摘要:

Interior spruce (Piceaglauca(Moench) Voss × PiceaengelmanniiParry) seedlings and emblings produced through somatic embryogenesis tissue culture were removed from frozen storage and tested with a stock quality assessment procedure prior to spring planting. Seedlings, compared with emblings, had greater height as well as shoot and root dry weights. Seedlings and emblings had similar root-collar diameter, buds per total shoot length, and needle primordia in their terminal buds. Seedlings and emblings had similar shoot form (i.e., branch quotient) and balance between their shoot and root system (i.e., plant water balance ratio). Emblings, compared with seedlings, had a lower osmotic potential at turgor loss point and symplastic fraction, plus a higher dry weight fraction and total turgor. Seedlings and emblings had similar osmotic potential at saturation and relative water content at turgor loss point. Seedlings and emblings had similar resistance to water movement through the plant–atmosphere continuum (Rpac) at 22 °C root temperature, though emblings had greaterRpacat 7.5 °C root temperature. Seedlings had greater net photosynthesis (Pn) than emblings over a 14-day period at both 7.5 and 22 °C root temperatures. Seedlings, compared with emblings, had greater root development over a 14-day period at 22 °C root temperature, though they had low and similar root development at 7.5 °C root temperature. BothPnand needle conductance (gwv) decreased as predawn shoot water potential (Ψpd) declined in seedlings and emblings. Nearly complete stomatal closure occurred at Ψpdless than −1.5 MPa, while similarly lowPnreadings (seedlings: −0.01 ± 0.04 μmol•m−2•s−1; emblings: 0.02 + 0.04 μmol•m−2•s−1) occurred between a Ψpdof −1.0 and −2.0 MPa. A performance potential index (PPI), which combines material and performance attributes in a comprehensive characterization of field performance potential, indicated that seedlings had a better PPI under optimum environmental conditions. However, seedlings and emblings had similar PPI under low temperature and drought conditions.

ISSN:0045-5067    

DOI:10.1139/x94-179

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Interior spruce (Piceaglauca(Moench) Voss × PiceaengelmanniiParry) seedlings and emblings produced through somatic embryogenesis tissue culture were planted on a reforestation site in the central interior of British Columbia. Gas exchange and water relations patterns were monitored over the first growing season and morphological development was monitored over two growing seasons. During shoot elongation, osmotic potential at saturation (Ψsat) and turgor loss point (Ψtlp) of seedlings and emblings increased, while their maximum bulk modulus of elasticity (ϵmax) and total turgor (Ψptotal) decreased, resulting in utilized turgor (Ψputil) exceeding 100%. From bud set in late July through October 8, Ψsatand Ψtlpdecreased, Ψ max and ϵPtotalincreased, with Ψputilbetween 55 and 70% for both seedlings and emblings. There were few seasonal differences in shoot water relations parameters of seedlings and emblings. One-year-old and current-year needle conductance (gwv) decreased as vapour pressure deficit (VPD) increased in a similar manner for both seedlings and emblings. Response surface models for net photosynthesis (Pn) of current-year needles showedPnto increase as photosynthetically active radiation (PAR) increased to around 1000 μmol•m−2•s−1, and thereafter remained stable, but as VPD increasedPndecreased at all PAR levels. Emblings, compared with seedlings, had 15% greaterPnunder optimal field site atmospheric conditions (i.e., VPD <3.0 kPa and PAR >1000 μmol•m−2•s−1). There was a linear increase inPnasgwvincreased in both seedlings and emblings, though 1-year-old needles had higherPnfor a given level ofgwvthan current-year needles. Height and diameter growth across the first and second growing seasons were similar for seedlings and emblings. Seedlings and emblings had similar total root weight after two growing seasons. After the first winter on the field site, survival was 87% for seedlings and 91% for emblings, while emblings had a lower proportion of their foliage damaged by winter conditions. Results indicate that seedlings and emblings were largely comparable in their field performance over two growing seasons on a reforestation site.

ISSN:0045-5067    

DOI:10.1139/x94-180

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

The problem of fitting height–diameter curves for repeated measurements on growth plots is addressed. The context of the problem is fitting historical data with varying sampling protocols and varying measurement accuracy. A key consideration is obtaining good estimates of top height and top-height increment. A particular model and objective function for fitting are presented. The model has two parameters for each measurement and one common parameter; limited crossovers in the height–diameter curves for the various measurements are allowed. The objective function minimizes errors in predicted height and in predicted change in height. The programming is described, and the availability of code is announced. Examples show both the strengths and weaknesses of this approach.

ISSN:0045-5067    

DOI:10.1139/x94-181

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Extension of the Richards biological growth function has been applied extensively to describe height growth patterns or to develop site index equations. We introduce a linear filter model to achieve the same goals. Although derivation of the filter model involves more computation, it compares well with the Richards growth model in accuracy when applied to a black spruce (Piceamariana(Mill.) B.S.P) stem analysis data set from northern Ontario. The main advantage of the filter model, however, is that it can be used as a base-age invariant site index model.

ISSN:0045-5067    

DOI:10.1139/x94-182

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Two different methods are applied to evaluate the variability of wood ability for Kraft pulping of 25 poplar clones (1-year-old trees). The first one consists in pulping almost all of the wood of each analyzed tree ("macropulpings"). The second one is based on pulping very small wood samples, entire cross sections close to 1 g, taken at 50-cm height (micropulpings and paper microtests). This paper presents the results found separately with the two methods for the following parameters: pulp yield, Kappa (κ) index or permanganate index, and average fiber length. We observed that the evaluations of these parameters deduced by microtests are always well correlated with those obtained from pulping of the whole trees. Moreover, the two methods reveal that the suitability of poplar wood for Kraft pulping is under genetic control at age 1. But for each parameter (especially the ratio (κ index)/(pulping yield)2and the average weighted fiber length), the differentiation of the clones is never exactly the same. Therefore, it is necessary to slightly modify the micropulping and microtests methodology to evaluate with better accuracy the pulp and paper properties of the whole trees.

ISSN:0045-5067    

DOI:10.1139/x94-183

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Predation by birds and insects and overwintering mortality of the white pine weevil,PissodesstrobiPeck, were examined in planted and seeded stands of jack pine (PinusbanksianaLamb.) in northern Ontario to develop recommendations for management. No significant difference was found in weevil damage to the stand and in mortality of weevils due to natural enemies between planted and seeded stands. On average, 7.3 ± 0.3 (mean ± 1 SE) weevils emerged as adults from dead terminals. Birds consumed up to 6.4% of late-larval and pupal weevils in planted stands and up to 8.9% in seeded stands. More weevils emerged from screened than from unscreened leaders, indicating a significant mortality of larvae and pupae, presumably owing to insect predators and parasitoids and high density of pupae. Overwintering mortality of adult weevils was 92% in the planted and 76% in the seeded stand. Mammalian predation significantly reduced survival of overwintering weevils. Factors related to other silvicultural treatments, such as the presence of weeds, may be affecting the survival ofPissodesstrobiand the susceptibility ofPinusbanksianastands toPissodesstrobiinfestation. The manipulation of both mammalian predation and overwintering sites should be emphasized in the management ofP.strobiinPinusbanksianaplantations.

ISSN:0045-5067    

DOI:10.1139/x94-184

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Serious malformation of tree stems and branches was first observed 17 months after plantingEucalyptusnitens(Deane & Maiden) Maiden trees on an improved pasture site in southern Tasmania. The trees were planted in a 52factorial fertiliser trial with application of nitrogen at 0, 60, 120, 240, and 480 kg/ha and phosphorus at 0, 30, 60, 120, and 240 kg/ha. The phosphorus was semibroadcast as a single dose just after planting in September 1990 and the nitrogen was applied over a 2-year period from planting. At 21 months of age, the degree of malformation increased significantly with increasing levels of nitrogen or phosphorus fertilisers and was most severe at the highest levels of application. There was a significant linear trend of decreasing diameter growth with increasing levels of phosphorus fertiliser. The concentration of Cu in the foliage was significantly lower in malformed than unaffected trees whilst other macro- and micro-nutrient foliar levels were within the normal range for healthy individuals. Whilst the symptoms appear similar to those of "Toorour syndrome" previously reported forPinusradiataD. Don on improved pasture sites in Australia, we believe the present symptoms may result from Cu deficiency induced at high fertiliser levels. The deformations substantially reduce the merchantability of trees from the plantation.

ISSN:0045-5067    

DOI:10.1139/x94-185

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Plant mixtures were established that differed in both proportion and density of loblolly pine (PinustaedaL.), sweetgum (LiquidambarstyracifluaL.), and broomsedge (AndropogonvirginicusL.). Soil moisture availability to the pine seedlings was quantified every 2 weeks by measuring predawn xylem pressure potentials. Temporal variation in pine water potential was accounted for by a water stress integral approach. Cumulative water stress integral values were calculated over four overlapping periods, from May to June, May to July, May to August, and May to September and compared with the mean seedling stem volume index at each period to determine competitive responses at the whole plant scale. Diurnal measures of stomatal conductance were taken each month to compare competitive responses at the leaf scale. In addition, environmental and plant responses that may control stomatal behavior were quantified. The pine water stress integral was strongly influenced by competing vegetation after the onset of a period of drought in early summer. The correlation between the water stress integral and pine growth increased after a significant drying period, accounting for more than half of the variation in stem volume index at the end of the first growing season. Stomatal conductance was also influenced by competition, with competitive effects more evident during times of drought. Conductance was most often related to bulk leaf water potential, which in turn was related to competitive effects on soil moisture availability. Vapor pressure deficit also influenced stomatal conductance, but this was largely unrelated to competitive effects.

ISSN:0045-5067    

DOI:10.1139/x94-186

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Edger and trimmer operators must make constant decisions in short time periods on the amount of materials to remove from boards produced in the sawmill. Their decisions directly affect the total volume, grade, and value of the boards, and they therefore directly affect the total value of lumber produced. In recent years, many softwood sawmills have installed computer controlled edgers and trimmers with scanners and optimizers to achieve higher recovery rates. Before similar, relatively expensive, technologies can be seriously evaluated for the hardwood industry, however, the current performance of edging and trimming operations must be known. Using a sample of 3360 boards, compiled from 37 hardwood sawmills located in 16 states, lumber grade, length, width, and dollar values obtained in edging and trimming operations were compared with values predicted by USDA Forest Service scientists for the same lumber. Significant differences between edging and trimming performance and predicted values were determined via statistical tests. A linear regression model was formulated to study the influence of overedging, overtrimming, and grade difference on the percentage of predicted dollar value achieved. It was found that most sawmills edged a relatively low proportion of their total production. In 99% of the boards, edging and trimming operations achieved similar values for grade and length to those predicted by the USDA scientists. The value of the lumber increased significantly as the amount of overedging decreased.

ISSN:0045-5067    

DOI:10.1139/x94-187

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Following pine seed germination, lipids in the megagametophyte are converted to sucrose, which is transported to the emerging seedling to support its growth. In several conifer species, an increase in the seedling starch content following germination has been reported. To further characterize this phenomenon, starch accumulation and localization, starch synthase (EC 2.4.1.21) activity (both soluble and granule-bound), and partitioning of exogenous14C-sucrose were determined following germination of pinyon (PinusedulisEngelm.) seeds. Starch was a minor component in dry embryos, accounting for only 3% of the dry weight. Starch levels increased 22-fold and 15-fold in the cotyledons and hypocotyl, respectively, by 8 days after germination. Starch accumulated to 65% of the dry weight in the cotyledons and 46% in the hypocotyl. The root and epicotyl accumulated relatively low levels of starch, only about 7%. Starch was localized primarily in the cortex and pith of the hypocotyl, the cortex of the cotyledons, and the root cap. Only granule-bound starch synthase showed a significant increase in activity during germination, and its changes more closely followed the pattern of starch accumulation. Exogenous14C-sucrose was partitioned primarily into starch. After a 24-h labeling period, starch in both the cotyledons and hypocotyl accounted for 38% of total label (61% of the incorporated label) in these organs. In the roots, starch accounted for only 2.5 and 14%, respectively, of the total and incorporated label. The spatial and temporal pattern of starch accumulation closely paralleled previously reported patterns for the activity of sucrose synthase, which is apparently associated with the sucrose–starch conversion. Starch accumulation in the seedling accounts for approximately 50% of the sucrose transported from the megagametophyte following pinyon seed germination. Thus, starch appears to serve as an important transitory carbon pool for the growing seedling and may serve additional functions during seedling development.

ISSN:0045-5067    

DOI:10.1139/x94-188

出版商:NRC Research Press    

年代:1994

数据来源: NRC