Harvest Cycle Research Articles

Potential Analysis of Atmospheric Water Harvesting Technologies from the Perspective of “Trading-in Energy for Water”

An applicable, high-volume, and sustainable water uptake technology can alleviate freshwater shortages, improve the energy utilization rate and promote the development of energy technology. Traditional seawater desalination, fog water, and dew collection are limited by the geographical environment, and the water resource transportation cost is high, or the water uptake volume is limited, so they cannot be used on a large scale. There are potential safety problems with wastewater reuse and recycled water. Atmospheric water harvesting technology uses energy for direct condensation or uses adsorbent to absorb water, which is characterized by strong sustainability, high applicability, decentralization, and stable water uptake. This study summarizes the working principle of mainstream atmospheric water harvesting technologies, mainly including condensation, absorption, and desorption water harvesting, and some active dew and fog collection technologies. It also theoretically analyzes the energy consumption of condensation and adsorption and desorption water harvesting technologies. Aiming at the problems of difficult condensing for direct condensation and long adsorption/desorption cycle of adsorption and desorption water harvesting, it summarizes the countermeasures of multi-stage condensation and multi-cycle adsorption and desorption. The development prospect of atmospheric water harvesting technologies is also discussed

Model-based investigations of ferroelectric energy harvesting with regard to an improvement of life span and operability

A new ferroelectric energy harvesting concept is investigated theoretically, based on a thermo-electromechanical multiscale constitutive framework in connection with the so-called condensed method. Taking advantage of comparatively large changes of strain and polarization due to domain switching, the electric output is higher compared to what is commonly known as piezoelectric energy harvesting. Dissipative self-heating and augmented damage accumulation, on the other hand, may impede the operability of the harvesting device, in particular if tensile stress is required for depolarization, as suggested by recent works. The new harvesting cycle thus dispenses with tensile stresses and instead exploits the potential of existing residual stresses. It is further investigated to which extent a bias field, commonly applied to support repolarization as an important stage of the cycle, can be omitted, saving considerable effort on the technical implementation. Process parameters are obtained from various simulations by pareto-optimization, considering, inter alia, the effect of ambient temperature.

Financial Analysis of Catfish Cultivation Businesses in Sedenganmijen Village, Krian District, Sidoarjo Regency

The title of this research is "Financial Analysis of Catfish Farming in Sedenganmijen Village, Krian District, Sidoarjo Regency," this study aims to conduct a financial analysis of catfish farming in Sedenganmijen Village, Krian District, Sidoarjo Regency. Six catfish cultivators were chosen as participants for this analysis. Detailed data encompassing variable costs, fixed costs, and total revenue was gathered from each participant. Using this information, the analysis involved computing the profit, Return Cost Ratio (R/C), and Benefit Cost Ratio (B/C) for each participant. The findings revealed that all six participants yielded substantial profits, ranging from 52% to 99% of their total incurred costs per harvest cycle. Additionally, the R/C analysis indicated ratios between 1.52 and 1.99, all exceeding 1, signifying favorable returns for each participant. Moreover, the B/C analysis showcased ratios between 0.52 and 0.99, all-surpassing 0, further supporting the viability of continuing catfish cultivation for these individuals. Given the positive outcomes across these three analyses, it is recommended that all six participants continue their catfish farming endeavors.

An overview of atmospheric water harvesting methods, the inevitable path of the future in water supply.

Although science has made great strides in recent years, access to fresh water remains a major challenge for humanity due to water shortage for two-thirds of the world's population. Limited access to fresh water becomes more difficult due to the lack of natural resources of water. Many of these resources are also contaminated by human activities. Many attempts have been made to harvest water from the atmosphere, and condensation systems have received much attention. One of the challenges in generation systems is the high consumption energy of the cooling feed, despite the generation of large amounts of water from the atmosphere. As other airborne contaminants condense with water vapor, the water after harvesting needs to be treated, which adds to construction and maintenance costs. Also, the need for high relative humidity in condensation systems has led scientists to find ways of atmospheric water harvesting at low relative humidity and use renewable energy sources. Sorption systems can absorb atmospheric water without the need for an energy supply and spontaneously. Desiccants such as silica gel and zeolite, due to their high affinity for water, can absorb water vapor in the air through physical or physicochemical bonding, but all of these have slow adsorption kinetics. Therefore, it takes a long time for the water harvesting cycle or they are not able to absorb water at low relative humidity, and others need a lot of energy for the water desorption phase. Metal-Organic Frameworks (MOF) are porous materials that, due to their special structure, are considered the most promising material for atmospheric water harvesting at low relative humidity. MOF-303 has been identified as the most efficient material to date and can harvest 0.7 liters of water per kilogram of MOF-303 at 10% RH and 27 °C. MOFs can harvest atmospheric water even in desert areas using only solar energy, and the water produced is drinkable and does not need to be treated. In this review, systems and methods of atmospheric water harvesting will be studied and compared and then the mechanism of adsorption and desorption in sorption systems will be discussed in detail.

Amazon Forest morphometry on the tree management of the second harvest cycle.

Knowledge of the morphometric relationships of Amazonian species can contribute to forest-sustainable tree management. The objective of this study is to describe and evaluate the morphometric relationships of 10 tree species from a tropical forest managed in a second cutting cycle. Morphometric data were collected in a forest located in the municipality of Itaúba (“Mato Grosso” state – MT, Brazil). In general, the DBH, Total Tree Height, and commercial morphometric parameters were similar for the species, except for copaiba, which presented a small value for minimum DBH, and low regeneration of the species in the area. The evaluated species showed a high value of Canopy Shape (average CS = 1.28) and the value of Canopy Proportion was 44.87%, slightly lower than those found in the literature. In the Salience Index, the data found ranged from 14 to 36, a result close to that expected for tropical forests. The average Slenderness Ratio (SR) observed in the area indicated that the trees are relatively robust and less prone to crown and trunk breaks. For the Salience Index, it was observed that the species showed a reduction of the index with the increase of DBH. There was a positive response for the relationships between variables evaluated, with 23.4% for the Canopy Diameter x DBH ratio (i.e., CD × DBH), 5.6% for the Canopy Ratio × DBH (CR × DBH), and 18.8% for the Total Height (HT × DBH). The morphometric correlations obtained low results (R²: 0.234; 0.056 and 0.188 respectively). However, the average correlation between Total Tree Height and DBH was expected to be higher due to changes in tree growth due to the intervention carried out in the forest.

Adaptive end‐effector pose control for tomato harvesting robots

AbstractThis paper investigates the development of a tomato‐harvesting robot operating on a plant factory and primarily studies the reachable pose of tomatoes in the nondexterous workspace of manipulator. The end‐effector can only reach the tomatoes with reachable poses when the tomatoes are within the nondexterous workspace. If the grasping pose is not reachable, it will lead to grasping failure. An adaptive end‐effector pose control method based on a genetic algorithm (GA) is proposed to find a reachable pose. The inverse kinematic solution based on analysis method of the manipulator is analyzed and the objective function of whether the manipulator has a solution or not is obtained. The grasping pose is set as an individual owing to the position of the tomatoes is fixed and the grasping pose is variable. The GA is used to solve until a pose that can make the inverse kinematics have a solution is generated. This pose is the reachable grasping pose of the tomato at this position. The quintic interpolation polynomial is used to plan the trajectory to avoid damage to tomatoes owing to fast approaching speed and a distance based background filtering method is proposed. Experiments were performed to verify the effectiveness of the proposed method. The radius of the workspace of the UR3e manipulator with the end‐effector increased from 550 to 800 mm and the grasping range expanded by 208%. The harvesting success rate using the adaptive end‐effector pose control method and trajectory planning method was 88%. The cycle of harvesting a tomato was 20 s. The experimental results indicated that the proposed tomato‐recognition and end‐effector pose control method are feasible and effective.

The size of clearings for charcoal production in miombo woodlands affects soil hydrological properties and soil organic carbon

Charcoal production is a major driver of forest degradation in miombo woodlands. Forests play a crucial role in regulating the hydrological cycle, so it is critical to understand how forest degradation and management practices impact water availability, particularly in drylands. Few studies have examined the effect of forest clearing size on the hydrological functioning of soil, particularly under real-world conditions where, following clearing, forests are subject to multiple and prolonged anthropogenic disturbances, as occurs in miombo woodlands which are cleared for charcoal production and commonly used for livestock grazing. The pilot project Transforming Tanzania's Charcoal Sector was established in 2012 with the aim of establishing a sustainable wood harvesting system for charcoal production based on rotational harvesting cycles that allow for natural forest regeneration. Two clearing sizes were established: large clearings (300 × 300 m) harvested by clear-felling, and small clearings (50 × 50 m) harvested in a checkerboard pattern. We examined the effect of these two clearing sizes on soil hydrological properties and soil organic carbon (SOC) in Kilosa district, Morogoro, Tanzania. Our analysis included four treatments: large clearings, small clearings, small intact plots (unharvested plots within the checkboard pattern), and village land forest reserve. For each treatment we assessed the tree cover and measured soil infiltration capacity, soil bulk density, SOC stock, and texture. We also examined the relationship between these variables and the distance to the closest road to better understand the impact of livestock and human disturbance. Our results show that large clearings had the lowest mean infiltration capacity (121 ± 3 mm h−1) and SOC stock content (12 ± 0.2 tonnes ha−1), and the highest bulk density (1.6 ± 0.005 g cm−3) of all the treatments. We found a positive relationship between infiltration capacity and basal area (R2 = 0.71) across all treatments. We also found that infiltration capacity, SOC stock and tree basal area increased with increasing distance from the closest road, while bulk density decreased. We conclude that, in terms of their impact on soil hydrological functioning and SOC stock, small clearings, while not completely unaffected, are better than larger ones. In small clearings, concurrent reductions in tree cover and a relatively low impact on soil hydrological properties could result in increased soil and groundwater recharge compared to unharvested forest areas. Controlling livestock grazing can further minimize soil degradation, producing additional gains.

Growing Season Harvests of Shrub Willow (Salix spp.) Have Higher Nutrient Removals and Lower Yields Compared to Dormant-Season Harvests

The commercial establishment of shrub willow (Salix spp.) biomass crops with three- or four-year harvest cycles raises concerns about nutrient removal (NR). In addition, leaf-on harvests outside of the typical harvesting window are becoming more prevalent with a changing climate, and require a better understanding of the potential impact of these changes on biomass production and NR. This study examined the time of harvest effects for six harvest dates on the nutrient and biomass removal of four shrub willow cultivars in central New York State. There were significant differences in biomass in the first-rotation harvest; yields ranged between 77 and 85 Mg ha−1 for the time of harvest treatments during the growing season, and between 93 and 104 Mg ha−1 after dormancy. Harvest timing had significant effects on N and K removal in the combined wood and foliar biomass. Willow harvested in October removed comparatively higher amounts of N (77.1 kg ha−1 year−1) and P (11.2 kg ha−1 year−1) than other harvests. Potassium removal was greater for plants harvested in June (51.2 kg ha−1 year−1) and August (52.5 kg ha−1 year−1). Harvest timing and cultivar interactions suggest that targeted cultivar selection and deployment could maintain yields and limit excess nutrient losses.

Soil Degradation Due to Conversion from Natural to Plantation Forests in Indonesia

Soil organic matter (SOM) is a crucial component of soil, through which physical, chemical, and biological characteristics interact in a local context. Within the forest category, the conversion of natural forests to monoculture plantations has raised concerns in Indonesia over the loss of soil functions, similar to conversion to agriculture. In natural forests, SOM can accumulate as part of a closed nutrient cycle with minimal nutrient losses; in plantation forestry, SOM decline and recovery can alternate over time, associated with larger nutrient losses. We reviewed existing studies to quantify how shifts from natural forests to short-rotation plantation forests (SRPF) affect SOM dynamics, soil nutrient contents, and soil-borne pathogens that cause disease. The review combines descriptive and quantitative methods (meta-analysis). The results show that conversion affects the soil C balance, soil structure and water balance, soil nutrient balance, and soil-borne diseases. Contributing factors include the reduced diversity of plant and rhizosphere communities, lower annual litter production, more uniform litter quality, and nutrient removal at the harvest cycle. Conversion from natural to plantation forest conditions also increases plant disease incidence by changing biological control mechanisms.

A study on thermally regenerative electrochemical cycles using various supercapacitors

• TRECs are implemented using different types of supercapacitors. • The TREC efficiencies are analyzed considering the energy losses. • The TRECs operate over voltage ranges that minimize the impact of self-discharge. • The TREC characteristics of the different supercapacitors are elucidated. Efficient energy harvesting systems have been developed to recover the low-grade waste heat that is generated by industries. Although there have been several kinds of research studies on thermally regenerative electrochemical cycles using electrochemical cells, an energy harvesting cycle using a lithium-ion capacitor and pseudocapacitor has not yet been examined. This study was conducted to implement a thermally regenerative electrochemical cycle with three different kinds of commercial supercapacitors: a lithium-ion capacitor, a pseudocapacitor, and an electric double-layer capacitor. The thermally regenerative electrochemical cycle of the supercapacitors was configured within a range of voltage values changed by the temperature in an open circuit. This was achieved by designing a reference voltage, i.e. , initial voltage, to minimize the effect of self-discharge. The energy harvesting work was analyzed in detail considering the effect of self-discharge. Under the assumption of heat recuperation efficiency of 100%, the thermally regenerative electrochemical cycle efficiencies of the lithium-ion capacitor, pseudocapacitor, and electric double-layer capacitor were 8.77%, 10.2%, and 10.4%, respectively. The energy loss of the pseudocapacitor, which was 34.1%, was the lowest value among those of all supercapacitors; it was confirmed that this pseudocapacitor energy loss was the result of self-discharge and internal resistance.

Confounding effects of harvesting on urban heat island intensity in a mid-sized city in Brazil

Urban heat island (UHI) studies have traditionally focused on the relative difference between air temperatures measured at an urban area and those at a rural location, taken as a reference. Whereas the influence of urban areas on UHI intensity has been abundantly explored, the impact of the choice of an adequate rural reference location, due to the frequent agricultural use of rural areas, still remains understudied. The issue of climate variability of rural areas is a determining factor for assessing UHI intensity. Brazil is the world's largest sugarcane producer, with a 33% share of the global market. Many mid-sized cities in the Brazilian state of São Paulo are located close to sugarcane fields, which all undergo the sugarcane growth cycle with defined pre-harvest and post-harvest stages. The aim of this study is to understand the interference of seasonal harvesting periods in sugarcane plantations on the development of UHI magnitudes in and around (at suburban locations) Piracicaba, located in the state of São Paulo, Brazil, at 22° 42′ 30“ S and 47° 38’ 01” W and characterized by Köppen-Geiger's Cfa, humid subtropical climate. We deployed a fully-equipped weather station at the site of a sugarcane crop at post- and pre-harvest and a small network of three weather stations provided with air temperature and humidity sensors in the city center and in suburban neighborhoods in Piracicaba. Pre-harvest showed the highest UHI intensities, though not confounding the analysis of intra-urban temperature differentiation patterns. Results stress the relevance of the choice of the baseline rural station in terms of temporal variability related to the sugarcane harvesting cycle.

Cultivation of Water Spinach (Ipomoea Reptans Poir) Production By Using Dft and Nft

Water spinach (Ipomoea reptans Poir) is one of the horticultural crops known for its very easy cultivation and fast harvest cycle and high nutritional value. This plant can be produced or cultivated hydroponically using NFT (Nutrient Film Technique) and DFT (Deep Flow Technique) systems. Cultivation of plants in the NFT system uses a sloping circuit with shallow nutritious water that circulates for 24 hours at a fast flow. The DFT system uses a closed-circuit insulated with stagnant water that circulates for 24 hours at a slow flow. Thus, this research was conducted to determine the differences in the production of water spinach in two hydroponic systems, namely NFT and DFT. The research was conducted using a Randomized Block Design (RAK) and observation method by observing plant height, number of leaves, wet weight, and root length. Data were analyzed using independent samples T-test with a prerequisite test in the form of the Shapiro-Wilk normality test. The results of this research showed that the cultivation of water spinach using NFT and DFT hydroponic systems had significant differences in plant height, number of leaves, root length, and wet weight. Water spinach production can be increased by using DFT compared to NFT.

Development of a dual-arm rapid grape-harvesting robot for horizontal trellis cultivation.

It is extremely necessary to achieve the rapid harvesting of table grapes planted with a standard trellis in the grape industry. The design and experimental analysis of a dual-arm high-speed grape-harvesting robot were carried out to address the limitations of low picking efficiency and high grape breakage rate of multijoint robotic arms. Based on the characteristics of the harvesting environment, such as the small gap between grape clusters, standard trellis, and vertical suspension of clusters, the configuration of the dual-arm harvesting robot is reasonably designed and analyzed, and the overall configuration of the machine and the installation position of key components are derived. Robotic arm and camera view analysis of the workspace harvesting process was performed using MATLAB, and it can be concluded that the structural design of this robot meets the grape harvesting requirements with a standard trellis. To improve the harvesting efficiency, some key high-speed harvesting technologies were adopted, such as the harvesting sequence decision based on the “sequential mirroring method” of grape cluster depth information, “one-eye and dual-arm” high-speed visual servo, dual arm action sequence decision, and optimization of the “visual end effector” large tolerance combination in a natural environment. The indoor accuracy experiment shows that when the degree of obscuration of grape clusters by leaves increases, the vision algorithm based on the geometric contours of grape clusters can still meet the demands of harvesting tasks. The motion positioning average errors of the left and right robotic arms were (X: 2.885 mm, Y: 3.972 mm, Z: 2.715 mm) and (X: 2.471 mm, Y: 3.289 mm, Z: 3.775 mm), respectively, and the average dual-arm harvesting time in one grape cluster was 8.45 s. The field performance test verifies that the average harvesting cycle of the robot with both arms reached 9 s/bunch, and the success rate of bunch identification and harvesting success rate reached 88 and 83%, respectively, which were significantly better than those of existing harvesting robots worldwide.

“Do you think it is a Pandemic?” Apocalypse, Anxiety and the Environmental Grotesque in Paolo Bacigalupi’s The Windup Girl

Paolo Bacigalupi’s The Windup Girl (2009), set in the post fossil-fuel, post turbo-capitalist country of Thailand, portrays the shocking after effects of bioengineering and gene-hack modifications in food crops. The narrative depicts a country tottering on the brink of an agricultural apocalypse on account of food production being severely affected by crop driven anomalies and rogue diseases such as “cibiscosis” and “blister rust” transmitted by variants of mutating pests. Natural seed stock becomes completely supplanted by the new genetically engineered seeds which become sterile after a single seasonal cycle of sowing and harvesting. The native population of Thailand is adversely affected by the pandemic scenario, which becomes aggravated by an expedient “scientocracy” that is at the heart of the neocolonial enterprises of American megacorporations and calorie companies like Agrigen, PurCal and Redstar who hail gene hacking as the new future of food resources and market profiteering. The consumption of the gene-hacked produce spreads through crops and affects the human body in unimaginable ways thereby resulting in a considerable rise of health issues including digestive and respiratory failures.
 This paper intends to articulate the idea of a pandemic, its historical understanding and affective influences in the context of a post techno-fossil fuel economy set in Thailand. It will analyse the idea of epidemiological colonialism; diseases introduced by colonising forces that reshape the natives’ existing environment thereby bringing forth a deep pandemic anxiety that percolates the collective memory of the Thai people. It also highlights how the novel portrays the conflict between traditional ecological knowledge systems and modern extractive enterprises that acts as a catalyst to hasten the destruction of sustainable systems of agriculture and food production that have endured the impact of climate change and ecological fallout. The paper will study the relevance of the pandemic as an agency of ecocatastrophe and its function in an eco-speculative science fictional narrative. Finally, the paper looks into the concept of the posthuman android, genetically modified humans in a “technologiade”, a society reconfigured by technoscience to resist the impact of environmental collapse, and explores how this trope is incorporated in Bacigalupi’s narrative to celebrate human striving for hope and survival in an imagined environmental future marked by a self-created agro-scientific grotesqueness.

Environmentally adaptive MOF-based device enables continuous self-optimizing atmospheric water harvesting

Harvesting water vapor from desert, arid environments by metal-organic framework (MOF) based devices to deliver clean liquid water is critically dependent on environment and climate conditions. However, reported devices have yet been developed to adapt in real-time to such conditions during their operation, which severely limits water production efficiency and unnecessarily increases power consumption. Herein, we report and detail a mode of water harvesting operation, termed ‘adaptive water harvesting’, from which a MOF-based device is proven capable of adapting the adsorption and desorption phases of its water harvesting cycle to weather fluctuations throughout a given day, week, and month such that its water production efficiency is continuously optimized. In performance evaluation experiments in a desert, arid climate (17–32% relative humidity), the adaptive water harvesting device achieves a 169% increase in water production (3.5 LH2O kgMOF−1 d−1) when compared to the best-performing, reported active device (0.7–1.3 LH2O kgMOF−1 d−1 at 10–32% relative humidity), a lower power consumption (1.67–5.25 kWh LH2O−1), and saves time by requiring nearly 1.5 cycles less than a counterpart active device. Furthermore, the produced water meets the national drinking standards of a potential technology-adopting country.

The Bio Economic Seaweed Model (BESeM) for modelling tropical seaweed cultivation – experimentation and modelling

The Bio Economic Seaweed Model (BESeM) is a model designed for modelling tropical seaweed cultivation. BESeM can simulate the common tropical seaweed cultivation system with multiple harvests per year, clonal reproduction and labour intensive harvesting and replanting activities. Biomass growth is modelled as a sigmoid, with growth being initially exponentially and eventually flattening off towards a maximum weight per plant or per square meter (wf,max). To estimate the latter, longer duration experiments than normal are needed – in the order of 100 days rather than 45 days. Drying (on platforms on the beach) is simulated as well as increase in harvested chemical concentration over time since planting, for harvested chemicals such as agar extracted from Gracilaria or carrageenan extracted from Kappaphycus or Euchema. BESeM has a limited number of parameters which makes it easily amenable to new sites and species. An experiment is presented for a site in Indonesia in which Gracilaria was monitored for 120 days in 6 nearby sites and from which BESeM model parameters were estimated. A simulation example is presented which illustrates how BESeM can be used to find the optimum combination of replanting weight and harvest cycle length (in days) for maximising gross and net farm income.

Avoiding electromechanical instability or loss of tension of dielectric elastomer generators with position-controlled cycles for enhanced energy harvesting

The maximum energy density of a dielectric elastomer generator (DEG) represents the potential energy harvesting capacity, which is determined by the material failure modes. The maximum energy density and the failure modes of DEGs in a force-controlled energy harvesting cycle have been evaluated. However, the position-controlled energy harvesting cycle that is widely used in DEGs has not been investigated. This paper explores the energy harvesting capacity of DEGs with rigid and flexible connections in a position-controlled cycle. The failure modes in a position-controlled cycle are analyzed and the electromechanical instability of DEGs with rigid and flexible connections is mainly focused on. On this basis, we study the maximum energy density of DEGs with diverse connections under different loading configurations. The results show that, compared with the force-controlled cycle, the position-controlled cycle can enhance the energy harvesting capacity of DEGs due to the avoidance of electromechanical instability or loss of tension. The conclusions and methods can help to evaluate the energy harvesting capacity and provide a safe region for the optimal design of DEGs in a position-controlled cycle.

Biochar Is Not Durable for Remediation of Heavy Metal-Contaminated Soils Affected by Acid-Mine Drainage

Biochar is a soil conditioner for enhancing plant growth and reducing plants’ uptake of heavy metals. However, the protonation of biochar surfaces in acid soils can weaken the capacity of biochar to reduce the phytoavailability of soil-borne heavy metals over time. The aim of this study was to test this hypothesis by performing a plant-growth experiment with five harvest cycles to examine the durability of rice-straw biochar for the remediation of an acidic-mine-water-contaminated soil. The application of the biochar significantly reduced the phytoavailability of the heavy metals and inhibited the plant uptake of cationic heavy metals but not anionic Cr. The beneficial effects of the biochar were weakened with the increasing number of harvest cycles caused by the gradual protonation of the biochar surfaces, which resulted in the desorption of the adsorbed heavy metals. The weakening capacity of the biochar to reduce the heavy-metal uptake by the vegetable plants was more evident for Cu, Zn, and Pb compared to Ni and Cd. The experimental results generally confirmed the hypothesis. It was also observed that the bioaccessible amount of various metals in the edible portion of the vegetable was also reduced as a result of the biochar application.

Determining the preliminary performance of selected Annonaceae cultivars in subtropical conditions

Plants phenology is extremely important tool for crop management, crop manipulation, and marketing. The objective of this research was to investigate the phenology and fruit quality of the several Annonaceae species under subtropical conditions of Homestead, Florida, USA. The study was carried out in an experimental sugar apple (Annona squamosa L.), orchard with cultivars: 'LeahReese', 'Lessard Thai' and 'Red' and the atemoya ‘Gefner’ (A. cherimola x A. squamosa L). Ten uniformly vigorous and healthy plants of each cultivar were selected. The fruit harvest period was similar for all the cultivars, except for sugar-apple 'LeahReese', which had the shortest harvest period of only 41 days. Multivariate analysis showed that 'Lessard Thai' and 'Red' sugar apple cultivars had smaller sizes and lower chemical quality. Cultivar "LeahResse" had the highest fruits, in addition, a strong correlation with the atemoya hybrid "Gefner". The sugar apples ‘Lessard Thai’ and 'Red' had similar phenology and had a 166-day pruning to harvest cycle. In contrast, 'LeahReese' sugar apple and 'Gefner' atemoya had significantly longer cycles of 182 and 196 days, respectively. The sugar apple 'LeahReese' had the best physical characteristics of the cultivars investigated, while the atemoya 'Gefner' had the best physiochemical characteristics and the longest shelf life.

Impact of a leaf‐cutting ant (Atta sexdens L.) on a Pinus taeda plantation: A 6 year‐long study

AbstractLeaf‐cutting ants are the most economically important pest of plantation forests in the Neotropics. These social insects can defoliate whole trees, reducing their growth ability and occasionally causing tree mortality. Control of leaf‐cutting ants in plantations is mainly carried out by using insecticides such as sulfluramid or fipronil. Foresters that adhere to voluntary sustainability certification systems are requested to implement integrated pest management programmes that reduce the use of insecticides. However, this approach is much delayed since it requires a better understanding of ant ecology, including quantitative data on the long‐term impact that leaf‐cutting ants have on tree plantations. In this study, we show, for the first time, the results on the long‐term impact of Atta sexdens L. on a Pinus taeda L. plantation in NE Argentina. The annual growth in diameter, height, volume and mortality of P. taeda trees in two 11 ha stands were evaluated up to the middle of the harvest cycle (i.e. 6 years). One of the stands had no control of A. sexdens nests, and in the other stand, all ant nests were removed (total control). After six years since planting, P. taeda trees show significant reductions in total height (19%), diameter at breast height (4.4%) and wood volume (21%) in sites with A. sexdens present. Moreover, tree mortality reached 31.2% when ants were present. Forest managers could use these results to improve their integrated management programmes, by better adjusting their economic damage threshold parameters.