Planting stress, water status and non-structural carbohydrate concentrations in Corsican pine seedlings

Two-year-old Corsican pine (Pinus nigra ssp. laricio var. Corsicana) seedlings were either well watered or subjected to a moderate drought for one month before being lifted from the nursery bed on October 9 and transplanted. Well-watered, non-transplanted seedlings served as controls. Needle predawn water potential (Psi(wp)), non-structural carbohydrate concentrations and plant development (survival, bud break, shoot elongation) were assessed before and during the first growing season after transplanting. On April 16, just before bud break, Psi(wp) was lower for the well-watered + transplanted and drought-conditioned + transplanted seedlings (Psi(wp) = -1.45 and -1.83 MPa, respectively) than for the controls (Psi(wp) = -0.56). There was a close relationship between the Psi(wp) measured on April 16 and bud break, shoot elongation and plant survival during the following growing period. Above a Psi(wp) of -1.1 MPa, all plants developed normally. Between -1.1 MPa and -1.6 MPa, bud break, and thus shoot elongation, did not occur in all plants. Between -1.6 MPa and -2.1 MPa, the plants were characterized by the absence of shoot growth, but mortality was zero. Below -2.1 MPa, there was a large increase in plant mortality. On April 16, starch concentrations were markedly lower in the roots of transplanted seedlings than in the controls. There was a positive correlation between Psi(wp) and root starch concentration. The Psi(wp) (-2.3 MPa) at which complete starch depletion was observed in the roots corresponded to the Psi(wp) below which plants did not survive. These results suggest that mechanisms specifically linked to altered water status and metabolic processes associated with altered carbohydrate status are involved in transplanting stress; however, it was not possible to disentangle the two effects. Drought conditioning did not lead to a marked increase in soluble carbohydrate concentrations, as reported for other species, and did not increase plant tolerance to transplanting stress.     

杉木、马尾松裸根苗水分关系研究

Water relation parameters of bare-root seedlings of Chinese fir (Cunninghamia lanceolata Hook.)and Masson pine (Pinus massoniana Lamb.)were measured and changes of root growth potential as well as field survival rate of both species were studied after the bare-root seedlings were exposed in a sunny field condition.the results showed that masson pine had a lower osmotic potential(-2.07Mpa) at turgor loss point and at full turgor(-1.29Mpa),compared with Chinese fir(-1.80Mpa and -1.08Mpa respectively).The parameter Vp/Vo(63.27%) of Masson pine was higher than that of chinese fir (58.03%).This means that Masson pine has a stronger ability to tolerate desiccation,compared to Chinese fir according to analysis of above water relation parameters.Root growth potential and field survival rate decreased with prolonging duration of exposure.The field survival rate of both species was reduced to less than 40% after the seedling being exposed only two hours.Water potentials of -1.60 Mpa and -1.70 Mpa were suggested to be critical values for Chinese fir and Masson pine respectively in successful reforestation.     

Water relation patterns of bare-root and container jack pine and black spruce seedlings planted on boreal cut-over sites

Water relation patterns and subsequent growth were studied on bare-root and container jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana (Mill.) B.S.P.) seedlings during the first growing season on boreal cut-over sites.Containerized seedlings of both species had greater needle conductance compared to bare-root seedlings over a range of absolute humidity deficits. Needle conductance of containerized seedlings in both species remained high during periods of high absolute humidity deficits and increasing plant moisture stress. Bare-root seedlings of both species had a greater early season resistance to water-flow through the soil-plant-atmosphere continuum (SPAC) than container seedlings. Resistance to water flow through the SPAC decreased in bare-noot seedlings of both species as the growing season progressed, and was comparable to container seedlings 9 through 14 weeks after planting. Four weeks after field planting jack pine container seedlings had greater new root development compared to bare-root seedlings, while at the end of the summer both stock types had similar new root development. Black spruce bare-root seedlings had greater new root development compared with container seedlings throughout the growing season.     

Effects of pre- and post-planting shading on growth of container Norway spruce seedlings

Norway spruce (Picea abies (L.) Karst.) is shade-tolerant and sensitive to high irradiance, summer frosts and winter desiccation, which can impair its reforestation success. In this study, artificial pre- and post-planting shading was examined to determine their effects on post-planting shoot and root growth as well as the vigor of one- and two-year-old Norway spruce seedlings. Three planting experiments were carried out on open nursery fields (Exp. 1, 2) and on a mounded forest clearcut in central Finland (Exp. 3). Before planting, the seedlings were stored over winter either in a freezer or on open fields under snow cover. For two weeks prior to planting, half of the seedlings were placed in the open and the other half under a horizontal shade netting (light transmittance 56 %) (Exp. 1, 2). All seedlings were planted with or without a vertical post-planting shade, which was located on the southern side. Post-planting shading enhanced shoot growth and reduced damage (better visual vigor and needle color and less pine-weevil damage) on Norway spruce seedlings for at least two years after planting (Exp. 2, 3). Those seedlings, that had been stored over winter in the open and kept in shade prior to planting seemed to benefit most from post-planting shading (Exp. 2). However, post-planting shading may give variable results, depending on the seedling quality and weather conditions after planting, and may even reduce shoot growth if no pre-planting shading is used (Exp. 1). Shoot growth may also be improved at the expense of root growth (Exp. 3). The costs of manufacturing and installing post-planting shades may limit their use in practice, for example, to selected regeneration sites where there is high risk of frost damage but where no alternative silvicultural procedure (shelterwood or nurse crop) has been used.     

Herbicides and planting date affect early performance of container-grown and bare-root loblolly pine seedlings in Alabama

The survival of bare-root and container-grown loblolly pine (Pinus taeda L.) seedlings exceeded 90% when outplanted in March at two sites in Lee County, Alabama. At both sites, soil moisture and seedling survival were greater in March than in May. A March herbicide application reduced weed biomass by 75–80% at both sites. At the moist site, herbicide application did not affect survival. However, at the drier site, a reduction in weed biomass increased both the percent soil moisture and the survival of May-planted bare-root seedlings. When soil moisture at planting time was less than 13% on a dry weight basis container-grown seedlings survived better than bare-root seedlings. At both sites, reduced weed competition resulted in greater seedling heights and diameters.Alabama Experiment Station Journal Series No. 9-85802.     

Water relations and morphological development of bare-root jack pine and white spruce seedlings: seedling establishment on a boreal cut-over site

Bare-root jack pine (Pinus banksiana Lamb.) and white spruce (Picea glauca (Moench) Voss) seedlings were planted on a boreal cut-over site and subsequent growth and seedling water relation patterns were monitored over the first growing season. Comparison of morphological development between white spruce and jack pine showed jack pine seedlings had greater new root development and a lower new shoot/new root ratio, while white spruce seedlings had greater new shoot development. Seasonal water relation patterns showed white spruce seedlings to have a greater decrease in xylem pressure potential (_x) per unit increase in transpirational flux density in comparison to jack pine seedlings. These results suggest that the greater resistance to water flow through the soil-plant-atmosphere continuum in white spruce seedlings compared to jack pine seedlings may be due to the relative lack of new root development in white spruce. Stomatal response of the seedlings showed that as absolute humidity deficit between the needles and air (AHD) increased, needle conductance (gwv) decreased in both species, but at low AHD levels white spruce had gwv approximately 35% higher than jack pine. For white spruce seedlings, gwv decreased as _x became more negative in a predictable curvilinear manner, while gwv of jack pine seedlings responded to _x with a threshold closure phenomenon at approximately - 1.75 MPa. Tissue water potential components for jack pine and white spruce seedlings at the beginning and end of the growing season showed jack pine to reach turgor loss at 76% relative water content while white spruce reached turgor loss at 88% relative water content. White spruce seedlings showed osmotic adjustment over the growing season, with an osmotic potential at turgor loss of - 1.27 MPa and - 1.92 MPa at the beginning and end of the growing season, respectively. Jack pine did not show any osmotic adjustment over the growing season. The implication of morphological development on water relation patterns are discussed with reference to successful seedling establishment.     

Effects of mechanized pine straw raking on population densities of longleaf pine seedlings

Longleaf pine communities occupy a small fraction of their original extent in the southeastern United States and are in great need of restoration and conservation management. Recent anthropogenic disturbances, such as pine straw raking, may interfere with seedling survival and, hence, restoration efforts. We examined the effects of mechanized straw raking on longleaf pine (Pinus palustris Mill.) seedlings (pre-grass stage, or <3-yr-old) in natural, fire-maintained plant communities in Croatan National Forest, North Carolina, by testing the effects of number of rakings (0–4 times during a 2-yr period (1992–1994)) and community type (pine-turkey oak, dry savanna, and mesic savanna) on seedling densities in 1-m² quadrats. Despite initial differences in densities of seedlings among communities, analyses of variance did not detect significant differences among communities as averaged over time and raking treatment. Both raked and unraked quadrats exhibited declines in seedling density during the study, but the declines were greater for raked quadrats. After 2 yr, initial densities were, on average, reduced by 34% in unraked quadrats and by 47%, 63%, 78%, and 77% in quadrats raked one, two, three, and four times, respectively. In quadrats raked four times, censuses performed after each raking indicated significant declines in densities in response to all but the first raking. Raking either injures pine seedlings directly and/or modifies microsite conditions in ways unfavorable for seedling survival. Having established a link between raking and mortality, we now recommend additional work to reveal the causal mechanisms. Land management decisions should accommodate the potential adverse effects of mechanized raking on pine regeneration.     

The biology of Lophodermella conjuncta Darker on Corsican pine needles

The biology of Lophodermella conjuncta on Corsican pine needles was studied. Results of a spore exclusion experiment and histological examination of needles indicated that infection of young current years needles occurred and that the fungus first colonized only the endodermis. Infection remained latent until symptoms developed, from hyphae penetrating the mesophyll from the endodermis, in July of the year following infection. Ascocarps were produced on second year needles by mid-August. Aseospores were trapped throughout the year.Infected needles were cast prematurely during the third season. The phenomenon of latent infection of pine needles by some pine needle fungi is discussed.     

混合接菌对马尾松苗木生长的影响

许多研究证明,菌根菌混合接种对宿主植物生长具有正效应。本试验中发现,504、EG、HX和Pt2四种菌根菌混合接种能显著促进幼苗生长,与单一接种相比有显著性提高。在促进幼苗生物量的积累上,四种菌根菌混合接种分别比504、EG、HX和Pt2单一接种增加了379.68%、184.84%、126.21%和38.21%,比对照增加了467.79%。     

Ectomycorrhizal development on pine by Pisolithus tinctorius in bare-root and container seedling nurseries

Vegetative inoculum of Pisolithus tinctorius (Pt) produced by Sylvan Spawn Laboratories (C:N 50) and by research methods (IMRD), spore-encapsulated seeds, spore pellets, and sprayed spores were compared for efficacy in forming Pt ectomycorrhizae on pines in operational bare-root nurseries in South Carolina, Florida, and Indiana and in microplots and containers in Georgia. Two rates of application (0.33 and 0.16 liter/m² of soil) of both sources of vegetative inoculum were similar in effect and formed abundant Pt ectomycorrhizae (Pt index > 50) and fruit bodies in all studies. Spore treatments formed consistently fewer Pt ectomycorrhizae than vegetative inoculum. The most effective spore treatment was spore encapsulated seeds. These results indicate that at a bed density of 270 seedlings/m², 0.6 to 0.7 liter of vegetative inoculum is needed to obtain Pt indices > 50 on 1,000 pine seedlings.     

木荷裸根苗和容器苗造林效果对比分析

采用一年生木荷容器苗和裸根苗在不同造林地类型上造林,比较造林效果。结果表明:木荷容器苗造林成活率和保存率在不同的造林地类型中均明显优于裸根苗。木荷容器苗造林树高生长和地径在不同的造林地类型中均明显优于裸根苗,并且差异显著。不同的造林地类型中,采伐迹地的成活率、保存率、树高生长量和地径生长量最好,其次为林冠下,再次为生物防火带。     

The status of Crumenula sororia infections in crops of Corsican pine

Nodal cankers caused by C. sororia on Corsican pine were three times as common as internodal cankers. Natural infections reached maximum incidence on the fourth internode from the apex in branches and stems, but on stem internodes only on the ninth internode down. The longitudinal rate of canker spread was approximately 4 times that of the tangential rate. Crops of Corsican pine on N-facing slopes were more severely infected than those on S-facing slopes or flat areas, but in all cases the frequency of infection increased progressively with crop age. Cankers on individual stems showed a highly significant concentration on Northerly and Easterly aspects. Evidence is presented which suggests that the temperature differentials observed on different sectors of tree trunks may influence the duration of water films and hence limit the time period during which spore germination is possible.     

Effect of thinning on the development of compression wood in stems of Corsican pine

This study considered the effects of thinning on the development of compression wood in stems of 35-year-old stand of Corsican pine (Pinus nigra L.). Part of the stand had been thinned at 5-yearly intervals and part left unthinned. Twenty trees each from the thinned and unthinned stands were randomly selected and felled. Measurements were made on tree height, stem diameter, stem slenderness and canopy depth. Wood samples were removed from the central part of the main log and cross-sectional measurements made on ring width, basic density and compression wood content. Cross-sectional area of compression wood was found to be three time higher in stems from the unthinned trees in comparison with those from the thinned trees. No significant differences in mean radial ring width or basic density were found between treatments. Correlations indicated that, with increasing in stem diameter, compression wood content increased in the unthinned trees, while a decline in compression was observed in the thinned trees. Tree height was also positively correlated with compression wood content in unthinned trees, while no equivalent relationship was observed in thinned trees. Observations from this study, while not conclusive, suggest that phototropic stimulus may be producing stem inclinations in the unthinned stand as trees compete for space in the canopy, whereas crown competition has been largely eliminated in the thinned stand; and that this is responsible for compression wood levels recorded in this study.     

Survival to prescribed fire of plantation-grown Corsican black pine in northern Portugal

Context

The current fire regime threatens black pine (Pinus nigra Arn.) persistence in the Mediterranean Basin, which recommends larger-scale fuel treatments. Prescribed burning is an option for stand protection but its use in young stands (which are particularly at risk) is hindered by the scarce knowledge on post-fire tree survival.

Aims

The objectives were to characterize bark thickness as a fire-resistance trait in P. nigra and to describe how post-fire tree survival responds to tree size and fire effects in a 16-year-old plantation.

Methods

Bark thickness was related to diameter at breast height and height in the stem. Metrics describing tree size and stem and crown damage were measured 1?year after prescribed burning in 259 trees. Tree survival was modeled with logistic regression and Classification and Regression Tree analysis.

Results

Bark thickness increased linearly with diameter at breast height (dbh) and decreased with height in the stem. Tree survival was primarily a function of crown injury. Stem damage was an influent factor in small trees.

Conclusion

Due to thinner bark and lower tolerance to crown damage, young P. nigra trees are less fire-resistant than other Mediterranean pines, e.g., Pinus pinaster. Prescribed fire should not be attempted if dbh <10?cm. Mechanical clearing is the treatment of choice in young stands with a significant shrub layer.     

Effects of application date and rate of foliar-applied glyphosate on pine seedlings in Turkey

Glyphosate is the herbicide most extensively used for site preparation and conifer release. It is a broadspectrum herbicide and therefore crop safety is a critical issue. This study assessed the early effects of 14 different treatments, including no weed control, manual weed control, and 12 foliar-applied herbicide treatments at low,intermediate, high, and highest application rates and application timing on glyphosate phytotoxicity of containerized seedlings of Austrian pine(Pinus nigra J.F.Arnold.), Scots pine(P. sylvestris L.) and maritime pine(P.pinaster Aiton), conifer species widely used for afforestation and supplementary plantings in Turkish forestry. In general, Scots pine seedlings were tolerant to glyphosate compared to the other species. Glyphosate phytotoxicity varied significantly according to the time and rate of application. Seedlings were relatively tolerant to glyphosate in April whereas they were intolerant in May. The highest herbicide rate(1.2% v:v) was consistently phytotoxic to all species. Moreover, the effect of herbicide rate on seedling survival and growth varied significantly according to application date(i.e., application rate 9 date interaction). Seedlings appeared tolerant to glyphosate at low and intermediate rates(0.2, 0.4% v:v) between midspring and mid-summer, whereas they demonstrated significant sensitivity to the highest rate across all time periods. Glyphosate at the high rate(0.8% v:v) was particularly more phytotoxic when applied in May. Application of glyphosate at rates up to 0.8% could be recommended for weed control without significant pine damage in midspring when the needles presumably have a dense leaf epicuticular wax layer limiting herbicide penetration.Applications of 0.8 and 1.2% v:v are not recommended during May–June.     

Effect of fertilization on growth and ectomycorrhizal development of container-grown and bare-root nursery conifer seedlings

The effect of three levels of fertilizer on thegrowth of three species of containerized-grownconifer seedlings (Pinus contorta, Picea glauca, and Picea mariana) and twospecies of bare-root conifer seedlings (Pinus sylvestris and Larix sibirica),and on the colonization of these seedlings bysix species of ectomycorrhizal fungi (Hebeloma longicaudum, Laccaria bicolor,Paxillus involutus, Pisolithustinctorius, Rhizopogon vinicolor andSuillus tomentosus), was studied. Thegrowth of the seedlings in both container-grownand bare-root nurseries increased as the levelsof fertilizer increased. For better seedlinggrowth and environmental quality it may be possible to reduce the level of fertilizers in commercial nurseries upto 33% by using selected mycorrhizal fungi.Ectomycorrhizal colonization in all seedlingswas not affected by fertilizer levels. Hebeloma longicaudum, L. bicolor, P.involutus, and P. tinctorius formedwell-developed ectomycorrhizae, whereasectomycorrhizal development by R.vinicolor and S. tomentosus was poor.Native mycorrhizal fungi colonizednon-inoculated control seedlings; however,their colonization was always lower than withinoculated fungi.     

Effects of serpentine soil factors on Virginia pine (Pinus virginiana) seedlings

Effects of simulated serpentine soil conditions (elevated Mg:Ca ratio and Ni concentration) on seedlings from populations of Virginia pine (Pinus virginiana Mill.) from serpentine and non-serpentine sites were evaluated in sand culture. We determined (1) how seedlings are affected by elevated Mg:Ca ratio and Ni concentrations, (2) if there are interactive effects between Mg:Ca ratio and Ni concentrations on seedling growth, needle pigment concentrations, and nutrition, and (3) if Virginia pine populations from serpentine areas are edaphic ecotypes. A Mg:Ca ratio of 5 and 50 microM Ni both reduced seedling growth compared with control seedlings grown in the presence of the standard Mg:Ca ratio of 0.5 and no Ni. Interactive effects between Mg:Ca ratio and Ni concentrations were highly significant for growth, foliar pigments, and needle and root elemental concentrations. Nickel-mediated reductions in growth and foliar pigment concentrations were less at the serpentine Mg:Ca ratio of 5 than at the standard (non-serpentine) Mg:Ca ratio of 0.5. Foliar N was reduced by Ni concentrations as low as 10 microM, and foliar and root K, Ca and P concentrations were significantly reduced by Ni concentrations above 25 microM, with greater reductions at a Mg:Ca ratio of 0.5 than at a Mg:Ca ratio of 5. There were no population x serpentine soil factor interactions for seedling growth, foliar pigment concentrations, or nutrition, suggesting that seedlings from trees growing on serpentine soils are not edaphic ecotypes. We conclude that serpentine conditions present at the site of seed collection have not resulted in the selection of edaphic ecotypes of Virginia pine with respect to Mg:Ca ratio and Ni concentration.     

干旱胁迫对马尾松苗木脯氨酸及游离氨基酸含量的影响

[目的]证实脯氨酸及游离氨基酸在马尾松苗木抵御干旱胁迫中积累并发挥作用,揭示其在不同胁迫时期含量的变化规律。[方法]选择5个种源马尾松苗木,设计3种水分梯度,开展为期54d干旱胁迫试验,分别于胁迫处理18d、36d和54d后测定苗木针叶内脯氨酸及游离氨基酸含量。[结果](1)脯氨酸及游离氨基酸含量在干旱胁迫18d后均无明显变化规律,但脯氨酸含量在干旱胁迫54d后、游离氨基酸含量在干旱胁迫36d后均呈随胁迫程度加深而上升的变化。(2)随胁迫时间的延长,脯氨酸的平均含量呈先降后升趋势,而游离氨基酸的平均含量呈先升后降趋势。(3)脯氨酸和游离氨基酸含量在不同种源苗木内的分布差异显著。在5个种源中,脯氨酸平均含量以浙江江山和湖南汝城种源排最高和最低,分别为91.33μg/g(DW)和69.16μg/g(DW);游离氨基酸平均含量以广东信宜和湖北大悟种源排最高和最低,分别为1 597.88μg/g(DW)和1 279.04μg/g(DW)。[结论]干旱胁迫下,脯氨酸及游离氨基酸均能在苗木体内合成,使苗木适应干旱环境而继续生长。     

浅谈红松育苗技术

红松是东北三大针叶用材树种之一 ,结合生产实际 ,提出了红松播种育苗从选地、种子处理、播种到管理等技术措施 ,为生产应用提供了切实可行的依据