Citrus Plantations Research Articles

Quantification Model of Residual Biomass in Citrus Uprooting

In this paper, the aerial biomass of citrus plantations in Spain was evaluated using destructive methods. Before cutting down the trees, their geometric variables were measured: trunk diameter at 10 cm from the ground (Dt), trunk perimeter at 10 cm from the ground (Pm), mean crown diameter (Dc), canopy height (Hc), and maximum crown height (Hmax). After geometric characterization of the tree, it was felled. This was performed with a chainsaw about 10 cm above the ground. After cutting down, trees with and without leaves were weighed, and biomass variables such as moisture, calorific value, elemental composition, and proximate analysis were measured. The predictive models obtained showed an r2 of 0.78. According to our analysis, in plantations in Spain, where the average plantation pattern is 4 × 4 m, the amount of carbon stored in a plot is 15 t of C per hectare. If leaves and wood are counted, the energy density in citrus plots can be estimated at 900 MJ/tree. However, if only wood is included in the calculation, the accumulated energy per tree is 750.3 MJ/tree, which represents 5.6 × 105 MJ/ha.

Suitability of two dwarfing citrus rootstocks for ‘Salustiana’ orange trees grown under super-high-density conditions with mechanical harvesting

ABSTRACT Even though super-high-density plantation systems could maximise yield per acre and induce an early entry production, a few research studies have been conducted on citrus crops in the Mediterranean Basin. In this study, we assessed the suitability of ‘Salustiana’ orange trees (Citrus sinensis) on two dwarfing rootstocks [Forner-Alcaide 418 (FA418) and Forner-Alcaide 517 (FA517)] under super-high-density plantation systems. Tree growth, yield and fruit quality of ‘Salustiana’ on both citrus rootstocks were evaluated. Furthermore, the suitability of mechanical harvesting was evaluated using an over-the-row continuous canopy shaker for this citrus plantation system. For this last purpose, the effects of mechanical harvesting on fruit detachment and fruit harvested and tree damage were analysed. The results showed that ‘Salustiana’ orange on FA517 obtained a better response than on FA418 in terms of vegetative growth, effective yield and fruit quality under super high-density conditions, also displaying a better response to mechanical harvesting with a high detachment efficiency of fruits. It emphasised the relevance of proper mechanical pruning to reduce the tree damage and improve the detachment efficiency by this canopy shaker. Thus, although the over-the-row canopy shaker requires some technical improvements, it showed a high potential for harvesting super-high-density citrus crops for the juice industry.

Variation of soil bacterial communities in a chronosequence of citrus orchard

PurposeSoil microorganisms are vital for soil ecosystems through bioconversion of soil nutrients and maintenance of soil fertility to promoting the growth and development of citrus. However, understanding of how different planting years affect the soil bacterial community structures as related to nutrient availability in citrus orchards is limited.MethodsHere, Illumina MiSeq technology was used to investigate changes in bacterial community structures with different ages of citrus orchards that were 2, 5, 10, 15, and 18 years old.ResultsThe data showed that (1) soil bacterial community structures changed over the different growth stages of citrus orchards. With the extension of plantation age, the microbial diversity of citrus orchards increased gradually so that it was highest in 10-year-old citrus plantations but then decreased where the diversity of 18-year-old citrus ages was significantly lower than that of 10 and 15-year-old ones. Proteobacteria, Actinobacteria, Acidobacteria, and Chloroflexi were the four dominant phyla in soil of citrus orchards, accounting for 30.85%, 24.89%, 14.27%, and 14.05% of the total soil bacterial communities, respectively. (2) Soil bacterial community structures in different succession stages were affected by soil pH and nutrients, in particular available potassium (AK).ConclusionThis study advances the understanding of soil microbiota of orchards and their interactions related to environmental factors in citrus orchard, which will improve our ability to promote the function of soil bacteria, so as to improve soil pH and reduce potassium (K) fertilizer input and improve the fruit quality.

A Simplified Model for Path Loss Estimation in Citrus Plantations at 3.5 GHz

Agriculture 4.0 represents a considerable increase in the number of sensors, as well as the appearance of new wireless technologies, which will meet the need to efficiently plan radio communication systems in agricultural environments. In this letter, a simplified model for path loss estimation in citrus plantations is proposed. The model assumes that, for long distances, the physical mechanism is a parallel transmission path over the treetops that can be modeled by multiple-knife-edge diffraction. In our scenario, where the height of the transmitter is above the height of the trees, we proposed to estimate the multiple-knife-edge diffraction contribution by the settled field defined by Walfisch and Bertoni. In this way, the propagation losses estimated by the model have been compared with measurements carried out at 3.5 GHz in a lemon plantation before and after the fruit were collected. It has been observed that the slope of the regression line of the measurements yields values of 3.6 (with fruit) and 3.7 (without fruit), which are close to the value estimated by the model (3.8). The standard deviation of the prediction error given by the difference of the observed and estimated values is 4.5 dB (with fruit) and 3.2 dB (without fruit).

Occurrence and Geographic Distribution of Plant-Parasitic Nematodes Associated with Citrus in Morocco and Their Interaction with Soil Patterns.

Plant-parasitic nematodes (PPNs) are found in citrus plantations throughout the world, but they are considered to be the most problematic pest in Morocco. Citrus fruit quality and yield have been adversely affected by PPNs. Due to data unavailability of nematodes associated with citrus, a detailed survey was conducted in the main citrus-growing regions of Morocco during 2020–2021 to assess the occurrence, distribution, and diversity of PPNs associated with rhizospheres of citrus trees. In addition, some soil properties have also been assessed for their impact on soil properties. Plant-parasitic nematode diversity was calculated using two ecological indexes, the Shannon diversity index (H′) and the Evenness index (E). The collected soil and root samples were analyzed, and eleven genera and ten species of plant-parasitic nematodes were identified. The results show that the most predominant PPN species were Tylenchulus semipenetrans (88%), Helicotylenchus spp. (75%), Pratylenchus spp. (47%), Tylenchus spp. (51%), and Xiphinema spp. (31%). The results showed that PPN distributions were correlated with soil physicochemical properties such as soil texture, pH levels, and mineral content. Based on the obtained result, it was concluded that besides the direct effects of the host plant, physicochemical factors of the soil could greatly affect PPN communities in citrus growing orchards.

SCIENTIFIC AND THEORETICAL FOUNDATIONS OF TRADITIONAL AND MODERN AGRO-ECOLOGICAL STUDIES OF GRAIN-SUITABLE SOILS IN AZERBAIJAN

On a global scale, a number of natural complexes and ecosystems have undergone significant transformations under the influence of agriculture. As a result, agricultural land of anthropogenic origin was formed, covering 1/3 of the globe (perennial crops, meadows and pastures, including 1.5 billion hectares of arable land). Thus, areas with artificial agro-ecosystems or phytocenoses, which are plowed annually, fertilized and controlled by other agro-technical and reclamation means, are classified as agricultural land of the field type. Likewise, orchards, berries, vineyards, tea and citrus plantations have formed perennial agro-ecosystems.

Strategi Pengembangan Desa Wisata Catur, Kintamani-Bangli Pada Masa Pandemi Covid-19

Bali is known as one of the best tourist destination islands in the world. Catur Village is one of the Balinese village which is designated as a Tourism Village by the Bangli Regency Government. Along with the government's efforts to promote tourism development, the Covid-19 Pandemic suddenly occurred. The tourism development program is not implementing as planned. This research will be carried out with a qualitative approach and SWOT-Interpretive analysis. The period before the Covid-19 pandemic was marked by the most visited natural attractions are citrus and coffee plantations, and also the acculturation of Balinese and Chinese cultures. The changing conditions of tourism activities during the Covid-19 pandemic in the Catur Tourism Village can be seen from the change in behavior in dealing with the New Normal Life. The life adaptation in the form of implementing the Health Protocol in a good and disciplined manner. The innovation and collaboration are conducted to produce herbal products. In the Pandemic of Covid-19, the Management Strategy in the Development of the Catur Tourism Village was carried out on the main platform "Innovation, Adaptation and Collaboration". Tourism segmentation in the future will be more to personalize, customize, localize, and smaller in size.
 Keywords: Development Strategy, Tourism Village, Covid-19 Pandemic, Catur Village.

EVALUATION OF ARCHITECTURAL COMPONENTS IN BAYUNG GEDE VILLAGE SETTLEMENT, BALI AS A TOURISM OF SPECIAL INTEREST

<p>Special interest tourism is one of the efforts to provide alternative tourist attractions and sustainable tourism development in Bali. Visits of both domestic and foreign tourists to Bali in the last 4 years (2015-2019) have increased by an average of 8%. Now the tourism sector in Bali, especially in Bangli Regency, is starting to investigate or explore the possible development of tourist attractions through the development of tourist villages. In this case, the development of special tourism, including the tourist village of Bayung Gede, Bangli is very dependent on the architectural components of traditional settlements and the traditions of the residents in it as a source of attraction and main attraction for tourists. However, the influence of tourism has led to the transformation of traditional settlements. In this case, the transformation has given rise to a paradoxical phenomenon where on the one hand traditional housing attracts tourists, on the other hand the presence of tourists has led to a transformation of the traditional settlements of an area. The purpose of this study is to examine the architectural components of the Bayung Gede Village settlement as a tourism potential based on special interest tourism and then to find out how far the tourism architectural potential is found and how strong the Bayung Gede Village settlement icon is as a special interest DTW. The method used is a qualitative-exploratory and descriptive method. The results show that the traditional settlement of Bayung Gede Village contains elements of special interest tourism such as elements of novelty seeking, quality seeking, enriching, rewarding, adventuring and learning, so that it has the potential as religious tourism (the existence of four types of graves), culture (settlement and residential layout) and citrus plantation sector agro-tourism in improving the economic sector of the community. Investigation and inventory of Bayung Gede traditional housing is an effort to find a village icon that has prestige that can attract tourists to visit and be able to compete with other tourist villages.</p>

Income analysis of integrated farming system of dairy cow breeding farm, earthworms (Lumbricus rubellus), andcitrus sinensis Valenciafarm. Case study in Dau District, Malang Regency, East Java, Indonesia

The integrated farming system between dairy cow breeding, earthworms (Lumbricus rubellus), and citrus (Citrus sinensis valencia) plantations provides regular income for farmers and sustainable farming. This research aims to analyze farmers’ income based on the integrated farming system that has been done on these three commodities. This study utilized quantitative and qualitative methods to analyze data. Data were collected through questionnaires to 15 farmers who are members of Gading Kulon Farmer Group in Dau District, Malang Regency, East Java, Indonesia followed by in-depth interviews with key respondents. The study showed that dairy cow breeding provided annual income which contributed up to 58% of household income. Meanwhile, earthworm farming provides weekly income and twice a year income for citrus farming. Depending on the land area, Earthworms farming contributed up to 10% of household income, and citrus plantation was 33%, depending on the land area owned by farmers. The average income of Dairy cow breeding was Rp. 163,308,000 per year; the Average Income of earthworms was Rp. 27,058,000 per year, and the average income of citrus plants was 92,480,000 per year. However, integrated farming of these commodities does not work well in the community due to farmers’ lack of land and capital. Moreover, most respondents indicated that they were interested only in citrus farming because it is easier compared to dairy cow breeding and earthworm farming. Good cooperation from various parties is needed to increase the importance of integrated farming with these three commodities for sustainable farming in Indonesia.

Internal flow of nutrients in organic farming systems in tidal swamp

Sustainable nutrient management is critical to the success of an agroecosystem. The potential of nutrient flow to agroecosystems in tidal swamps can be observed in several of soil and water management. Tidal swamp land management based on surjan and tabukan system are often used to farm several sub-agricultures, namely rice fields, ponds, and citrus plantations. This study aimed to determine N nutrients’ input, output, and internal flow in organic farming systems. This study is limited to observing the internal components. The integrated organic farming system in tidal swampland, usually used for orange in the raised beds and rice in the sunken beds/wetland sections or fishponds, demontrated the potential for inorganic N-flow between farming sub-systems and between components within the system. Scenarios for the use of rice straw for external production sub-systems such as for citrus plantations and composting for external purposes need consideration. This potential can be a sub-component of nutrient input for other sub-systems or the next planting season. The simulation of the integrated rice-citrus-fishpond agroecosystem model showed a positive nutrient balance, especially N nutrients. This model needs to be further developed.

Prevalence of Mild T30, T3, and Severe VT Strains of <i>Citrus tristeza</i> Virus in Central-Northern Veracruz, Mexico

The presence and distribution of Citrus tristeza virus (CTV) strains on plants of four citrus species required analysis of plants showing small fruits, yellowing, and twig dieback. Typical citrus tristeza symptoms showed in citrus plantations in Veracruz, Mexico, and caused gradual deterioration, low yield, and death of the plants. Seven citrus-growing municipalities in Central and Northern Veracruz presented the severe VT strain: the incidence in seven of the eight sampled municipalities ranged from 7% in Alamo to 50% in Tihuatlan. As for the T30 strain, its presence and distribution ranged from 17% in Tihuatlan to 83% in Cuitlahuac. Values for the T3 strain went from 20% in Castillo de Teayo to 50% in Papantla. In Tihuatlan, two samples were positive for the T36 strain. Only Citrus sinensis has historical recording infections by severe strains of CTV, unlike other important citrus species. The incidence of orchards quickly declining increases rapidly in Veracruz, the largest citrus producer in Mexico. It becomes critical as the predominant and sensitive rootstock is sour orange (Citrus aurantium). It is important to note that the specific primers used could not be identified in 29% of the samples, suggesting that they could be other than T30, T3, VT, and T36 strains.

Trends in the development of citrus growing in the Republic of Kazakhstan

The goal – is to identify the possibilities and prospects of citrus production in the Republic of Kazakhstan, the economic feasibility of growing citrus crops in the country in compareson with imported products, as well as the benefits for entrepreneurs in their cultivation, storage, delivery and sale. Research methods – statistical, analytical, abstract-logical. Results – the areas of use of citrus fruits in various industries are shown: agriculture, food industry, medicine, etc. Foreign experience is presented. Statistical data on prices, import of citrus fruits to the territory of the republic are analyzed. The factors that restrain obtaining their large quantities are summarized: increased competition from the CIS and foreign States; poorly developed infrastructure for processing these fruits, transport logistics, marketing of the finished product range, insufficient investor interest. Conclusions – effective government support for the industry is needed, as well as updating the material and technical base of breeding and seed-growing economic entities, application of the latest technologies, digitalization aimed to increase yields, production of environmentally friendly products, creating the necessary conditions for promoting Kazakhstani citrus products for export, organizing joint trade missions and consistency between manufacturers of the member countries of the Eurasian Economic Union and other foreign partners. Medicine rates citrus crops an extremely important place in the rational human diet, since vitamins and mineral salts contained in them are the same important nutrients as proteins, fats and carbohydrates. Over the past century, citrus plantations have taken the first place in world horticulture, leaving apple, pear, plum and cherry orchards far behind.

PKM PENINGKATAN NILAI TAMBAH LIMBAH KULIT KOPI PADA KELOMPOK WANITA TANI DI KAWASAN WISATA KINTAMANI, BANGLI-BALI

Belantih Village, which is located in the western part of the Kintamani tourist area with beautiful scenery and landscapes and fertile soil, is a dominant center for producing horticultural products, coffee and citrus plantations. Most of the people of Belantih Village still rely on working in the agricultural sector as their main source of income. Taking advantage of the development of tourism, farmers can fill tourism needs by cultivating plants properly. Until now, in Belantih Village, the most developed plants are beans, tomatoes, cabbage, eggplant, chilies covering 11.13 ha, while for citrus fruits it is 175 ha and coffee plants are 282 ha. To support the growth and development of plants in addition to using inorganic fertilizers, most farmers still use organic fertilizers derived from cow and chicken manure which are easily available in large quantities and can meet the needs of a fairly large planting area from outside the Belantih Village area. Until now, the source of organic fertilizer that can actually be utilized from coffee rind waste from the rest of the wet processing or other processing from factories around Belantih Village is still not processed further in order to improve the quality of the waste as a source of fertilizer. This opportunity can actually be used by women farmer groups as an opportunity to supply organic fertilizer from solid coffee husk waste. The nutrient content contained in coffee husk waste when given a touch of technology will be a source of nutrients for plants. The purpose of this PKM activity is to increase the knowledge and skills of partners in coffee cultivation and after post-harvest the use of coffee husk waste as organic fertilizer in substituting the use of inorganic fertilizers in partner areas. In addition, it can be an alternative that solid coffee husk waste for communities around partners can be used as organic fertilizer in fertilizing cultivated plants in addition to organic fertilizers from cows and chickens that have been used today. The touch of technology in the processing of coffee skin waste is expected to add value to the fertilizer produced. Activities are carried out with counseling, discussions, direct practice in the field. This PKM program was carried out in a women's farmer group "Merta Sari Sabang" in Belantih Village, Kintamani District - Bangli Regency, Bali Province. From this activity, the output target to be achieved is that partner groups are independently able to utilize solid waste properly into "solid organic fertilizer" (POP) so as to increase the income of partner groups.

Intensive citrus plantations suppress the microbial profiles of the β-glucosidase gene

Increases in the input of chemical fertilizer and rapid decline of soil organic matter have increased serious demand for sustainable agriculture. Cellulose is an important component of soil organic matter, which strongly affects global carbon cycle and crop yields in the agroecosystem. β-glucosidases (BG) convert cellobiose to glucose, providing carbon for soil microorganisms and plants. However, little is known about the structure of β-glucosidase gene (GH3)-harboring microbial community and its functions in response to long-term intensive cropping with frequent fertilization. In this study, quantitative PCR (qPCR) and high-throughput sequencing were used to determine the abundance of bacterial and fungal GH3 gene as well as the diversity of GH3-harboring community in intensified citrus orchards of different ages (5-year, 15-year and 30-year), or under different management practices (straw application on the surface, peanut planting between rows and control) for 15 years. The adjacent natural forest and grass soils were used as reference to investigate the effect of intensive citrus plantation on soil BG enzyme activity and the GH3 gene. The results revealed that citrus plantation significantly reduced soil GH3 gene abundance, especially for the bacterial GH3 gene. The higher abundance of bacterial GH3 gene than that of fungal GH3 gene in the soil highlighted the key role of bacterial GH3 gene in regulating soil BG enzyme activity. Among the reservoirs of the GH3 gene, Proteobacteria, Acidobacteria, Firmicutes and Actinobacteria were the main bacterial phyla, while Ascomycota was the only dominant fungal phylum. Citrus plantation caused soil bacterial community varied from Proteobacteria-dominant to Acidobacteria-dominant and reduced BG enzyme activity. The higher diversity of the bacterial community indicated that bacteria play a dominant role in the conversion of cellobiose to glucose. Citrus plantation and plantation age strongly influenced the diversity and structure of β-glucosidase gene-harboring community. A significant decline occurred in bacterial diversity along with increasing citrus plantation age. The community diversity exhibited a clear land-use specific pattern, as indicated by the obviously different community structure between the forest soil and citrus soil. Among the detected environmental factors, SOC, bacterial β-glucosidase gene abundance and the community diversity were the most important factors controlling soil BG enzyme activity. These results indicate that citrus plantation with long-term fertilization suppresses the abundance of the β-glucosidases gene, and the bacterial β-glucosidase gene contributes more to the BG enzyme activity than the fungal gene.

Notes on the Citrus Rust Mite, Phyllocoptruta oleivora (Ashmead), as a Major Pest of Citrus in Indonesia

Most citrus farmers in Indonesia believed that rust on citrus fruits resulted from insect attacks. This research aims to determine the cause of rust on citrus fruit and its damage intensity. The study was carried out in commercial citrus plantations in three provinces, on Citrus sinensis and C. reticulata plantations in East Java, C. reticulata and C. suhuensis in West Kalimantan and C. suhuensis in North Sumatra. An additional observation was also conducted to collect mite specimens on citrus plantations in Malang, East Java. Scanning Electron Microscope (SEM) and light microscope were used to observe and identify each collected sample. Results showed that the cause of rust-colored citrus fruit in three provinces is the citrus rust mite, Phyllocoptruta oleivora (Ashmead). It belongs to the family Eriophyidae with two pairs of legs with regular segmentation, five-rayed featherclaws, and a net pattern on prodorsum. The specific damage produced by this mite is rust-colored symptoms. Damage intensity of citrus rust mite in tree provinces averaging 32.6%, ranging from 30 to 40%, and ca. the mite attacks 90% of citrus fruits. Predaceous mites, predaceous insects, and entomo-acaropathogenic fungi are found on plantations.

Suppressed phosphorus-mineralizing bacteria after three decades of fertilization

Phosphorus (P) mineralization from organic matter is one of the most important microbially-driven soil processes in natural ecosystems. However, little is known about how long-term fertilization affect the abundance, diversity and community composition of these important organisms in croplands wherein P is directly supply via fertilizers. Here, we investigated the fate of phosphorus-mineralizing bacteria in a citrus plantation chronosequence (5–30 years) including information on management practices (no covering, straw covering and peanut covering after 15 years). We found that the diversity and abundance of phoD-harboring bacteria and the activity of phosphatase was largely suppressed after 30 years of fertilization. Moreover, long-term fertilization altered the bacterial community associated with P mineralization, decreasing the relative abundance of Methylobacterium, Aquabacterium and Rhizobacter in comparison with adjacent natural forests. Remarkably, land management practices associated with land covering helped to increase the diversity of phoD-harboring bacteria, after 15 years of experiment. This result is likely associated with the entrance of organic matter to the system. Our results provide new evidence that long-term fertilization drastically suppressed the abundance and diversity of bacteria associated with P mineralization, with implications for soil health and sustainability.

Runoff and soil conservation effects in Nagpur mandarin orchard under a sub-humid tropical climate of central India

Limited availability of water and nutrients in soil affects the yield and longevity of citrus plantation. Conservation of rainfall runoff not only enhances water availability but improves the nutritional status in soil which might increase the orchard efficiency in citrus. Keeping this in view, a long term (7 years) experiment was imposed to study the response of Nagpur mandarin (Citrus reticulate Blanco) orchard in relation to fruit yield, water use, water productivity, sustainability of production and energy use efficiency to various conservation practices (CPs) on 12% land slope in a vertisol of central part of India. The CPs tested, against without conservation practice (WCP) were continuous trenching (CT) and staggered trenching (ST) alone and with grass mulch (GM). All the treatments were imposed in randomized block design (RBD) with 4 replications. The combined use of CT and GM conserved the highest rainfall runoff (48%), soil (51%), organic carbon (OC, 52%) and nutrients (43–53%) compared with WCP in mandarin orchard. The GM enhanced the available nutrients (N, P, K, and Cu) and OC contents in soil. The relationship between rainfall and runoff was linear (R2 = 0.85–0.93) in the plots with CPs, whereas in WCP plot, it was exponential (R2 = 0.88). However, the runoff was linearly related to soil loss under both CPs (R2 = 0.76–0.91) and WCP (R2 = 0.79). The empirical models developed were found reasonably accurate in predicting the runoff and soil loss with R2 value of 0.81–0.93 and 0.87–0.96, respectively. The soil water content was improved by 3–55% in different CPs compared with WCP. The CT with GM improved the fruit yield by 53%, utilizing 31% less water which resulted in 53% higher physical water productivity (PWP) and 123% higher irrigation water productivity (IWP) than that in WCP. The fruit quality (juice content, total soluble solids, acidity and ascorbic acid content) under CT with GM was better than that in WCP. The sustainability yield index (SYI) and energy use efficiency (EUE) under CT with GM were increased by 25.4% and 39.4%, respectively, compared with WCP. Overall, these results reveal that the CT with GM could be imposed to sustain and enhance yield and water productivity, by conserving rainwater and soil in citrus orchards of water scarce regions.

Description of an Australian endemic species of Trioza (Hemiptera: Triozidae) pest of the endemic tea tree, Melaleuca alternifolia (Myrtaceae).

Psyllids, also known as jumping plant lice, are phloem feeding Hemiptera that often show a strict species-specific relationship with their host plants. When psyllid-plant associations involve economically important crops, this may lead to the recognition of a psyllid species as an agricultural or horticultural pest. The Australian endemic tea tree, Melaleuca alternifolia (Maiden & Betche) Cheel., has been used for more than a century to extract essential oils and, long before that, as a traditional medicine by Indigenous Australian people. Recently, a triozid species has been found to damage the new growth of tea trees both in Queensland and New South Wales, raising interest around this previously undocumented pest. Furthermore, adults of the same species were also collected from Citrus plantations, leading to potential false-positive records of the exotic pest Trioza erytreae (Del Guercio 1918), the African Citrus psyllid. Here we describe for the first time Trioza melaleucae Martoni sp. nov. providing information on its distribution, host plant associations and phylogenetic relationships to other Trioza species. This work enables both morphological and molecular identification of this new species, allowing it to be recognized and distinguished for the first time from exotic pests as well as other Australian native psyllids. Furthermore, the haplotype network analysis presented here suggests a close relationship between Trioza melaleucae and the other Myrtaceae-feeding Trioza spp. from Australia, New Zealand, and Taiwan.

Long Term Application of Fertilizers in Eastern Amazon and Effect on Uranium and Thorium Levels in Soils

In recent years, the use of fertilizers has increased in the Amazon. Phosphate fertilizers, which are commonly used, can present high concentrations of radioelements. In the present study, the activity concentrations of uranium (U) and thorium (Th) in Oxisols and Ultisols cultivated with citrus (Citrus sinensis (L.) Osbeck), oil palm (Elaeis guineensis Jacq.) and black pepper (Piper nigrum L.), with 26, 10 and 5 years of implantation, respectively, were evaluated. The potential risk of contamination was estimated by the enrichment (EF) and bioaccumulation (BAF) factors. Pearson’s correlation coefficients indicated a significant relationship between the concentrations of U and Th in soil and plant and the soil properties pH, Ca2+, Mg2+, K+ and P. The enrichment (EF < 2) and bioaccumulation (0.01 < BAF < 0.05) factors were low. In plant tissues, the concentrations of 238U followed the order: citrus > black pepper > oil palm, and the concentrations of 232Th followed the sequence: black pepper >> citrus > oil palm. The activity concentrations of 238U and 232Th in the soil cultivated with black pepper, as well as in the soil of the reference area close to the citrus plantation, were higher than the world average values of 35 and 30 Bq kg−1, respectively, established by the United Nations Scientific Committee on Effects of Atomic Radiation. Perennial crops that are fertilized annually must be monitored by environmental agencies due the accumulation of elements that can promote potential risks to human health.

Monitoring three-decade dynamics of citrus planting in Southeastern China using dense Landsat records

Across Southeastern China, the expansion of citrus plantation has underpinned substantial economic development at the expense of forest cover and associated ecosystem services. The high-order complexity of citrus planting dynamics requires more detailed observations. To achieve this goal, we developed a novel monitoring scheme by integrating multi-epoch land cover classification and continuous change detection on the Google Earth Engine (GEE) platform using all available Landsat archives (1986–2018). First, a stable/changed area masking approach was adopted. Then, the GEE-based Continuous Change Detection and Classification (GEE-CCDC) algorithm was applied to detect the timing and position of citrus planting-related land cover changes. Finally, the effectiveness of the scheme was validated both spatially and temporally. We applied the proposed scheme in Xunwu, a typical County in Southeastern China where continuous expansion was disrupted by an outbreak of Huanglongbing (HLB, a destructive citrus disease). The validation results indicate that the multi-epoch classification effectively identified the stable, abandoned, and newly cultivated areas related to citrus planting. Within these areas, our monitoring of citrus planting dynamics had an overall temporal accuracy of 90.59% and a mean detection date deviation of −13.21 days (leading). Based on the change detection results, we found a two-stage change pattern, namely a continuous expansion period (1986–2016) followed by a disturbance period (2017–2018). Moreover, almost half of the orchards were cultivated in regions with an elevation and slope of 301–400 m and 11–20°. During the continuous expansion period, a total of 497.85 km2 natural lands were converted for citrus planting. Affected by the HLB outbreak, both orchard abandonment (114.66 km2) and new orchard cultivation (36.87 km2) were detected during the disturbance period. The proposed scheme offers a useful tool for cash crops management, and highlights the value of dense satellite data in monitoring the extent of ongoing human appropriation of natural ecosystems at a large scale and long-term.