Search Results (16)

Acacia hybrid (Acacia mangium Willd. × A. auriculiformis A. Cunn. Ex Benth.) dominates plantation wood production in central Vietnam. Dependence on a single species may increase biological risks. The potential of eucalypt as an alternative was examined by comparing the growth and survival of acacia hybrid and eucalypt hybrid (Eucalyptus urophylla S.T. Blake × E. pellita F. Muell.) clones in Quang Tri province at three planting densities (1333, 1667 and 2222 trees ha⁻¹). The experiment was planted on an eroded shallow soil common in the region. At age 5 years, survival of acacia (74%) was higher than that of eucalypt (67%), a consequence of high mortality from wind damage for one eucalypt clone. Eucalypt was taller by about 2 m, but stem diameters of acacia and eucalypt were very similar. For both taxa, diameter decreased significantly as planting density increased. Across planting densities, mean standing volume was 107 and 108 m³ ha⁻¹ for acacia and eucalyptus, respectively. Linear regressions of stocking at 5 years on volume accounted for over half of the variance in acacia and eucalypt plot volumes, demonstrating the strong effect of stocking on yield. There were similarly strong effects of stocking on stem diameter. Acacia hybrid plantations of nearby small growers had stockings at age 5 years that averaged over 2500 stems ha⁻¹. Growers planted at higher densities and allowed their trees to multi-stem. Their standing volumes at age 5 years ranged from 83 to 102 m³ ha⁻¹. Understanding how to reduce tree mortality would assist growers to choose planting densities and stand management that optimise growth, log diameter classes and net returns. Full article

The WUSCHEL-related homeobox (WOX) gene family are key players in the rooting process. Eucalyptus is an important plant species of artificial forests in China. It is mainly grown through tissue culture of many excellent clonal materials, in which rooting is a key step. In the present study, by using the genome data of Eucalyptus grandis, Corymbia citriodora, E. pellita, and E. urophylla × E. grandis, the members of the eucalyptus WOX gene family were identified and analyzed by bioinformatics techniques. The eucalyptus WOX gene family members are unstable proteins, with 7 acidic proteins and 24 basic proteins, and no signal peptide region was detected. Subcellular localization prediction indicated that all these proteins are localized in the nucleus. Motif analysis showed that eucalyptus WOX genes share the same motifs. Phylogenetic tree and gene expression analyses revealed that the eucalyptus WOX genes are highly conserved during the evolution process. Moreover, the WOX protein sequences are also highly conserved within the species, with higher similarity between woody plants. The EupWOX gene showed tissue-specific expression, with EupWOX1 and EupWOX11 specifically expressed in the roots of E. urophylla × E. pellita clonal tissue culture during the late-stage rooting. This finding suggests that EupWOX1 may be a key regulatory gene induced by the root primordium and is critically related to the rooting rate. EupWOX1, EupWOX5, and EupWOX13 could be the key regulatory genes for adventitious root formation. EupWOX1, EupWOX5, and EupWOX13 could be the key regulatory genes for the elongation of adventitious roots and the growth of adventitious lateral roots. EupWOX5 and EupWOX13 could play a critical role, not only in the formation of adventitious roots and adventitious lateral roots of E. urophylla clonal tissue culture but also in the root elongation process. These results will help us understand the complexity of rooting in different lines and provide valuable information for future functional characterization of specific genes in eucalyptus clones. Full article

The deployment of Eucalyptus pellita trees that are resistant to Ceratocystis manginecans is essential for the commercial plantations and therefore the sustainability of forest industries in Southeast Asia that utilize this resource. Current screening procedures are time-consuming and expensive but could be expedited with the aid of marker-assisted selection and breeding. The identification of genotypes with resistance to the disease may be facilitated if microsatellite markers developed in other Eucalyptus species are transferable and can be linked to quantitative trait loci (QTL) for disease resistance. This possibility was tested in 111 full-sib progenies and their parents by genotyping with 49 microsatellite markers developed in other Eucalyptus species. Disease development was assessed after stem inoculation with C. manginecans isolate Am60C. The disease index (DI) varied from 0 to 20% of stem length. There was a continuous distribution of resistant and susceptible seedlings with 60% in the resistant category. Of the 30 acceptable markers, 17 (56%) defined two linkage groups (LG). In each LG, one QTL with a significant logarithm of odds (LODs > 13) was identified. The transferability of microsatellite markers developed in other Eucalyptus species facilitated the rapid identification of LGs and QTLs in E. pellita. To further refine the linkage map, the testing of more microsatellite markers and a larger population of progenies are required. Full article

Commercial plantations of Eucalyptus species have been established in Malaysia, especially during the past 10 years, with the aim of sustaining the supply of wood and timber products for industrial use in Malaysia. As part of an assessment of fungal diseases affecting Eucalyptus species in four regions in Malaysia, including Kelantan, Pahang, Sabah, and Selangor, stem canker disease was discovered to be a widespread disease infecting Eucalyptus species in Malaysia. This study aimed to identify the fungus-causing stem canker disease, test its pathogenicity in Eucalyptus, and determine the mating type of isolates from the infected trees. The fungi were identified based on morphology and through comparisons of DNA sequence data from the ITS, β-tubulin 2 gene, and TEF-1α gene regions. Phylogenetic analyses showed that the causal agent of the stem canker was Chrysoporthe cubensis infecting Eucalyptus plantations in Pahang and Chrysoporthe deuterocubensis infecting Eucalyptus plantations in Kelantan, Sabah, and Selangor. We believe this is the first report of Chrysoporthe cubensis-infected Eucalyptus in Malaysia and Southeast Asia, while Chrysoporthe deuterocubensis is the first-reported species infecting Eucalyptus pellita in Malaysia. Moreover, the fact that the mating-type MAT1-1 and MAT1-2 genes and the pheromone genes ppg1, ppg2, pre1, and pre2 were identified in all isolates indicates that Chrysoporthe cubensis and Chrysoporthe deuterocubensis are homothallic mating systems. Pathogenicity was tested on a 3-year-old standing tree, 1-year-old seedling, and detached healthy leaves, which were re-isolated for fulfilling Koch’s postulates. In pathogenicity trials, both Chrysoporthe cubensis and Chrysoporthe deuterocubensis gave rise to lesions on wounded Eucalyptus. Both Chrysoporthe spp. were equally pathogenic to Eucalyptus urograndis and Eucalyptus pellita and should be regarded as a biosecurity concern in Malaysia’s forest plantation industry. Full article

How much transpiration water consumption varies between eucalyptus species is unknown, making the suitability of a particular eucalyptus species for large-scale planting in a given area, or whether interspecific differences need to be taken into account for eucalyptus water consumption estimates, uncertain. Here, Eucalyptus camaldulensis Dehnh. (Ec), Eucalyptus pellita F. v. Muell. (Ep), the most resistant species, and Eucalyptus urophylla S.T. Blake × Eucalyptus grandis Hill ex Maiden (Eug), the most widely planted species, were monitored for sap flow. Their stand transpiration was also estimated and its relationship to various influencing factors analyzed for the same stand age and site, and predictive models for daily transpiration (T) developed. The results showed that the T of all eucalyptus species was jointly influenced by meteorological factors, soil water content (SWC), and leaf area index (LAI), with great variation in the T response to each influencing factor among species. Accordingly, we developed species-specific transpiration prediction models that could adequately explain the changed T of each species (R²-values: 0.863–0.911). There were significant differences in the stand daily mean sap flow density (J_C) and transpiration among the three species. Although Ec had a significantly lower J_C than Ep, it was significantly higher than Eug on all timescales, where the mean annual J_C of Ep (0.11 cm min⁻¹) was 1.4 and 2.6 times that of Ec (0.08 cm min⁻¹) and Eug (0.042 cm min⁻¹), respectively. Transpiration of Eug was significantly less than Ep, but significantly greater than Ec on all timescales, where the annual transpiration of Ep (743.41 mm) was 2.4 and 1.5 times that of Ec (311.52 mm) and Eug (493.58 mm), respectively. These results suggest that interspecific differences cannot be ignored when estimating transpiration rates in Chinese eucalyptus plantations, whose amount of water use should be considered when choosing the most optimal species to plant regionally. Full article

Eucalyptus pellita can be regenerated through coppice. We report on the first known study of full-rotation productivity of E. pellita coppice and seedling re-establishment methods. We conducted this study at a high productivity site in South Sumatra, with the objectives to (1) evaluate the productivity of a first rotation of coppice stand in comparison with a replanted seedling crop, (2) investigate the effect of nitrogen (N) and phosphorus (P) fertiliser application on growth, and (3) examine the effect of timing of coppice stem number reduction on growth. The experiment was laid out in a randomised complete block design replicated five times. At the end of rotation (6 years after establishment) the coppice stand had substantially higher productivity (height 23.7 m, diameter 16.4 cm, volume 269.9 m³ ha⁻¹, and MAI 45.0 m³ ha⁻¹ y⁻¹) compared to the replanted seedling stand (height 20.5 m, diameter 13.8 cm, volume 193.6 m³ ha⁻¹, and MAI 32.3 m³ ha⁻¹ y⁻¹). Coppice stand also had higher biomass production but slightly lower wood density than the seedling stand. Neither stand responded to application of N fertiliser, and only the seedling stand responded positively to P fertiliser addition. Coppice reduction to one stem at 2 months after tree felling produced the stand with slightly greater diameter than that at 4 months after tree felling, but had approximately the same volume. Full article

Plantation forests have been strongly established in Indonesia, with Acacias and Eucalyptus as the most common species. Using a single species in a large plantation may affect its sustainability because of the threat from biotic and abiotic factors. The soil microbiome is key to an ecological process strongly associated with both biotic and abiotic factors. However, research aiming to understand soil microbial communities in plantation forests in Indonesia is still limited. We analyzed the soil bacterial communities from six sites of plantation forests and three sites of conservation areas representing natural forest ecosystems. We produced approximately 140,136 reads from nine soil samples and generated 2385 total OTUs from the reads. The ten most abundant phyla were Proteobacteria, Acidobacteria, Actinobacteria, Chloroflexi, Firmicutes, Bacteroidetes, Verrucomicrobia, Nitrospirae, Gemmatimonadetes, and Planctomycetes. At the phylum level, the relative abundance of microbes in E. pellita plantation forests and natural forests was similar, except for Bacteroidetes. The richness and diversity of the microbiomes were slightly lower in the plantation forests than in the natural forests. Minor variations in the soil’s chemical properties may be responsible for the variations in the microbiome between natural and plantation forests. According to RDA, the K, total N, and organic C were positively correlated with the bacterial diversity, while the pH was negatively correlated. There was a positive correlation between the abundance of Bacteroidetes and the K content. However, there is not much information regarding this relationship. Full article

We report on a study of mid-rotation weed control and nutrient management in Eucalyptus pellita plantations in South Sumatra. The study was established at two contrasting sites (representing high and low productivity for the region) that had previously carried three rotations of Acacia mangium. A combination of weed control, nitrogen (N), and phosphorus (P) fertiliser were applied at 1 and 2 years after establishment. We found that the addition of up to 250 kg N ha⁻¹ applied either at 1 year or 2 years after planting did not improve growth. The application of P (30 kg P ha⁻¹) at age 1 year (in addition to 12 kg P ha⁻¹ applied at planting) did not enhance tree growth either. Keeping the plantation free from weed competition throughout rotation (full weed control) enhanced wood volume up to age 4 years at the high-productivity site, while it improved wood volume up to the end of rotation at age 6 years at the low-productivity site. An additional experiment assessing the effect of weed control in the early phase of plantation establishment revealed that weed competition reduced young tree growth of E. pellita substantially. The results of the studies support the current practice of plantation management of E. pellita in the region that applied only P fertiliser at planting time and that kept trees free from weed competition before canopy closure. Full weed control throughout rotation is worth practicing at lower-productivity sites to achieve maximum productivity. Full article

Eucalyptus is a diverse genus from which several species are often deployed for commercial industrial tree plantation due to their desirable wood properties for utilization in both solid wood and fiber products, as well as their growth and productivity in many environments. In this study, a method for monitoring the health status of a 22.78 ha Eucalyptus pellita plantation stand was developed using the red-green-blue channels captured using an unmanned aerial vehicle. The ortho-image was generated, and visual atmospheric resistance index (VARI) indices were developed. Herein, four classification levels of pest and disease were generated using the VARI-green algorithm. The range of normalized VARI-green indices was between −2.0 and 2.0. The results identified seven dead trees (VARI-green index −2 to 0), five trees that were severely infected (VARI-green index 0 to 0.05), 967 trees that were mildly infected (VARI-green index 0.06 to 0.16), and 10,090 trees that were considered healthy (VARI-green index 0.17 to 2.00). The VARI-green indices were verified by manual ground-truthing and by comparison with normalized difference vegetation index which showed a mean correlation of 0.73. This study has shown practical application of aerial survey of a large-scale operational area of industrial tree plantation via low-cost UAV and RGB camera, to analyze VARI-green images in the detection of pest and disease. Full article

We report on experimental studies conducted in South Sumatra with interrelated objectives to (i) examine the trends in production covering 30 years, including three rotations of Acacia mangium followed by Eucalyptus pellita which replaced A. mangium for managing the widespread threat of diseases; (ii) understand the effects of inter-rotation slash and litter management applied to acacia (legacy effects) on E. pellita growth; (iii) assess the long term changes in the top soil layer arising from above; (iv) evaluate, through a network of experiments, across the landscape, the nature and extent of growth responses to additional phosphorus. This data was also used to explore some of the critical site and stand variables which determine the variations in productivity and responses to management. The current growth rates of E. pellita are lower than those achieved in A. mangium. The management-legacy effects by conserving site resources provides a sustainable base for the growth of E. pellita, but for further increase in productivity, additional management actions are necessary. Changes in soil pH, carbon, N and extractable P were relatively small after four rotations. Supply of P at planting gave wood volume gains at harvest, ranging from 16 to 66% across sites. The plinthite layer in the soil profile was related to productivity, with higher growth rates of E. pellita occurring when the plinthite was at deeper layers. There is much scope for increasing productivity per unit area in this landscape, and available knowledge can be synthesized into a package of best practices for application. Management should aim to improve the quality of inter-rotation management to ensure more than 90% survival, and fast growth rates during the first 2 years. We provide a framework for further research and for refining management to produce the much needed additional domestic wood supply for the local industry. Full article

Eucalyptus pellita F. Muell. is currently the predominant tree species deployed for tree plantation establishment in some parts of Borneo, particularly Sabah state, Malaysia. Its low disease susceptibility, good growth and form, and desirable wood properties make E. pellita particularly suitable for plantation development in the wet tropical regions of south-east Asia. In spite the many positive traits, practical field observations indicate that the species is susceptible to end-splitting. There is some anecdotal evidence to suggest a genetic relationship with the incidence of end-split, although these observations were not statistically tested. This study evaluates the occurrence of end-splitting in five-year old plantation E. pellita in Sabah as affected by family and growth attributes. An existing progeny tree breeding trial, involving seeds that originated from Papua New Guinea, China, Vietnam, Australia, Sabah, and Sarawak with 106 families, was used to carry out the split assessment. Logs from the second thinning were cut into 2.2-m-long sections. The end splits were measured three days later; the incidence and severity of splitting were assessed at both the large and small ends of each log by using a designated split scoring system. The study shows that 99% of all log cross sections (per cut surface) experienced signs of splitting, with an average of 2.7 splits per cut surface. Overall, 54% of all splits were classed as ‘Three-Quarter Radial Splits’ while the occurrence of internal splits was negligible. Split severity showed a heritable and significant difference (h² = 0.24 at p ≤ 0.05) among the family levels. Splitting was also significantly related to growth factors such as tree height and diameter at breast height (DBH). The findings suggest that end-splitting is caused by family–environment interactions. This offers the opportunity to improve the wood resource of E. pellita via breeding strategies. Full article

Eucalyptus pellita is known as attractive biomass, and it has been utilized for eucalyptus oil, furniture, and pulp and paper production that causes a significant amount of byproducts. Liquid hot water treatment depending on combined severity factor (CSF) was subjected to isolate hemicellulose fraction from E. pellita and to produce xylooligosaccharides (XOS). The xylan extraction ratio based on the initial xylan content of the feedstock was maximized up to 77.6% at 170 °C for 50 min condition (CSF: 1.0), which had accounted for XOS purity of 76.5% based on the total sugar content of the liquid hydrolysate. In this condition, the sum of xylobiose, xylotriose, and xylotetraose which has a low degree of polymerization (DP) of 2 to 4 was determined as 80.6% of the total XOS. The highest XOS production score established using parameters including the xylan extraction ratio, XOS purity, and low DP XOS ratio was 5.7 at CSF 1.0 condition. XOS production score evaluated using the CSF is expected to be used as a productivity indicator of XOS in the industry (R-squared value: 0.92). Full article

Bacterial wilt is one of major threats to eucalyptus plantations which may cause significant losses. Until now, study about bacterial wilt on Eucalyptus pellita in Indonesia has been very limited, especially about the presence of the pathogen on or in the seeds. This study aims to provide evidence of the existence of the R. solanacearum bacterium on or in E. pellita seeds. Detection of seed-borne bacteria is determined by several approaches such as (i) direct detection using universal and selective media in the laboratory, (ii) the nursery test, and (iii) species-specific molecular detection. The results of our study indicate that R. solanacearum can be detected from eucalyptus seeds using universal and selective media in the laboratory, nursery test, and molecular-based detection using the Enrichment PCR method. The bacterial inoculum is also proven to exist both on the surface of and inside the eucalyptus seeds. This is the first report that R. solanacearum is a seed-borne pathogen in E. pellita seeds. Previous studies in different agricultural systems show that the effective method used to control the pathogen is through seed treatments using biological, physical, and chemical approaches. Full article

Soil microorganisms and extracellular enzymes play important roles in soil nutrient cycling. Currently, China has the second-largest area of eucalyptus plantations in the world. Information on the effects of eucalyptus age and species of trees on soil microbial biomass and enzyme activities, however, is limited. In this paper, the soil microbial biomass and enzyme activities were studied in eucalyptus plantations with different ages (1 and 5⁺ years) and species of trees (E. urophylla×E. grandis, E. camaldulens and E. pellita) in South China. The results showed that both plantation age and eucalyptus species could affect the total microbial biomass and fungal biomass, whereas the bacterial biomass was affected only by plantation age. The fungal biomass and the fungi-to-bacteria ratio significantly increased along with increasing plantation age. Similarly, the plantation age and eucalyptus species significantly affected the enzyme activities associated with carbon cycling (β-xylosidase, β-d-glucuronidase, β-cellobiosidase and β-glucosidase). The activities of β-d-glucuronidase and β-glucosidase were significantly higher in the E. camaldulens plantation. The enzymes involved in nitrogen (N-acetyl-glucosamidase) and sulfur (sulfatase) cycling were only affected by the eucalyptus plantation age and species, respectively. The results highlight the importance of the age and species of eucalyptus plantations on soil microbial activities. Full article

Eucalyptus pellita has rapidly emerged as the species that has replaced Acacia mangium in broad-scale commercial plantations in Indonesia following widespread losses due to disease and in soils that have suffered a steady decline in phosphorus (P) under plantation forestry. Conversion from a nitrogen (N)-fixing to a non-N fixing species is expected to change the nutrient dynamics and the management required to maximise productivity. In this study in South Sumatra, responses of E. pellita to the application of N, P, potassium (K) and calcium (Ca) fertilisers were assessed at a number of trials on sites with varying site history; A. mangium was planted at one site to compare the species’ responses to N and P. The growth of E. pellita responded significantly (p < 0.01) to P’s application but not to N, K or Ca, with the addition of P increasing the stem volume by 32.6 m³ ha⁻¹ at 3 years of age compared with no addition of P fertiliser; the demand for P in the first two years of growth was, respectively, 4.8 and 6.8 kg ha⁻¹. This positive and large response appears to be because E. pellita has a lower efficiency in its use of P than A. mangium and is, therefore, more responsive than A. mangium to the addition of P. The reason for the lack of response to N remains unclear, although demand for N as well as K and Ca was high. These results suggest that sites recently converted to E. pellita from A. mangium and also new ex-native forest sites will be likely to only respond to P addition and that the response of E. pellita is likely to be greater than for A. mangium to maximise yield. At present, additional N, Ca or K fertilisers are not required, but this may change in the future. Full article