Effects of two iron sources on iron and cadmium allocation in poplar (Populus alba) plants exposed to cadmium

Effects of 10 microM cadmium (supplied as Cd nitrate) on the utilization and allocation of iron (Fe) were investigated in poplar (Populus alba L.) plants grown in nutrient solution with Fe(III)-EDTA or Fe(III)-citrate as the Fe source. The effects of Cd were also compared with those of Fe deprivation. The accumulation of Fe in roots was 10-fold higher in plants grown with Fe-citrate than with Fe-EDTA. Cadmium decreased leaf chlorophyll concentrations and photosynthetic rates, and these decreases were more marked in plants grown with Fe-citrate than with Fe-EDTA. In both Fe treatments, addition of Cd caused large increases in root and shoot apoplasmic and non-apoplasmic Cd contents and increases in root Fe content; however, Cd decreased shoot Fe content, especially in plants grown with Fe-citrate. New leaves of plants grown with Fe-citrate had small cellular (non-apoplasmic) Fe pools, whereas these pools were large in new leaves of plants grown with Fe-EDTA. Non-apoplasmic Cd pools in new leaves were smaller in plants grown with Fe-citrate than with Fe-EDTA, indicating that inactivation of non-apoplasmic Cd pools is facilitated more by Fe-EDTA than by Fe-citrate. In the presence of Cd, Fe-EDTA was also superior to Fe-citrate in maintaining an adequate Fe supply to poplar shoots. Differences in plant responses to Fe-EDTA and Fe-citrate may reflect differences in long-distance transport of Fe rather than in acquisition of Fe by roots.     

Economic utility of 3D remote sensing data for estimation of site index in Nordic commercial forest inventories: a comparison of airborne laser scanning,digital aerial photogrammetry and conventional practices

ABSTRACT

Forest productivity is a crucial variable in forest planning, usually expressed as site index (SI). In Nordic commercial forest inventories, SI is commonly estimated by a combination of aerial image interpretation, field assessment and information obtained from previous inventories. Airborne laser scanning (ALS) and digital aerial photogrammetry (DAP) data can alternatively be used for SI estimation, however the economic utilities of the inventory methods have not been compared. We compared seven methods of SI estimation in a cost-plus-loss analysis, by which we added the expected economic losses due to sub-optimal treatment decisions to the inventory costs. The methods comprised direct and indirect estimation from combinations of ALS, DAP and stand register data, and manual interpretation from aerial imagery supported by field assessment and information from previous inventories (conventional practices). The choice of method had great impact on both the accuracy and the economic value of the produced estimates. Direct methods using bitemporal ALS and DAP data gave the best accuracy and the smallest total cost. DAP was a suitable and low-cost data source for SI estimation. Estimation from single-date ALS and DAP data and age obtained from the stand register provided practical alternatives when applied to even-aged stands.     

Eine Methode zur integrierten Bekämpfung des Rüsselkäfers (Hylobius abietis L.)

Zusammenfassung Es wird gezeigt, da? es m?glich ist, durch die Anwendung subletaler Konzentrationen des Insektizids DTHP, d. h. durch eine allgemeine Schw?chung des Organismus erwachsener Rüsselk?fer (Hylobius abietis L.), eine geeignete Disposition dieses Sch?dlings zur Infektion durch den parasitischen PilzBeauveria bassiana (Bals-Criv.) Vuill. herbeizuführen. Die K?fer, die in Fangrinden oder Fallen an Kiefern? stchen — welche in ein kombiniertes Pr?parat einer 0,05% DTHP-Suspension (Organophosphorverbindung vom Dipterex-Typ, technischer Block 0,0-Dimethyl-2,2,2-trichlor-1-hydroxy?thyl-phosphonat) mit 0,1% Sporen vonBeauveria bassiana getaucht worden waren — konzentriert wurden, nahmen keine Nahrung mehr auf und starben allm?hlich ab. Wie die histologischen Untersuchungen gezeigt haben, wurden Erkrankung und Tod der K?fer durch den genannten parasitischen Pilz herbeigeführt. Obwohl nur zwei Vergleichsfl?chen zur Verfügung standen, ist aus dem obengesagten klar, da? bei der Anwendung des kombinierten Pr?parates mit einer gewissen selektiven Wirkung gerechnet werden kann: W?hrend an der nur mit 1% DTHP behandelten Versuchsfl?che ungef?hr 2,5% nützlicher Insekten unter den get?teten K?fern festgestellt wurden (vor allem Laufk?fer der GattungPterostichus), betrug der Prozentsatz der get?teten nützlichen Insekten bei der Anwendung des kombinierten Pr?parates (DTHPBeauveria bassiana-Sporen) nur 0,25%. Die angeführten Versuche bewiesen die Anwendbarkeit der Kombination von Insektiziden — in subletalen Dosen oder Konzentrationen — mit Sporen parasitischer Pilze.     

First results on synchrony between seasonal pattern of pheromone trap captures of cotton bollworm, <Emphasis Type="Italic">Helicoverpa armigera</Emphasis> and appearance of freshly emerged larvae on developing cobs of corn hybrids

Synchrony between development of five corn hybrid varieties of various seasonal growing rates (FAO numbers), seasonal flight pattern of male cotton bollworm, Helicoverpa armigera Hb. (Lepidoptera: Noctuidae), as monitored by pheromone traps, and the subsequent appearance of newly hatched larvae on developing cobs were studied at Mezőhegyes, South-Hungary, in 2003 and 2004. The phenological stages of corn hybrids were evaluated using the Iowa State University Scale (R₁–R₅), the flight of male moths was monitored by large capacity, funnel type of pheromone traps and the appearance of freshly hatched larvae on developing cobs were counted by visual inspection. The synchrony between the flight peak of male moths and the peak apperance of L₁ larvae on cobs was investigated by cross-correlation. In 2003 (average daily temperatures 20.7°C, average daily relative humidity 59.9% for the period of 4–18 July) “DK 391”, “DK 443” and “Maraton” hybrid varieties already reached silking stage (R₁) by the time when pheromone traps indicated a peak, at 7 July (peak capture at 3-day intervals 755.5 males/traps). The number of L₁ larvae peaked on developing cobs of these varieties also at 7 July (7.0, 4.0 and 3.8 larvae/50 cobs, respectively). The synchrony between the flight peak of male moths and the peak appearance of L₁ larvae on cobs was proven (LAG = 0). A rather similar trend was observed in “Vilma” hybrid variety: it reached R₁ stage at 7 July, and L₁ larvae appeared only a few days later (11 July, 3.8 larvae/50 cobs) (LAG = −1). However, “Maxima” hybrid variety reached R₁ stage 1 week later (14 July) than the time of peak captures. Here L₁ larvae peaked as late as at 18 July (0.8 larvae/50 cobs), i.e., only after the cob had reached R₁ stage (LAG = −3). A reverse order of dates of R₁ stage and peak capture was observed in “Maxima” in 2004 (average daily temperatures; 22.5°C, average daily relative humidities 72.6% for the period of 15 July–6 August): it reached R₁ stage at 19 July, while peak trap captures were recorded at 6 August (peak capture at 3-day intervals 20.5 males/traps). L₁ larvae were found in the highest numbers on 2 August (1.5 larvae/50 cobs), practically in synchrony with peak caputres (LAG = 0). “Káma” reached R₁ stage in 16 July, and L₁ larvae peaked at 2 August (1.3 larvae/50 cobs) (LAG = 0). On the rest of the corn varieties larvae were found only in too numbers for performing statistical analysis. We conclude that in order to predict the appearance of L₁ larvae, the phenological stage of the corn variety and the seasonal flight pattern of moths, as measured by large capacity pheromone traps, should be considered in combination. If the corn variety already reached R₁ stage, L₁ larvae appear on cobs as early as the time of peak flight of moths. However, no young larvae appear on cobs despite of high trap captures, until the corn reaches the R₁ stage. These findings are discussed in the view of specifying optimal timing of a pesticide application.     

Soil temperature,gas exchange and nitrogen status of 5-year-old Norway spruce seedlings

Five-year-old Norway spruce (Picea abies (L.) Karst.) seedlings were subjected to three simulated growing seasons in controlled environment chambers. Plants were acclimated to a soil temperature of 16 degrees C during the first and third growing seasons, but were allocated at random to soil temperature treatments of 9, 13, 18 and 21 degrees C during the second growing season. Low soil temperature during the second growing season depressed stomatal conductance and photosynthetic rate (A) per unit of projected leaf area, although intercellular CO2 concentrations did not differ significantly between treatments. At all soil temperatures, total chlorophyll concentration first decreased and then increased, although the rate of increase and the final concentration increased with soil temperature, which may explain the effect of soil temperature on A. Neither chlorophyll a/b ratio nor leaf nitrogen concentration was significantly affected by soil temperature. Treatment differences disappeared during the third simulated growing season when plants were again acclimated to a soil temperature of 16 degrees C.     

Testing and evaluation of natural durability of wood in above ground conditions in Europe – an overview

Natural durability of wood is determined by the European standard EN 252 for specimens in ground contact and EN 113 for basidiomycetes in the laboratory, but no test exists for above ground conditions. For above ground conditions, the European prestandard ENV 12037 and EN 330 are used to determine the durability of treated wood. The most important factors for fungal establishment on the surface and within wood are the moisture content, the surrounding temperature, and the relative humidity. Strength tests are the most sensitive for decay detection, but neither strength tests nor identification of fungi responsible for the decay are included in the standards of above ground durability in field tests. To detect decay, visual examination, pick or splinter tests, and mass loss determination are used. Identifying fungi with traditional methods, e.g., growth on solid medium, is time consuming and complicated. Molecular methods like polymerase chain reaction and sequencing do not require mycological skill for identification to species level, and furthermore the methods do not depend on the subjective judgement like most traditional methods, but are based on the objective information of the target organism (e.g., nucleotide sequences). The next generation of standard field tests will probably consider the drawbacks of standard tests today and be rapid and include both quality tests like molecular identification and nondestructive quantitative tests, e.g., acoustic tests. Laboratory tests can be improved by using fungi identified from field trials and by combining different fungi in the same test and thus simulate degradation in practice.     

Influence of nitrogen fertilization on minerals, carbohydrates, amino acids and phenolic compounds in beech (Fagus sylvatica L.) leaves

Beginning in 1985, plots in a 120-year-old beech (Fagus sylvatica L.) stand in the province of Scania, southern Sweden were fertilized annually with ammonium nitrate. In August 1989, leaves from both fertilized and unfertilized trees were analyzed for mineral nutrients, soluble carbohydrates, amino acids and phenolic compounds. Leaf concentrations of total nitrogen were increased by N fertilization. Ammonium was not detected in the leaves, but NO(3) (-) was increased by up to 65% as a result of N fertilization. Nitrogen fertilization decreased foliar concentrations of P and Cu, leading to a nutrient imbalance relative to N. Of the free amino acids, glutamic acid and aspartic acid predominated and, together with glutamine and asparagine, were significantly increased by N fertilization. The concentrations of amides were 2-4 times higher in fertilized trees than in unfertilized trees. Soluble carbohydrates did not change in response to N fertilization, but total phenolic compounds decreased markedly. The reduced concentration of phenolics may explain the greater susceptibility to parasite attacks of trees exposed to N deposition and excess N.     

Characterization of juvenile wood to mature wood transition age in black spruce (Picea mariana (Mill.) B.S.P.) at different stand densities and sampling heights

The radial pattern of both maximum ring density and ring area of 36 black spruce trees were used to determine the transition age from juvenile wood to mature wood. The data were obtained by X-ray densitometry and both segmented linear and polynomial regressions were used to point out the age of the juvenile wood boundary. Three stand densities (1,790, 2,700 and 3,400 stems/ha) and three sampling heights (2.4, 5.1 and 7.8 m) were studied. Although maximum ring density and ring area presented similar radial patterns, they gave two significantly different results of transition ages. The maximum ring density over-estimated the transition age (17.6 years) in contrast to ring area (14 years). The results show that the transition from juvenile wood to mature wood occurred after 12 years at 7.8 m (versus 13.1 years at a height of 5.1 m, and 17.6 years at 2.4 m). Although transition age occurred later in the high stand density group (21 years), the difference was not significant between the three stand density groups. Nevertheless, transition age remains difficult to determine since no standard definition exists. The transition occurs over years, and most probably a transition wood exists between juvenile wood and mature wood. Estimation of the juvenile wood proportion in volume shows that it remains constant along the stem and it increases with stand density.     

Mechano-sorptive effects in wooden material

Summary The effects on wood of simultaneous mechanical and moisture loading are studied. In order to clarify the mechano-sorptive behaviour of wood, a review of different phenomena presented in the literature is included. Based on this review a constitutive model is proposed for the case of uniaxial stress in the longitudinal direction. The validity of the model is checked independently against test results. The calculations show that the model is capable of describing the response of wood with reasonable accuracy. Simulations indicate that the response of small test specimens is more difficult to describe than that of larger beams. Some differences in behaviour are found to depend on loading mode and nature of moisture cycling. Very large and fast moisture cycles seem to give larger mechano-sorption than smaller variations. The results of the simulations show that there is a significant influence of strain on the shrinkage and swelling response.