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PubMed2000

Needle and stem wood production in Scots pine (Pinus sylvestris) trees of different age, size and competitive status.

We studied effects of tree age, size and competitive status on foliage and stem production of 43 Scots pine (Pinus sylvestris L.) trees in southern Finland. The tree attributes related to competition included foliage density, crown ratio and height/diameter ratio. Needle mass was considered to be the primary cause of growth through photosynthesis. Both stem growth and foliage growth were strongly correlated with foliage mass. Consequently, differences in growth allocation between needles and stem wood in trees of different age, size, or position were small. However, increasing relative height increased the sum of stem growth and foliage growth per unit foliage mass, indicating an effect of available light. Suppressed trees seemed to allocate more growth to stem wood than dominant trees, and their stem growth per unit foliage mass was larger. Similarly, trees in dense stands allocated more growth to stem wood than trees in sparse stands. The results conformed to the pipe model theory but seemed to contradict the priority principle of allocation.

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PubMed1987

Physiology and genetics of tree growth response to moisture and temperature stress: an examination of the characteristics of loblolly pine (Pinus taeda L.).

Water stress and temperature impose fundamental limits to forest productivity. Stresses caused by fluctuating or extreme temperatures or limited water availability vary both seasonally and from year to year. The role of these stresses should be considered when investigating the causes of declines in forest productivity. Forest growth, or carbon gain, can be related quantitatively to three components: leaf area, rate of net photosynthesis and rate of respiration. This paper examines effects of temperature and water supply on these components with particular reference to loblolly pine (Pinus taeda L.), a species of economic importance in the southeastern United States where declines, of unknown cause, in forest productivity have been reported.

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PubMed1987

Micropropagation of mature Calabrian pine (Pinus brutia Ten.) from fascicular buds.

Dormant meristems of fascicles explanted from 10-year-old, field-grown trees of Pinus brutia Ten. were cultured in vitro. Browning of cultured fascicles was reduced by including 150 mg l(-1) sodium diethyldithiocarbamate (SDD) in a cytokinin-containing medium. The stage of development of fascicles when placed in culture affected both shoot-bud production and the degree of browning. Only fascicles at an advanced stage of development had a high rate of shoot-bud production. Fascicles cultured for 6 weeks in initiation medium containing 150 mg l(-1) SDD and then for 4 weeks in initiation medium containing 1 mg l(-1) insoluble polyvinylpolypyrrolidone showed the highest rate (23%) of shoot-bud development and the lowest rate (15%) of browning. Elongation of activated shoot buds was considerably enhanced by reducing the concentration of cytokinin in the culture medium. Only shoots >/= 20 mm in height were capable of producing further crops of buds and shoots. When treated with a combination of auxin and cytokinin, only 16% of the elongated shoots produced roots.

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PubMed1987

Carbon allocation, root exudation and mycorrhizal colonization of Pinus echinata seedlings grown under CO(2) enrichment.

Increased exudation of carbon compounds from roots may provide a mechanism for enhancement of nutrient availability to plants growing in a CO(2)-enriched atmosphere. Therefore, the effect of atmospheric CO(2) concentration on carbon allocation and root exudation was investigated in Pinus echinata Mill. (shortleaf pine) seedlings. After 34 and 41 weeks, seedlings growing in 695 microl l(-1) CO(2) allocated proportionately more (14)C-labeled photosynthate to fine roots than did seedlings growing in ambient air. This was associated with greater fine root mass and mycorrhizal density in CO(2)-enriched plants after 34 weeks. Exudation of soluble, (14)C-labeled compounds from roots also was greater in these plants at 34 weeks, but the effect of CO(2) concentration on exudation did not persist at 41 weeks.

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PubMed1987

Effects of low night temperature and light on chlorophyll fluorescence of field-grown seedlings of Scots pine (Pinus sylvestris L.).

In vivo chlorophyll fluorescence kinetics was observed in naturally regenerated and planted Scots pine (Pinus sylvestris L.) seedlings growing at two adjacent sites in northern Sweden. Some seedlings were shaded from direct solar radiation and some were protected from frost at night. Air temperature and solar radiation were monitored. In vivo chlorophyll fluorescence kinetics of current-year needles was measured at both room temperature and 77 K. On clear days during August, variable fluorescence of photosystem II of needles from exposed, naturally regenerated seedlings was reduced by night frosts, whereas frost caused little change in fluorescence of needles from shaded seedlings. Overnight frost-protection reduced the inhibition of photosystem II by direct sunlight. Recovery from photoinhibitory damage occurred on cloudy days. In September, the decline of variable fluorescence of photosystem II was more pronounced in unshaded than in shaded seedlings, and coincided with frosts at night. In addition, the reduction in variable fluorescence was larger for planted seedlings than for naturally regenerated seedlings. It is suggested that the inhibition of photosystem II activity was caused by an interaction between low temperatures and light. Natural night frosts are proposed to increase the susceptibility to photoinhibition in the following day(s).

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PubMed1988

Chlorophyll and carotenoid concentrations in two varieties of Pinus ponderosa seedlings subjected to long-term elevated carbon dioxide.

Two varieties of ponderosa pine (Pinus ponderosa Dougl. var. scopulorum (Rocky Mountain variety) and P. ponderosa var. ponderosa (Sierran variety)) seedlings were subjected to elevated atmospheric CO(2) for two and a half years. The CO(2) concentrations were ambient, ambient + 75 microl l(-1), ambient + 150 microl l(-1) and ambient + 300 microl l(-1), or approximately 350, 425, 500 and 650 microl l(-1) CO(2). After one and a half years of exposure to elevated CO(2) and until the end of the study, seedlings of both varieties showed symptoms of stress including mottling, mid-needle abscission and early senescence. In both varieties, exposure to CO(2) concentrations greater than ambient + 75 microl l(-1) resulted in lower chlorophyll a, chlorophyll b and carotenoid concentrations. At elevated CO(2) concentrations, the concentrations of pigments in needles of the Sierran variety were lower than those in the Rocky Mountain variety. Also, at elevated CO(2) concentrations, the pigment concentrations in the 1-year-old needles of both P. ponderosa varieties were lower than those in current-season needles.

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PubMed1988

Long-term elevation of atmospheric CO(2) concentration and the carbon exchange rates of saplings of Pinus taeda L. and Liquidambar styraciflua L.

The relationship between carbon exchange rate (CER) and internal CO(2) concentration was measured in leaves of saplings of Liquidambar styraciflua L. (sweetgum) and Pinus taeda L. (loblolly pine) grown from seed for more than 14 months at atmospheric CO(2) concentrations of either 350 or 500 microl l(-1). An elevated concentration of CO(2) during growth reduced CER at any given internal CO(2) concentration in sweetgum, but not in loblolly pine. Stomatal limitation of CER showed little response to concentration of CO(2) during measurement, but was higher in both species when grown at 500 than at 350 microl l(-1) CO(2). The net effect of a long-term increase in CO(2) concentration from 350 to 500 microl l(-1) was an increase in CER of loblolly pine, but a slight decrease in CER of sweetgum. It is suggested that the depression of CER in sweetgum resulted from a reduction in the activity of ribulose-1,5-bisphosphate carboxylase-oxygenase.

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PubMed1989

Aboveground production and N and P use by Larix occidentalis and Pinus contorta in the Washington Cascades, USA.

Aboveground net primary production (ANPP) and N and P use patterns were determined for western larch (Larix occidentalis Nutt.), a deciduous conifer, and lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.), an evergreen conifer, in the Cascade Mountains of Washington, USA. Western larch and lodgepole pine retranslocated 87 and 66% of foliage N and 66 and 78% of foliage P, respectively. At the stand level, N use efficiency of western larch was greater than that of lodgepole pine, whereas P use efficiency of lodgepole pine was greater than that of western larch. Western larch and lodgepole pine were comparable in ANPP and production efficiency (ANPP/foliage mass) if needle longevity is considered. The similarity in ANPP of the evergreen lodgepole pine and the deciduous western larch may be related in part to the lower initial construction cost of the foliage, and the efficient use of nitrogen by western larch.

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PubMed1989

Variation in growth and osmotic regulation of roots of water-stressed maritime pine (Pinus pinaster Ait.) provenances.

Hydroponically cultivated Pinus pinaster Ait. seedlings of a drought-sensitive population from France (Landes) and of a more drought-adapted population from Morocco (Tamjoute) were subjected to a progressive increase in water stress by additions of an osmoticum (polyethylene glycol 600) to the nutrient solution. The final osmotic potential (Psi(ms)) of the nutrient solution was achieved over a period of up to 6 days, and ranged from -0.03 (control, no added osmoticum) to -0.8 MPa. In the 6 days during which water stress was imposed, roots elongated faster in the Moroccan provenance than in the French provenance, but the applied water deficits did not inhibit root elongation in either population. Among treatments, root dry weight per unit root length, total root dry weight and root/shoot dry weight ratio increased with decreasing Psi(ms) in both provenances. Both the water potential (Psi(w)) of the roots (apices) and the water potential difference between the roots and the nutrient solution decreased as Psi(ms) decreased. The reduction in Psi(w) was matched by a decrease of comparable magnitude in cell osmotic potential (Psi(pi)) so that root turgor was unaffected by the Psi(ms). Osmotic adjustment was greater, however, in the Moroccan provenance than in the French provenance. Consequently, under the osmotically imposed water stress, the water potential difference between root and nutrient solution was greater in the Moroccan provenance than in the French provenance. Similar changes in plant water relations were observed when seedlings were grown in drying sand.

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PubMed1989

Carbohydrate relations during propagation of cuttings from sexually mature Pinus banksiana trees.

Concentrations of glucose, sucrose, soluble reducing sugars, starch and total non-structural carbohydrate were determined during propagation of cuttings from sexually mature Pinus banksiana Lamb. trees. Such cuttings rarely initiate adventitious roots whatever the method or duration of propagation. Terminals, needles, and upper and basal stem segments of cuttings were analyzed at Day 0 and every 2 days for 18 days. Comparison of the results with those of earlier studies with cuttings of P. banksiana seedlings, which root readily, indicated pronounced differences in carbohydrate concentrations and partitioning between the two types of cutting. Compared with those from seedlings, cuttings from sexually mature trees exhibited: (1) more total non-structural carbohydrate in each tissue at Day 0; (2) decreasing rather than increasing total carbohydrate (mainly starch) concentrations in each tissue during propagation; (3) different carbohydrate concentration ratios in each tissue during propagation; and (4) higher sucrose concentrations in terminals during propagation, relative to concentrations at Day 0. Cuttings from sexually mature trees also differed from cuttings of seedlings in having a much lower rate of dry matter accumulation during propagation. These findings suggest that the poor rooting ability of cuttings from sexually mature P. banksiana is not attributable to a lack of total carbohydrate, but that the rooting abilities of cuttings from seedlings and from sexually mature trees differ because of differences between the two types of cutting in rates of net photosynthesis and starch metabolism. The difference in starch metabolism becomes apparent during the first 2 days of propagation.

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PubMed1989

Growth and soluble proteins of cell cultures derived from explants and protoplasts of Pinus pinaster cotyledons.

Pinus pinaster Ait. cell suspension cultures were derived from chopped cotyledons and from cotyledon protoplasts. When transferred after 12 weeks in culture, growth of both cell types showed a lag of 5 days followed by an exponential phase of 14 days for the protoplast-derived cells and 23 days for the organ-derived cells. During the exponential growth phase, packed cell volume of protoplast-derived cultures increased 7-fold and that of organ-derived cultures 13-fold. During the stationary phase, the diameters of protoplast-derived cells averaged 80 microm and those of organ-derived cells 100 microm. After 30 days, the media containing protoplast-derived and organ-derived cells decreased in osmolarity by 50 and 120 mOs per kg water, respectively, and in pH by 1.4 and 2.0 units, respectively. Throughout the growth cycle, protein content per unit of packed cell volume was always at least 35% higher in the protoplast-derived cultures than in the organ-derived cultures. Two-dimensional electrophoretic separation of soluble proteins revealed three peptides present in protoplast-derived cells that were absent from organ-derived cells and two peptides present in organ-derived cells that were absent from protoplast-derived cells. Other peptides differed quantitatively between the cell types.

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PubMed1990

Influence of male cones on early season vegetative growth of Pinus contorta trees.

On average, branches of Pinus contorta Dougl. bearing male cones had 35 fewer needle pairs than equivalent vegetative branches, and significantly fewer differentiated primordia (i.e., male cones + needle pairs + sterile cataphylls). It was estimated that the formation of male cones results in a 27-50% reduction in the number of needles per male cone-bearing branch. In early spring, branches bearing male cones had on average 23% (0.44 g) more dry weight than vegetative branches. On average, 95% of the dry weight of male cone-bearing branches was allocated to the terminal shoot (54% of which was male cones) and 5% to the lateral shoots. By comparison, vegetative branches allocated 85% of their total dry weight to the terminal shoot and 15% to the lateral shoots. These findings suggest that male cones may reduce the photosynthetic potential of the trees which bear them.

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PubMed1990

Ozone, acidic rain and soil magnesium effects on growth and foliar pigments of Pinus taeda L.

Height and diameter growth, biomass accumulation and leaf pigment concentrations were measured in loblolly pine (Pinus taeda L.) seedlings grown in soil containing 12 or 35 microg Mg g(-1) and exposed from May to October to subambient, ambient, or twice-ambient ozone (O(3)), and to simulated acidic rain with a pH of either 4.0 or 5.3. At the end of one growing season, height and diameter growth of seedlings exposed to twice-ambient O(3) were not statistically different from those of seedlings exposed to subambient O(3). Biomass of all plant parts was reduced by 7 to 16% in response to increasing O(3) concentration. No statistically significant growth responses to rain chemistry or soil magnesium status were observed, and there were no statistically significant interactive treatment effects. Needle pigment concentrations were not significantly affected by rain chemistry or soil Mg status and there were no visible signs of injury to needles that could be attributed to O(3) stress or Mg deficiency. Concentrations of chlorophyll a and b, and carotenes were 23, 30 and 21% higher (P </= 0.05) respectively, in seedlings exposed to twice-ambient O(3) than in seedlings from the other ozone treatments. There were no interactive treatment effects on needle pigment concentrations.

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PubMed1990

Influence of female cones on the vegetative growth of Pinus contorta trees.

Branches of Pinus contorta Dougl. bearing two-year-old female cones initiated fewer lateral buds than vegetative branches. However, the number of lateral shoots that differentiated and grew was not reduced on female cone-bearing branches. Neither the number nor the weight of female cones influenced the length of the terminal shoot. The total length of all lateral shoots was positively associated with the weight of two-year-old female cones. Branch units with two-year-old female cones produced significantly more total dry weight in the current year than vegetative branch units. There was, however, no significant reduction in the dry weight of terminal and lateral shoots. Branches bearing female cones allocated between 17 and 45% of the current year's dry weight to two-year-old cones and between 1 and 5% was allocated to one-year-old female cones. Female cones therefore apparently do not reduce the photosynthetic potential of trees. The influence of female cones compared with male cones on the growth of trees is discussed.

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PubMed1990

Induction of acropetal (14)C-photosynthate transport and radial growth by indole-3-acetic acid in Pinus sylvestris shoots.

The relationship between radial growth and assimilate movement was determined in one-year-old Pinus sylvestris (L.) cuttings collected during the dormant period and reactivated for 1-27 days under environmental conditions favorable for growth. The cuttings were either left with buds intact, defoliated along the distal 8 cm, or debudded and treated apically with 0 or 1 mg g(-1) indole-3-acetic acid (IAA) in lanolin. Radial growth was measured as tracheid production and bark radial width. The distribution of (14)C-photosynthate 1 or 5 days after exposure to (14)CO(2) was used to indicate assimilate movement. Debudding inhibited tracheid production and decreased acropetal (14)C-photosynthate transport, whereas applying IAA to debudded cuttings promoted both these processes and, in addition, induced vigorous callus growth within the bark immediately below the application point. Distal defoliation markedly increased the amount of (14)C-photosynthate transported toward the apex without altering how debudding and exogenous IAA affected tracheid production and the distribution of (14)C-photosynthate. The production of tracheids induced by apically applied IAA in debudded and distally defoliated cuttings increased progressively in material collected on September 9, October 14 and November 24, whereas bark radial width and acropetal (14)C-photosynthate movement increased only between the first two collection dates. Ringing midway between the IAA source and the bottom of the distally defoliated region with a lanolin mixture of 10 mg g(-1)N-1-naphthylphthalamic acid (NPA), 1 mg g(-1) methyl-2-chloro-9-hydroxy-fluorene-9-carboxylic acid (CF) or 10 mg g(-1) phenylacetic acid (PAA) reduced radial growth and [1-(14)C]IAA transport below the ring and locally promoted radial growth and accumulated radioactivity above. (14)C-Photosynthate transport into the region above the ring either was not altered (CF, PAA) or was increased (NPA). The results indicate that apically applied IAA induces the acropetal movement of (14)C-photosynthate in debudded P. sylvestris shoots by locally promoting activity correlated with tracheid and callus production rather than by affecting radial growth or phloem transport processes, or both, at a distance below the IAA source.

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PubMed1990

Assessing seasonal leaf area dynamics and vertical leaf area distribution in eastern white pine (Pinus strobus L.) with a portable light meter.

We evaluated the ability of a portable light meter (Sunfleck Ceptometer, Decagon Devices, Pullman, WA, USA) to quantify seasonal photosynthetically active radiation (PAR, 400-700 nm) interception, projected stand leaf area index (LAI), and vertical LAI distribution in a 32-year-old eastern white pine (Pinus strobus L.) plantation. Canopy PAR transmittance measured with the ceptometer was converted to LAI with the Beer-Lambert Equation. The ceptometer was sensitive to changes in PAR transmittance resulting from foliage growth. Predicted stand LAI ranged from 3.5 in the dormant season to a maximum of 5.3 in late July. Predicted LAI values were within 9% of values determined from destructive sampling. Published canopy extinction coefficients (k) were inadequate for converting PAR transmittance data to stand LAI because a significant amount of PAR was intercepted by dead branches and stems below the forest canopy. Because of interception by dead branches and stems, we estimated k = 0.84, which is substantially higher than previously reported values. The ceptometer was also sensitive to seasonal changes in PAR transmittance within the canopy. However, in contrast to predictions based on the Beer-Lambert Law, the relationship between proportional PAR transmittance (Q(i)/Q(o)) and cumulative LAI within the canopy was linear. Thus, vertical LAI distribution was best estimated with a linear model, as opposed to the non-linear model assumed in the Beer-Lambert Equation. We hypothesize that the linear relationship was a result of a gap in the canopy which was not represented by the cumulative leaf area distribution estimation procedure.

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PubMed1990

Architectural distribution of foliage in individual Pinus radiata D. Don crowns and the effects of clumping on radiation interception.

The architectural arrangement and leaf area of representative branch units, on one branch complex from each cluster on the stem, were measured on six trees in a widely spaced 7-year-old Pinus radiata D. Don plantation. There was a linear relationship between leaf area and the basal area of branch complexes. Assuming similarity in the arrangement of branch units within concomitant branch complexes at each cluster, the 3-dimensional distribution of leaf area density (leaf area per unit volume) in an array of cubic cells, each 10(-3) m(3), comprising the volume of each tree crown, was reconstructed. The fraction of cells in which foliage was present varied from 0.08 to 0.23 in the crowns with the highest (Tree 4) and lowest (Tree 3) degree of clumping, respectively. This difference was related to the number, length, and leaf area per unit length of Order 3 branch units, in particular. The actual distributions of leaf area density were used with a simple radiative transfer model to estimate the probability of penetration of beam and diffuse photosynthetically active radiation (PAR) through individual tree crowns. The average probability of beam penetration was greater for the tree with the most clumped foliage than for the tree with the least clumped foliage. For both trees, the average probabilities of penetration were greater than the values that would have resulted if a random distribution of foliage had been assumed. The negative binomial model was used to estimate an index of foliage dispersion for the tree crowns. For beam PAR, the index of foliage dispersion was 3.3 and 2.3 for the trees with the most, and the least clumped foliage, respectively. These results were supported by analysis of the architectural arrangement of foliage in the tree crowns. For two days in summer, the assumption that leaf area density was randomly distributed would have resulted in a 20 to 30% overestimation of intercepted PAR flux by the tree crowns.

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PubMed1990

The interaction between leaf longevity and shoot growth and foliar biomass per shoot in Pinus contorta at two elevations.

Leaf longevity ranged from an average of 5 to 18 years in individual trees of lodgepole pine (Pinus contorta Dougl. ssp. latifolia D.K. Bailey) from six even-aged stands in central Colorado, USA, of which three were at an elevation of 2800 and three at an elevation of 3200 m. Leaf longevity was 38% greater and annual shoot growth increment was 33% less in trees growing at 3200 m than in trees growing at 2800 m elevation. There was no difference in leaf biomass per shoot between the trees at the two elevations. These results suggest that leaf longevity is greater on shoots with low annual growth potential. Thus, a slow-growing tree at high elevation (low annual shoot growth potential) can have the same amount of foliage per shoot as a fast-growing tree at lower elevation. This plasticity in leaf longevity enables a consistency in foliar biomass per shoot, which may contribute to the wide range of sites and environments that lodgepole pine occupies successfully.

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