Within-stem variations in mechanical properties of <Emphasis Type="Italic">Melia azedarach</Emphasis> planted in northern Vietnam

Within-stem variations in the mechanical properties of 17–19-year-old Melia azedarach planted in two sites in northern Vietnam were examined by destructive and nondestructive methods. Wood samples were collected from 10, 50, and 90% of the radial length from pith on both sides (North and South) at 0.3, 1.3, 3.3, 5.3, and 7.3 m heights above the ground. The mean values in whole trees of wood density (WD), modulus of rupture (MOR), modulus of elasticity (MOE), and dynamic modulus of elasticity (E_d) at 12% moisture content were 0.51 g/cm³, 78.58 MPa, 9.26 GPa, and 10.93 GPa, respectively. Within the stem, the radial position was a highly (p?<?0.001) significant source of variation in mechanical properties. MOR, MOE, and E_d increased from pith to bark. WD had a strong positive linear relationship with both MOR (r?=?0.85, p?<?0.001) and MOE (r?=?0.73, p?<?0.001). This suggests that it is potentially possible to improve mechanical properties through controlling WD. MOR had also a strong linear relationship with E_d (r?=?0.84, p?<?0.001). This indicates that E_d is a good indicator to predicting the strength of wood if the density of measured element is known. Besides, the stress wave method used in this study provides relatively accurate information for determining the stiffness of Melia azedarach planted in northern Vietnam.     

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.     

The colonisation of Scots pine (<Emphasis Type="Italic">Pinus sylvestris</Emphasis> L.) by <Emphasis Type="Italic">Tomicus minor</Emphasis> Hartig in southern Poland: modelling and monitoring

Tomicus minor Hartig (Col., Curculionidae, Scolytinae), occurring on Pinus sylvestris L., is a species which demonstrates high reproductive capability on weakened stands, accelerating the process of forest death. In protected areas, T. minor is regarded as a sensitive bioindicator that reacts to decline in the health and vitality of forests. Although there have been many publications concerning T. minor, no precise method has yet been given for estimating its population so as to enable the monitoring of forest vitality and assessment of the role played by T. minor in the forest ecosystem. The aim of the present work is to develop a statistical method for estimating populations of T. minor, requiring minimum work and interference with the forest ecosystem and permitting the computation of estimation errors. Research was carried out in the years 1992–2011 in pine stands aged over 80 years, growing in a variety of habitats and situated at varying distances from sawmill timber yards. Attack density of T. minor was measured on trap logs made from uninfested living trees. The population of T. minor on the trap logs was described using a multiple linear regression model with two explanatory variables. Among the features investigated, the T. minor population was found to depend significantly on the number of egg galleries on the fifth metre of the trap log counted from the thinner end (p < 0.001) and on the diameter of the trap log in bark at the thinner end (p < 0.05). The model explains approximately 85% (R ² = 0.8564) of the variation in the total number of T. minor egg galleries on the trap logs. The numbering of units beginning from the thinner end of the log enabled increased precision in determining the model parameter resulting from the concentration of egg galleries on certain units of the log. In all validated plots, the mean real and model values for the number of T. minor egg galleries on the trap logs are similar (p > 0.5), confirming the high accuracy of the developed model.     

Effects of peeling and steam-heating treatment on mechanical properties and dimensional stability of oriented <Emphasis Type="Italic">Phyllostachys makinoi</Emphasis> and <Emphasis Type="Italic">Phyllostachys pubescens</Emphasis> scrimber boards

Epidermal peeling treatment (EPT) and steam-heating treatment (SHT) are two popular pretreatments for bamboo processing. This study examined the effects of EPT and SHT on strength properties, profile density distribution, internal bond strength (IB), rate of springback, nail withdrawal resistance, and dimensional stability of oriented bamboo scrimber board (OBSB) made of moso bamboo (Phyllostachys pubescens Mazel) and makino bamboo (P. makinoi Hayata) strips. Results obtained using non-destructive testing (NDT) revealed that EPT for moso bamboo in the processing of OBSB caused lower ultrasonic-wave velocity (V_u) and dynamic modulus of elasticity (DMOE_u) parallel to the fiber direction, but higher V_u and DMOE_u perpendicular to the fiber direction. However, EPT slightly affected variations in modulus of elasticity (MOE) and modulus of rupture (MOR) of moso bamboo. In contrast, the effects of SHT on V_u and DMOE_u were inconsistent and insignificant among the OBSB samples. On the other hands, SHT caused increasing in MOE and MOR of OBSB, but leads to decrease in MOE and MOR of OBSB comprising bamboo strips after EPT. Both EPT and SHT contributed to more uniform profile densities in OBSB and had a positive impact on nail withdrawal resistance. EPT increased IB of moso bamboo and SHT enhanced IB of makino bamboo with epidermis only. Bamboo strips after SHT resulted in significant decrease in water absorption of all OBSB specimens. Reduction in swelling as a result of SHT not only improved the dimensional stability of OBSB but also enhanced strength.     

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.     

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.     

A novel cold-inducible promoter,P<Emphasis Type="Italic">ThCAP</Emphasis> from <Emphasis Type="Italic">Tamarix hispida</Emphasis>, confers cold tolerance in transgenic <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

Our previous studies have revealed that the ThCAP gene plays a vital role in transgenic Populus (P. davidiana × P. bolleana) in response to cold stress. However, the regulatory mechanism of ThCAP gene expression has been unclear. In this study, the 5′ flanking region of the ThCAP promoter (PThCAP) was cloned using a genome-walking method. By analyzing cis-acting regulatory elements of PThCAP, a DRE motif and MYC and MYB elements were found to be located in the promoter. To identify the regulatory elements that control the expression of the ThCAP gene promoter, a series of deletion derivatives of PThCAP, P1–P5, from the translation start code (?1538, ?1190, ?900, ?718 and ?375 bp), were fused to the GUS reporter gene, and then each deletion was stably introduced into Arabidopsis thaliana plants. Deletion analysis of the promoter suggested that only the P2 fragment had strong GUS expression in leaves and roots of A. thaliana exposed to low temperature stress. These results suggest that this 290-bp region (?1190 to ?900 bp), as an important part in PThCAP, was associated with cold tolerance of A. thaliana. Our results provide evidence for the regulatory mechanism of ThCAP gene involved in the response to cold stress, and that the gene is promising candidate gene for genetic improvement of crops.     

Direct and admixture toxicity of diatomaceous earth and monoterpenoids against the storage pests <Emphasis Type="Italic">Callosobruchus</Emphasis><Emphasis Type="Italic">maculatus</Emphasis> (F.) and <Emphasis Type="Italic">Sitophilus oryzae</Emphasis> (L.)

We investigated the effects of two commercial diatomaceous earth based insecticides (DE), Protect-It^® and SilicoSec^®, the nano-structured silica product AL06, developed by the section for Urban Plant Ecophysiology at Humboldt University Berlin, and the monoterpenoids, eugenol, and cinnamaldehyde on two stored product pests, Callosobruchus maculatus and Sitophilus oryzae. Protect-It^® was more effective than SilicoSec^® against C. maculatus while the reverse was true for S. oryzae. Generally C. maculatus was more sensitive towards DE and silica treatment than S. oryzae. Mortality rate of both pest species increased when DE’s were applied to food commodities previously treated with a monoterpenoid. In admixture experiments, the toxicity of SilicoSec^® + cinnamaldehyde (LD₅₀ = 42.73 ppm), SilicoSec^® + eugenol (LD₅₀ = 24.30 ppm), and Protect-It^® + eugenol (LD₅₀ = 2.60 ppm) was increased over DE alone against S. oryzae. Both substances showed a synergistic effect considering their co-toxicity coefficient relative to the LD₅₀-value. In contrast, we could not find any synergistic effects in experiments with C. maculatus. Here only Protect-It^® + cinnamaldehyde (LD₅₀ = 20.84 ppm) showed an additive effect while all other combinations of monoterpenoid and DE indicated antagonistic effects. In addition to contact insecticidal effects both monoterpenoids showed a strong fumigant action. The presented results indicate that the natural product DE has great potential to replace synthetic pesticides commonly used in stored product pest management. Efficacy of DE can be improved by adding certain monoterpenoids against certain insect pests.     

Identification of pests and assessment of their damage on <Emphasis Type="Italic">Carapa procera</Emphasis> and <Emphasis Type="Italic">Lophira lanceolata</Emphasis> in Burkina Faso,West Africa

Nontimber forest products are a source of income for women in rural African communities. However, these products are frequently damaged by insect pests. The present study investigates the diversity and damage rates of insect pests that attack Carapa procera seeds and Lophira lanceolata fruits. The experiment was set up in western Burkina Faso and, for C. carapa, consisted of pests collected from seeds that had fallen to the ground and from stockpiled seeds. For L. lanceolata, pests were collected from fruits on the trees, and on the ground. The collected samples were sent to the laboratory to estimate the proportion of damaged seeds/fruits and rear the insects. The results showed that Ephestia spp., Tribolium castaneum, Oryzeaphilus spp., and Tenebroides mauritanicus were the pests of Carapa procera seeds and Lophira lanceolata fruits. Ephestia spp. was recorded as the main pest of both C. procera and L. lanceolata, whereas T. castaneum was only detected from seeds of L. lanceolata. For C. procera, the stocks were the most infested (29 %) by Ephestia spp. The infestation rate of fruits of L. lanceolata by Ephestia spp. on trees (31.42 ± 3.75 %) was less than the rate of fruits by T. castaneum on the ground (44.00 ± 3.5 %). The different body sizes of Ephestia spp. may indicate the occurrence of two putative species, one from C. procera and another one from L. lanceolata. This work provides important information that could contribute to the setting up of a local-scale sustainable management framework for oil tree pests in Burkina Faso and surrounding countries.     

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.     

Optimal timing of early genetic selection for sawn timber traits in <Emphasis Type="Italic">Picea abies</Emphasis>

In breeding Norway spruce, selection for improved growth and survival is performed at age 10–15 years in order to optimize genetic gain per year. We investigated whether a selection based on wood traits such as density and grain angle, measured under bark in the field at the same age would be informative enough with respect to structural quality traits of sawn boards. To achieve this objective, a sawing study was conducted on the butt logs of 401 trees from a 34-year-old Norway spruce progeny trial situated in southern Sweden. Stem discs were excised from the top of the logs and radial profile data of grain angle, and wood density was recorded for specific annual rings. The sawn and dried boards were assessed for structural traits such as twist, board density, bending stiffness (static modulus of elasticity, sMoE) and bending strength (modulus of rupture, MoR). Additive genetic correlations (r_a) between single annual ring density measurements and board density, sMoE and MoR were consistently strong (r_a>?0.7) for annual rings 5–13. Genetic correlations of similar magnitude between grain angle and board twist were estimated for all investigated annual rings (from 2 to around 26 under bark). Consequently, it was found that indirect selection for wood density and grain angle at the tree age 10–16 years would result in more genetic gain per year than selection at later ages. This makes it feasible to perform simultaneous selection of progeny in the field for both growth and wood traits at similar ages.     

Efficacy of low temperatures for the control of all life stages of <Emphasis Type="Italic">Plodia interpunctella</Emphasis> and <Emphasis Type="Italic">Liposcelis bostrychophila</Emphasis>

The insecticidal effect of low temperatures for the control of all life stages of two stored-product insects, Plodia interpunctella and Liposcelis bostrychophila, was evaluated under laboratory conditions. The temperatures tested were 0, ??5, ??10 and ??15 °C, and, at these temperatures, the insects were exposed for 2, 4 and 8 h and also for 1, 2, 3 and 7 days. Regarding P. interpunctella, the most cold-tolerant life stage was larvae, given that 2 days of exposure were needed for complete (100%) mortality at ??10 °C. Moreover, all larvae were dead at ??15 °C even after 2 h of exposure. Eggs of P. interpunctella were susceptible to cold, as mortality was complete after 7, 1 day, 2 and 2 h at 0, ??5, ??10 and ??15 °C, respectively. L. bostrychophila was by far less susceptible than P. interpunctella. For this species, adults were still alive even after 7 days at ??10 °C, while complete mortality was achieved only after 1 day at ??15 °C. Eggs of L. bostrychophila were the most cold-tolerant life stage, as survival was observed even after 3 days at ??15 °C. The results of the present study provide the first data set on which all life stages of P. interpunctella and L. bostrychophila are evaluated for their susceptibility to cold treatments in a standardized series of exposures and temperatures. These results are expected to further encourage the “real world” application of cold treatments for the disinfestation of durable stored-products.     

Antibacterial activity of Nepalese wild mushrooms against <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> and <Emphasis Type="Italic">Propionibacterium acnes</Emphasis>

The present study aims to reveal the antibacterial potential of the wild mushrooms of Nepal. Despite the recognition of the medicinal potential of the natural resources in this country, a systematic study on the bioactivities of the wild mushrooms is still lacking. Therefore, in an attempt to fill this gap, ethanol extracts of 90 Nepalese wild mushroom samples were tested for antibacterial activity against Staphylococcus aureus and Propionibacterium acnes. Staphylococcus aureus was comparatively more susceptible with Inonotus clemensiae exhibiting the least minimum bactericidal concentration (MBC) of 100 μg/mL. The major compound in I. clemensiae was identified to be hispidin using high resolution liquid chromatography–electron spray ionization mass spectrometry (LC–ESI-MS) and nuclear magnetic resonance (NMR) analyses. Furthermore, the minimum inhibitory concentration (MIC) and MBC values of hispidin were determined to be 25 and 100 µg/mL for S. aureus and P. acnes, respectively. These findings show that the Nepalese wild mushrooms have the potential to be a novel addition to the functional ingredients industry due to their strong antibacterial potential.     

Fumigant activity of <Emphasis Type="Italic">Illicium verum</Emphasis> fruit extracts and their effects on the acetylcholinesterase and glutathione<Emphasis Type="Italic"> S</Emphasis>-transferase activities in adult <Emphasis Type="Italic">Sitophilus zeamais</Emphasis>

The insecticidal activity of Illicium verum Hook. f. against Sitophilus zeamais Motschulsky adults were identified, and the underlying mechanisms were studied. Extracts from I. verum fruits in methyl alcohol (MA), ethyl acetate (EA), and petroleum ether (PE) were tested by fumigation in a hermetic container to determine their toxicity. The effects of the three extracts on the activity of acetylcholinesterase (AChE) and glutathione S-transferases (GSTs) of S. zeamais were determined in vivo. All extracts showed strong fumigant activity. The fumigant effects were enhanced with increased dosage and prolonged exposure time. 1.25, 2.50, 5.00, 10.00, and 20.0 mg/l doses of the MA, EA, and PE extracts caused the mortalities from 8.37 to 90.26 %, 21.81 to 95.89 %, and 15.84 to 92.57 %, respectively, at 72 h after treatment. Consequently, the most effective dose of the MA, EA, and PE extracts is the 20.0 mg/l. The LD₅₀ of the MA, EA, and PE extracts at 72 h after treatment were 7.10, 3.93, and 4.55 mg/l, respectively. The activities of AChE and GSTs were notably inhibited by the three extracts, as compared with the control, with strong dose- and time-dependent effects. The inhibition strength of the three extracts on AChE and GSTs activities were in the following order: EA extract > PE extract ≥ MA extract. Therefore, I. verum extracts could be explored as novel natural fumigants for the future control of stored-product insect pests.     

Osmoregulators in <Emphasis Type="Italic">Hymenaea courbaril</Emphasis> and <Emphasis Type="Italic">Hymenaea stigonocarpa</Emphasis> under water stress and rehydration

The objective of this work was to evaluate the effect of different water deficiency and rehydration levels on the concentrations of osmoregulators in two plant species (Hymenaea courbaril and H. Stigonocarpa) in the Amazon. We adopted a 2 × 5 × 5 factorial system, referring to 2 species (H. courbaril and H. stigonocarpa) and 5 stages of hydration and rehydration. The five hydration and rehydration stages were established in: (1) Control treatment E0; (2) Plants with 13 days of stress after incubation—E13; (3) Plants with 26 days of stress E26; (4) The plants that were established after 26 days after incubation and rehydrated for two days (RD2); (5) rehydrated for two days (RD4). The plants that were established after 26 days after incubation and rehydrated for four days. The experiment totaled fifty young plants with five replicates. Biochemical measurements were performed at the beginning of the experiment (E0) at 13 (E13) and 26 (E26) days after the water stress, in which the plants were rehydrated, repeating the analyses after two (RD2) and four (RD4) days. Both species increased the sucrose concentration by 18%, with a decrease of 52% in starch content. The RD4 time presented the highest mean starch concentration (0.19 mmol g^?1 of the residue for H. courbaril and 0.27 mmol g^?1 of residue for H. stigonocarpa). Increased proline concentrations were recorded for controls until RD2 for both species. For glycine betaine, the highest increases in treatments E26 and RD2 were observed for the H. courbaril species. Our rehydration period was not sufficient for total recovery of pre-stress concentrations of all studied solutes.     

A generalized algebraic difference approach allows an improved estimation of aboveground biomass dynamics of <Emphasis Type="Italic">Cunninghamia lanceolata</Emphasis> and <Emphasis Type="Italic">Castanopsis sclerophylla</Emphasis> forests

Key message

A generalized algebraic difference approach (GADA) developed in this study improved the estimation of aboveground biomass dynamics of Cunninghamia lanceolata (Lamb.) Hook and Castanopsis sclerophylla (Lindl.) Schott forests. This could significantly improve the fieldwork efficiency for dynamic biomass estimation without repeated measurements.

Context

The estimation of biomass growth dynamics and stocks is a fundamental requirement for evaluating both the capability and potential of forest carbon sequestration. However, the biomass dynamics of Cunninghamia lanceolata and Castanopsis sclerophylla using the generalized algebraic difference approach (GADA) model has not been made to date.

Aims

This study aimed to quantify aboveground biomass (AGB, including stem, branch and leaf biomass) dynamics and AGB increment in C. lanceolata and C. sclerophylla forests by combining a GADA for diameter prediction with allometric biomass models.

Methods

A total of 12 plots for a C. lanceolata plantation and 11 plots for a C. sclerophylla forest were selected randomly from a 100 m × 100 m systematic grid placed over the study area. GADA model was developed based on tree ring data for each stand.

Results

GADA models performed well for diameter prediction and successfully predicted AGB dynamics for both stands. The mean AGB of the C. lanceolata stand ranged from 69.4 ± 7.7 Mg ha^?1 in 2010 to 102.5 ± 11.4 Mg ha^?1 in 2013, compared to 136.9 ± 7.0 Mg ha^?1 in 2010 to 154.8 ± 8.0 Mg ha^?1 in 2013 for C. sclerophylla. The stem was the main component of AGB stocks and production. Significantly higher production efficiency (stem production/leaf area index) and AGB increment was observed for C. lancolata compared to C. sclerophylla.

Conclusion

Dynamic GADA models could overcome the limitations posed by within-stand competition and limited biometric data, can be applied to study AGB dynamics and AGB increment, and contribute to improving our understanding of net primary production and carbon sequestration dynamics in forest ecosystems.

     

Selection of arbuscular mycorrhizal fungal strains to improve <Emphasis Type="Italic">Casuarina equisetifolia</Emphasis> L. and <Emphasis Type="Italic">Casuarina glauca</Emphasis> Sieb. tolerance to salinity

Key message

Selection of the best salt-tolerant combination of Casuarina sp. and arbuscular mycorrhizal fungi (AMF) is one of the key criteria for successful setup of saline land rehabilitation program.

Context

Land salinization is a serious problem worldwide that mainly leads to soil degradation and reduces crop productivity. These degraded areas could be rehabilitated by planting salt-tolerant species like Casuarina glauca Sieb. and Casuarina equisetifolia L. These are pioneer plants, able to form symbiotic associations with arbuscular mycorrhizal fungi (AMF), ectomycorrhizal fungi (EMF), and nitrogen-fixing bacteria.

Aims

The aim of this study was to select the highest salt-tolerant combination of Casuarina/AMF that can be used for the rehabilitation of lands degraded by salinity.

Methods

C. equisetifolia and C. glauca were grown in sandy sterile soil in the greenhouse and inoculated separately with Rhizophagus fasciculatus (Thaxt.) C. Walker & A. Schüßler, Rhizophagus aggregatus (N.C. Schenck & G.S. Sm.) C. Walker, and Rhizophagus intraradices (N.C. Schenck & G.S. Sm.) C. Walker & A. Schüßler. After confirming the establishment of a symbiosis, the plants were watered with gradually increasing concentrations of saline solution. After harvest, size and biomass of the seedlings, root colonization by AMF, and AMF metabolic activities were evaluated.

Results

A larger growth was obtained in the two species when the individuals were inoculated with R. fasciculatus. Root colonization rates did not differ among fungal species, but fungal metabolic activities were higher in mycorrhizal roots of C. glauca plants inoculated with R. fasciculatus.

Conclusion

Among the three mycorrhizal fungi, R. fasciculatus was more efficient in association with Casuarinaceae species under salt stress. Our results suggest that selection of appropriate fungal strains is crucial to improve plant performance in saline soils.

     

Effects of <Emphasis Type="Italic">Eucalypt</Emphasis> and <Emphasis Type="Italic">Acacia</Emphasis> plantations on soil water in Sumatra

Indonesia’s pulp and paper industry needs a large area of sustainably grown plantations to support its continued development. Acacia mangium has been the key species underpinning the pulp and paper industries in Sumatra, however increased disease pressure on A. mangium is expected to require large-scale conversion of Acacia plantations to Eucalyptus in the near future. The effect of such a large scale change in plantation species on soil moisture, for both tree production, and catchment hydrology is unknown. In this study we sought to characterize the impacts of plantation species (Acacia or Eucalyptus) and nitrogen management, on soil moisture, soil water depletion and depth to groundwater under stands of Acacia mangium and Eucalyptus pellita over the first 2–3 years after establishment. The study was conducted in experiments at four sites in Sumatra, Indonesia. Soil moisture and soil water depletion were not influenced by plantation species or fertilizer treatment. Soil moisture content and soil water depletion were strongly influenced by shallow groundwater at two of the four sites, however depth to groundwater did not influence stem growth. Results from the field trials cautiously suggest that large scale conversion of Acacia mangium to Eucalypt species in these regions is unlikely to result in increased moisture stress, nor is conversion of plantation species likely to lead to substantial differences in catchment hydrology. This study demonstrated the importance of conducting multi-site studies when investigating biophysical relationships in forest/plantation systems.     

Expression of a scorpion toxin gene <Emphasis Type="Italic">BmKit</Emphasis> enhances the virulence of <Emphasis Type="Italic">Lecanicillium lecanii</Emphasis> against aphids

Lecanicillium lecanii has been developed as biopesticides and widely used in the biological control of several insects in agricultural practice. However, the poor efficacy has blocked its application. The genetic manipulation has been proved as a useful tool to improve the virulence of entomopathogenic fungus. In this study, a scorpion toxin gene (BmKit) from Buthus martensi was cloned and transferred into L. lecanii and then its resulting activity against cotton aphids (Aphis gossypii) was assessed. The results showed that the engineered strain BmKit-12 grew significantly quicker than WT in host insects. The median lethal concentration (LC₅₀) for BmKit-12 was 7.1-fold lower than that for WT, and the median survival time (LT₅₀) for BmKit-12 was reduced by 26.5 % compared with that for WT. Although the conidial yield was reduced by 31.4 % on insect cadavers, the mycelia growth, sporulation, and conidia germination of BmKit-12 on plates were not significantly different from WT. Considering the lower amount of mycelia for BmKit-12 in host insects in late growth stage (fungal sporulation stage), we think the expression of BmKit may not affect the capability of sporulation. In conclusion, the expression of BmKit gene can significantly enhance the pathogenicity of L. lecanii against cotton aphids in a relatively cost-effective way.     

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.