Needle Dry Weight Research Articles

Effect of exogenous gibberellin A4/7 on tracheid production, longitudinal growth and the levels of indole‐3‐acetic acid and gibberellins A4, A7 and A9 in the terminal shoot of Pinus sylvestris seedlings

Gibberellin A4/7 (GA4/7) was applied twice weekly to 2‐year‐old Pinus sylvestris (L.) seedlings in each of two years, starting close to budbreak and ending after shoot elongation, but before cambial activity ceased. In 1988, the GA4/7 was injected into the 1987 terminal shoot (0, 0.2 or 2 mg seedling−1 application−1), while in 1990 it was applied as a soil drench (0, 10 or 50 mg seedling−1 application−1). In the 1988 experiment, GA4/7 treatment promoted diameter growth, and tended to increase both longitudinal growth and the indole‐3‐acetic acid (IAA) level in the 1988 terminal. In the 1990 experiment, GA4/7 treatment increased tracheid production, longitudinal growth, and the cambial region IAA concentration in the 1990 terminal, but did not affect its pith diameter, needle number, needle dry weight, or needle IAA level. Tracheid production in the previous‐year's terminal was also promoted in both experiments. The 50 mg GA4/7 soil drench markedly elevated the concentrations of GA4, GA7 and GA9 in the needles and cambial region of the 1990 terminal, while the 10 mg treatment raised the GA4 level in the cambial region, providing evidence that GA4 and GA7 applied to the roots reaches the shoot system. The results support the hypothesis that the exogenous GA4/7‐induced stimulation of tracheid production in the terminal shoot of intact plants is mediated through an increase in the IAA level in the cambial region. However, per se activity of GA4, GA7 or their metabolites cannot be ruled out.

Comparison of methods for estimating surface area of water-stressed and fully hydrated pine needle segments for gas exchange analysis.

A nondestructive technique for repeatedly estimating total surface area of water-stressed pine (Pinus taeda L.) fascicle segments was evaluated. Fascicle radius was measured with a digital caliper and needle surface area calculated on the assumption that the needles were segments of a cylinder. High correlations (r >/= 0.94) were found between surface area estimated in this way and surface area calculated (a) from needle displacement, also on the assumption that needles are segments of a cylinder, and (b) from needle dry weight using a regression between dry weight and surface area estimated from needle displacement. The caliper-radius method gave slightly lower estimates of surface area than the other methods. However, differences among surface area estimates made with the three methods and between estimates made on water-stressed and fully hydrated needles were small relative to variances of leaf gas exchange measurements.

Nutrient retranslocation within the foliage of Pinus sylvestris.

During the period 1983-1987, retranslocation of N, P, K, Ca, Mg, Mn, Zn, Fe, B and Al within the foliage of Scots pine (Pinus sylvestris L.) was studied in sapling, pole-stage and mature stands in eastern Finland. Needle concentrations of the mobile nutrients N, P, and K varied seasonally because of retranslocation. In unfertilized plots, needle contents of N, P and K decreased 62-92% during senescence and needle dry weight decreased 19-51%. In some years, needle contents of Ca, Mn, Zn, Fe, B and Al increased during senescence. Retranslocation was more efficient from needles with greater dry weight. In the fertilized, pole-stage stand, needle dry weight did not decrease at senescence four years after fertilization and nutrient content decreased less than in the other years. In the mature stand, there were no clear differences in needle dry weight and nutrient changes during senescence between years or between unfertilized and fertilized plots.

Nutrient leaching from conifer needles in relation to foliar apoplast cation exchange capacity

Limited evidence to date suggests that acidic precipitation promotes leaching of nutrient cations from conifer foliage. In order to evaluate the relative contribution of the apoplast cation exchange complex and symplast nutrient pools to the leached ions, the magnitude of foliar leaching in response to acidic solutions was compared to foliar apoplast cation exchange capacity (CEC) for two conifer tree species ( Pseudotsuga menziesii and Picea engelmanii). Leaching potential was determined by immersing detached needles in acidic solutions (pH5·6, 3·1, 2·1) over a range of time intervals (1, 4, 8, 24 h) and foliar apoplast cation exchange capacity was determined by potentiometric titration. Leaching increased with decreasing pH and increasing time of immersion. At pH values 2·1 and 3·1, equivalents of H + depleted from the acidic solutions approximated equivalents of base cations gained by the solutions. Maximum amounts leached were less than 40 μeq g −1 dry weight of needles for the combination of calcium, magnesium and potassium. Measured foliar apoplast CEC for these species was approximately 120 μeq g −1 dry weight of needles. These relative magnitudes indicate that the apoplast rather than the symplast provided the leached ions. Because the apoplast foliar cation exchange capacity appears to be large relative to the rates of H + diffusion across the cuticle, it may help to insulate the symplast nutrient reservoir from exposure to the H + of acidic solutions bathing the foliage.

The effect of root pruning on the maturation of loblolly pine (Pinustaeda) plantlets, rooted hypocotyls, and seedlings

Loblolly pine (Pinustaeda L.) tissue culture plantlets, seedlings, and rooted hypocotyls were subjected to three root-pruning treatments (control, half apices pruned, all apices pruned) to determine if pruning could alter the maturation state of the shoots, and if there was a correlative alteration of shoot cytokinin levels. Height, multiple characteristics of shoot morphology correlated with maturation, and root morphology were assessed. In comparisons with control plantlets, pruning significantly decreased plant height in half-pruned and all-pruned plantlets, needle length in all-pruned plantlets, terminal bud length and diameter in half-pruned and all-pruned plantlets, and needle dry weight in half-pruned plantlets. When these shoot morphological characteristics were regressed against height, the half-pruned plantlets appeared more juvenile than controls for both terminal bud length and diameter. All-pruned plantlets did not differ from controls. In comparisons of the three intact plant types, the plantlets were more mature than seedlings and rooted hypocotyls based on assessments of terminal bud length, terminal bud diameter, and needle length. However, in the half-pruned treatment these three characteristics did not differ among plantlets, seedlings, and hypocotyls, showing that they were equivalent for maturation status. Root pruning significantly increased the number of root apices for all plant types but did not increase plantlet or rooted hypocotyl cytokinin levels.

Temporal variation in nutrient concentrations of Pinus sylvestris needles

Temporal variation in nutrient concentrations of Scots pine (Pinus sylvestris L.) needles was studied during a three‐year period in three stands of differing stages of development. Concentrations of N, P and K varied significantly between years; this variation was related to differences in needle dry weight. Concentrations of all measured nutrients (N, P, K, Ca, Mg, Mn, Cu, Zn, Fe, B) and Al varied between seasons; this variation was related to nutrient mobility and the annual physiological cycle. Concentrations of the mobile nutrients N, P and K decreased in spring and early summer during shoot and needle elongation and increased in late summer and autumn during needle senescence and litterfall. Concentrations of Mg, Cu, Zn and B followed somewhat similar patterns. The poorly mobile nutrients Ca, Mn and Fe accumulated gradually in needles during each growing season. Needle nutrient concentrations were stable during the nonactive period.

The influence of simulated shadelight and daylight on growth, development and photosynthesis of Pinus radiata, Agathis australis and Dacrydium cupressinum

Abstract. Juvenile seedlings, micropropagated plantlets, and adult rooted cuttings of Pinus radiata, together with seedlings of Agathis australis and Dacrydium cupressinum, were grown under either high (670/μmol m−2 s−1) or low (200 μmol m−2 s−1) photosynthetic photon flux density (PPFD) and, at low PPFD, under three red:far‐red (R/FR) conditions, approximately simulating canopy shadelight, daylight and one intermediate value. In all types of P. radiata, a shade‐intolerant species, stem height and diameter, stem and needle dry weight, and apical dominance were markedly increased by a reduction in R:FR ratio while fascicle density was decreased. In contrast, these increases were considerably less for the shade‐tolerant D. cupressinum and moderately tolerant A. australis. With the exception of the P. radiata seedlings, height growth was greatest in all species under high compared to low PPFD for daylight R:FR ratio conditions. Total shoot (or plant) dry weight was increased approximately two‐fold in all species and types by the higher PPFD. Shoot extension rates were negatively correlated with calculated phytochrome photoequilibrium with P. radiata, the most shade‐intolerant species, having the highest change in rate per unit change in photoequilibrium (i.e. very responsive), and D. cupressinum, the most shade tolerant species evaluated, having the smallest change (i.e. largely unresponsive). Within the spectral quality treatments at low PPFD, it is suggested that higher rates of dry matter accumulation under the low R:FR ratio were the result of reduced mutual shading of adjacent leaves as a consequence of photomorphogenically‐controlled internode lengths rather than of enhanced photosynthesis per se. The significance of the results is discussed in relation to planting stock management in nurseries, the management of forest canopies for understorey seedling growth, and to the construction of representative growth simulation models. Consequences for controlled environment lighting are also considered.

Total wood, sapwood, and heartwood in branch bases of three conifers

Branches were cut from forest-grown, 15- to 85-year-old Picearubens, Pinusstrobus, and Tsugacanadensis trees. For 1139 branches we measured (i) cross-sectional sapwood, colored heartwood, and total wood areas at the branch base, (ii) dry weight of the needles and wood, and (iii) age. Branch age was a poor predictor of wood areas at the branch base. Regression analysis showed that branch wood dry weight was the best predictor of total wood area. Sapwood area was predicted equally well by needle dry weight or as a percentage of total wood area. The prediction was improved by using needle dry weight plus total wood area as variables. The mean ratio of sapwood area to needle dry weight was 0.72 mm2/g for Picearubens, 1.19 mm2/g for Tsugacanadensis, and 1.62 mm2/g for Pinusstrobus. Colored heartwood formed in the center of all branches older than 8 years. Heartwood area was a greater proportion of total wood area in older branches than in younger branches of any given tree, although absolute heartwood area was as variable as total wood area. The best estimates of heartwood area were obtained by subtracting estimates of sapwood area from total wood area. Heartwood area of the oldest branches (8–46 years) from each tree was 7–96% of total wood area at the branch base.

Carbon, water and nitrogen relations in evergreen and deciduous conifers

Comparisons of carbon, water and nitrogen relations in 33-year-old trees were made among evergreen spruce (Picea abies L.) and three deciduous larch species (Larix decidua Mill., L. leptolepis Gord. and their hybrid L. dec. x lep.), in a field experiment near Bayreuth (West Germany). Nitrogen content per unit dry weight was higher in larch needles than in spruce needles as was the photosynthetic capacity per unit of needle dry weight and area. Area related water demand of the deciduous needles was higher at the needle and crown level than in spruce, whereas evergreen spruce needles displayed a higher water use efficiency. However, because of foliage longevity and thus lower carbon investment in current-year foliage, spruce trees achieved the same stem increment as larch trees of similar age and height. A simulation illustrates that evergreen trees are able to achieve annual carbon gains comparable to deciduous trees because deciduous trees have a higher water demand and nitrogen investment in the current-year needles compared with evergreen trees that depend on longevity of functioning needles.

Carbon dioxide assimilation and growth of red spruce (Picea rubens Sarg.) seedlings in response to ozone, precipitation chemistry, and soil type.

The influence of ozone, mist chemistry, rain chemistry, and soil type on CO2 assimilation and growth of red spruce (Picea rubens Sarg.) seedlings was investigated over a 4-month period under controlled laboratory and glasshouse conditions. Growth was evaluated through interval estimates of aboveground relative growth rates (RGR) and the partitioning of biomass components at harvest to root, stem, and needle fractions. Precipitation chemistry treatments and O3 exposure dynamics were based on reported characteristics of air chemistry and/or deposition in high-elevation forests of eastern North America. The two soils were collected from Camels Hump in the Green Mountains of Vermont and Acadia National Park on the Maine coast. Soil from Acadia had higher organic content, higher levels of extractable base cations, and lower levels of extractable aluminum and heavy metals. The only treatment variables that consistently influenced the growth of P. rubens were soil type and rain chemistry. In comparison with seedlings grown in soil from Acadia National Park, those grown in Camels Hump soil had significantly less needle (27%), stem (33%), and root (26%) biomass at harvest and statistically lower aboveground RGR within 2 months after initiation of the treatments. Seedlings grown in Camels Hump soil had significantly higher levels of aluminum (6.5X), copper (1.4X), and nickel (2.7X) in new needle tissue. The only influence of precipitation chemistry on the growth of P. rubens was a pattern of greater root and shoot biomass in seedlings experiencing the more acidic rain treatments. Interactive effects among the main treatment variables (e.g., acidic mist and O3, acidic rain and soil type) on seedling growth were not notable. Rates of CO2 assimilation and transpiration on a per gram needle dry weight basis [mol·g-1·s-1] were not influenced by any of the main treatment variables or their interaction. Because neither soil type nor precipitation chemistry influenced the efficiency of CO2 assimilation per gram dry weight of needle tissue, the physiological mechanism underlying the growth response of P. rubens is attributed to a change in either whole-plant allocation of carbon resources or a direct toxic effect in the rhizosphere on root growth.

Foliage and canopy characteristics in relation to aboveground dry matter increment of seven jack pine provenances

This paper reports on foliage and tree size data collected in 1984 in an Ontario Pinusbanksiana Lamb, (jack pine) provenance trial established in 1954 at the Petawawa National Forestry Institute, Chalk River, Ont. The ratio of total needle area to needle dry weight of seven provenances showed a substantial within-tree, between-tree, and between-provenance variation that was associated with position within the tree and the average provenance tree size. Provenance mean values ranged from 11.7 to 14.3 m2/kg. The highest values were found in the tallest trees. Tree size and dry matter content varied significantly among provenances, but the relative growth rates of stem volume and aboveground biomass between the ages of 29 and 34 years averaged 5.7 and 4.9% per year in all provenances respectively. Aboveground dry matter production per hectare per year increased linearly with increasing projected leaf area index. The average increase was 1.9 t dry matter per l m2 increase in the leaf area index. Projected leaf area indices for optimally stocked stands averaged 5.0 m2/m2. The results indicated an almost constant net assimilation rate of 1.9 g aboveground dry matter per square decimetre of projected foliage per year in all provenances. Canopy foliage area was strongly correlated with basal area at 1.3 m and stem cross-sectional area at the base of the live crown. Total foliage area per unit basal area averaged 0.31 m2/cm2 at breast height and 0.70 m2/cm2 in the live crown. No significant differences were found between provenances.

Planting site storage: effects on survival and growth of overwinter-stored Scots pine (Pinussylvestris) containerized seedlings

Survival and growth of outdoor- and cold-stored (−5 °C) Pinussylvestris (L.) containerized seedlings were studied following field storage in wax-lined cardboard boxes at the planting site during three growing seasons. Planting dates varied from early May until late June. The negative effects on subsequent growth were more pronounced for outdoor-stored seedlings. Planting site storage during the period of shoot elongation especially limited subsequent growth of those seedlings. Shoot and needle growth, stem diameter, and dry weight of the shoot and foliage mass were successively depressed by later planting dates for both outdoor-and cold-stored seedlings. No significant differences could be found in survival or growth of outdoor- and cold-stored seedlings that had not been stored at the site before planting. For planting dates in June, dry weight of the shoot and needle growth were depressed compared with seedlings planted in May.

Level of sugars in Scots pine trees of different sensitivity to fluoride and sulphur dioxide

AbstractOn the average there is in the needles of the studied pines 1.9 and 4.9% of reducing sugars in the fresh and dry weight of wintertime needles respectively. There is 1.4% glucose of needle fresh weight (3.0% of needle dry weight) while for fructose the corresponding values are 0.8 and 2.1%. The relative ratio of glucose to fructose was on the average 1.33. Trees more tolerant to fluorides and sulphur dioxide emitted from the phosphate fertilizers factory have a statistically significant lower level of directly reducing sugars in the dry weight of needles (37.1 mg/g) compared to sensitive trees (50.5 mg/g). The control (more tolerant trees) accumulate more glucose and fructose than sensitive ones.

Seedling Spacing in the Nursery in Relation to Growth, Yield, and Performance of Stock

In three experiments coastal and interior varieties of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). Sitka spruce (Picea sitchensis (Bong.) Carr), white spruce (Picea glauca (Moench.) Voss), lodgepole pine (Pinus contorta var. latifolia Engelm) and western red cedar (Thuja plicata Donn.) were grown at a range of spacings, within drills 15 cm apart, at four nurseries in coastal British Columbia. In a fourth experiment the frequency distribution of seed spacings achieved with three types of precision seeders was examined.A 1 cm increase in spacing increased seedling dry weight by 0.5–1.5 g and root collar diameter by 0.2–0.25 mm. up to a spacing of about 8–10 cm. Above this spacing response was less. Height of two-year old (2-0) seedlings was increased little, or even decreased by wider spacing. Height:diameter ratios decreased sharply and shoot:root dry weight ratios decreased or remained unchanged with wider spacing. The number of needle primorida in 2-0 Douglas-fir buds increased up to a spacing of 2 cm. The number of first and second order branches was also increased in 2-0 seedlings of this species by wider spacing. Needle dry weight and area measurements suggested Douglas-fir from wider spacing had more sun type needles than those from closer spacing, which had more shade type needles. Only small increases in root growth capacity (RGC) were associated with wider spacing. None of the precision seeders tested achieved anything like perfect precision of seed placement. With irregularity added by 10–20% non-viable seed and winter mortality, truly precision spaced stands of 2-0 seedlings could not be achieved under existing conditions. Increased spacing of 2–5 cm between seedlings, depending on species and nursery, was justified by yield of acceptable seedlings when culling standard was increased to a root collar diameter of about 6 mm.Three years after planting, survival of white spruce was increased 11% by wider spacing in the nursery, and the corresponding value for Sitka spruce two years after planting was 13%. Seedlings of both species from wider spacings maintained a height and diameter advantage over those from close spacing.

Morphological and chemical traits of pine needles of trees in a gap caused by root rot

AbstractSome morphological traits of the crown (length and dry weight of needles, length of shoots) and chemical composition of the needles (content of nitrogen, phosphorus, potassium, calcium and magnesium) of a tree remaining in the middle of a Fomes annosus‐rot gap in a 55‐year‐old pine stand, were compared to the same traits from trees at the edges of the gap. The central tree (C) was intermediate in morphological traits. The lowest concentrations of N, P, and K were found in needles of the central (C) tree and, respectively, the highest ones in needles of the tree classified as weakened (I) and standing at the edge of the gap.

Effects of simulated acid rain on germination and early growth of Douglas-fir and ponderosa pine

Germination percentage of Douglas-fir (Pseudotsuga menziesii) was reduced by 30% by severe acid-rain treatment (pH 2.0), and seedlings that germinated at pH 2.0 soon died from fungal attack. Less acidic treatments did not affect germination. Two-year-old seedlings of Douglas-fir and ponderosa pine (Pinus ponderosa) planted in native granitic soil and sprayed for 12 weeks with acid (2∶3, sulfuric: nitric) at pH 5.6, 4.0, 3.0 and 2.0, also showed little effects except at pH 2.0. There were no significant differences (atp<0.05) between acid treatments for length and for dry weight of needles that developed during acid treatment. However, at pH 2.0, needles exhibited white acid burns, brown tips, and seedlings became limp and wilted; symptoms worsened with duration of treatment. Both new and old needles eventually died at pH 2.0. Implications of this study are discussed.

Clonal response of eastern white pine to low doses of O3, SO2, and NO2, singly and in combination

Eight clones of eastern white pine (Pinusstrobus L.) in three pollutant sensitivity groups (sensitive, intermediate, and tolerant) were exposed to 0.05 or 0.10 μL/L of ozone, sulfur dioxide, and (or) nitrogen dioxide 4 h daily for 35 consecutive days. Visible symptoms, length, and dry weight of 1st-year needles were determined to evaluate clonal response to these pollutants. A general response within sensitivity groups to all three pollutants, singly and in combination, was not observed. The sensitivity of the clones was dependent on the type of pollutant, its concentration, and the plant response used as the indexing factor. The amount of area injured was categorically differentiable among the three sensitivity groups but varied within the same group. Needle length was an inconclusive measure of clonal pollutant sensitivity, whereas needle dry weight was the parameter best associated with clonal pollutant sensitivity. These results demonstrate that a single response parameter is of limited value in determining plant sensitivity to air pollutants.

A new multivariate approach to foliar analyses for diagnostic purposes in mature Scots pine stands

The relationship between the needle dry weight and the contents of particular nutrients in pine needles is studied using multiple regression and path coefficient analysis. By joint use of all the information thus obtained it is possible to reach an objective assessment of the nutrient status of mature pine stands and to plan adequate fertilization without recourse to uncertain critical nutrient levels and to the difficult-to-interpret tree growth response. An example is presented of the application of this approach to a 72-year-old Scots pine stand.

Estimating Crown Biomass in Loblolly Pine Plantations in the Carolina Flatwoods

Diameter at breast height, crown class, total height, height to base of live crown and dry weight of crown components from whorls at measured heights were sampled from trees on 182 plots in North and South Carolina in summer, 1977. Equations were derived to estimate crown branchwood, needle and total dry weight for branches, trees and stands. The branch model is based on a logarithmic transformation of Huxley's allometric equation, giving dry weight as a function of branch basal diameter, relative height of the branch and stand age. The tree model uses either diameter at breast height and crown ratio, or diameter at breast height, age and stand basal area as independent variables. Crown mass per acre is predicted from site index, age and stand basal area. The accuracy and precision of the procedures were evaluated using an independent set of data and found to be satisfactory at the 1% level. Trends of crown biomass change were investigated and results suggest that it forms a smaller proportion of total biomass on higher quality sites.

Variation in isoabienol content in Pinus sylvestris needles

The diterpene alcohol isoabienol occurs in some individual pine (Pinus sylvestris L.) trees, in which it constitutes 0.6–1.0% of the needle dry weight, and is totally lacking in others. Isoabienol can be found only in the needles, mainly in fully outgrown needles, not in shoot axis tissue, wood, or cortex oleoresin. If sampling is limited to mature needles, within-tree, within-clone, and seasonal variations are insignificant, making isoabienol a suitable marker substance for studies of chemotaxonomy and population genetics. Isoabienol occurs more frequently in northerly provenances than in southerly. No correlation could be shown between isoabienol occurrence and the monoterpene or resin acid composition of the needles. There was no family-level correlation between isoabienol occurrence and resistance towards the pathogenic fungus Gremmeniella abietina.