Susceptibility of different provenances of Pinus sylvestris,Pinus Contorta and Picea abies to Gremmeniella abietina

In a randomized block factorial experiment, 1200 seedlings from four provenances, each of Pinus sylvestris, Pinus contorta and Picea abies were inoculated with conidia (2 × 10⁴ and 1 × 10⁶ conidia/seedling) of Gremmeniella abietina (Brunchorstia pinea), isolated from P. contorta plantations in northern Sweden. A further 600 seedlings were left as controls. The occurrence of symptoms and the extension of dead tissues on the annual shoots were recorded 13 months after inoculation. Only the higher spore dose resulted in significant infection. P. sylvestris and P. contorta seedlings were equally susceptible (53% infected), and significantly more infected than P. abies seedlings (39%). The annual shoots of P. sylvestris and P. abies were affected to 43% and 37% of their length, which was significantly more than 15% of the length of P. Contorta shoots. The frequency of affected seedlings differed between the most southern and northern provenances of P. sylvestris and P. abies, and between the northwestern and the south-eastern provenance of P. contorta Twenty-six months after inoculation, a higher proportion of P. contorta seedlings than P. sylvestris and P. abies seedlings had recovered, and a lower proportion of P. contorta than P. sylvestris and P. abies seedlings had died. This paper discusses why P. sylvestris was found to be more susceptible to G. abietina than P. contorta in this experiment, while the reverse is found in plantations in northern Sweden.     

Effects of Eucalyptus obliqua (L'Herit) density on young stands of even-aged Pinus radiata (D. Don)

In a 10-year-old Pinus radiata plantation, increasing densities of Eucalyptus obliqua, a woody weed species, caused reductions in the canopy leaf area and total stem volume of P. radiata. As the density of E. obliqua increased stand volume (the sum of stem volumes of the two species) was constant, but the sum of projected leaf area of the two species decreased. Higher E. obliqua density also resulted in higher mean height to diameter ratio of P. radiata. With increasing E. obliqua density the size distribution of P. radiata became more positively skewed and the size hierarchy of P. radiata increased. The effects of E. obliqua density on P. radiata are more likely due to below-ground competition than competition for light above-ground. Understanding the effects of E. obliqua density on the characteristics of P. radiata can benefit weed control programs and subsequent management of plantations with naturally regenerated E. obliqua.     

Infection of Picea sitchensis and Pinus contorta stumps by basidiospores of Heterobasidion annosum

Infection of Pinus contorta and Picea sitchensis stumps by basidiospores of Heterobasidion annosum is extremely variable, both within and between sites, but in general P. sitchensis stumps are less sus-ceptible than those of P. contorta. Measurement of the cross-sectional area occupied by H. annosum on each stump provides a more sensitive test of species susceptibility than assessment of the proportion of stumps infected. P. sitchensis stumps become infected on a variety of soils but there is evidence to suggest that infection may be reduced by high rainfall. In some infected stumps, H. annosum is confined to the lower stump tissues. Its absence from the upper portion of the stump may be due to replacement by other micro-organisms or, alternatively, physical conditions in the upper stump tissues may prevent its continued survival after infection has taken place. In both species, but more commonly in P. sitchensis, some stumps remain alive for at least two years after felling, particularly on peat soils, due to the presence of root grafts with neighbouring trees. Results for P. sitchensis suggest that infection occurs more readily in living stumps than in those which die rapidly after felling. The viability of H. annosum basidiospore suspensions can be determined more accurately and more rapidly on a selective agar medium than on conifer stem sections.     

Frost tolerance of various Pinus pure species and hybrids

Pinus species are widely planted by the South African forestry industry and are utilised for pulp, paper and saw timber products. Historically, Pinus patula Schiede ex Schltdl. et Cham. was the most widely planted commercial species in the summer rainfall area, but has come under severe threat due to the fungus Fusarium circinatum. Fusarium circinatum causes mortality in nurseries and in-field after establishment. Other Pinus species, such as P. tecunumanii F.Schwerdtf. ex Eguiluz et J.P.Perry and P. oocarpa Schiede ex Schltdl., have been crossed with P. patula to increase tolerance to F. circinatum and these hybrids have largely overcome the post-planting mortality problem. However, these hybrid-partner species are more prone to frost damage. This study reviewed laboratory screening techniques to assess the frost tolerance level of a range of Pinus pure species and hybrids. In vitro screening was done with the electrolyte leakage and whole-plant freezing techniques. Seedlings and rooted cuttings from a range of genotypes, supplied by Sappi, were tested in vitro at different target temperatures (?3, ?6, ?9 and ?12 °C) to determine their relative frost tolerance. These genotypes included a range of Pinus pure species, four interspecific hybrids (P. patula × P. tecunumanii low elevation [LE], P. patula × P. tecunumanii high elevation [HE], P. elliottii Engelm. × P. caribaea Morelet), and a three-way cross (P. patula × (P. patula × P. oocarpa)). Results from this study indicated that the electrolyte leakage technique was a reliable method to determine frost tolerance under laboratory conditions, with similar pure species rankings as experienced under field conditions. The interspecific hybrids of P. patula × P. tecunumanii LE and HE ranked intermediate between the parental species and the P. patula × P. tecunumanii HE hybrid was more frost tolerant than the P. patula × P. tecunumanii LE hybrid.     

Haustorial morphology of Cronartium conigenum in naturally infected cones of three Pinus species from Guatemala1

Haustorial morphology of the cone-rust pathogen, C. conigenum, was investigated among naturally infected female strobili of three Guatemalan pines, P. maximinoi, P. pseudostrobus, and P. oocarpa. Among the three pine species, haustorial shapes and sizes were more variable in P. maximinoi and P. oocarpa than in P. pseudostrobus. The haustorial shapes and sizes were more variable in parenchyma cells of the cortex, xylem, and pith than in the cells in the phloem, xylem rays, and tracheids. The haustoria were also present in larger numbers in the parenchyma cells of the cortex, xylem, and pith than in phloem parenchyma cells and tracheids. In living cells, the tips of some haustoria were appressed to the host nuclei.     

Report of a 60 month study on litter production,changes in soil chemical properties and productivity under Poplar (P. deltoides) and Eucalyptus (E. hybrid) interplanted with aromatic grasses

Quantity of litter fall, its chemical composition, nutrient addition and changes in chemical constituents of soil were studied under agroforestry systems involving Populus deltoides and Eucalyptus hybrid tree with intercrops of Cymbopogon martinii Wats and Cymbopogon flexuosus Wats in the tarai tract of Kumaon hills of U.P. India. P. deltoides had significantly more diameter (63%) as compared to E. hybrid. There was decrease in herb (5.4%) and oil yield (15.4%) of grasses due to trees, but both the grasses did not affect the performance of trees. On an average, dry litter production of P. deltoides was 5.0 kg tree⁻¹ year⁻¹ where as of E. hybrid 1.5 kg tree⁻¹ year⁻¹. The litter of P. deltoides contained 1.3 times more N and 1.5 times P and K of E. hybrid. Addition of N, P and K through P. deltoides litter was 36.6, 91.6, and 69.9 per cent more than E. hybrid litter, respectively. Under these two canopies soil organic carbon was enhanced by 33.3 to 83.3 per cent, available N by 38.1 to 68.9 per cent, available P by 3.4 to 32.8 per cent and available K by 5.8 to 24.3 per cent over control (no tree canopy) in 0—15cm layer. P. deltoides plantation was superior to E. hybrib in enriching the soil.     

Growth of axenic cultures of Cronartium flaccidum on callus tissue from Pinus nigra var. laricio and Pinus sylvestris

The callus-fungal method was employed to test the response to C. flaccidum of the highly susceptible P. nigra var. laricio and the resistant P. sylvestris, and to ascertain whether results obtained with this method matched in planta observations. Calli were inoculated with axenie cultures of C. flaccidum obtained by incubating basidiospores on modified Schenk and Hildebrandt medium. Several parameters were evaluated. Colony growth was more rapid on P. nigra var. laricio. Colonies were dense on P. nigra var. laricio, but sparse on P. sylvestris. Aerial hyphae growth was abundant on P. nigra var. laricio, but less frequent on P. sylvestris. Hyphal branching began after 18 h on P. nigra var. laricio and after 45 h on P. sylvestris. Necrosis of the host cells set in after 24 h on P. nigra var. laricio, and after 70 h on P. sylvestris. The number of cells with plasmolysis was much larger in P. nigra var. laricio than in P. sylvestris. These results were consistent with the known resistance of the two species on whole plants.     

Effects of nitrogen on the growth and competition between seedlings of two temperate forest tree species

To understand how coexisting temperate tree species react to nitrogen (N) addition, seedlings of two coexisting species, Phellodendron amurense Rupr. and Fraxinus mandshurica Rupr. were transplanted to a controlled environment. Seedlings were then planted in two competition scenarios, control and mixed, and then subjected to four N addition treatments. The seedling growth parameters and competition effect were monitored and analyzed. The height and stem-base diameter showed a positive response to the N addition in all competition scenarios except for mixed P. amurense, which responded negatively. Chlorophyll content of the seedlings showed a positive relationship to N addition while the chlorophyll a/b showed a complex trend. The addition of N showed a positive relationship to the competition effect of diameter growth in both species and height growth in P. amurense. These results indicate that F. mandshurica may be more sensitive to N addition and could benefit more from N addition than P. amurense. With an increasing N input from the atmosphere, forests may be more suitable for F. mandshurica reducing the abundance of P. amurense.     

Propagation of two miombo woodland trees by leafy stem cuttings obtained from seedlings

The rooting ability of leafy stem cuttings harvested from four to five month old seedlings of B. spiciformis Benth and P. angolensis DC was tested in low-technology non-mist propagators suitable for the rural tropics. Both species were successfully rooted; P. angolensis was a faster rooting species (86% after 61 days) compared with B. spiciformis (59% after 154 days). Regression analysis suggested that P. angolensis had more stored carbohydrates, which facilitated its rooting while B. spiciformis was more dependant on current assimilates produced during the period of propagation. The results of this study suggest that it is possible to develop clones of genetically superior trees of B. spiciformis and P. angolensis for use in agroforestry or reforestation programmes.This revised version was published online in November 2005 with corrections to the Cover Date.     

Enzymatic saccharification and ethanol production of <Emphasis Type="Italic">Acacia mangium</Emphasis> and <Emphasis Type="Italic">Paraserianthes falcataria</Emphasis> wood,and <Emphasis Type="Italic">Elaeis guineensis</Emphasis> trunk

We examined the saccharification and fermentation of meals from Acacia mangium wood, Paraserianthes falcataria wood, and Elaeis guineensis trunk. The levels of enzymatic hydrolysis of cellulose and ethanol production were highest for P. falcataria wood and lowest for A. mangium wood. Ultrasonication pretreatment of meal further increased the rates of hydrolysis and ethanol production in meal from P. falcataria wood. Through this pretreatment, hemicelluloses (xylan and xyloglucan) and cellulose were released in the meal from P. falcataria wood. Loosening of hemicellulose associations can be expected to make P. falcataria wood more useful for bioethanol production.     

Decomposition and phosphorus release from organic residues as affected by residue quality and added inorganic phosphorus

The combined use of organic residue and inorganic fertiliser-phosphorus (P) is appropriate in meeting both the short and long-term P requirement of crops. To assess the influence of added inorganic fertiliser-P on the processes of decomposition and P release from the residue and the relationships with quality, prunings of Gliricidia sepium, Leucaena leucocephela, Senna siamea, Acacia mangium and Paraserienthus falcataria were incubated without and with added inorganic fertiliser-P for 56 days. Soil was added only as inoculum. Decomposition rate and amounts of acid extractable-P (P release) were in the same order: G. sepium >S. siamea > L. leucocephela >P. falcataria > A. mangium. Unlike the other residues, A. mangium released no P despite the loss of half its mass during the 8 weeks of incubation. The residue P content correlated with P release. However, decomposition rate did not correlate with residue P content but with the lignin, polyphenol and cellulose content, and ratios to P. These ratios were negatively correlated with P release suggesting that lignin and polyphenol contents influence P release more when the residue-P content is low. Results suggest that rate of decomposition influences the release of P. The critical residue P content for P release was estimated to be 0.12% < P < 0.19%. Added P had no effect on decomposition and P release from the residues.     

Alternative pine hybrids and species to Pinus patula and P. radiata in South Africa and Swaziland

Through the collaborative efforts of companies affiliated with the International Program for Tree Improvement and Conservation (Camcore), a number of pine hybrids have been produced over the last decade. Many of these have been planted in trials across southern Africa that broadly represent winter and summer rainfall areas, with the latter ranging from warm to cold temperate sites. The five-year survival and growth of the hybrids and other pines in 12 of these trials were compared with Pinus radiata in the winter rainfall, and P. patula in the summer rainfall, regions where these species have been planted extensively. Except for the highest altitude site, where freezing conditions are common, the survival of most hybrids and tropical pines was better than P. patula or P. radiata. This was, in part, attributed to their improved tolerance to the pitch canker fungus, Fusarium circinatum, which was present in the nursery at the time of planting. In the winter rainfall area, the P. elliottii × P. caribaea hybrid, P. maximinoi and, surprisingly, the P. patula hybrids performed well. In the summer rainfall regions, hybrids with tropical parents such as P. caribaea, P. oocarpa and P. tecunumanii were more productive in the subtropical/warm temperate zone and, with increasing elevation, those hybrids crossed with P. patula performed relatively better. The P. patula × P. tecunumanii hybrid, particularly when crossed with low-elevation P. tecunumanii, performed exceptionally across most sites.     

Variation in pitch canker resistance among provenances of <Emphasis Type="Italic">Pinus patula</Emphasis> and <Emphasis Type="Italic">Pinus tecunumanii</Emphasis> from Mexico and Central America

Pinus patula and high-elevation (HE) sources of P. tecunumanii exhibit intermediate levels of resistance to pitch canker (Fusarium circinatum), compared to extremely resistant species such as P. oocarpa, and extremely susceptible species such as P. radiata. Seedlings from 20 P. patula provenances and 15 HE P. tecunumanii provenances were artificially inoculated with the pitch canker fungus at 21 and 12 weeks of age, respectively, and assessed for resistance 12–20 weeks later. There was important provenance variation in pitch canker resistance for both species. The 20-week LiveStem percentage ranged from 70.3% to 43.6% among the P. patula provenances and 59.6% to 11.7% among HE P. tecunumanii provenances. There was a geographic pattern to the provenance variation, and in both species, low altitude sources demonstrated more resistance than those from high elevation. Provenance variation in pitch canker resistance could be useful when making selection and breeding decisions with these species.     

Future outlook for Pinus patula in South Africa in the presence of the pitch canker fungus (Fusarium circinatum)

Approximately 50% of the area planted to softwood trees in South Africa has been established with Pinus patula, making it the most important pine species in the country. More effort has gone into developing this species for improved growth, tree form and wood properties than with any other species. This substantial investment has been threatened in the last 10 years by the pitch canker fungus, Fusarium circinatum. The fungus infects and contaminates nursery plants and, once transferred to the field, causes severe mortality of young trees in the first year after establishment. Although nurserymen have some control of the disease, it is recognised that the best long-term solution to mitigate damage because of F. circinatum infection is to identify tolerant species, clones and hybrids for deployment in plantations in the future. Research has shown that alternative species such as P. tecunumanii, P. maximinoi and P. elliottii are suitable for warm sites. Pine hybrids, particularly between P. patula and the high-elevation sources of P. tecunumanii, appear to be a suitable replacement on subtemperate and temperate sites. Although these alternative species and hybrids are more sensitive to subfreezing temperatures than P. patula, their planting range can be increased by including cold tolerance as a selection criterion. Future breeding efforts will most certainly focus on improving the tolerance of pure P. patula to F. circinatum, which can be achieved by identifying specific family crosses and tolerant clones. The commercial deployment of disease-tolerant control-pollinated P. patula and hybrid families will most likely be established as rooted cuttings, which requires more advanced propagation technology. In the long term, new seed orchards comprised of P. patula clones tolerant to F. circinatum could be used to produce seed for seedling production.     

基于cpDNA rps16序列分析兰考泡桐与白花泡桐和毛泡桐的遗传关系

【目的】通过测序法分析兰考泡桐与白花泡桐和毛泡桐在叶绿体rps16序列上的遗传差异,旨在分析三者之间在叶绿体基因上的变化特点和规律,探讨其种间的遗传关系。【方法】选取兰考泡桐、白花泡桐和毛泡桐各15个样本,对其提取的DNA用PCR扩增获得特异片段,并将其纯化与测序。利用软件Clustal X 2.0对所得序列进行排序;运行MEGA 4软件,进行多序列比对,分析其序列特征,并计算出K2P遗传距离。【结果】(1)对获得的rps16序列进行测定分析,得兰考泡桐序列长度分别为932 933 bp;白花泡桐序列长度为932 bp;毛泡桐序列长度分别为916918 bp。对所得rps16序列进行排序后的长度为938 bp,平均GC含量为34.31%。3个种所代表的个体之间共有10个变异位点,占整个序列长度的1.07%。其中有9个变异位点属于碱基插入或缺失类型,占变异位点总数的90%,占整个序列长度的0.96%。有1个变异位点属于碱基替换类型,占整个变异位点总数的10%,占整个序列长度的0.11%。(2)整个rps16片段的序列共有10个变异位点,其中兰考泡桐与白花泡桐在总的变异位点上,具有一致的碱基位点9个,占总变异的90%。而兰考泡桐与毛泡桐相比,没有相同的碱基。【结论】根据三种泡桐的rps16序列的序列特征和变异位点的分析,表明在叶绿体遗传方面,兰考泡桐具有与白花泡桐更多相似的遗传物质,其亲缘关系较近。综上所述,推测兰考泡桐与白花泡桐可能来自同一母系遗传。     

Influence of site factors on the impact of Phytophthora cinnamomi in cork oak stands in Portugal

Although decline of cork (Quercus suber) and holm oak trees (Quercus rotundifolia) has been described in Portugal in the late years of the 19th century, its development has become a motive of high concern during the last two decades. The presence of Phytophthora cinnamomi in cork and holm oak stands was surveyed in four different regions of the country (Trás‐os‐Montes, Alentejo, Ribatejo and Algarve) during 1995–98. Tree decline severity, sudden death and site characteristics were assessed in 56 sites representing varied conditions. The pathogen was isolated from oak roots and rhizosphere samples in 27 of those places. Other plant species from natural vegetation were sampled in three active disease centres. This survey showed that 56% of the surveyed species of shrub flora were infected with P. cinnamomi, which was detected mainly on species belonging to the families Ericaceae, Cistaceae and Leguminosae. Recovery of P. cinnamomi was more frequent in shallow soils (Leptosols and complex Leptosols and Luvisols). These soils are more common in the south (Algarve), where decline has a high impact. Soils with low fertility and low mineral nutrient levels, particularly phosphorus, seemed to favour infection. Site aspect and topographic tree situation were also evaluated. Sites facing south showed higher occurrence of P. cinnamomi, which was also more frequent in slopes and valleys than on hilltops. In Algarve, a relationship could be established between the crown status and the presence of P. cinnamomi in roots and rhizosphere. Different morphotypes of P. cinnamomi could be distinguished in vitro, and their occurrence in the field was correlated with particular site characteristics. Further research needs and management strategies to limit the extension of the disease are discussed.     

Efficacy of Clausena anisata and Plectranthus glandulosus leaf powder against Prostephanus truncatus (Coleoptera: Bostrichidae) and two strains of Sitophilus zeamais (Coleoptera: Curculionidae) on maize

Powdered leaves of Clausena anisata and Plectranthus glandulosus were evaluated on Cameroonian and German strains of Sitophilus zeamais and Prostephanus truncatus for their insecticidal activities, the effects on progeny production, grain damage and population increase by admixing powders and maize grains. The two powders caused significant mortality of the three insects with P. glandulosus being far more effective than C. anisata. P. truncatus was less susceptible to P. glandulosus powder compared with the two strains of S. zeamais. The German strain (LD₅₀ = 2.75 g/100 g grain) of S. zeamais was less susceptible to P. glandulosus powder than the Cameroonian strain (LD₅₀ = 1.86 g/100 g grain). P. glandulosus unlike C. anisata powder, considerably reduced grain damage, progeny production and population increase. This study shows that there is a great potential for the powder of P. glandulosus as a promising grain protectant for integration within the subsistence farming systems of sub-saharan Africa.     

Fungi dangerous at Pinus contorta with special reference to pathogens from North Europe

Examples are given of North American fungi potentially dangerous to Pinus contorta plantations in northern Europe. The pathogenicity of North European fungi is discussed. P. contorta was found to be immune or nearly immune to all European rust fungi, more resistant than P. sylvestris to Phacidium infestans and Lophodermium pinastri, but less resistant to Crumenulopsis sororia and Discella strobilina. For other fungi no such clearcut conclusions could be drawn.     

One-hundred-year foliage comparison of Pinus ponderosa and Pinus sylvestris under dry growing conditions in Brandenburg,Germany

Abstract

The dynamics of six different needle parameters of Pinus sylvestris L. and Pinus ponderosa Dougl. ex P. & C. Laws. were examined retrospectively for a 112-year-old mixed stand in Brandenburg, Germany, using the needle trace method. Similarities were found in needle production, needle loss and needle density. However, needle age, needle retention and total number of needles revealed significant differences between the tree species, with higher values for P. ponderosa. Pinus ponderosa yielded approximately twice as much mean whole-crown needle dry mass as P. sylvestris. Furthermore, different branching systems could be detected between the species, with both pines following “Corner's rule”. The results suggest that under identical growing conditions, P. ponderosa exhibits more efficient water use and can therefore maintain a bigger crown (as the basis for increased growth) than P. sylvestris.     

Family variation in diameter growth and acoustic velocity in three 5‑year‑old South African‑grown Pinus elliottii×Pinus caribaea progeny trials established on three diverse sites

This paper discusses family differences in the stiffness of young Pinus elliottii×P. caribaea wood and how these differences relate to differences in growth rate and altitude. Trees for measurement were obtained from three 5?year?old progeny trials established at three diverse sites on the estate of Komatiland Forests (Pty) Ltd. The trials included the following controls: P. elliottii, P. patula, P. taeda, P. patula×P. tecunumanii and P. tecunumanii. Diameter at breast height and sound velocity (which has a direct relationship with wood stiffness) were measured on all healthy trees. Virtually all of the species and hybrids exhibited marked decreases in growth rate and velocity (stiffness) with increasing altitude; the effect on velocity was most likely partly due to the inverse relationship that normally exists between wood density and altitude in most pines. Differences in growth rate explained only a small proportion of the total variation in velocity. The average sound velocities of P. patula, P. patula×P. tecunumanii and P. tecunumanii surpassed the velocity values of most of the P. elliottii×P. caribaea crosses at all three sites. Results of Spearman rank correlations of average treatment velocity between sites suggested only some similarity in the ranking orders among sites. The inverse effect of altitude on wood stiffness suggests that trees grown at increased altitudes are likely to yield wood with higher proportions of wood not meeting the minimum stiffness requirement for structural lumber at final harvest. The wood of some P. elliottii×P. caribaea crosses would be particularly vulnerable. Considering the large variation found, presumably largely genetic, there can be little doubt that a good opportunity exists for the development of genotypes more suitable for planting at higher altitudes.