Litterfall,decomposition and nutrient release of <Emphasis Type="Italic">Shorea robusta</Emphasis> and <Emphasis Type="Italic">Tectona grandis</Emphasis> in a sub-tropical forest of West Bengal,Eastern India

We studied leaf litter fall, decomposition and nutrient release patterns of Shorea robusta and Tectona grandis by using a litter bag technique to better understand the release pattern of nutrients to soil from leaf litter. Annual litterfall varied from 13.40 ± 2.56 t ha^?1 a^?1 for S. robusta to 11.03 ± 3.72 t ha^?1 a^?1 for T. grandis and the decay constant (k) of decomposed leaf litter was distinctly higher for T. grandis (2.70 ± 0.50 a^?1) compared to S. robusta (2.41 ± 0.30 a^?1). Biomass loss was positively correlated with the initial litter C, WSC, C/N and ash content in S. robusta and N, P and K concentration for T. grandis. Biomass was negatively correlated with lignin and L/N ratio for S. robusta and L, WSC, L/N and C/N ratio for T. grandis (P < 0.01). Nutrient use efficiency (NUE) and nutrient accumulation index (NAI) of S. robusta was higher than for T. grandis. The retranslocation of bioelements from senescent leaves ranked as P > N > K. Annual N, P and K input to soil through litterfall differed significantly between the two species in the following order: N>K>P. S. robusta was superior in terms of K and P return and T. grandis was superior in terms of N return. The two tree species showed a similar patterns of nutrient release (K > P > N) during decomposition of their leaf litter. Nutrients of N, K and P were the primary limiting nutrients returned to soil through litterfall with important roles in soil fertility and forest productivity.     

Quantification of organic carbon and primary nutrients in litter and soil in a foothill forest plantation of eastern Himalaya

The present study was an effort to understand the amount of litter fall and its subsequent decomposition and quantify the release of available nutrients and soil physicochemical characteristics in plantations of four forest tree species(Lagerstroemia parviflora, Tectona grandis, Shorea robusta and Michelia champaca) in the Chilapatta Reserve Forest of the Cooch Behar Wildlife Division in the Terai zone of West Bengal, India. The most litter(5.61 Mg ha~(-1))was produced by T. grandis plantation and the least(4.72 Mg ha~(-1)) by L. parviflora. The material turnover rate to the soil through decomposition from total litter was fastest during the first quarter of the year and subsequently decreased during the next two quarters. The material turnover rate was only 1 year, which indicates that more than90% of the total litter produced decomposed within a year.The available primary nutrient content in litter varied across the four plantations over the year. The plantations generally did not significantly influence the soil physical characteristics but did significantly influence the availability of primary nutrients and organic carbon at two depths(1–15 and16–30 cm) over the year. The availability of soil primary nutrients in the four plantations also increased gradually from the first quarter of the year to the third quarter and then decreased during the last quarter to the same level as in the first quarter of the year at both depths. The availability for soil organic carbon in the plantations followed a similar trend. The amount of litter produced and the material turnover in the soil in the different plantations differed, influencing the nutrient availability and organic carbon at the plantations. The amount of soil organic carbon was highest for T. grandis(2.52 Mg ha~(-1)) and lowest for L. parviflora(2.12 Mg ha~(-1)). Litter is the source of soil organic matter,and more the litter that is produced by the plantations, the higher will be the content and amount of soil organic carbon in the plantation.     

A comparison of decomposition dynamics among green tree leaves,partially decomposed tree leaf litter and their mixture in a warm temperate forest ecosystem

Decomposition dynamics were compared among green tree leaves, partially decomposed tree leaf litter (i.e., decayed tree leaf litter on forest floor) and a mixture of the two in a warm temperate forest ecosystem in central China to test the influence of litter chemical quality on the degree of decomposition. The study was conducted in situ at two contrasting forest sites, an oak forest dominated by Quercus aliena var. acuteserrata Maxim., and a mixed pine and oak forest dominated by Pinus armandii Franch. and Q. aliena var. acuteserrata. We found marked differences in the rate of decomposition among litter types at both forest sites; the litter decomposition constant, k, was about 39 % greater at the oak forest site and more than 70 % greater at the pine-oak forest site, for green leaves than for partially decomposed leaf litter. The decomposition dynamics and temporal changes in litter chemistry of the three litter types also greatly differed between the two forest sites. At both forest sites, the higher rate of decomposition for the green leaves was associated with a higher nitrogen (N) content and lower carbon to N ratio (C/N) and acid-unhydrolyzable residue to N ratio (AUR/N). We did not find any non-additive effects when mixing green leaves and partially decomposed leaf litter. Our findings support the contention that litter chemical quality is one of the most important determinants of litter decomposition in forest ecosystems at the local or regional scale, but the effect of litter chemical quality on decomposition differs between the contrasting forest types and may vary with the stage of decomposition.     

Decomposition of Mongolian pine litter in the presence of understory species in semi-arid northeast China

The effects of understory plant litter on dominant tree litter decomposition are not well documented especially in semi-arid forests. In this study, we used a microcosm experiment to examine the effects of two understory species (Artemisia scoparia and Setaria viridis) litter on the mass loss and N release of Mongolian pine (Pinus sylvestris var. mongolica) litter in Keerqin Sandy Lands, northeast China, and identified the influencing mechanism from the chemical quality of decomposing litter. Four litter combinations were set up: one monoculture of Mongolian pine and three mixtures of Mongolian pine and one or two understory species in equal mass proportions of each species. Total C, total N, lignin, cellulose and polyphenol concentrations, and mass loss of pine litter were analyzed at days 84 and 182 of incubation. The chemistry of pine litter not only changed with the stages of decomposition, but was also strongly influenced by the presence of understory species during decomposition. Both understory species promoted mass loss of pine litter at 84 days, while only the simultaneous presence of two understory species promoted mass loss of pine litter at 182 days. Mass loss of pine litter was negatively correlated with initial ratios of C/N, lignin/N and polyphenol/N of litter combinations during the entire incubation period; at 182 days it was negatively correlated with polyphenol concentration and ratios of C/N and polyphenol/N of litter combinations at 84 days of incubation. Nitrogen release of pine litter was promoted in the presence of understory species. Nitrogen release at 84 days was negatively correlated with initial N concentration; at 182 days it was negatively correlated with initial polyphenol concentration of litter combinations and positively correlated with lignin concentration of litter combinations at 84 days of incubation. Our results suggest that the presence of understory species causes substantial changes in chemical components of pine litter that can exert strong influences on subsequent decomposition of pine litter.     

Different population performances of <Emphasis Type="Italic">Frankliniella occidentalis</Emphasis> and <Emphasis Type="Italic">Thrips hawaiiensis</Emphasis> on flowers of two horticultural plants

Gardenia jasminoides and Rosa chinensis are economically important horticultural plants in China. Frankliniella occidentalis and Thrips hawaiiensis are serious coexisting pests that previously demonstrated opposite population trends on G. jasminoides and R. chinensis flowers. To further study the different performances between F. occidentalis and T. hawaiiensis, we investigated their population dynamics in the field (for 5 years) and their life history characteristics on the two flowers in the laboratory. In the field, the density of F. occidentalis was lower than that of T. hawaiiensis on G. jasminoides but was higher than that of T. hawaiiensis on R. chinensis. Under laboratory conditions, F. occidentalis showed significantly slower development, and lower survival and fecundity levels than T. hawaiiensis on G. jasminoides, but the opposite was true on R. chinensis. Significant differences in the net reproductive rate (R ₀) between F. occidentalis and T. hawaiiensis were observed, with respective values of 38.66 ± 2.85 and 47.91 ± 2.70 on G. jasminoides, and 55.64 ± 2.15 and 32.45 ± 2.16 on R. chinensis. The intrinsic rates of increase (r _m ) of F. occidentalis and T. hawaiiensis were 0.156 ± 0.008 and 0.198 ± 0.007, respectively, on G. jasminoides, and 0.172 ± 0.003 and 0.165 ± 0.002, respectively, on R. chinensis. Thus, the performances of both thrips with respect to population size in the laboratory were in accordance with those in the field, suggesting that the innate capacity for insect population increases may directly impact their population dynamics in fields. Thus, the population performance of different thrips species on flowers is species-dependent, which could be exploited in thrips control programs by breeding pest-resistant cultivars.     

Effects of <Emphasis Type="Italic">Verticillium nonalfalfae</Emphasis> on <Emphasis Type="Italic">Ailanthus altissima</Emphasis> and associated indigenous and invasive tree species in eastern Austria

The naturally occurring Verticillium nonalfalfae shows promise for biocontrol of the highly invasive Tree of Heaven (Ailanthus altissima), but might also bear a risk for non-target tree species. In this study, we conducted inoculations on potted seedlings of A. altissima as well as on eight indigenous and two invasive tree species associated with Tree of Heaven in Austria. Although vascular discolourations developed in all inoculated tree species, V. nonalfalfae was reisolated from Ailanthus and eight of the ten non-target-species, whereas typical disease symptoms and mortality only occurred on A. altissima. Results confirmed high susceptibility (S) of A. altissima to V. nonalfalfae but indicated tolerance (T) of Acer campestre, Acer pseudoplatanus and Quercus robur, possible resistance (PR) of Fraxinus excelsior, Populus nigra, Tilia cordata, Ulmus laevis and Ulmus minor and resistance (R) of Fraxinus pennsylvanica and Robinia pseudoacacia to this potential biocontrol agent. Results from seedling inoculations were confirmed by cursory field observations in Ailanthus-inoculated forest stands, where admixed A. campestre, A. pseudoplatanus, F. excelsior, Populus alba, R. pseudoacacia and U. laevis canopy trees remained asymptomatic, while mortality was induced in Ailanthus.     

Communities of saprobic fungi on leaf litter of <Emphasis Type="Italic">Vismia guianensis</Emphasis> in remnants of the Brazilian Atlantic Forest

We examined the mycobiota associated with Vismia guianensis leaf litter in three Atlantic Forest remnants of Brazil’s semiarid region. Among the study sites, two remnants were protected forest reserves, whereas the third was influenced by major anthropogenic activities. Eighteen litter samples were collected in wet and dry seasons and were processed by particle filtration technique. A total of 4750 fungal isolates of 142 taxa were identified. Species richness was higher in litter samples collected during wet season. Nonmetric multidimensional scaling multivariate analysis showed differences in the composition of fungal communities among the sampling sites and the seasons. Analysis of similarity showed that the differences were statistically significant (R = 0.85; P = 0.0001). Our findings revealed that spatial and temporal heterogeneity, and human activities had significant impacts on the saprobic fungi of V. guianensis leaf litter.     

Effects of climatic conditions on tree-ring widths of three deciduous broad-leaved tree species at their northern distribution limit in Mont St. Hilaire,eastern Canada

This study examined the effects of climatic conditions on tree-ring widths of red oak (Quercus rubra), sugar maple (Acer saccharum) and American beech (Fagus grandifolia) at their northern distribution limit in Mont St. Hilaire, eastern Canada. A residual chronology of tree-ring width index was developed for each species. The tree-ring width of Q. rubra showed negative and positive correlations with May temperature and June precipitation in the current year, respectively. A. saccharum also showed similar patterns with Q. rubra, i.e., negative and positive correlations with June temperature and precipitation in the current year, respectively. F. grandifolia showed neither positive nor negative correlations with temperature and precipitation. The expressed population signals of tree-ring width chronologies of the three species indicated that climatic factors more greatly influenced the variations in tree-ring widths in the order Q. rubra > A. saccharum > F. grandifolia. Therefore, the radial growth of Q. rubra was most restricted by drought stress in early summer among the three species. Global warming is suggested to affect the radial growth of the three species differently by increasing drought stress at Mont St. Hilaire in eastern Canada.     

紫金山两种主要林型有机物层中丝状真菌多样性

本文对紫金山两种主要林型,栓皮栎林(Quercus variabilis)和马尾松-枫香(Pinus massoniana-Liguidam barformasana)混交林的有机物层(L, F, H层及土壤淋溶A层)可培养丝状真菌多样性进行了研究。通过分离鉴定,共得到真菌67种,其中接合菌3种、子囊菌5种、半知菌类56种和未确定种3种,半知菌类最为丰富。两种林型分解真菌优势种群为链格孢(Alternaria sp.)、曲霉(Aspergillus spp.)、枝孢(Cladosporium sp.)、毛霉(Mucor sp.)、青霉(Penicillium sp.)、木霉(Trichoderma spp.)、根霉(Rhizopus sp.)、粘帚霉(Gliocladium sp.)。混交林型中真菌的种类和数量明显高于栓皮栎林。两个林型均以F层真菌种类最多,但F层之间和L层之间真菌多样性差异较大。在混交林型中从马尾松针叶上分离的真菌种类和数量比从枫香上分离得到的少; 从马尾松针叶上分离的真菌丰富度随着有机物层深度增加而增加,枫香则反之。比较两个林型以及混交林的两种落叶上真菌种类发现,随着有机物层深度的增加,真菌的种类差异性却随之减少,即同时出现在两个林型或两种针叶上的真菌种类增多。真菌种类随着分解过程的进行具有明显的演替现象。混交林型中同一层内不同落叶上分解真菌多样性的差异,表明凋落物基质的差异是决定真菌种类和数量的重要因素     

Seed bank and regeneration dynamics of <Emphasis Type="Italic">Emmenopterys henryi</Emphasis> population on the western side of Wuyi Mountain,South China

Emmenopterys henryi Oliv. (Rubiaceae) is an endangered tree species that is native to China. The wild populations of E. henryi have declined rapidly because of its poor natural regeneration, but the actual regeneration processes are not yet understood. In field tracking surveys and experiments in the Wuyishan Nature Reserve in Southeast China to determine the most important stage that affects the regeneration process, seed bank characteristics, seed germination, and seedling growth dynamics were studied in the typical habitats of E. henryi, Phyllostachys pubescens and broad-leaved forests. Results showed that in both P. pubescens and broad-leaved forests, more than 70% of the E. henryi seeds were distributed in moss and litter layers, and few were found in the soil beneath them. However, seed germination in the soil layer was significantly higher than in the moss and litter layers. Seed density, overall seed quality, and germination rate in the broad-leaved forest were significantly higher than in P. pubescens forest. Seed germination was highest in the microsites around the edge of the crown projection area of E. henryi mother trees. The order of survival rate of the seedlings on different ground surfaces was soil > moss > litter. In both habitats, the average seed density was 24.9 seeds m^?2, and the total germination rate was less than 3.5‰. However, seedlings developed from only 1% of the germinated seeds, indicating that the seed germination is the most important stage in the natural regeneration of E. henryi.     

Tree leaves of <Emphasis Type="Italic">Salix babylonica</Emphasis> extract as a natural anthelmintic for small-ruminant farms in a semiarid region in Mexico

The study aimed to test the potential anthelmintic activity of Salix babylonica (SB) extract for the control of gastrointestinal and pulmonary parasites in sheep and goats under field conditions. A representative sample of 20 % of all animals reared in 8 sheep and 7 goat farms was used in the study. Animals from each farm were randomly selected for a total number of 93 sheep and 75 goats. Animals suffered a natural gastrointestinal nematode infection and had never been treated with chemical anthelmintic drugs. The SB extract (20 mL) was orally administered weekly before the morning feeding to each animal for 60 days. Fecal eggs or oocysts were counted at 0, 1, 20, 40, and 60 days after starting the extract administration. Differences (P < 0.01) in the fecal oocyst and egg output of Eimeria, Dictyocaulus, and Moniezia were observed between sheep and goats. In addition, the treatment influenced (P < 0.05) egg outputs of Cooperia, Dictyocaulus, and Trichuris. Fecal egg or oocyst counts of Haemonchus contortus, Eimeria, Cooperia, Chabertia, Dictyocaulus, Moniezia, and Ostertagia were time-dependent (P < 0.05). For sheep, administration of SB decreased (P < 0.05) the fecal eggs count of H. contortus, Cooperia, Chabertia, Dictyocaulus, Moniezia, and Trichuris. After 20 days of treatment, H. contortus, Cooperia, or Moniezia were not detected. For goats, SB reduced (P < 0.05) the fecal egg counts of H. contortus, Cooperia, Chabertia, and Moniezia. Moreover, decreases were observed (P < 0.05) for Chabertia, Trichostrongylus, and Ostertagia. Eggs of H. contortus and Moniezia were not present in the feces after 1 day of administration of the extract. It could be concluded that the weekly administration of SB extract at 20 mL per animal can be used to treat gastrointestinal and lung nematodes of small ruminants in organic and traditional farming systems of tropical regions.     

Effects of litter quality and climate change along an elevational gradient on litter decomposition of subalpine forests,Eastern Tibetan Plateau,China

Temperature and freeze-thaw events are two key factors controlling litter decomposition in cold biomes.Predicted global warming and changes in freeze-thaw cycles therefore may directly or indirectly impact litter decomposition in those ecosystems. Here, we conducted a2-year-long litter decomposition experiment along an elevational gradient from 3000 to 3600 m to determine the potential effects of litter quality, climate warming and freeze-thaw on the mass losses of three litter types [dragon spruce(Picea asperata Mast.), red birch(Betula albosinensis Burk.), and minjiang fir(Abies faxoniana Rehd. et Wild)]. Marked differences in mass loss were observed among the litter types and sampling dates. Decay constant(k) values of red birch were significantly higher than those of the needle litters. However, mass losses between elevations did not differ significantly for any litter type.During the winter, lost mass contributed 18.3–28.8 % of the net loss rates of the first year. Statistical analysis showed that the relationships between mass loss and litter chemistry or their ratios varied with decomposition periods. Our results indicated that short-term field incubations could overestimate the k value of litter decomposition.Considerable mass was lost from subalpine forest litters during the wintertime. Potential future warming may not affect the litter decomposition in the subalpine forest ecosystems of eastern Tibetan Plateau.     

Rhizosphere and bulk soil enzyme activities in a <Emphasis Type="Italic">Nothotsuga longibracteata</Emphasis> forest in the Tianbaoyan National Nature Reserve,Fujian Province,China

The rhizosphere, distinct from bulk soil, is defined as the volume of soil around living roots and influenced by root activities. We investigated protease, invertase, cellulase, urease, and acid phosphatase activities in rhizosphere and bulk soils of six Nothotsuga longibracteata forest communities within Tianbaoyan National Nature Reserve, including N. longibracteata + either Phyllostachys pubescens, Schima superba, Rhododendron simiarum, Cunninghamia lanceolata, or Cyclobalanopsis glauca, and N. longibracteata pure forest. Rhizosphere soils possessed higher protease, invertase, cellulase, urease, and acid phosphatase activities than bulk soils. The highest invertase, urease, and acid phosphatase activities were observed in rhizosphere samples of N. longibracteata + S. superba. Protease was highest in the N. longibracteata + R. simiarum rhizosphere, while cellulase was highest in the pure N. longibracteata forest rhizosphere. All samples exhibited obvious rhizosphere effects on enzyme activities with a significant linear correlation between acid phosphatase and cellulase activities (p < 0.05) in rhizosphere soils and between protease and acid phosphatase activities (p < 0.05) in bulk soils. A principal component analysis, correlating 13 soil chemical properties indices relevant to enzyme activities, showed that protease, invertase, acid phosphatase, total N, and cellulase were the most important variables impacting rhizosphere soil quality.     

Genetic diversity in two threatened species in Vietnam: <Emphasis Type="Italic">Taxus chinensis</Emphasis> and <Emphasis Type="Italic">Taxus wallichiana</Emphasis>

Taxus chinensis and T. wallichiana in have been threatened in their distribution areas in recent decades because of their over-exploitation and reduction and destruction of native habitats. Determining the genetic diversity in populations of the two species will provide guidelines for their protection and preservation. Two hundred and fifteen trees from six populations of T. chinensis and 150 sampled trees of T. wallichiana were sampled. Six microsatellite primer pairs selected from 16 primer pairs were used to investigate genetic variation at the population and species levels. Five yielded polymorphic alleles, and among the 13 putative alleles amplified, 11 were polymorphic (accounting for 76.33 %).Shannon’s information index (I) and percentage of polymorphic bands (PPB) (I = 0.202 and PPB = 67.22 % for T. chinensis; I = 0.217 and PPB = 65.03 % for T. wallichiana). Both species had low levels of genetic diversity (mean H _o = 0.107, H _e = 0.121 for T. chinensis; H _o = 0.095, H _e = 0.109 for T. wallichiana). Genetic differentiation among populations was higher (F _ST = 0.189) for T. chinensis and lower (0.156) for T. wallichiana, indicating limited gene flow (Nm) among populations for T. chinensis (0.68) and T. wallichiana (0.65). Variation among individuals of T. chinensis was 63.59 and 73.12 % for T. wallichiana. Thus, the threatened status of the two conifers is related to a lack of genetic diversity. All populations are isolated in small forest remnants. An ex situ conservation site should be established with a new population for these species that comprises all the genetic groups for the best chance to improve their fitness under environmental stresses.     

Carbon storage in biomass,litter, and soil of different native and introduced fast-growing tree plantations in the South Caspian Sea

Replantation of degraded forest using rapidgrowth trees can play a significant role in global carbon budget by storing large quantities of carbon in live biomass,forest floor,and soil organic matter.We assessed the potential of 20-year old stands of three rapid-growth tree species,including Alnus subcordata,Populus deltoides and Taxodium distichum,for carbon(C) storage at ecosystem level.In September 2013,48 replicate plots(16 m × 16 m) in 8 stands of three plantations were established.36 trees were felled down and fresh biomass of different components was weighed in the field.Biomass equations were fitted using data based on the 36 felled trees.The biomass of understory vegetation and litter were measured by harvesting all the components.The C fraction of understory,litter,and soil were measured.The ecosystem C storage was as follows: A.subcordata(626.5 Mg ha~(-1)) [ P.deltoides(542.9Mg ha~(-1)) [ T.distichum(486.8 Mg ha~(-1))(P \ 0.001),of which78.1–87.4% was in the soil.P.deltoides plantation reached the highest tree biomass(206.6 Mg ha~(-1)),followed by A.subcordata(134.5 Mg ha~(-1)) and T.distichum(123.3 Mg ha~(-1)).The highest soil C was stored in theplantation of A.subcordata(555.5 Mg ha~(-1)).The C storage and sequestration of the plantations after 20 years were considerable(25–30 Mg ha~(-1) year~(-1)) and broadleaves species had higher potential.Native species had a higher soil C storage while the potential of introduced species for live biomass production was higher.     

Yield and Nutrient Content of Chestnut (<Emphasis Type="Italic">Castanopsis piriformis</Emphasis>) in Natural Central Highlands Forests,Vietnam

Chestnuts have historical importance as a food source worldwide. Planting of chestnuts has focused on a few species, including Castanea dentata, Castanea sativa, Castanea mollissima, and Castanea crenata, although others species are also edible. Castanea species are members of the beech family (Fagaceae) and are native to tropical and temperate areas. In this study, the yield and nut quality of Castanopsis piriformis in natural forests of the Central Highlands of Vietnam were investigated to provide evidence that C. piriformis is worth growing as a food species. Data were collected from 12 plots of 50 m × 50 m size located in four altitude zones. Nuts were collected from three to five chestnut trees in each plot judged to be of typical sized based on diameter at breast height and crown diameter. Average dry yield of nuts was found to be elevation-dependent, being highest at 500–1000 m (1152 kg/ha/year), decreasing to 815 kg/ha/year below 500 m, and to 770 kg/ha/year at 1000–1500 m. The lowest yield was observed at above 1500 m (252 kg/ha/year). Protein and lipid contents in the kernels of C. piriformis chestnut were 4.4 and 0.1 %, respectively. Glucose accounted for 73.1 % and was significantly higher than that of commercially grown Castanopsis boisii chestnuts in Northern Vietnam. With the current price of 0.6 US$/kg nuts, collecting nuts growing in natural forest can bring at least 480 US$/ha/year to local people. These results indicate the possibility of growing and consuming C. piriformis chestnut as a crop to decrease poverty. However, governmental support is required for the sustainable development of C. piriformis.     

Assaying the allelopathic effects of <Emphasis Type="Italic">Eucalyptus camaldulensis</Emphasis> in a nursery bed incorporated with leaf litter

Allelopathic effects of Eucalyptus camaldulensis Dehnh. were confirmed in Petri dish and pot experiments in our previous studies. However, the degree to which such effects under controlled experiments exist in more complex ecological settings remains to be tested. Thus, the present study was carried out by incorporating different proportions of ground litter of E. camaldulensis in soil. The growth of three agricultural crops: falen (Vigna unguiculata (L.) Walp.), chickpea (Cicer arietinum L.), and arhor (Cajanus cajan (L.) Millsp.), and two tree species, kala koroi (Albizia procera (Roxb.) Benth.) and ipil ipil (Leucaena leucocephala (Lam.) de Wit) were tested. There were inhibitory effects of leaf litter on germination, shoot and root growth, leaf number, and collar diameter as well as a reduction of nodulation by legume crops (25–80% reduction). The extent of the effects was dependent on the proportion of leaf litter, the species and the type of traits. In contrast to shoot growth, the effect on root growth was more severe. No effect on germination was found with the agriculture crops while the two tree species showed reduced germination. The effect was greater in the presence of higher proportions of leaf litter mixed in soil while in some cases lower proportions stimulated growth. Not all species were suppressed; A. procera, C. cajan, V. unguiculata showed compatible growth while C. arietinum and L. leucocephala were found incompatible. This study provides evidence that E. camaldulensis has allelopathic potential under field conditions and a careful selection of associated crops in agroforestry systems is highly recommended.     

Analysis of floral scent emitted from <Emphasis Type="Italic">Syringa</Emphasis> plants

Syringa is an important aromatic woody angiosperm that is widely planted in gardens. Its dry flowers are traditionally used to manufacture infusions and spices in China. In this study, the floral volatiles emitted from nine different Syringa species and varieties, viz. S. chinensis, S. p rotolaciniata, S. o blata, S. o blata var. giraldii, S. o blata var. plena, S. v ulgaris ‘Mrs Harry Bickle’, S. v ulgaris ‘Bright Centennial’, S. v ulgaris ‘White Spires’, and S. v ulgaris ‘President Lincoln’ were collected by the dynamic headspace technique, and then identified by automated thermal desorption–gas chromatography/mass spectrometry. There were significant differences in components and corresponding contents of floral scent emitted from the nine Syringa species and varieties. Among the detected components, β-ocimene exhibited the highest content, accounting for more than 70 % of the floral scent of S. p rotolaciniata, S. o blata var. giraldii, and S. v ulgaris ‘Bright Centennial’. A significant daytime variation of floral scent emitted from S. p ekinensis was recorded, especially for benzaldehyde, whose content first increased and then decreased. We studied the scent emitted from the in vitro flowers of S. v ulgaris ‘Pres Lincoln’ during the process of natural drying. Alcohol compounds were released in the greatest content, and the content of 2-ethyl-1-hexanol accounted for about 40 % of the total release amount. The results described the emission pattern and mechanisms of floral scent in Syringa.     

Factors affecting field performance of pheromone traps for tobacco beetle, <Emphasis Type="Italic">Lasioderma serricorne</Emphasis>, and tobacco moth, <Emphasis Type="Italic">Ephestia elutella</Emphasis>

Tobacco beetle, Lasioderma serricorne (F.) (Coleoptera: Anobiidae), is one of the most serious insect pests of stored tobacco, and traps baited with the female-produced sex pheromone, serricornin, are used for monitoring the pest. In two trapping experiments carried out in tobacco warehouses in Greece, two commercially available trap and lure systems for L. serricorne were found to be equally effective in terms of the numbers of beetles trapped. In contrast to previous reports, anhydroserricornin was unattractive and lures containing serricornin and anhydroserricornin were less attractive than lures containing serricornin only. The sex pheromone of the other main insect pest of tobacco, Ephestia elutella (Hübner) (Lepidoptera: Pyralidae), could be added to the lures without affecting the attractiveness of either pheromone to their respective species. Lures remained attractive for at least 4 weeks under field conditions, and, in laboratory tests, release of pheromone could still be detected after 30 days at 27 °C. The stereoisomeric composition of the serricornin in the two commercial lures was similar with high proportions of the attractive (4S,6S,7S)-isomer. The proportion of the (4S,6S,7R)-isomer was low, and this is known to reduce the attractiveness.     

Chemical composition,antioxidant and antibacterial activities of extracts from <Emphasis Type="Italic">Schinus molle</Emphasis> wood branch growing in Egypt

In the present work, for the first time, the chemical components of essential oils (EOs) and extracts from wood branch (WB) resulted from the tree pruning wastes of Schinus molle L. grown in Egypt were evaluated for their antioxidant and antibacterial activities. EOs, methanol (ME), dichloromethane (DCME) and water (WE) extracts as antioxidant and antibacterial activities were measured. Total phenolic and flavonoid contents as well as analysis of extracts by gas chromatography–mass spectrometry (GC–MS) were reported. The major components in EOs were α-elemol, β-pinene, and α-phellandrene, in ME were 6-(4-chlorophenyl)-3-cyano-4-(N-benzylpiperazino)-2H-pyran-2-one, and 2-naphthalene methanol, decahydro-α,α,4a-trimethyl-8-methylene, in DCME were 12-methyl-E,E-3,13-octadecadien-1-ol, and 1,2-benzenedicarboxylic acid, dioctyl ester, and in WE were β-eudesmol, and (Z,Z,Z)-9,12,15-octadecatrienoic acid, 2,3-dihydroxypropyl ester. The highest total antioxidant activity was found with EOs (90 ± 1.23 %) and WE (86.30 ± 1.40 %). The lowest IC₅₀ values of 13.11 ± 3.00, and 12.66 ± 2.15 μg/mL were found with WE and EOs, respectively. EOs and WE were observed to have good antibacterial activity against Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Escherichia coli, Sarcina lutea, Pseudomonas aeruginosa, and Micrococcus luteus. In conclusion, the Schinus molle L. WB EOs and extracts might, indeed, be used as a potential source for pharmaceutical or food industries.