values would improve field performance was to some extent verified for pine seedlings while no correlations could be registered for spruce. Reasons for these results are discussed.     

Root-associated fungi of healthy-looking Pinus sylvestris and Picea abies seedlings in Swedish forest nurseries

The aim of this study was to assess fungal communities in roots of healthy-looking Pinus sylvestris L. and Picea abies (L.) Karst. seedlings in nine forest nurseries in Sweden using a combination of traditional culturing and direct sequencing of internal transcribed spacer of fungal ribosomal RNA (ITS rRNA) from the roots. Culturing from 1800 surface-sterilised root segments resulted in 2387 fungal cultures representing 42 different taxa. Direct sequencing from 180 root segments resulted in 119 ITS rRNA sequences representing 25 different taxa. In total, 55 different fungal taxa were detected using both methods. Although direct sequencing was more efficient than culturing in detecting different fungal taxa, both methods provided complementary information about fungal communities in roots since each detected rather different groups of fungi. The most dominant taxa detected by culturing were Trichoderma viride Pers. (19.5%), Phoma mucivora Davey & Currah (19.1%), Phialocephala fortinii Wang & Wilcox (17.4%) and Meliniomyces variabilis Hambl. & Sigler (10.2%), while Thelephora terrestris Ehrh. (26.1%), Unidentified sp. NS126 (25.2%) and Heliotales sp. C20 (10.1%) were most commonly detected by direct sequencing. In conclusion, results showed that forest nurseries in Sweden harbour diverse communities of fungi associated with the roots of healthy-looking P. sylvestris and P. abies seedlings. Although fungal communities were often dominated by saprotrophs and endophytes, several facultative pathogens were also detected indicating that under suitable conditions they may be a potential threat to the plants.     

Temperature step response of dehardening in Pinus sylvestris seedlings

The time constant of the dehardening of one‐year‐old Scots pine (Pinus sylvestris L.) seedlings was studied in three experiments started at different times of the year. The seedlings were transferred from outside to the different controlled conditions in January (Exp. 1), March (Exp. 2) and April (Exp. 3). Changes in the frost resistance of the seedlings were followed on the basis of the temperature response of the specific impedance difference in the shoot. The time constant for dehardening at a temperature of 7.5°C was found to be about 12 days in Exp. 1, about 8 days in Exp. 2, and about 5 days in Exp. 3. the terminal bud burst when the frost resistance of the shoot had risen to about ‐10°C.     

Incidence of Gremmeniella abietina in planted seedlings of Picea abies and Pinus sylvestris in northern Finland

The ascomycete Gremmeniella abietina causes a disease (scleroderris canker) on conifers. The pathogen kills terminal shoots and branches of Pinus sylvestris and Picea abies, sporulates on host shoots and causes leader changes (i.e. dieback). Damage caused by G. abietina was investigated in young P. abies and P. sylvestris plantations in northern Finland. Side branches from seedlings of both species and the main stems of P. sylvestris were collected from three sites in two locations (Poksa 1 and 2, Kivalo) in northern Finland. The number of cankers and leader changes was counted in branches of each age (i.e. year) in a total of ca. 6300 shoots of P. abies and 1200 shoots of P. sylvestris. Cankers were common on both P. abies and P. sylvestris in Poksa 1 (2002–2008) and on P. abies in Poksa 2 (1998–2001). In Kivalo, cankers occurred only sporadically on P. sylvestris. Leader changes were most frequent in 1999–2009 in Poksa 1, in 2001–2009 in Poksa 2 and in 2003 in Kivalo. Cankers and other symptoms of infection were more obscure on P. abies than on P. sylvestris. According to both conidial morphology and molecular analysis, the strain of G. abietina infecting both P. abies and P. sylvestris was small‐tree type (STT). This is the first report of G. abietina, STT or B type, injuring P. abies in plantations.     

Climatic response of Picea glauca seedlings in a forest-prairie ecotone of western Canada

We examined radial and height growth-climate relationships of juvenile white spruce in three contrasting microenvironments within a prairie-forest ecotone of western Canada. The three microenvironments were (1) the understory of mature trembling aspen (Populus tremuloides Michx.) groves, (2) the understory of mature white spruce (Picea glauca (Moench) Voss) tree islands, and (3) the open prairie outside the influence of mature trees. Interannual patterns in radial and height growth from each of the three environments were related to the regional climate (temperature and precipitation). The growth-climate relationships identified indicated that growth of juvenile white spruce was conditioned primarily by direct moisture stress during the wettest month of the year, namely June precipitation in the current growing season (t). The growth of juvenile white spruce also responded secondarily to moisture stress indirectly induced by high temperatures in June (t). The results support the general understanding that the southern limit of conifer species in western Canada is controlled mainly by moisture stress either directly by low precipitation or indirectly due to temperature-induced drought stress.     

Ectomycorrhizal fungi affect the physiological responses of Picea glauca and Pinus banksiana seedlings exposed to an NaCl gradient

We tested the effects of ectomycorrhizal (ECM) inoculation on greenhouse-grown white spruce (Picea glauca (Moench) Voss) and jack pine (Pinus banksiana L.) seedlings to be used for revegetation of salt-affected tailing sands resulting from the exploitation of oil sand in northeastern Alberta, Canada. White spruce and jack pine seedlings were inoculated with three ECM fungi selected for their in vitro tolerance to excess Na+ and Cl-: Hebeloma crustuliniforme (Bull) Quel. UAMH 5247, Laccaria bicolor Maire (Orton) UAMH 8232 and a Suillus tomentosus (Kauff.) Sing., Snell and Dick isolate from a salt-affected site. The physiological responses of the seedlings to a gradient of NaCl concentration (0, 50, 100 and 200 mM) were assessed over four weeks by: (1) Na+ accumulation and allocation; (2) chlorophyll a fluorescence; (3) growth, (4) water content; and (5) organic osmolyte accumulation. Jack pine seedlings were more sensitive than white spruce seedlings to increasing Na+ and Cl- concentrations. Both species showed decreasing biomass accumulation, and increasing concentrations of organic osmotica and Na with increasing NaCl concentration. White spruce seedlings inoculated with the S. tomentosus isolate had the best growth response at all NaCl concentrations tested. Although jack pine seedlings inoculated with the L. bicolor or S. tomentosus isolate exhibited the highest growth in the 50 and 100 mM NaCl treatments, both fungi increased the photochemical stress and dehydration of their hosts in the 200 mM NaCl treatment. At the latter concentration, jack pine seedlings inoculated with H. crustuliniforme showed the greatest tolerance to salt stress. Although the different fungi altered the physiological response of the host in different ways, inoculation with salt-stress-tolerant ECM fungi increased growth and reduced the negative effects of excess NaCl. Use of controlled mycorrhization may increase survival of coniferous seedlings used for revegetation of salt-affected sites.     

Effects of exogenous gibberellin and auxin on shoot elongation and vegetative bud development in seedlings of Pinus sylvestris and Picea glauca

The hormonal control of stem unit (foliar appendage and axillary structure, if present, plus subtending internode) number and length was investigated in shoots of Scots pine (Pinus sylvestris L.) and white spruce (Picea glauca (Moench) Voss). Seedlings were treated with six gibberellins (GA1, GA3, GA4, GA5, GA9 and GA20) and two auxins (indole-3-acetic acid (IAA) and naphthaleneacetic acid (NAA)) when either neoformed growth was occurring or the terminal vegetative bud was developing. Hormones were applied by drenching the shoot tip, injecting the stem or spraying the foliage. Combined results for all three application methods indicated that shoot elongation in first-year seedlings (i.e., neoformed growth) was promoted in both species by GA1, GA3, GA4 and, less obviously, by GA9. This promotion was attributable to an increase in length, rather than number, of stem units. However, the number of stem units formed during terminal bud development, as reflected in the number of needles (white spruce) or cataphylls (Scots pine) present on the shoot resulting from the terminal bud, was stimulated by GA1, GA3 and GA4 in both species and by GA9 in Scots pine. The GA-induced increase in the number of preformed stem units was associated with increased bud width in white spruce and increased bud length and resulting shoot length in Scots pine. In contrast, application of IAA or NAA either did not affect or inhibited both neoformed growth and terminal bud stem unit number, depending on the application method and concentration. We conclude that, in the Pinaceae, (1) GA stimulates the activity of both the subapical meristem during neoformed growth and the apical meristem during vegetative bud development, and (2) the early non-hydroxylation pathway, via GA9, is the major route of GA biosynthesis. The role of auxin in the control of stem unit number and length remains to be resolved.     

Epicuticular wax of needles of Pinus cembra,Pinus sylvestris and Picea abies

Epicuticular wax composition and its variation with needle age was analysed chemically. Needles were taken from conifers at the highest altitude of their local distribution. Quantitative and qualitative differences in the composition of the three conifer waxes were found. Increasing needle age influenced the wax composition in Pinus cembra and Picea abies.     

Effects of site preparation on soil properties and on morphology of Pinus sylvestris and Picea abies seedlings sown at different dates

The aims of the study are to find out the effects of site preparation on soil properties and on the morphology of three-year-old Pinus sylvestris L. and Picea abies (L.) Karst. seedlings sown at different dates along a slope with variation in soil texture, water, and fertility. Based on the hypothesis that soil texture affects soil water content, water retention capacity, and nutrient content, we studied site preparation of varying intensities: exposed C horizon, mounds (broken O/E/B horizons piled over undisturbed ground), and exposed E/B horizon. Though the growing time difference between sowings was about one month, after three growing seasons, spring-sown seedlings were larger than summer-sown seedlings. P. sylvestris seedlings were largest with mounds and smallest with exposed C horizon, but site preparation did not affect the morphology of P. abies seedlings.     

Effects of aluminium and calcium on Picea abies seedlings

Newly‐germinated Norway spruce seedlings were grown for 15 weeks in pots of iron podzol soil that received additions three times a week of nutrient solution containing six levels of Al (0, 0.37, 0.74, 1.5, 3.0 or 6.0 mM) and two levels of Ca (0.09 or 0.46 mM). The Ca concentrations in shoots and roots decreased with increasing Al levels. Growth was suppressed at 0.74 mM Al in the nutrient solution, which gave 0.5 mM Al in saturated soil extracts at the end of the experiment.     

Aluminium concentration versus the base cation to aluminium ratio as predictors for aluminium toxicity in Pinus sylvestris and Picea abies seedlings

Aluminium (Al) toxicity is considered an important factor in forest deterioration caused by soil acidification. A ratio of base cations (BC) to Al in the soil solution lower than 1 is widely used as an indicator for potentially adverse effects on tree health. In our view, the validity of the assumptions underlying the use of the BC:Al ratio as an indicator for Al toxicity in trees has never been evaluated properly.Here, we evaluate the importance of the base cations Ca and Mg in counteracting Al toxicity. Pinus sylvestris and Picea abies seedlings were grown on nutrient solution with a range of Al (0–0.25–0.5–1–2 mM) and base cation (0.25–0.5–2 mM) concentrations, giving BC:Al ratios of 1 at different levels of Al. Increasing concentrations of Al in solution caused growth reductions, which could not be counteracted by increasing concentrations of BC in solution with P. sylvestris and only partly counteracted with P. abies. Increased concentrations of Al in solution decreased the concentrations in shoot and root of both Ca and Mg, while increased concentrations of BC in solution increased tissue concentrations of BC. Growth reductions were, however, not a result of BC deficiencies, as growth reduction already occurred in tree seedlings that maintained adequate concentrations of Ca and Mg.All growth and uptake variables measured showed a higher or equal correlation with the absolute concentrations of Al or Al+BC in solution than with the BC:Al ratio. We conclude that Al toxicity is determined solely by the concentration of Al in solution. Shoot growth decreased significantly as dissolved Al increased at a constant BC:Al ratio of 1. In P. abies, but not in P. sylvestris, dissolved BC can positively affect uptake of BC and growth, which might partly alleviate the toxic effects of Al. Our results show that the mechanistic explanation for the effect of the BC:Al ratio is insufficient to describe Al toxicity. Care should be taken when using models based on the BC:Al ratio to predict the effect of Al on tree growth.     

Steady-state nutrition of Pinus resinosa seedlings: response to nutrient loading, irrigation and hardening regimes

To test effects of fertilization on late-season growth and nutrient content of container-grown red pine (Pinus resinosa Ait.), seedlings were subjected to a factorial combination of two fertilization regimes (exponentially increasing concentrations providing 25 (1N) and 75 (3N) mg N seedling(-1), respectively) and two irrigation regimes (well-watered and water-stressed) followed by drought-hardening or nonhardening. The fertilization treatments gave rise to steady-state nutrition in the seedlings during the prehardening phase. The 3N treatment increased macronutrient uptake significantly more than dry matter production, particularly in the roots, giving rise to what has been called luxury consumption of nutrients, or nutrient loading. Nutrient loading was higher in well-watered seedlings than in water-stressed seedlings. Among well-watered seedlings, relative growth rate of nutrient-loaded seedlings was more sensitive to drought during the hardening phase than that of nonloaded seedlings. However, when watering was resumed at the end of the hardening treatment, the relative growth rate of the nutrient-loaded seedlings (421%) exceeded that of the nonloaded seedlings (213%). Nitrogen accumulation was also higher in nutrient-loaded seedlings than in nonloaded seedlings during the post-hardening phase.     

Susceptibility of different provenances of Pinus sylvestris,Pinus Contorta and Picea abies to Gremmeniella abietina

In a randomized block factorial experiment, 1200 seedlings from four provenances, each of Pinus sylvestris, Pinus contorta and Picea abies were inoculated with conidia (2 × 10⁴ and 1 × 10⁶ conidia/seedling) of Gremmeniella abietina (Brunchorstia pinea), isolated from P. contorta plantations in northern Sweden. A further 600 seedlings were left as controls. The occurrence of symptoms and the extension of dead tissues on the annual shoots were recorded 13 months after inoculation. Only the higher spore dose resulted in significant infection. P. sylvestris and P. contorta seedlings were equally susceptible (53% infected), and significantly more infected than P. abies seedlings (39%). The annual shoots of P. sylvestris and P. abies were affected to 43% and 37% of their length, which was significantly more than 15% of the length of P. Contorta shoots. The frequency of affected seedlings differed between the most southern and northern provenances of P. sylvestris and P. abies, and between the northwestern and the south-eastern provenance of P. contorta Twenty-six months after inoculation, a higher proportion of P. contorta seedlings than P. sylvestris and P. abies seedlings had recovered, and a lower proportion of P. contorta than P. sylvestris and P. abies seedlings had died. This paper discusses why P. sylvestris was found to be more susceptible to G. abietina than P. contorta in this experiment, while the reverse is found in plantations in northern Sweden.     

Solution aluminum and transpiration in Picea rubens and Gleditsia triacanthos seedlings

Soil solution Al may contribute to red spruce (Picea rubens Sarg.) decline by inhibiting transpiration (Klein 1985). This study examines how Al affects transpiration in red spruce and honeylocust (Gleditsia triacanthos L.) seedlings and explores mechanisms for the observed responses. Red spruce seedlings were grown in dilute nutrient solutions containing 0 to 925 microM Al at pH 4.5 or 3.8. Solution Al had no effect on the transpiration, root hydraulic conductivity (K(r)) or shoot water potential (Psi) of red spruce. Transpiration of honeylocust was higher in the presence of 100 to 350 microM Al than 0, 500, or 600 microM Al. The Al-induced increases in transpiration of honeylocust were unrelated to shoot Psi or root K(r), but were closely correlated with the greater root lengths produced by intermediate levels of Al. In neither species was transpiration correlated with tissue concentrations of Al, P, K, Ca or Mg.     

落叶松人工林下红皮云杉和青海云杉的幼苗更新

落叶松幼苗在其人工林内难以更新。为探讨红皮云杉和青海云杉幼苗是否具有在落叶松人工林内成功定植并替代落叶松更新的潜力,采用红皮云杉和青海云杉幼苗在不同落叶松人工林(样地Ⅰ:1 300株·hm^-2的平地,样地Ⅱ,660株·hm^-2的平地;样地Ⅲ,330株·hm^-2的平地;样地Ⅳ,660株·hm^-2的坡地)下进行人工更新。结果表明:1)样地Ⅰ和样地Ⅱ更适宜红皮云杉和青海云杉幼苗的存活,且同一样地内,红皮云杉幼苗的成活率均高于青海云杉的;2)同一样地内,红皮云杉幼苗的地上生物量均高于青海云杉的,并且在样地Ⅰ和样地Ⅱ红皮云杉的地上生物量显著高于青海云杉的;3)在不同落叶松人工林样地,红皮云杉和青海云杉幼苗的1级根均有较好的外生菌根侵染;4)红皮云杉幼苗的1级根直径受环境影响较大,而青海云杉幼苗的1级根皮层厚度受环境影响较大。同一样地内,2种云杉幼苗的1级根解剖结构除在样地Ⅳ表现出明显的差异外,在其它样地基本无显著差异。红皮云杉和青海云杉幼苗均适宜在落叶松人工林内存活,但相对高密度的林分更适宜云杉幼苗的生长,且红皮云杉比青海云杉更具生长优势。     

Induction of hairy and normal roots on Picea abies,Pinus sylvestris and Pinus cortorta by agrobacterium rhizogenes

Two‐ to three‐week‐old seedlings of Picea abies, Pinus sylvestris and Pinus contorta were inoculated with the supervirulent strain Agrobacterium rhizogenes R1600 2cm above the base of the hypocotyl; other treatments included inoculation with Agrobacterium tumefaciens strain A281 (pTVK291) or mock inoculation. Hairy or highly branched roots formed on 2–3% of seedlings of all 3 species that were infected by R1600 but on none of the other seedlings. Normal adventitious roots were also induced on 5–10% of Agrobacterium‐treated seedlings but none appeared on the other seedlings. Opine assays and growth rates of hairy and normal roots indicated that only roots with the hairy morphology were transformed.     

Effects of some seed-borne fungi on Picea glauca and Pinus strobus seeds

Effects of inoculations of nine fungi to prechilled and nonchilled seeds of Picea glauca and Pinus strobus were studied in unsterilized and sterilized nursery soils, and a peat-vermiculite-perlite mixture. All the fungi demonstrated weak pathogenicity to seeds.     

Study on the physiological indices of Pinus sibirica and Pinus koraiensis seedlings under cold stress

Although Pinus sibirica and Pinus koraiensis are resistant to cold or low temperatures in the cold temperate regions of the northern hemisphere,the former has a stronger cold resistance.Research has been limited to the comparison of physiological responses of the two species to cold stress.In this study,5-year-old seedlings of P.sibirica and P.koraiensis were subjected to six temperature treatments,[20℃(control),0℃,-20℃,-40℃,-60℃,and-80℃],under different stress periods(6,12,24,and 48 h).The results showed that differences in each physiological index were significant between P.sibirica and P.koraiensis,except for the permeability of cell membranes,reactive oxygen species,proline and soluble proteins.An ANOVA test indicated that there were extreme differences among the temperatures for each index,stress time and temperature 9 time for most indices.All indices showed a similar trend for P.sibirica and P.koraiensis with decreasing temperature or the extension of stress time.Soluble sugars and proline increased at 0 to-20℃and then remained unchanged with temperature decline.Other indices showed an increase from 20 to-20℃,stable from-20 to-40℃and a decrease from-40 to-80℃.All the indices increased and then declined along with the prolonged cold stress time,except for the control.From 0 to-40℃,the permeability of cell membranes,relative conductivity,reactive oxygen species and malonaldehyde of P.koraiensis seedlings were higher than in P.sibirica,but superoxide dismutase,peroxidase,catalase activity and soluble sugars,proline,and soluble proteins content emerged as opposite.This study compared the physiological mechanism responses to cold stress between P.sibirica and P.koraiensis to provide the basis for the introduction,distribution,and genetic improvement of these coniferous species.     

Infection of Picea sitchensis and Pinus contorta stumps by basidiospores of Heterobasidion annosum

Infection of Pinus contorta and Picea sitchensis stumps by basidiospores of Heterobasidion annosum is extremely variable, both within and between sites, but in general P. sitchensis stumps are less sus-ceptible than those of P. contorta. Measurement of the cross-sectional area occupied by H. annosum on each stump provides a more sensitive test of species susceptibility than assessment of the proportion of stumps infected. P. sitchensis stumps become infected on a variety of soils but there is evidence to suggest that infection may be reduced by high rainfall. In some infected stumps, H. annosum is confined to the lower stump tissues. Its absence from the upper portion of the stump may be due to replacement by other micro-organisms or, alternatively, physical conditions in the upper stump tissues may prevent its continued survival after infection has taken place. In both species, but more commonly in P. sitchensis, some stumps remain alive for at least two years after felling, particularly on peat soils, due to the presence of root grafts with neighbouring trees. Results for P. sitchensis suggest that infection occurs more readily in living stumps than in those which die rapidly after felling. The viability of H. annosum basidiospore suspensions can be determined more accurately and more rapidly on a selective agar medium than on conifer stem sections.     

红松播种育苗技术的研究

文章在田间试验的基础上,对红松育苗技术进行了比较系统的研究,结果表明：红松育苗最佳播种期为地表5cm深处温度高于10℃,培育2年生播种苗的播种量为0.5 kg/m2、培育3年生留床苗的播种量为0.34 kg/m2,大粒种子出苗早并且苗木整齐,每天15：00浇水对苗木生长有利。