Fruit Removal Research Articles

Function of leafy sepals in Paris polyphylla: photosynthate allocation and partitioning to the fruit and rhizome.

Paris polyphylla Smith var. yunnanensis (Franch.) Hand.-Mazz. is a rhizomatous, herbaceous, perennial plant that is used as a medicinal plant with a variety of pharmacological activities. However, the functions of the green, leafy sepal of this plant are poorly understood. The main objectives of this study were to: (a) test the hypothesis that sepals make measurable contributions to fruit development and rhizome growth; and (b) investigate the allocation and partitioning of photosynthates produced by sepals and leaves to fruit and rhizome. Net photosynthetic rate, photosynthetic pigment composition and δ13C values were similar for sepals and leaves. Sepal-darkening and sepal-removal treatments resulted in smaller fruit size and decreased rhizome biomass, whereas fruit removal led to a decrease in calyx size and an increase in rhizome yield and saponin content. Fruit and seed mass were positively and linearly related to calyx size. These results indicate that photosynthates produced by sepals are involved in the fruit growth and seed development and that developing fruit and rhizomes compete for the photosynthates exported by leaves. We propose that the sepals of P. polyphylla function partly as leaves to compensate for reproductive costs. Fruit removal increased carbon partitioning to the rhizome and improved rhizome yield and quality, offering a useful strategy for the domestication of this valuable medicinal plant.

The Effects of Shaking Frequency and Amplitude on the Detachment of Estahban Dried Fig (Ficus carica cv. Sabz)

The aim of this study was to determine the most suitable shaking frequency and amplitude for shake harvesting Esfahan's edible fig (Ficus carica cv. Sabz). A hand held limb shaker with adjustable shaking frequency and amplitude was used for this study. A 3x3 factorial experiment with three levels of oscillating frequency (10, 12 and 14 Hz) and three levels of shaking amplitude (20, 32.5 and 45 mm) was conducted to investigate the effects of shaking frequency and amplitude on fruit detachment. Analysis of variance and mean comparison of fruit detachment data showed that the effects of shaking amplitude and shaking frequency on fruit detachment were significant. The percentage of unripe fruit detachment significantly increased at higher levels of shaking amplitude and frequency. Complete ripe fruit detachment (100%) and relatively high unripe fruit detachment (16.9%) was obtained at a shaking amplitude of 45 mm and frequency of 14 Hz, but a shaking amplitude of 45 mm and shaking frequency of 10 Hz with high ripe fruit detachment (93.3%) and acceptable unripe fruit detachment (9.4%) is recommended. Harvesting rate during 5s of shaking was measured which showed that the optimum time needed to harvest a limb is only 4s. Comparison of mean values of cumulative fruit removal of 60% (T60) and 90% (T90) at frequency amplitude combinations indicated that the shaking duration necessary for 60% and 90% fruit removal both followed a decreasing trend by increasing the shaking amplitude and frequency. This study suggests the feasibility of utilizing limb shakers as a practical approach for selective harvesting of ripe fruits.

Fruit removal by hornbills in a semi-evergreen forest of the Indian Eastern Himalaya

Abstract:We tested the hypothesis that seed size influences which frugivores eat fruits, and the size and nature of disperser assemblages in Pakke Tiger Reserve, India. Four tree species had large seeds (> 18 mm width) that could be handled by birds with large gape widths, while two tree species had smaller seeds (< 7 mm width) falling within the gape size range of many frugivores. We tested whether (1) disperser assemblage and activity reflected seed size, and (2) large-gaped hornbills were more effective at fruit removal of tree species with large seeds, than of those with smaller seeds and many dispersers. Day-long watches were conducted in 2005 at trees ofDysoxylum binectariferum(three in 2005 and nine in 2006),Chisocheton cumingianus(nine),Aglaia spectabilis(seven),Polyalthia simiarum(nine),Litsea monopetala(four) andCinnamomum bejolghota(two in 2005 and six in 2006) to determine which frugivores visited trees and ate fruit. Disperser visitation and species diversity per tree to species with medium-sized seeds averaged 85 visits and 10 species d−1, contrasted with five visits by one frugivore species to large-seeded tree species. Seed removal rates per tree averaged 486 seeds d−1from medium-seeded tree species, but 10 seeds d−1from large-seeded species. Hornbills (Bucerotidae) andDucula badia(Columbidae) removed large seeds from capsules ofAglaia spectabilis,Chisocheton cumingianusandDysoxylum binectariferum(Meliaceae). Primates, civets and bats also consumed drupes of large-seededPolyalthia simiarum(Annonaceae).Anthracoceros albirostrishornbills were important dispersers ofLitsea monopetala(Lauraceae), a medium-seeded tree with a large disperser assemblage. Conversely, hornbills were quantitatively inconsequential forCinnamomum bejolghota(Lauraceae), another medium-seeded tree species with several dispersers. Results suggest that the size and activity of disperser assemblages accurately reflects seed size. While hornbills were quantitatively important dispersers of large-seeded tree species, their effectiveness for trees with small- to medium-sized seeds depended on the tree species.

ROBOTIC MASS REMOVAL OF CITRUS FRUIT

Labor availability for harvesting is a worldwide problem. In attempts to address this, fruit harvesters have tried the mechanical methods of trunk shaking, canopy shaking, raking and mass mechanical penetration. Though they are economical alternatives for harvesting nuts, olives, cherries and prunes, these brute-force mechanical methods have found limited application to citrus. As an alternative to brute-force methods, articulated robotics with intelligent sensing has also been tried, but challenges include recognizing and locating the fruit and detaching it economically. Any mechanical or robotic system must be economically sound to warrant its use as an alternative to hand picking. Energid Technologies Corporation, based in Cambridge, Massachusetts, is developing a practical robotic fruit picking system whose concept is driven by the economics of mass harvesting while leveraging machine vision and robotic guidance and control. The system uses flexible tubes with removal tools at one end that can be individually fired pneumatically and steered robotically with sensor input coming from a grid of machine vision cameras.

USE OF AN ABSCISSION AGENT FOR HARVESTING MANDARINS IN SPAIN

Spain accounts for more than 55% of the European citrus production and is predominantly oriented towards fresh market. Harvesting accounts for more than 50% of production costs and methods of mass harvesting are under research. Abscission agents decrease fruit detachment force of mature fruits before harvest, thus improving harvesting machines performance. However, they may affect the production of the following season or blemish the fruit skin, making the product unmarketable for whole fruit, fresh consumption. This work was aimed at studying whether the application of ethephon improves mechanical harvesting of mandarins and affects the quality of fruit, the physiology and yield of trees. Trees were harvested with a trunk shaker, and ethephon was sprayed at 600 and 1200 mg/L in 4 and 7 L/tree applications in commercial orchards. The use of ethephon affected the amount of radiation intercepted by the canopy at long term in the first year, but it did not in the second year. It also slightly improved fruit removal but increased defoliation.

Frugivoría y dispersión de semillas de la palma Oenocarpus bataua (Arecaceae) en un bosque de los Andes colombianos

Seed dispersal is a key process that determines the spatial structure and dynamics of populations of plants, establishes the potential area of recruitment and in this way, the basis for subsequent processes such as predation, germination, competition and growth. The purpose of this research was to identify the guild of frugivores of the Oenocapus bataua palm in fragments of Andean forest, determine the effective dispersers and relate the spatial distribution of palm populations with the dispersion of seeds. To this end, between August 2005-June 2006, observations of the removal of fruits from eight clusters were done, and counting of consumption of fruits beneath 78 palms with mature fruits was undertaken; focal observations of 13 individuals during 90 hours; registration of frugivory with photographic traps during 165 days/nights for a total of 195 photographs and 144 consumption events; experiments with dispersion using 751 perforated fruits/seeds attached to strings and finally, plots to determine spatial distribution all were carried out. In the study area at least five species of mammals ate, dispersed, buried (Sciurus granatensis, Microsciurus mimulus, Dasyprocta punctata y Proechimys sp.), cover (Marmosa robinsoni) and carried the fruits of O. bataua off to caves (Marmosa robinsoni y Proechimys sp.) without damaging the seed. A 21.7% of the fruits were dispersed, 13.2 gnawed or peeled, 5.6% covered, buried and carried to caves. The average distance of removal of seeds and fruits was 3.1m although in a lesser proportion, dispersion events of >50m were recorded. The abundant production of fruits, their size and weight, their intense removal by frugivores, the short dispersion distances, the absence of large size frugivores (reduced by hunting and fragmentation), that might perform long-distance dispersion, and the increase of rodents, especially squirrels, that strongly pressure the fruit resource, generate a spatially restricted seed rain of seeds responsible for the aggregate patterns of distribution of seeds, seedlings and subsequently of juveniles and sub-adults. However the short time and high percentage of seed germination and the robustness of seeds and seedlings give O. bataua the capacity to survive in dense aggregations. Therefore, despite the limitations on dispersion, this is a dominant species in the study area. Populations of O. bataua have been reduced by intense exploitation and by the transformation and reduction of their natural habitat. The over-exploitation of the fruits or the juvenile phases of this palm can affect the age structure and population dynamics. Therefore, the management and exploitation of this palm in the future will depend to large degree on the conservation of forest habitats.

Effect of Loosening Agent Sprays on the Efficiency of the Mechanical Harvesting of ‘Arbequina’ Olives

The aim of this work was to evaluate the effect of ethephon (2-chloroethylphosponic acid), applied either alone or in combination with phosphorus compounds, on olive trees (Olea europaea L.) to improve the efficiency of mechanical harvesting. The trial was carried out in mature ‘Arbequina’ olive trees located in northeast Spain during the 2007 and 2008 olive crop seasons. In 2007, the olive trees were sprayed with 300 or 500 mg·L−1 of ethephon combined with two phosphoric formulations: monopotassium phosphate (MKP), at 15 g·L−1 or 30 g·L−1 and monoammonium phosphate at 15 g·L−1. In 2008 olive trees were sprayed with two ethephon concentrations (150 or 300 mg·L−1) in combination with 15 g·L−1 or 30 g·L−1 MKP or alone. Harvesting was performed with a commercial trunk shaker. Data were analyzed as a randomized complete block design with eight replications. Fruit removal force (FRF), ripeness index, fruit weight, natural drop, shaking efficiency (SE), leaf drop (LD), oil content, and bloom intensity of the next year’s bloom were measured. The trial treatments did not significantly affect ripeness index or oil content. Ethephon reduced FRF and increased shaking efficiency with significant differences. P compounds did not seem to affect FRF and LD. Small amounts of ethephon (150 mg·L−1) caused a large degree of fruit loosening (a 77% reduction in FRF at 11 days), which was sufficient to improve the efficiency of mechanical harvesting with minimal leaf drop.

Interactions between Ants and Non‐myrmecochorous Fruits in Miconia (Melastomataceae) in a Neotropical Savanna

AbstractThe aim of this study was to evaluate the role of ants as secondary seed dispersers of six primarily bird‐dispersed Miconia species in the cerrados of southeastern Brazil. Vertebrate exclosure and seed germination experiments were performed for M. albicans, M. alborufescens, M. corallina, M. ferruginata, M. ibaguensis, and M. irwinii. Excluding vertebrates did not significantly alter fruit removal rate for any of the Miconia species relative to open controls. Fruits on stalks and fallen fruits were removed and transported to nests mainly by species of Atta, Acromyrmex, and Ectatomma (dispersal distance ranging from 0.1 to 45.2 m), while Camponotus ants tended to be observed removing the fruit pulp (seed cleaning) where the fruits were found. Seed manipulation by Atta decreased germination of M. irwinii, but not M. ferruginata. Germination did not occur in intact fruits, and thus seed cleaning was an important service provided by the ants. Ant nest soils did not inhibit germination of any of the Miconia species, suggesting they are a good substrate for long‐lived Miconia seeds. We conclude that ant activity could have important effects on the fate of Miconia seeds adapted for bird dispersal.

Leaf photosynthetic and morphological responses to elevated CO2 concentration and altered fruit number in the semi-closed greenhouse

Semi-closed greenhouses have been developed to reduce the energy consumption in horticulture. In these greenhouses, CO2 concentration is higher than in the conventional modern greenhouses due to the reduction of window ventilation. Photosynthetic and morphological acclimation to elevated CO2 has been found in many plant species with feedback inhibition being the main mechanism to explain this. The aim of this study was to investigate the occurrence of photosynthetic and morphological acclimation to elevated CO2 concentration in the semi-closed greenhouse. Our hypothesis was that photosynthetic and morphological acclimation to elevated CO2 concentration only occurred in plants with low sink strength. Experiments were carried out with tomato plants with varying fruit loads in a semi-closed greenhouse and a conventional modern greenhouse. Our results showed that photosynthetic acclimation to elevated CO2 concentration only occurred when the number of fruits was considerably reduced. Elevated CO2 as well as fruit removal reduced specific leaf area. Reduction in photosynthesis rate was associated with, but not caused by reduced stomatal conductance. The increase of dry matter production in the semi-closed greenhouse was mainly explained by a higher CO2 concentration compared to the open greenhouse. We suggested that elevated CO2 concentrations in the semi-closed greenhouse do not cause feedback inhibition in high producing crops, because the plants have sufficient sink organs (fruits) to utilise the extra assimilates.

The effect of NAA (1-naphthalene acetic acid) and AVG (aminoethoxyvinylglycine) on physical, chemical, colour and mechanical properties of Braeburn apple

Abstract Recently, plant growth regulators have been used for multiple purposes in tree fruits. NAA (1-naphthalene acetic acid) and AVG (aminoethoxyvinylglycine) have been widely used in apple fruit. NAA and AVG have been used to control preharvest fruit drop and improve the quality of fruit. In this study, the effects NAA (20 mgL–1), AVG (500 mgL–1) and control (non treatment) treatments on physical, chemical, colour characteristics and mechanical properties of apple (cv. Braeburn) were investigated. The higher length, width, thickness, geometric mean diameter, fruit mass, surface area, projected area, volume, fruit and bulk densities were obtained in AVG treatment. Total acidity, total soluble solid content and starch starch index were higher in control as compared to NAA and AVG treatments. Total phenolic content of the flesh apple was higher than the other treatments. While total antioxidant activities of skin and flesh fruit were higher in AVG according to FRAP method, total monomeric anthocyanin was lower in AVG as compared to the other treatments. AVG treatment generally had positive impacts on fruit removal force, skin and flesh firmnesses because retarding the fruit ripening.

Shifts in community structure of tropical trees and avian frugivores in forests recovering from past logging

Logging is one of the most pervasive threats to biodiversity in tropical forests. In this study, we concurrently examined the responses of the avian frugivore community and the community of fruiting trees to past logging in a tropical forest in northeastern India. We predicted that the abundance of, and visitation by large-bodied frugivores would be lower in logged forests, resulting in reduced seed dispersal and recruitment of biotically dispersed species (especially large-seeded species). Data were collected from two logged and unlogged sites using (a) belt transects for estimating avian frugivore abundance (b) fruiting tree watches to quantify frugivore visitation and (c) vegetation plots to characterize recruitment. Our results show that differences in the abundance of bird species between logged and unlogged sites was correlated with body mass, with larger species being scarcer and smaller species more abundant in logged areas. Correspondingly, visitation rates by large avian frugivores was lower in logged compared with unlogged sites. Finally, biotically dispersed tree species, especially large-seeded species, had lower recruitment in logged forests, potentially due to lowered visitation rates and decreased fruit removal by large bodied avian frugivores. In the long term, these differences in recruitment may result in a tree community shift towards small-seeded biotically dispersed species and abiotically dispersed species in logged areas.

Impact of habitat structure and fruit abundance on avian seed dispersal and fruit predation

So far, it is poorly understood how differential responses of avian seed dispersers and fruit predators to changes in habitat structure and fruit abundance along land-use gradients may translate into consequences for the seed dispersal of associated plants. We selected a gradient of habitat modification (forest, semi-natural, and rural habitat) characterized by decreasing tree cover and a high variation in local fruit availability. Along this gradient we quantified fruit removal by avian seed dispersers and fruit predators from 18 Sorbus aucuparia trees. We analyzed the relative importance of tree cover and fruit abundance in explaining species richness, abundance and fruit removal rates of both guilds from S. aucuparia trees. Species richness and abundance of seed dispersers decreased with decreasing tree cover, whereas fruit removal by seed dispersers decreased with decreasing fruit abundance independent of tree cover. Both variables had no effect on species richness, abundance and fruit removal by fruit predators. Consequently, seed dispersers dominated relative fruit removal in fruit-rich sites but the dispersal/predation ratio shifted in favor of predation in fruit-poor habitat patches. Our study demonstrates that variation in local habitat structure and fruit abundance can cause guild-specific responses. Such responses may result in a shift in fruit removal regimes and might affect the dispersal ability of dependent fruiting plants. Future studies should aim at possible consequences for plant recruitment and guild-specific responses of frugivores to disturbance gradients on the level of entire plant–frugivore associations.

Dispersão de sementes de Melocactus glaucescens e M. paucispinus (Cactaceae), no Município de Morro do Chapéu, Chapada Diamantina - BA

Objetivou-se identificar os dispersores de duas espécies de Melocactus, verificar o padrão de liberação dos frutos, correlacionando-o com a remoção por frugívoros e variação térmica do cefálio, bem como caracterizar a distribuição espacial. Para tanto, foram realizadas observações focais, testes de germinação, registros da emergência, extrusão e remoção de frutos, da temperatura do cefálio, de interações formigas-diásporos e distribuição espacial. Lagartos (2 espécies) e formigas (3 espécies) foram os dispersores das espécies estudadas. A dormência das sementes não foi quebrada pela passagem pelo trato digestivo dos lagartos. As maiores taxas de remoção dos frutos pelos lagartos ocorreram nas horas centrais do dia, coincidindo ou sendo posterior aos picos de extrusão. As taxas de emergência e extrusão foram mais intensas pela manhã, o que aumentou as chances de remoção dos frutos no dia da liberação, evitando dissecação e predação. Não houve correlação entre a liberação dos frutos e a variação térmica do cefálio. O desenvolvimento do fruto gera tensão nas fibras do cefálio que promove sua emergência ou expulsão. A expulsão de frutos emergidos pode ser auxiliada pela dilatação das fibras em resposta ao aquecimento, tensão da união das fibras na base e saída de outros frutos. A distribuição espacial dos indivíduos parece ser influenciada pelo comportamento dos dispersores.

Neighborhood effects on seed dispersal by frugivores: testing theory with a mistletoe–marsupial system in Patagonia

The outcome of the dispersal process in zoochorous plants is largely determined by the behavior of frugivorous animals. Recent simulation studies have found that fruit removal rates and mean dispersal distances are strongly affected by fruiting plant neighborhoods. We empirically tested the effects of conspecific fruiting plant neighborhoods, crop sizes, and plant accessibility on fruit removal rates and seed dispersal distances of a mistletoe species exclusively dispersed by an arboreal marsupial in Northern Patagonia. Moreover, in this study, we overcome technical limitations in the empirical estimation of seed dispersal by using a novel 15N stable isotope enrichment technique together with Bayesian mixing models that allowed us to identify dispersed seeds from focal plants without the need of extensive genotyping. We found that, as predicted by theory, plants in denser neighborhoods had greater fruit removal and shorter mean dispersal distances than more isolated plants. Furthermore, the probability of dispersing seeds farther away decreased with neighborhood density. Larger crop sizes resulted in larger fruit removal rates and smaller probabilities of longer distance dispersal. The interplay between frugivore behavioral decisions and the spatial distribution of plants could have important consequences for plant spatial dynamics.

The ecological effects of the ant–hemipteran mutualism: A meta-analysis

Ant–hemipteran mutualism has a variety of ecological effects on the host plants, but the magnitude and moderators of those effects are poorly known. We evaluated this issue by conducting a meta-analysis based on 49 published studies. Results showed that the mutualism had significant protective effects on the host plans, although those effects did not lead to enhanced plant growth or reproductive performance. Both herbivores and predators on plants were strongly suppressed by the mutualism; a similar pattern was also detected for fruit removal. The ecological effects of the mutualism tended to be more consistent and stronger in tropical and subtropical regions, whereas in temperate regions, none of the tested variables was significantly affected by the mutualism. The protective effects of the mutualism on plants were independent of plant life form and the invasiveness of ants. The effect of the mutualism on predators varied with plant life form. The study confirmed that the ant–hemipteran mutualism has a wide range of ecological influences on plants and highlights the significance of a common and wide-spread mutualism.

Optimum Operating Parameters for a Rotary Drum Shaker for Harvesting Jatropha curcas L.

The objective of this study was to determine the optimum amplitude and frequency of operation for the rotary shaker drum of an experimental canopy shaker used for harvesting Jatropha curcas L. A constrained optimization technique that required the removal of yellow and brown fruits to be as high as possible and the removal of green fruits to be as low as possible was used to determine the optimum operating parameters. The optimum operating condition that retained 90% of the green fruits on the plant was found to be an amplitude of 7.2 cm (2.9 in.) and a frequency of 2.4 Hz. The removal efficiencies for yellow and brown fruits were found to be 75.8% and 80.2%, respectively, for this operating condition. When the objective function of the optimization procedure was changed to limit the amount of green fruits harvested to be no more than 10% of the total fruits harvested to ensure oil quality, the optimum operating parameters were found to be an amplitude of 8.0 cm (3.2 in.) and a frequency of 3.2 Hz for the shaker drum. The removal efficiencies for the yellow and brown fruits for this operating condition were 83% and 89%, respectively. An evaluation of plant damage revealed that no serious damage occurred to Jatropha curcas L. plants when the vibratory shaker drum was operated even under aggressive harvesting conditions that involved an amplitude of 7.6 cm and a frequency of 5.0 Hz.

Performance Evaluation of Mechanical Cherry Harvesters for Fresh Market Grade Fruits

Rising harvest costs and looming labor shortages are threatening profitability in the sweet cherry (Prunus avium L.) industry. The current study obtained baseline data on performance and efficiency for potential mechanical or mechanically-assisted systems for improving harvest efficiency of fresh market grade sweet cherries. We compared a prototype system that detaches fruit using impact force, with a system that detaches fruit using vibration, through a series of excited vibration tests. A group of single axial accelerometers were installed at different locations in sweet cherry trees to record the acceleration in response to applied force. From field experiments with accelerometers and assessment of fruit removal, we found that energy transmission along the woody structure differed with different excitation modes. The vibratory shaker resulted in higher efficiency of fruit removal and less fruit damage compared with impact harvester. Obtained results provide some critical information required for designing a more effective mechanical harvester with better produce quality.

Bottlenecks for plant recruitment in woodland remnants: An ornithochorous shrub in a Mediterranean ‘relictual’ landscape

Habitat fragmentation may lead to declines in plant populations and ultimately to extinction through a disruption of demographic processes, which may result in bottlenecks or even a collapse in regeneration. Nevertheless, very few studies have assessed the net effects of habitat fragmentation on plant recruitment integrating its multiple demographic processes. Using data from a four-year field study, we analyze how habitat fragmentation affects particular demographic processes and the overall magnitude of plant recruitment. We use as a case study the bird-dispersed shrub Myrtus communis in Mediterranean woodland patches within an extremely fragmented landscape (∼1% woodland cover). By means of observations and experiments, we quantified fecundity, fruit removal by frugivores, seed rain, post-dispersal seed predation by rodents and seedling emergence and survival. Within each patch, we quantified post-dispersal processes in different target microhabitats. We considered the life cycle to be a combination of consecutive life stages connected by transitional processes with specific probabilities. We calculated the overall probability of recruitment for each patch as the product of all of these probabilities. The demographic processes negatively affected by fragmentation were bird-generated seed rain and seedling emergence and survival, which were attributable, respectively, to lower fruit abundance and poorer habitat quality in the smaller patches. The negative effect of fragmentation on M. communis recruitment became stronger when all the demographic processes were integrated. Of all processes, seedling emergence and, above all, seedling survival were clearly bottlenecks for recruitment that were associated with habitat fragmentation. Results from our observations and experiments were consistent with natural patterns of regeneration given that we found higher seedling densities in larger patches and old population structures (with no saplings/juveniles) in some small patches. Our study shows that habitat fragmentation has serious negative effects on recruitment in M. communis due to demographic bottlenecks in seedling establishment. The available evidence (this and a companion study) suggests that the impoverishment of habitat quality associated with habitat fragmentation (edge effects, disturbances associated with management and microhabitat availability) can explain these results. Given that restoration at a landscape scale is likely to be extremely difficult, initial management actions should aim to improve habitat quality in the smallest woodland remnants.

Interspecific and annual variation in pre‐dispersal seed predation by a granivorous bird in two East Asian hackberries, Celtis biondii and Celtis sinensis

Pre-dispersal seed predation by granivorous birds has potential to limit fruit removal and subsequent seed dispersal by legitimate avian seed dispersers in bird-dispersed plants, especially when the birds form flocks. We monitored pre-dispersal seed predation by the Japanese grosbeak, Eophona personata, of two bird-dispersed hackberry species (Cannabaceae), Celtis biondii (four trees) and Celtis sinensis (10 trees), for 3 years (2005, 2007 and 2008) in a fragmented forest in temperate Japan. Throughout the 3 years, predation was more intense on C. biondii, which, as a consequence, lost a larger part of its fruit crop. Grosbeaks preferred C. biondii seeds that had a comparatively lower energy content and lower hardness than C. sinensis, suggesting an association between seed hardness and selective foraging by grosbeaks. In C. biondii, intensive predation markedly reduced fruit duration and strongly limited fruit removal by seed dispersers, especially in 2007 and 2008. In C. sinensis, seed dispersers consumed fruits throughout the fruiting seasons in all 3 years. In C. biondii, variation in the timing of grosbeak migration among years was associated with annual variation in this bird's effects on fruit removal. Our results demonstrate that seed predation by flocks of granivorous birds can dramatically disrupt seed dispersal in fleshy-fruited plants and suggest the importance of understanding their flocking behaviour.

Experimental sink removal induces stress responses, including shifts in amino acid and phenylpropanoid metabolism, in soybean leaves.

The repeated removal of flower, fruit, or vegetative buds is a common treatment to simulate sink limitation. These experiments usually lead to the accumulation of specific proteins, which are degraded during later stages of seed development, and have thus been designated as vegetative storage proteins. We used oligonucleotide microarrays to assess global effects of sink removal on gene expression patterns in soybean leaves and found an induction of the transcript levels of hundreds of genes with putative roles in the responses to biotic and abiotic stresses. In addition, these data sets indicated potential changes in amino acid and phenylpropanoid metabolism. As a response to sink removal we detected an induced accumulation of γ-aminobutyric acid, while proteinogenic amino acid levels decreased. We also observed a shift in phenylpropanoid metabolism with an increase in isoflavone levels, concomitant with a decrease in flavones and flavonols. Taken together, we provide evidence that sink removal leads to an up-regulation of stress responses in distant leaves, which needs to be considered as an unintended consequence of this experimental treatment.