Shoots Of Scots Pine Research Articles

Tracheid Production in Response to Changes in the Internal Level of Indole-3-Acetic Acid in 1-Year-Old Shoots of Scots Pine

Different concentrations of indole-3-acetic acid (IAA) were applied in lanolin to 1-year-old shoots of Pinus sylvestris (L.) in a manner known to stimulate cambial activity. The internal concentration of free IAA was measured at a distance below the application point by combined gas chromatography-selected ion monitoring-mass spectrometry using [(13)C(6)]IAA as a quantitative internal standard, and related to the production of tracheids at the same site. The experiment was performed with: (a) debudded cuttings, where the major source of endogenous IAA, the apical buds, were replaced with exogenous IAA, and (b) intact, attached shoots, where endogenous IAA was supplemented by applying IAA around the circumference of the shoot. In both experimental systems, an increase in the internal IAA level was positively related to increased tracheid production. It was also demonstrated that the concentration of internal IAA measured at the sampling site was comparable with endogenous IAA levels found in intact control shoots, and that a wide range of applied IAA concentrations was associated with a relatively small range of internal IAA levels.

Effects of aluminium and mineral nutrition on growth and chemical composition of hydroponically grown seedlings of five different forest tree species

Forest die-back and impaired tree vitality have frequently been ascribed to Al-toxicity and Al-induced nutritional disorders due to increased acidification of forest soils. Therefore, in this experiment effects of Al were studied on growth and nutrient uptake with seedlings of five different forest tree species. During growth in culture solutions with and without Al all five species proved to be very Al-tolerant, despite high accumulation of Al in roots. In the coniferous evergreens Douglas-fir and Scots pine shoot as well as root Al concentrations were significantly higher than in the deciduous broad-leaved species oak and birch. Larch showed intermediate Al levels.

Infection experiments with Gremmeniella abietina on seedlings of Norway spruce and Scots pine

AbstractConidia of Gremmeniella abietina infected and caused disease symptoms in annual shoots of both Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) seedlings. In Norway spruce shoots the infection remained largely latent, with only a few seedlings showing symptoms. Mycelial growth inside the shoots was faster in Scots pine than in Norway spruce and was favoured by low temperature in both hosts. The shoots of Norway spruce seedlings had higher endophyte populations than those of Scots pine, and the populations were decreased by low temperatures. Reductions in the normal epiphytic or endophytic flora by acid mist treatments seemed to favour the development of G. abietina.

Variation in the pine stem rust fungus Peridermium pini in the United Kingdom

Peridermium pini aeciospores from lesions on Scots pine (Pinus sylvestris) in Scotland and in Thetford Forest, East Anglia, differed in terms of germ tube morphology and cytology. The former produced long aseptate germ tubes containing a pair of nuclei. The latter produced short septate germ tubes, each cell containing a single nucleus. One third of the ‘Scottish’ germ tubes ended in a vesicle. Nuclei could be counted in only a small proportion of ungerminated aeciospores. On average 83% of Scottish spores had two nuclei and 4% had one. The equivalent figures for Thetford spores were 66 and 20%. A small number of aeciospore samples from other parts of England resembled Scottish spores rather than Thetford spores in germ tube morphology and cytology.Both Scottish and Thetford spores proved capable of causing infection of wounded Scots pine shoots. In addition, some Thetford spores caused infection on leaf discs taken from certain Paeonia cultivars. From these results it is concluded that two distinct forms of Peridermium pini exist in the UK. The implications of this finding are discussed in relation to the history of pine stem rust in the country and the genetics and taxonomy of P. pini.

Photosynthesis of a scots pine shoot: Test of a shoot photosynthesis model in a direct radiation field

The photosynthetic light curves of eight Scots pine ( Pinus sylvestris L.) shoots, each with a different structure, were measured in a direct radiation field at different positions relative to the radiation beam. Using a model of shoot geometry, the irradiance distributions on the needle surface area of the same shoots were simulated in each position. Using measurements of shoot photosynthesis, the photosynthetic light curve for a needle surface area element (a small area on the needle surface) was estimated indirectly for each shoot. Shoot photosynthesis was then calculated from the estimated photosynthetic light response curve of a needle surface area element and the irradiance distribution on the surface area of needles. Calculated rates for shoot photosynthesis agreed well with the measured rates. The mean irradiance on the needle surface area was the major component causing variation in the light response of a shoot irradiated from different directions, but the shape of the irradiance distribution on the needle surface area had a considerably smaller effect.

Free amino acid and protein levels, and γ‐glutamyltransferase activity inPinus sylvestrisapical buds and shoots during the growing season

Free amino acid and protein levels, and γ‐glutamyltransferase activity in apical buds and shoots of Scots pine during the growing season. The aim of the study was to obtain the basic information about nitrogen mobilization needed in carrying out studies on the optimal nitrate and ammonium ratios in the metabolism of Scots pine (Pinus sylvestris L.). Considerable seasonal changes in the concentrations of free amino acids and other ninhydrin‐positive low molecular‐weight compounds were observed in the buds and shoots of Scots pine. 43 different amino compounds were identified, the concentrations of arginine, glutamine, glutamic acid, γ‐aminobutyric acid, alanine and aspartic acid being highest at the break of dormancy. The amounts of certain amino compounds decreased during the growing season, those of arginine, ethanolamine and various ammonium compounds in particular. The amount of glutamic and aspartic acids, glycine, alanine and γ‐aminobutyric acid, however, remained relatively constant. The protein con...

Stomatal Conductance and Photosynthesis in a Mature Scots Pine Forest. III. Variation in Canopy Conductance and Canopy Photosynthesis

(1) Water loss from coniferous plantations may lead to water shortages in regions of scarce water supply. To model growth and transpiration from a forest canopy over a year or more, it is necessary to know how conductance and photosynthesis of the entire canopy changes with season and weather. (2) The stomatal conductance and photosynthesis of current-year shoots of Scots pine (Pinus sylvestris) growing in eastern England were measured at different levels in the canopy throughout a year. Canopy conductance and canopy photosynthesis were calculated for the hours of measurement. (3) The diurnal behaviour of canopy conductance and canopy photosynthesis was substantially the same as that of the shoots. Maximum values of canopy conductance (1.6 cm s-1) occurred in September and minimum values after mid-day in July and August. Maximum rates of canopy photosynthesis (>1.2 mg m-2 s-1) occurred in October. (4) The major determinant of canopy conductance during the growing season was water vapour saturation deficit, except during periods when air temperature was less than 10 OC or incident quantum flux density was low, particularly at dawn and dusk. Canopy conductance declined sensitively with saturation deficit between 0.5 and 15 kPa but then remained constant at larger deficits. Stomatal closure at large saturation deficits had a major influence on canopy conductance in July and August, in spite of an increasing leaf area index as the new shoots elongated during this period. (5) Rate of canopy photosynthesis was strongly dependent on the quantum flux density except at high temperatures and large saturation deficits when canopy photosynthesis was also limited by canopy conductance. The response of canopy photosynthesis to light incident above the canopy was linear except at both high light and large saturation deficits when hysteresis occurred. (6) The relationship between canopy photosynthesis and canopy conductance was curvilinear at large saturation deficits but independent of conductance at small deficits.

Stomatal Conductance and Photosynthesis in a Mature Scots Pine Forest. II. Dependence on Environmental Variables of Single Shoots

SUMMARY (1) Water use by coniferous plantations may lead to water shortages in regions where water is a scarce resource. To be able to estimate transpiration in relation to assimilation of carbon over a year, it is necessary to know how stomatal conductance and CO2 uptake change with environmental variables. (2) The stomatal conductance and photosynthesis of current-year shoots of Scots pine (Pinus sylvestris) growing in eastern England were measured at different levels in the canopy and correlated with local values of the main environmental variables. (3) The major determinant of stomatal conductance during the growing season was atmospheric water vapour saturation deficit, except during periods when air temperature was less than 10 OC or incident quantum flux density was low, particularly at dawn and dusk. Stomatal conductance declined sensitively with water vapour saturation deficit between 0- 5 and 1 * 5 kPa but then remained constant at larger deficits. (4) Light-saturated values of stomatal conductance decreased with depth in the canopy but it was not possible to determine the response curve between stomatal conductance and light adequately from the data.

Photosynthesis of a scots pine shoot: simulation of the irradiance distribution and photosynthesis of a shoot in different radiation fields

Using a model of shoot geometry the distribution of irradiance at the needle surface area of a shoot in different radiation conditions is simulated and shoot photosynthesis calculated. It is shown that the distribution of irradiance is very sensitive to radiation field geometry, affecting the efficiency of the utilization of radiant energy in photosynthesis. As a result, the photosynthetic response of a shoot in natural conditions is, for instance, highly dependent on the proportions of direct and diffuse solar radiation, being higher the greater is the proportion of diffuse radiation.

Photosynthesis of a Scots pine shoot: The effect of shoot inclination on the photosynthetic response of a shoot subjected to direct radiation

A set of photosynthetic responses of a Scots pine ( Pinus sylvestris L.) shoot to light was derived from the shoot geometry and the photosynthetic response of a single needle. Computations showed that the shape of the photosynthesis light-curves varies substantially depending on the direction of radiation relative to the shoot position. Differences in the initial and maximum rates of photosynthesis were due to changes in the effective projection area and the irradiated fraction of the shoot, respectively.

Direct and indirect effects of light on stomata. I. In Scots pine and Sitka spruce

Abstract. The response of stomatal conductance to broadband blue and red light was measured in whole shoots of Scots pine and Sitka spruce, two species which have low stomatal sensitivity to CO2. In Scots pine, blue light was more than three times more effective than red light (on an incident quantum basis) in opening stomata, particularly at low quantum flux densities (<100μmiol m−2 s−1). However, the apparent quantum yield of net CO2 assimilation rate in blue light was only half that in red light. The contrasting effects of red and blue light on conductance and assimilation led to higher intercellular CO2 concentrations (Ci) in blue light (up to 100 μmol mol−1 higher) than in red light. Similar results were obtained with Sitka spruce shoots, though differences in the effectiveness of red and blue light were less marked. In both species, both red and blue light increased conductance in normal and CO2‐free air, indicating that neither red nor blue light exert effects through changes in Ci or mesophyll assimilation. However, decreases in Ci caused increases in conductance in both red and blue light, suggesting that these direct effects of light are not wholly independent of CO2.

Identification of endogenous N-(3-indoleacetyl)aspartic acid in scots pine( Pinus sylvestris L.)by combined gas chromatography-mass spectrometry, using high-performance liquid chromatography for quantification

N-(3-indoleacetyl)aspartic acid (IAAsp), a conjugate of the phytohormone 3-indoleacetic acid (IAA), was conclusively identified by combined gas chromatograhy-mass spectrometry (GC—MS) in dormant shoots of Scots pine ( Pinus sylvestris L.). A procedure based on reversed-phase liquid chromatography and flurescense detection is described for quantitative analysis of IAAsp levels in pine tissue. The current year's shoots of dormant seven-year-old trees of Scots pine contained 60 ng/g IAAsp fresh weight. The sensitivity of this method for IAAsp, applied to this material, was 1 ng, and 200 pg for pure standard. The preceding clean-up of the extract included the use of Amberlite XAD-7, a polyacrylic ester, which transfer organic compounds from a water phase to small volumes of organic solvents, an excellent alternative to the often used buffer-organic solvent extractions.

Uptake of SO2 in shoots of Scots pine: field measurements of net flux of sulphur in relation to stomatal conductance

Abstract. Net fluxes of gaseous sulphur compounds, water vapour and carbon dioxide to current‐ and one‐year‐old shoots of Scots pine were simultaneously measured in the field. The shoots were fumigated in temperature‐controlled assimilation chambers with sulphur dioxide at concentrations ranging from 40 to 250 μg m−3 (15–95 ppb). The hypothesis that stomatal opening regulates the uptake of sulphur dioxide was tested. The following conclusions were reached concerning the dry deposition of sulphur dioxide to a dry coniferous shoot.There was a marked diurnal variation in the uptake rate of sulphur dioxide. The net deposition velocity of sulphur was about three times higher during the day than during the night during July‐October. Stomatal opening was not the primary factor controlling the dry deposition rate of sulphur dioxide. The net dry deposition rate was significantly smaller than the calculated rate based on stomatal conductances for water vapour.Part of this deviation could be explained by re‐emission of reduced sulphur compound(s) from the needles. The re‐emission of sulphur was a light‐dependent process and might be of great significance for the sulphur balance calculations.A variable deposition velocity should be used in atmospheric transport models to account for the diurnal and seasonal variation in the surface resistance of a dry canopy.

Uptake of SO2 in shoots of Scots pine: field measurements of net flux of sulphur in relation to stomatal conductance

UPTAKE OF SO2 IN SHOOTS OF SCOTS PINE - FIELD-MEASUREMENTS OF NET FLUX OF SULFUR IN RELATION TO STOMATAL CONDUCTANCE

Seasonal Variations in the Occurrence of Indole‐3‐Acetic‐Acid in Buds of Pinus silvestris

AbstractStudies with a fluorescence spectrophotometer and gas chromatography confirm earlier results that IAA occurs in buds and sprouting shoots of Scots pine. IAA could be found during the whole vegetation period but not during winter dormancy. The largest amount was obtained during shoot growth in spring and early summer. During the most intensive elongation phase, a gradient could be found in the concentration of auxin with the highest amount in the basal part and a decreasing concentration upwards in the shoot.