Cell wall formation in secondary xylem of Pinus strobus L.

Summary Vesicular membrane-bound bodies that participate in forming the cell wall of differentiating xylem cells in white pine appeared on electron microscopical examination to originate from the Golgi apparatus. Golgi bodies released vesicles that contained dark material, fibrillar material, or no contents. The vesicles were seen at different stages on their path to the cell wall; their contents came in contact with the wall by fusion of vesicular membranes with the plasmalemma. Individual filaments of fibrillar material within the vesicles were 60 to 80 Å in diameter; structurally they resembled the fibrillar component of the existing wall and became intertwined with the wall. The authors assume the dark material in the Golgi-derived vesicles represents the hemicellulosic and the pectic components of the wall, and the fibrillar material, the cellulosic.Maintained in cooperation with the University of Wisconsin.     

东部白松在辽宁的引种

对辽宁多年来引种东部白松的生长、物候、生长节律等进行了综述,研究结果表明东部白松是辽宁引种成功的优良树种,引进优良的种源可以显著地提高生长量。为了保证东部白松在辽宁的科学发展,提出了可行的建议。     

Natural Variation in Seed Characteristics of Eastern White Pine (Pinus strobus L.)

Natural variation in seed characteristics of eastern white pine (Pinus strobus L.) trees and its relationship with the size, form, and crown class of parent trees was examined in second-growth, white pine mixedwood stands in Ontario. Cones were collected prior to and following partial harvesting of two stands during 2 years of above-average seed production. Fully enlarged seed extracted from mature cones was X-rayed to determine seed yield per cone, the percentage of sound, partially filled, and empty seed, and the sound seed mass for each tree. Variation in seed yield per cone, the proportion of sound, partially filled, and empty seed, and seed mass was much greater among individuals than between stands or seed years. The strength and significance of the relationship of seed mass with sound seed yield differed with stand and seed year. In uncut stands, seed mass was higher for trees with dominant crown class, larger live crown ratios, and smaller height to diameter ratios, suggesting tree vigour and microsite quality influence seed mass. Proportion of partially filled seeds was significantly reduced in both stands in the second year likely due to increased growing degree days during female gametophyte development. The implications of these results to natural and artificial regeneration of white pine are discussed.     

Photosynthesis, water relations, and growth of planted Pinus strobus L. on burned sites in the southern Appalachians

We measured net photosynthesis, leaf conductance, xylem water potential, and growth of Pinus strobus L. seedlings two years after planting on two clear-cut and burned sites in the southern Appalachians. Multiple regression analysis was used to relate seedling net photosynthesis to vapor pressure deficit, seedling crown temperature, photosynthetically active radiation (PAR), needle N, xylem water potential, and soil water, and to relate seedling size and growth to physiological measurements (average net photosynthesis, leaf conductance, and cumulative xylem water potential), soil water, needle N, seedling temperature, and PAR. Seedling net photosynthesis was significantly related to vapor pressure deficit, midday water potential, crown temperature, and PAR (r(2) = 0.70) early in the growing season (May 1992) with vapor pressure deficit alone explaining 42% of the variation. As neighboring vegetation developed, light became more limiting and significantly reduced seedling net photosynthesis later in the growing season (July, August, and September). Final seedling diameter was significantly related to competitor biomass, average photosynthetic rate, and needle N (r(2) = 0.68).     

Crown architecture of understory and open-grown white pine (Pinus strobus L.) saplings

Crown architecture and growth allocation were studied in saplings of eastern white pine (Pinus strobus L.), a species classified as intermediate in shade tolerance. A comparison was made of 15 understory saplings and 15 open-grown saplings that were selected to have comparable heights (mean of 211 cm, range of 180-250 cm). Mean ages of understory and open-grown trees were 25 and 8 years, respectively. Understory trees had a lower degree of apical control, shorter crown length, and more horizontal branch angle, resulting in a broader crown shape than that of open-grown trees. Total leaf area was greater in open-grown saplings than in understory saplings, but the ratio of whole-crown silhouette (projected) leaf area to total leaf area was significantly greater in understory pine (0.154) than in open-grown pine (0.128), indicating that the crown and shoot structure of understory trees exposed a greater percentage of leaf area to direct overhead light. Current-year production of understory white pine was significantly less than that of open-grown white pine, but a higher percentage of current-year production was allocated to foliage in shoots of understory saplings. These modifications in crown structure and allocation between open-grown and understory white pine saplings are similar to those reported for more shade-tolerant fir (Abies) and spruce (Picea) species, but the modifications were generally smaller in white pine. As a result, white pine did not develop the flat-topped "umbrella" crown structure observed in understory fir and spruce, which approaches the idealized monolayer form that maximizes light interception. The overall change to a broader crown shape in understory white pine was qualitatively similar, but much more limited than the changes that occurred in fir and spruce. This may prevent white pine from persisting in understory shade as long as fir and spruce saplings.     

东部白松种源引进苗期选择研究

对从加拿大引进的29个东部白松种源种子在辽宁清原进行了3年苗期试验。结果表明,东部白松生产力随纬度增高而加快,生长与纬度呈单向渐变地理模式。方差分析结果表明东部白松不同种源之间生长量存在显差异,筛选的6个优良种源,苗高遗传力12％～27％,遗传增益9．3％～19％,直接引种这些优良种源造林可获得显的增产效益。     

不同种源东部白松苗期光合作用研究

为选择适合辽宁地区生长的东部白松种源,研究了东部白松不同种源苗期的光合效率。结果表明：东部白松净光合速率和蒸腾速率日变化均为双峰型。8：00时,不同种源的净光合速率为7.83～17.96μmol.m-2.s-1,蒸腾速率为2.63～6.33 mmol.m-2.s-1。10：00时,不同种源的净光合速率为3.58～18.60μmol.m-2.s-1,蒸腾速率为1.92～6.68 mmol.m-2.s-1。方差分析表明,不同种源的东部白松净光合速率和蒸腾速率均差异明显。相关性分析表明,生长指标和光合作用指标之间表现为正相关,其中当年树高生长量同净光合速率和蒸腾速率相关性较高,说明光合作用指标可作为东部白松东部种源选择的依据。     

Regeneration patterns of Eastern white pine (Pinus strobus L.) in hardwood-dominated forests in Virginia, USA

Eastern white pine (Pinus strobus L.) is a moderately shade-tolerant species that co-occurs with hardwood tree species in many forests of the eastern United States, as well as in pure stands. The species is valued for its timber, as well as for wildlife and recreation. Regeneration of this species is somewhat unpredictable and often occurs in patches of similarly-aged cohorts. We described the regeneration patterns of this species and examined their relation to environmental variables within hardwood forests of southwestern Virginia, USA. An average of 5.3 white pine patches per ha were observed in this study. The majority of patches consisted of saplings (85%), with 9% of patches in pole size classes, and 6% in seedling size classes. The average density of patches was 43.5 stems with an average age of 20 years. The size of patches averaged 80.6 m². The total density of seedlings and the number of regeneration patches of all sizes of regeneration (seedlings, saplings, and poles) in plots was related to the surrounding density of large white pine trees (potential seed trees). The density of seedlings or patches was not significantly related to current vegetation cover or soil surface cover variables, but more than half of regeneration patches were located in or adjacent to old canopy gaps, most of which were old logging gaps. While seedling regeneration may occur within the understory of these forests near seed trees, advancement to the sapling and pole stage appears to be associated with canopy gap formation.     

东部白松1年生苗木小拱棚越冬防寒试验

东部白松是辽宁引种成功的优良树种,苗木防寒是育苗成败的关键措施。文章通过对当年播种苗木进行小拱棚和常规覆草越冬防寒对比试验,结果表明:2种防寒措施差异显著,小拱棚越冬防寒比常规覆草越冬,不仅苗木保存率提高15%,平均苗高提高3.405cm,而且方法简单,经济实用,是可行的实用技术。     

Comparative mast seed production in unmanaged and shelterwood white pine (Pinus strobus L.) stands in central Ontario

The effect of the seed cut of the uniform shelterwood silvicultural system on white pine seed production, seed characteristics, and seed viability during 2 mast seeding events was examined in operationally harvested second growth, white pine-dominated forest stands in central Ontario. Seed traps placed along transects in unmanaged and shelterwood stands in each of 3 blocks were used to monitor seed production in 2000 and 2006 (4 and 10 years after harvesting). During these 2 mast seed years between 386,000 and 2,730,600 seed ha^?1 were produced among study stands. Total seed production expressed on a per hectare and unit pine basal area basis did not differ by harvest treatment or among blocks in either year. Variability in seed production among stands was primarily due to differences in stand structure, with seed production positively related to white pine basal area. Seed characteristics were largely similar between harvested and unmanaged stands and between seed years. Seed viability was relatively high in both years, with seed from shelterwoods germinating slightly slower than those from unmanaged stands. Seed quality, as estimated by laboratory germination performance, was higher in 2006 than 2000, likely due to improved seed development and maturation in the warmer, wetter growing season of 2006. Our results suggest that the seed cut of the uniform shelterwood system applied to second growth white pine stands is unlikely to adversely affect white pine seed production, seed quality, or potential for natural regeneration during mast seeding events.     

Cold hardiness of interspecific hybrids between Pinus strobus and P. wallichiana measured by post-freezing needle electrolyte leakage

Interspecific hybrids between eastern white pine (Pinus strobus L.) and Himalayan blue pine (P. wallichiana A. B. Jacks.) were developed in Ontario, Canada, to introduce blister rust (Cronartium ribicola Fisch.) resistance genes to P. strobus. There is concern that introducing blister rust resistance has resulted in reduced cold hardiness of the progeny compared with non-hybridized eastern white pine. To test the efficacy of backcrossing with P. strobus to improve cold hardiness, 1-year-old seedlings from hybrid crosses differing in P. strobus genome composition were artificially freeze-tested. In Experiment 1, unhardened seedlings were allowed to acclimate to progressively lower temperatures in a growth room, whereas in Experiment 2, seedlings were hardened outdoors under natural weather conditions in Sault Ste Marie, Ontario. Needle cold injury was determined by calculating relative electrical conductivity based on post-freezing electrolyte leakage. Results indicated that needle fascicles from unhardened seedlings of all genotypes in the greenhouse tolerated -5 degrees C for 3 hours with little or no injury. Cold hardiness increased in parallel with declining growth room minimum temperature over the 7-week period of hardening. Cold hardiness was improved for hybrid crosses with increased Pinus strobus genome composition in Experiment 2, but the results were less conclusive in Experiment 1.     

A Reappraisal of the Importance of Cronartium ribicola on Pinus strobus in Great Britain

Because of the possibility of serious infection by Cronartiumribicola (White pine blister rust), Pinus strobus, the Weymouthpine, is now very rarely planted in British forests. An assessment,in 1962, in a number of experimental forest plots of P. strobusestablished in 1953 and 1954 showed that initial infection ofthe trees while growing in the nursery may be an important factorin causing later damage and losses in the forest. The resultsalso indicated that the risk of infection in plantation cropsas a result of spore dispersal from black currants in the localityis much lower than is generally thought. It is suggested thatif P. strobus is raised in nurseries which are relatively isolatedfrom currants and if protective chemical spraying against thedisease in the nursery is carried out, the incidence of infectionin plantations at least half a mile from the nearest currantsis likely to be low. The disease cannot spread within a pinecrop by direct transmission from tree to tree.     

东部白松试管芽诱导和增殖技术研究

以东部白松种子和幼嫩顶芽为外植体,研究影响试管芽获取的关键因子、增殖的最佳培养基种类及添加激素种类和浓度组合,有效建立了东部白松无菌试管芽增殖体系。结果表明：以0～4℃沙藏6周的东部白松种子为外植体,用0．I％HgCl2消毒10min,获得了无菌试管芽,试管芽的最佳增殖培养基为B5＋ZT 0．6mg／L＋IBA 0．4mg／L,增殖系数达4．09。     

Effects of soil organic matter,moisture, shading and ash on white pine (Pinus strobus L.) seedling emergence

The effects of soil organic matter, soil moisture, shading and ash on white pine (Pinus strobus L.) emergence were investigated using soil monoliths in greenhouse experiments. White pine seedling emergence increased with soil organic matter removal, and levelled with the elimination of the litter and fermentation layers, where seedling emergence did not significantly increase further. Increased shade and soil moisture levels also improved seedling emergence whereas ash had no or little impact on white pine seedling emergence. The silvicultural implications of these findings are discussed with regard to white pine management.     

Studies on the epiphytic bacteria on Populus tremula L. and Populus alba L. at the time of optimal and minimal cambium activity and infection by Venturia

The participation of epiphytic bacteria in the groups of bacteria dominating on the shoots and root collars of two year aspen and white poplar differs both in quantity and quality and depends on the chemical composition of the diffusion exudates related to cambium activity. This indicates that epiphytic bacteria can utilize carbon sources in the exudates and transform lignin precursors.     

Susceptibility of Healthy and Ozone-injured Needles of Pinus strobus to Invasion by Lophodermium pinastri and Aureobasidium pullulans1

Lophodermium pinastri and Aureobasidium pullulans were the fungi most often associated with foliar symptoms, including those caused by ozone, on Pinus strobus in the field. Following artificial inoculation of ozone-fumigated and untreated foliage on pine seedlings, L. pinastri was Isolated without relation to visible symptoms of ozone injury. A, pullulans was isolated only from tissues killed by ozone. No evidence of additive or interacting effects of ozone and the fungi was found.     

Analysis of acetylated wood by electron microscopy

The properties of acetylated solid wood were investigated earlier, in particular the anti-shrink efficiency and the resistance against decay. This study focuses on the possible changes and damage to the wood structure due to an acetylation process leading to weight per cent gains of up to 20%. Electron microscopy (SEM and TEM) was used to investigate the fine structure of acetylated beech, pine and spruce. Cell wall swelling was observed, but no evidence of damage could be seen as a result of the acetylation procedure. The fine structure of the wood tissue such as the pits and the thin parenchyma walls appeared untouched.     

欧洲赤松引种试验

本文介绍了在建始县长岭岗林场引种欧洲赤松的16a结果,显示该树种适应本地立地条件,在海拔1200～1800 m范围内均生长较好。比国内其他地方引种的生长要快,有巨大生产潜力。     

火炬松芽苗移栽容器育苗技术

介绍了火炬松形态特征及生物学特性,并论述了其种子处理、苗床、育苗基质的准备,播种、芽苗移栽、幼苗的管理以及病虫害防治等技术措施。