Young Needles Research Articles

Mercury concentrations in black spruce (Picea mariana Mill. B.S.P.) and lichens in boreal Quebec, Canada

Mercury content was analysed in black spruce bark and needles and in the epiphytic lichens found growing on trees. The samples were collected in two distinct boreal forests of northeastern Canada (province of Quebec). The chosen sites were far from direct industrial mercurcy sources, and were located close to man made lakes of different ages. The objective of the study was to determine the role of atmospheric transport in the mercury contamination of trees growing in close proximity to reservoirs, both old and recently flooded. The lichen samples contained the highest mercury concentrations; 400–800 ng/g. They were several times higher than in the bark and one to two orders of magnitude greater than that found in the needles. The mercury concentrations measured in the lichens were significantly different between the two reservoir sites, whereas those of the needles and bark were not. The mercury concentrations in the black spruce bark sampled near the reservoirs were almost twice as high (∼130 ng/g) as those measured in the bark of black spruce trees growing near natural lakes (40–70 ng/g). However no differences were found between the mercury concentrations of young needles sampled close to reservoirs and those sampled near natural lakes, suggesting the existince of a relatively low but stable level of mercury in the local atmosphere.

Phytohormones in Needles of Healthy and Declining Silver Fir ( Abies alba Mill.): II. Abscisic Acid

Summary Abscisic acid (ABA) and trans-ABA (t-ABA) were quantified in needle extracts from silver fir (Abies alba Mill.) and spruce trees (Picea abies [L.] Karst.) using gas chromatography with electron capture detection. In current-year needles of fir trees in the Northern Black Forest, high concentrations of ABA (up to 126 nmol g dw-') were found while needles elongated. Apart from this observation, levels of ABA exhibited no general seasonal trend. However, in autumn a -short-term. elevation in levels of ABA was detected. Therefore, it cannot be ruled out that other «short-term» alterations of levels of ABA, which have not been detected, do exist. Without water stres, ABA concentrations did not exceed 2 nmol g dw-1 in mature needles and showed no clear variation with needle age. During water stres, levels of ABA increased up to about 19 nmol g dw-1 with levels being highest in the youngest needles. t-ABA concentrations in fir needles were independent of needle ABA levels while levels of t-ABA in spruce needles rose with increasing levels of ABA. No differences were seen between healthy and declining fir trees, while trees were well supplied with water, but during water stres, levels of ABA in declining trees were always higher than in healthy trees. It is concluded that the factors that cause silver fir decline do not directly influence levels of ABA in the foliage but make trees more sensitive to water stres by affecting either the stomata or the root system.

Effects of phosphorus deficiency and recovery fertilization on growth, mineral concentration, and ultrastructure of Scots pine needles

During the first year of a 2-year field experiment (1989–1990), 3-year-old Scots pine (Pinussylvestris L.) seedlings were watered with phosphorus-deficient nutrient solutions containing no phosphorus (0%) or 30% of the optimal phosphorus supply. A complete nutrient solution was used as the control. In the second growing period, the seedlings were divided into two groups, a deficiency and a recovery treatment, to follow the further development of, and recovery from, symptoms. Phosphorus contents in both current- and previous-year needles in both deficiency groups decreased clearly during the first growing period. Limited growth was observed at both deficiency levels after 10 weeks of treatment. The first ultrastructural symptom, swelling of cristae and subsequent dilatation of whole mitochondria, was observed after 16 weeks of treatment in the current-year needles. In addition to this symptom, the previous-year needles had an increase in the number and translucency of plastoglobuli, a decrease of granum thylakoids, and an increase in the density of the stroma in chloroplasts. After the second growing period, the same changes were observable in the phosphorus-deficient seedlings. In the young needles grown during the recovery fertilization period, slight swelling of mitochondria was detected and recovery of the previous-year needles was not complete. The results of this experiment suggest that the swelling of mitochondria is a characteristic symptom of phosphorus deficiency at the ultrastructural level in different needle generations. All the symptoms, when occurring together, may be used in identifying a moderate phosphorus-deficiency stress in seedlings.

Evidence for recrystallization of epicuticular wax on needles ofPinus sylvestris

Very young Scots pine needles were found to have a higher percentage of their peristomal rim surface area covered with amorphous wax than needles sampled 5 weeks later. This, in combination with the observation of wax crystalloids (rodlets) on top of amorphous wax crusts, is interpreted as evidence for wax recrystallization

Endophytic fungi in Scots pine needles: spatial variation and consequences of simulated acid rain

Within- and among-tree variation in assemblages of endophytic fungi in Scots pine (Pinus sylvestris) needles were studied in a subarctic area where background pollution values are low; the effects of tree density and prolonged simulated acid rain on the occurrence of endophytic fungi were investigated. The needle endophyte most frequently isolated was Cenangium ferruginosum, accounting for 64% of all fungal individuals, followed by Cyclaneusma minus (12% of all individuals). Old needles were colonized more frequently by endophytes than young ones. In young needles the colonization by endophytes increased during the summer, whereas in old ones no seasonal variation was detected. Endophyte colonization was positively correlated with stand density and was reduced on pines treated with spring water acidified with either sulphuric acid alone or in combination with nitric acid. In contrast, nitric acid alone did not affect endophyte colonization. Key words: endophytes, needles, pine, Pinus, simulated acid rain, stand density.

Epicuticular Leaf Waxes in the Evolution of the Plant Kingdom

Needle waxes of conifer trees consist of homologues of fatty acids, nonacosan-10-ol and predominantly bifunctional lipids with chain lengths C12 to C16, the α-ω-diols and above all the ω-OH-fatty acids, free or in form of their inner esters, the estolides. On young needles crystalloids in the shape of small round tubules formed by nonacosan-10-ol always can be observed. Leaf waxes of deciduous trees have a quite different composition. They consist mostly of homologous series of hydrocarbons, wax esters, aldehydes, alcohols and fatty acids. Further lipids are found on occasion, for example benzyl acyl esters or acetates and often triterpenoids as well. The surface wax ultrastructures of deciduous trees differ from species to species according to wax composition. Liriodendron leaves have surface crystalloids in the shape of transversally ridged rodlets formed by hentriacontan-16-one, Tilia leaves show quandrangular rodlets formed by β-amyrenyl acetate, Quercus has fringed edged platelets formed by tetracosanol. Fagus and Castanea trees have no wax crystalloids, but only a sculptured surface structure on the upper leaf side. Gingko leaf waxes have an intermediate composition. Dominant are the homologue lipid components similar to those of deciduous trees, but nonacosan-10-ol is also present and thus the surface ultrastructure shows small round tubules like those of conifer needles. There are fundamental differences between epicuticular leaf waxes of gymnosperms and angiosperms, fundamental evolutionary influences are found to affect the wax compositions and surface ultrastructures of these different plant classes.

Cytotoxicity and insecticidal activity of endophytic fungi from black spruce (Picea mariana) needles

Hyphae and hyphal extracts from fungi isolated from inside healthy black spruce needles were assayed for their effect on spruce budworm (Choristoneura fumiferana Clem.) cell cultures and larvae. Isolates were from needles of four age-classes (current –3 years old) collected throughout a 4-month sampling period. Hyphal extracts from 21 of the 100 isolates tested were toxic to spruce budworm cell cultures and isolates from older needles (2 and 3 years old) negatively affected cells more frequently (p < 0.05) than isolates from younger needles (current and 1 year old). Hyphae from five isolates and hyphal extracts from seven increased mortality (p < 0.05) when fed to second instar larvae in a laboratory bioassay. Development was delayed and larval dry mass reduced when budworm were fed hyphae from Cryptocline abietina Petrak (isolate number 69). Larval dry mass was reduced when budworm were fed the extract from Aureobasidium pullulons (de Bary) Am. (isolate 87) but increased when fed Cryptocline abietina (isolates 40 and 80), a coelomycete (isolate 12), and Hormonema dematioides (isolates 28, 63, and 96).Key words: endophytic fungi, budworm, Choristoneura fumiferana, Picea mariana, toxicity.

Structure of the Needles in the Early Phases of Development in Pinus ponderosa P. et C. Lawson with Special Reference to Plastids

Before they emerged from the fascicular sheath, the tissues of young needles of Pinus ponderosa P. et C. Lawson already showed some characteristics typical of mature needles. The organelles, particularly the plastids, had undergone different development. The plastids in different types of cell varied in their ultrastructure and in association with the endoplasmic reticulum (ER). A sheath of ER was observed around the amoeboid plastids in epidermal cells, epithelial cells of resin ducts and maturing transfusion tracheids whereas there was no ER sheath around the young mesophyll chloroplasts, the fusiform chloroplasts in some transfusion tracheids and the proplastids in xylem and phloem cells. The content of chlorophyll (a+b) was 0·85 g kg-1 dry matter and chlorophyll a/b ratio was 2·70. The needles may become photosynthetically active whilst still within the fascicular sheaths.

The Relationship of Nitrate Reductase Activity to Uptake and Assimilation of Atmospheric15NO2-Nitrogen in Needles of Norway Spruce (Picea abies[L.] Karst.)

Abstract Using 15NO2, relations between nitrate reductase activity and stomatal conductance, 15N-uptake and 15N-glutamate were studied in the two youngest needles flushes of potted Norway spruce (Picea abies [L.] Karst.). There were linear correlations between the stomatal conductance and the 15N-uptake and between the 15N-uptake and nitrate reductase (E.C. 1.6.6.1/1.6.6.2) activity. The 15N labelling of free glutamate shows the assimilation of NO2 from the atmosphere in addition to the nitrogen from the soil. The portion of glutamate originating from 15NO2 was linearly related to nitrate reductase activity in spring experiments. This indicates that this enzyme activity reflected the rate of NO2-assimilation.

Seasonal Changes in Nitrogen Metabolism of Spruce Needles ( Picea abies (L.) Karst.) as Affected by Water Stress and Ambient Air Pollutants

Summary Sixteen-year-old spruce trees ( Pice abies ) enclosed in their natural habitat in open-top chambers with charcoal-filtered and non-filtered air were studied from 1988 -1991 to evaluate the long-term impact of ambient air pollutants on needle nitrogen metabolism (contents of soluble protein and amino acids and activities of glutamine synthetase and glutamate dehydrogenase). Investigation of diurnal variations in soluble amino acid contents revealed a maximum of glutamate, serine and glycine and a minimum of aspartate at noon. The typical ontogenetic curves in nitrogen metabolism of young needles from flushing until October of the next year consisted of distinct phases: (1) within the first vegetation period a strong increase in needle protein and enzyme activities, (2) during winter a decrease in amino acid content, (3) in springtime a maximum in amino acid content, (4) in early summer a temporary decrease in protein content, and (5) in late summer an increase in arginine content in some trees. Beside seasonal changes, levels of the parameters were found to vary strongly between trees and over the four years of investigation. No relationship could be found between parameters of needle nitrogen metabolism and soil nitrate or ammonium concentrations. However, there was a relationship between the soil water potential and protein content (r = 0.8) and glutamine synthetase activity (r = 0.6) in the needles, indicating that both parameters increase under conditions of water stress. These physiological alterations are supposed to be based on stress-induced translocation of nitrogen from the old to the young foliage. Trees kept in chambers with non-filtered air showed higher levels of protein and glutamine synthetase activity than trees of the clean air treatment. However, the edaphic data indicate this hardly to be an effect of ambient ozone levels, but of differences in soil water status between the two variants.

Incipient Forest Decline in the Province of Trento (Northern Italy). Preliminary Sem Observations and Consideration of Inorganic Components of Leaves and Roots

Abstract One year old needles of both healthy and damaged silver fir and Norway spruce from the area of Trento (Northern Italy) were observed by SEM. Needles of damaged trees show quite evident structural alterations of epidermis, expecially epicuticular waxes. Roots and needles of both fir and spruce are also tested for their metal content. Evidence is reported of an increasing concentration of Fe, Mg and Ca in roots of plants grown on alkali soil. Ca, and to a lesser extent Fe, Al and Pb, appears to be more present in old needles, whereas K and Mg exhibit higher amounts in young needles. Some indications are found between damage and the content of some metals such as Mg and Mn in needles.

Effects of air pollutants on the growth and antioxidative system of Norway spruce exposed in open-top chambers

Grafted Norway spruce trees were subjected to exposure beginning in April 1988, to one of four different air treatments in open-top chambers: Charcoal filtered air (CF), non-filtered air (NF), non-filtered air with the addition of O 3 during summer (NFO), and SO 2 plus NO 2 during winter (NFOSN). CF trees were considered as the reference group. No effects on growth parameters were observed. Samples of the two youngest needle year classes were taken late in November 1989 for enzyme determinations. The activity of ascorbic acid peroxidase (A-POD) increased the same level in all treatments, and activities of catalase and dehydroascorbic acid reductase (DHA-R) increased only in NF and NFO treatments. A higher level of activity in the NFOSN treatment was observed only for glucose-6-phosphate-dehydrogenase (Glc6PDH) and non-specific peroxidase (POD). Isoelectric focusing of POD showed a changed pattern in the NFOSN treatment. Neither activity nor isoelectric focusing of superoxidase dismutase (SOD) was changed in any of the treatments.

Distribution and amounts of taxol in different shoot parts of Taxus cuspidata.

Different fresh shoot parts of male and female plants of Taxus cuspidata were extracted and analysed for taxol concentration by high performance liquid chromatography (HPLC). Extracted parts included: young needles (first 10 top needle pairs of 30 cm long branches), old needles (last 10 needle pairs of 30 cm long branches), green bark, dark bark (with intense secondary growth), young wood (originally surrounded by green bark), wood (originally surrounded by dark bark), young stems (surrounded by green bark and devoid of needles), and mature male cones. Dichloromethane extracts were analysed by HPLC and diode array spectroscopy. Taxol identification was done by retention time, U.V. spectra, and spiking with an authentic taxol standard; 1H-NMR analysis was done for needle extracts. All parts except male cones had measurable amounts of taxol; no effect of plant sex on taxol levels of the plant parts analysed was observed. Results indicated that the bark accounted for almost all the taxol present in stems devoid of needles. Needles showed the highest levels of taxol (overall average of 0.035 +/- 0.006% of the extracted dry weight), significantly higher than those displayed by dark bark samples (0.012 +/- 0.001% of the extracted dry weight). Different needle post-harvesting procedures were evaluated in relation to taxol yields, 96 h dark incubation at -12 degrees C and 96 h dark incubation at 25 degrees C under vacuum gave taxol yields equivalent to those of freshly extracted samples. However, results obtained for 96 h dark incubation at 60 degrees C indicated some extent of taxol degradation.

Early effects of hydrogen fluoride on water relations, photosynthesis and membrane integrity in eastern white pine ( Pinus strobus) seedlings

Eastern white pine ( Pinus strobus L.) seedlings were treated with 0.5 and 2 ppb hydrogen fluoride (HF) for 1–28 days and water relations, photosynthesis and membrane integrity were studied to determine the mechanism of fluoride action on plants. The first symptoms of fluoride injury appeared on young needles as tip necrosis after 20 days of 0.5 ppb HF treatment, and 5 days of 2 ppb HF treatment. Both HF levels reduced transpiration rates in seedlings treated for 1, 7 and 27 days, but had little effect on net photosynthesis. The initial decline in transpiration rates was not accompanied by an increase in tissue fluoride levels. Reduced transpiration was a possible cause of higher water potentials and water contents in fluoride-treated seedlings compared with control plants. Changes in membrane permeability were among the earliest noticeble effects of HF and greater electrolyte leakage was observed from seedlings treated for 2 and 8 days with HF compared with the controls. The results of this study suggest that cell membranes are among the initial sites of fluoride action on plants.

Studies on leaching from spruce twigs and beech leaves

Leaching, depending on the acidity of the eluent, was investigated for K, Mg and Mn. The curves for the leachate concentration versus time could be described by a power function. Leaching from old needles exceeded leaching from young needles to a high degree, but the ratios of the leached elements were almost equal. A method for continuous measurements of pH change in solutions contacting plant materials was developed. The results were in agreement with data on acidity changes in water falling through spruce or beech canopies.

L-Phenylalanine ammonia-lyase in suspension culture cells of spruce (Picea abies)

The activity of l-phenylalanine ammonia-lyase (PAL) (EC 4.3.1.5) was determined in seedlings, callus cells, cell suspension cultures and in young needles of spruce (Picea abies) (L.) (Karst). PAL activity increased up to 10 fold in response to transferring suspension cultured cells into new cultivation medium. PAL was also induced about 10 fold when callus cells were transferrd into liquid medium. The increase was transient and it required the presence of a carbohydrate.

Needle and lichen sulphur analyses on two industrial gradients

Total S concentrations in Scots pine (Pine sylvestris L.) needles and the lichen Hypogymnia physodes collected from the vicinity of an oil refinery in southern Finland and a steel works in northern Finland were used as a bioindicator for SO2 deposition. The mean total S concentration in the youngest pine needles decreased by 22% (p <0.001) and that of the second youngest needles by 28% (p < 0.001) as emissions from the oil refinery were reduced by nearly 50% from 1980 to 1985. Total S concentration in both needles and lichens were higher in the vicinity of the oil refinery due to the greater influence of long-range transport S deposition in southern Finland. The two industrial plants had approximately equal SO2 emissions in 1985. The results suggest that the total S concentration in pine needles is a better indicator of SO2 changes in the ambient air, while that in Hypogymnia physodes seems to be a better bioindicator of total S deposition, past and present.

Carbon and nitrogen isotope ratios in different compartments of a healthy and a declining Picea abies forest in the Fichtelgebirge, NE Bavaria.

Natural carbon and nitrogen isotope ratios were measured in different compartments (needles and twigs of different ages and crown positions, litter, understorey vegetation, roots and soils of different horizons) on 5 plots of a healthy and on 8 plots of a declining Norway spruce (Picea abies (L.) Karst.) forest in the Fichtelgebirge (NE Bavaria, Germany), which has recently been described in detail (Oren et al. 1988a; Schulze et al. 1989). The δ13C values of needles did not differ between sites or change consistently with needle age, but did decrease from the sun-to the shade-crown. This result confirms earlier conclusions from gas exchange measurements that gaseous air pollutants did no long-lasting damage in an area where such damage was expected. Twigs (δ13C between-25.3 and-27.8‰) were significantly less depleted in 13C than needles (δ13C between-27.3 and-29.1‰), and δ13C in twigs increased consistently with age. The δ15N values of needles ranged between-2.5 and-4.1‰ and varied according to stand and age. In young needles δ15N decreased with needle age, but remained constant or increased in needles that were 2 or 3 years old. Needles from the healthy site were more depleted in 15N than those from the declining site. The difference between sites was greater in old needles than in young ones. This differentiation presumably reflects an earlier onset of nitrogen reallocation in needles of the declining stand. δ15N values in twigs were more negative than in needles (-3.5 to-5.2‰) and showed age- and stand-dependent trends that were similar to the needles. δ15N values of roots and soil samples increased at both stands with soil depth from-3.5 in the organic layer to +4‰ in the mineral soil. The δ15N values of roots from the mineral soil were different from those of twigs and needles. Roots from the shallower organic layer had values similar to twigs and needles. Thus, the bulk of the assimilated nitrogen was presumably taken up by the roots from the organic layer. The problem of separation of ammonium or nitrate use by roots from different soil horizons is discussed.

Growth and uptake of N, P, K and B by Pinus radiata D. Don in response to applications of borax

Leader dieback associated with B deficiency in P. radiata D. Don plantations was treated with borax applied at rates of 50, 100 and 150 kg ha−1. This initially increased B in foliage from 5 to 40, 80 and 110 μg g−1 respectively, and was followed by a rapid decline and stabilisation at around 25 μg g−1 for the duration of the study. Annual fluctuations in foliage B levels were strongly correlated with rainfall during the preceding spring and summer. Uptake of N, P and K increased as a result of applied B and comparison of the distribution of these nutrients in crowns of fertilized and unfertilised trees six years after application indicated continued uptake of these nutrients probably as a result of improved root growth due to B. Foliage concentrations of B like N, P and K, increased in young needles towards the upper crown and this, together with a decline in needle concentrations of B as foliage aged, indicated some redistribution of B from older to new foliage. A limit of 5 μg g−1 was found below which little redistribution seems to occur.

Nitrogen fixation at phyllospheric level in coniferous plants in Italy

The results of a three year investigation on phyllospheric nitrogen fixation in Pinus nigra and Pseudotsuga menziesii growing in Central Italy are reported. The highest levels of nitrogen fixation in Pinus nigra and Pseudotsuga menziesii needles were reached during spring in three year old needles (from 6.1 to 7.6 and from 8.1 to 10.2 nmoles of N2 fixed h-1 g-1 needles) collected in the center of the canopy, while the lowest values (less than 1.5 and 3.0 nmoles of N2 fixed h-1 g-1 needles) were detected during summer in young needles collected in the lateral branches (areas more exposed to the light and with low humidity). Microorganisms belonging to the genera Pseudomonas, Bacillus, Achromobacter, Klebsiella and Mycobacterium were isolated from the needles of either Pinus nigra or Pseudotsuga menziesii.