Search

Despite the application of girdling technique for several centuries, its impact on the metabolic shifts that underly fruit biology remains fragmentary. To characterize the influence of girdling on sweet cherry (Prunus avium L.) fruit development and ripening, second-year-old shoots of the cultivars 'Lapins' and 'Skeena' were girdled before full blossom. Fruit characteristics were evaluated across six developmental stages (S), from green-small fruit (stage S1) to full ripe stage (stage S6). In both cultivars, girdling significantly altered the fruit ripening physiognomy. Time course fruit metabolomic along with proteomic approaches unraveled common and cultivar-specific responses to girdling. Notably, several primary and secondary metabolites, such as soluble sugars (glucose, trehalose), alcohol (mannitol), phenolic compounds (rutin, naringenin-7-O-glucoside), including anthocyanins (cyanidin-3-O-rutinoside, cyanidin-3-O-galactoside, cyanidin-3.5-O-diglucoside) were accumulated by girdling, while various amino acids (glycine, threonine, asparagine) were decreased in both cultivars. Proteins predominantly associated with ribosome, DNA repair and recombination, chromosome, membrane trafficking, RNA transport, oxidative phosphorylation, and redox homeostasis were depressed in fruits of both girdled cultivars. This study provides the first system-wide datasets concerning metabolomic and proteomic changes in girdled fruits, which reveal that shoot girdling may induce long-term changes in sweet cherry metabolism.

Impacts of forest management practices on soil carbon (C) and nitrogen (N) dynamics remain under debate due to complex interactions between belowground biogeochemical processes. To optimize practices that minimize soil C and N losses, we investigated the effects of management practices on soil C and N fluxes, including the leaching of dissolved organic C (DOC) and N, by comparing clearcutting, stem girdling (removal of the bark and phloem tissue), and control treatments in a Japanese cedar plantation. Canopy opening by clearcutting is hypothesized to have a greater effect on soil C loss and the leaching of nitrate-N relative to girdling. Results showed that clearcutting increased soil heterotrophic respiration (organic matter decomposition) and lead to a loss of soil organic C (2.9–3.7 Mg C ha−1 yr−1). Higher litter inputs from girdled tree dieback caused an increase in DOC fluxes from the organic horizon, whereas the loss of fresh litter inputs decreased DOC fluxes from the organic horizon following clearcutting. Clearcutting increased nitrate-N leaching by 3.3–4.8 kg N ha−1 yr−1 due to the loss of plant N uptake and the increased mineralization of soil organic matter, but high C/N ratios in dissolved organic matter limited nitrate leaching in the girdled treatment. Effects of forest management practices on soil C loss and nitrate leaching loss could be variable, but the slash application in clearcutting and the slow dieback in stem girdling could mitigate soil C loss and nitrate leaching loss.

To investigate the importance of shoot-to-root communication in modulating tissue phytohormone balance as the soil dries, root and leaf hormonal profiles were determined in soybean plants (Glycine max L. Merr. cv. Siverka) exposed to factorial girdling (achieved surgically on Day 0 by excising the phloem with a sharp razor blade thereby disrupting basipetal hormone transport) and soil drying treatments. Plants were randomized into 2 groups: girdled and intact plants, and each girdled group was further separated into two groups: well-watered and soil drying. Thus the experiment was a two (± girdling) x two (± soil drying) factorial experiment. Within 26 h while the soil was still moist, girdling increased root ACC (by 11-fold) and decreased root ABA concentrations (by 28 %), decreased foliar iP, tZ and GA concentrations (by up to 90 %), and increased foliar ABA and JA concentrations (by 1.6- and 4.9-fold respectively) compared to intact plants, but only leaf ABA concentration correlated with partial stomatal closure. Two days of soil drying increased root ABA and JA concentrations in intact plants, and both hormones significantly decreased in roots of girdled plants compared to intact plants. Soil drying increased foliar iP, ABA, JA and SA concentrations by 1.3-, 2.5-, 1.3- and 1.4-fold respectively compared to well-watered intact plants by the end of the experiment, but girdling prevented this foliar iP, ABA, JA accumulation compared to droughted intact plants. Thus, girdling affects the co-ordination of root and leaf phytohormone concentrations such as JA and ABA, which may transiently modulate stomatal closure. However, leaf ABA concentration varied consistently with root ABA concentration across all treatments, and explained more of the variation in stomatal conductance than any other hormone or leaf water potential., PC thanks the SEW-REAP Project (EuropeAid ECRIP ICI+/2014/348- 010) and a Lancaster University Faculty studentship for supporting his PhD research

Hazelnut (Corylus avellana L.) is an important nut crop with clear mast seeding behaviour leading to alternate yield and, thus, to management issues. It was hypothesized that masting is associated to accumulation/depletion of carbon within storage tissues (i.e. stem, large branches, roots). We hypothesized that fruit yield depends both on carbon fixed by leaves on the same branch and carbon stored in the main stem. We therefore conducted a manipulation of carbon sink-source resources on fruit-bearing branches of C. avellana cv. ‘Tonda di Giffoni’ by combining girdling and defoliation on a set of branches. We measured the number and diameter of nuts and leaves, the dry weight of fruits and seeds and the amount of blanks over the growing season. We also estimated the whole tree leaf area by allometric equations and the tree yield by collecting all nuts separately on 15 trees at maturity. The average seed dry mass in the un-defoliated girdled treatment was significantly lower than the control (0.5 vs. 0.9 g) suggesting that the fruit-bearing branches need to import carbon from the main stem and that the carbon autonomy of fruit-bearing branches is not supported during kernel maturation process. We also observed that the correlation at whole tree level between leaf area and seed mass is strong in non-masting years, while it becomes weaker in masting years reinforcing the hypothesis that the productivity of masting yields also relies on stored resources.

The prolonged absence of fire in Oregon white oak (Quercus garryana) woodlands and savannas of the Pacific Northwest has resulted in substantial conifer encroachment over the past century. Use of low intensity prescribed burns often lacks sufficient intensity to kill larger encroached trees, requiring alternative approaches. In the Bald Hills region of Redwood National Park, managers have implemented girdling treatments to kill Douglas-fir (Pseudotsuga menziesii) over the past two decades with the objective of recovering remnant oaks and restoring historical woodland area. We surveyed 258 girdled Douglas-fir to examine the effectiveness of girdling treatments to create snags and the impacts of girdling on tree regeneration and fuel recruitment over a 17 year time since girdling chronosequence. Girdling was successful in killing 91% of the treated Douglas-fir independent of the method used (axe or chainsaw). Larger trees with a low girdle width-to-tree diameter ratio tended to survive girdling. Trees with a girdle width-to-tree diameter ratio ≥1 were most effective at killing trees. Snags generated through girdling decayed over time but did not significantly reduce in height over the time period examined. Bird activity was observed on 19% of snags across the chronosequence but 88% of 10 y old snags had signs of bird foraging. Fine woody fuel loading and fuelbed depths were potentially elevated 7 years after treatment but did not persist through the time period examined. Regeneration of Douglas-fir and oaks were highly variable and did not seem to be clearly linked to girdling activity. Our results indicate that girdling is a highly effective treatment to kill Douglas-fir and aid restoration of Oregon oak woodlands with limited negative impacts on surface fuel hazards or regeneration.

Ocotea bullata (Burch.) Baill. (Lauraceae) and Curtisia dentata (Burm.f.) C.A.Sm . (Curtisiaceae) are two South African indigenous medicinal tree species of which the bark is overexploited due to its high demand in the local medicinal plant trade. The bark of O. bullata is used for headaches, as an emetic for both nervous and urinary disorders, and for diarrhea, whereas the bark of C. dentata is taken for stomach ailments, diarrhea and sexually transmitted diseases. Curtisia dentata bark is further applied as an aphrodisiac, and to “purify the blood”. Due to uncontrolled harvesting of bark by informal commercial harvesters, these trees are often found girdled in natural areas. The removal of bark from a tree affects its foliage, flowering, fruiting, seeding, basal sprouting and rooting since the removal of phloem tissue during girdling affects both the basipetal flow of carbohydrates from the canopy of the tree to the root system and the acropetal flow of amino acids, sugars and hormones from the roots to the canopy. This study investigated whether the flow of sucrose can be restored in girdled O. bullata and C. dentata trees using the technique of bridge-grafting. A total of 300 bark samples were collected bi-monthly over a 12-month period to perform targeted 1H NMR based metabolomic analyses to determine the sucrose concentration of each sample. Fluctuations in sucrose concentrations occurred at every sampling date, however, sucrose dynamics in the bridge-grafted trees appeared to be restored after one year.

Cross-pollen parents can affect fruit set and yield, and can influence fruit and seed characteristics of many tree crops. Available carbohydrates also limit fruit set and yield, and tree carbohydrates can be manipulated by girdling trees and by defoliation. We investigated how different macadamia cross pollen-parents and the availability of carbohydrates interact to modify macadamia fruit set, kernel yield and kernel size. We manipulated tree carbohydrates by selecting different branch sizes and girdling branches on macadamia cultivar ‘HAES 246’ (‘246’) maternal trees. We applied pollens from two different commercial cultivars, ‘HV A16’ (‘A16’) and ‘HAES 814’ (‘814’) in two experiments. In Experiment 1, two branch sizes, 150 leaves and 500 leaves were girdled. In Experiment 2, three branch sizes, 150 leaves, 300 leaves and 500 leaves were both girdled and ungirdled. Final fruit set and kernel yield per branch were significantly higher on the girdled 500 leaf branches compared with the girdled 150 leaf branches in both experiments (P

The effect of carbohydrate supply on stem CO2 efflux and its temperature sensitivity is crucial in predicting forest carbon cycling under climate change and forest management but has been rarely reported. In this study, we altered carbohydrate supply via stem girdling and investigated the effect of nonstructural carbohydrate concentration on stem CO2 efflux and its temperature sensitivity in Chinese fir and sweetgum trees in spring and winter. The stem CO2 efflux of Chinese fir increased significantly above the girdle in spring and winter, but decreased below the girdle in winter. The stem CO2 efflux of sweetgum increased above the girdle and decreased below the girdle in spring but not in winter. Seasonal variations in the response of stem CO2 efflux to girdling were associated with the changes in stem soluble sugar and starch concentration, especially in sweetgum tree. Girdling altered Q10 of the stem CO2 efflux, and this effect was dependent on location, season and species. Compared with the Q10 of the stem CO2 efflux in non-girdled trees, that of CO2 efflux in Chinese fir increased by 45% above the girdle but decreased by 16% below the girdle in winter. These values also exhibited 6% and 11% responses in spring. By contrast, the Q10 of the stem CO2 efflux in sweetgum increased by 95% above the girdle and decreased by 45% below the girdle in spring. However, these values were nearly constant in winter. We concluded that the effect of carbohydrate supply on stem CO2 efflux and its temperature sensitivity depends on season and species. Therefore, the vital role of carbohydrate supply that regulates stem CO2 efflux and its temperature sensitivity should be considered for the understanding and modeling of forest carbon cycling response to forest management, especially under global climate changes.

Black bear (Ursus americanus) damage to trees in the Pacific Northwest is common, although volume and economic losses are unknown. Common measures to quantify bear damage to conifers at large scales rely solely on aerial estimates of red tree crowns (caused by complete girdling) and broad assumptions about stand characteristics. We surveyed 122 vulnerable stands in the Coast Range and western Cascades of Oregon using both aerial surveys and ground surveys. Then, we modeled 4 damage scenarios (Salvage; Total Loss; Root Disease; and Combined Damage) with the Forest Vegetation Simulator (FVS) growth and yield model and the Fuel Reduction Cost Simulator (FRCS). Damage polygons, digitized in real time from aerial surveys identifying red (dead or dying) tree crowns, overestimated bear damage by approximately 5-fold due to misclassification with root disease, and failed to detect partially peeled trees that contributed to economic loss. Damage polygons assessed from the air generally did not include red crowns, and were a mean distance of 58.8 m (SE = 8.8) from damage polygons’ outer edges to the nearest red crown. We accounted for mortality and volume losses from partially girdled trees that did not show red crowns in our Salvage scenario, whereas we assumed that all bear-peeled trees resulted in complete loss in the Total Loss scenario. At the landscape scale, economic loss was ≤0.35% of net present value under both damage scenarios, while processing bear damage trees (Salvage) was the most efficacious option. At the landscape scale, our worst-case scenario (Total Loss) resulted in an estimated loss of $56/ha to bear damage, 10-fold less than a previously reported estimate of $585/ha. Root disease was a more prevalent damage agent than bear damage but did not affect net present value at harvest. The majority (92%) of bear damage observed in ground surveys was older (>2 yrs) and existed at a low frequency (1.5 bear damaged trees/ha) and severity across the landscape. Our results suggest that black bear damage is not uniformly distributed and that perceived impact varies with spatial scale. On-the-ground monitoring of the status of bear damage across the western Oregon landscape will identify hot spots of severe peeling and provide an understanding of these changes over time.

Ecological forestry is a management approach that uses natural disturbance processes as models for designing silvicultural prescriptions that restore or sustain ecosystem biodiversity and function in actively managed forests. We evaluated how a novel ecologically-based multi-cohort silvicultural treatment affects the soil microbial community (SMC) and tested whether supplemental dead wood in the form of girdled trees alters these effects. We also tested SMC function by measuring soil CO2 flux over multiple growing seasons, and examined if these patterns were related to soil microbial groups. Our experimental harvests were conducted in second-growth northern hardwood forests in northern Wisconsin, USA. Treatments included a modified shelterwood harvest (SH), a shelterwood harvest plus dead wood supplementation (SH + CWD), and an unharvested control; here we report responses three to five years post-treatment. The SMC composition (determined using PLFA) in both harvests was significantly different from the control, a difference driven by greater bacterial abundance in the harvested areas, and particularly by gram negative bacteria in SH. Microbial community composition was not significantly different between the two harvests (SH and SH + CWD). Total soil respiration was significantly lower in SH than in the control and SH + CWD treatments, a difference most likely driven by a reduction of the autotrophic respiration component in SH treatments due to harvesting, while in the SH + CWD treatment roots from living girdled trees contributed to autotrophic soil respiration. The relationship between the SMC and soil respiration varied with treatment and season. In general, soil respiration in the unharvested controls was most significantly correlated with microbes that relate to autotrophic respiration sources, while respiration in SH + CWD was most significantly correlated with heterotrophic microbes. These results indicate that, although the SMC composition was affected by forest harvesting practices incorporating live and dead biological legacies, supplementing the number of standing dead trees through girdling and felling maintained SMC function, as measured through total soil respiration, an indicator of some important aspects of ecosystem function.

Constructed wetland (CW) wastewater treatments could be potential hotspots of greenhouse gas emissions to the atmosphere when removing pollutants, and the existence of wetland plants is an important factor in carbon and nitrogen cycling in CWs. In this study, the wetland mesocosms planted with Phragmites australis were conducted by using the novel plant-girdling method to assess the role of plants in potential O2, N2O, CO2 and CH4 production and transport in treating wastewaters with and without carbon sources. The system with girdling plant showed an obvious decrease of O2 release, but the higher O2 release rates of 157.78 mg O2 m-2 d-1 was obtained with an addition of carbon source. Average values of N2O, CO2 and CH4 fluxes in wetland mesocosms were 0.85 mg N2O m-2 d-1, -152.4 mg CO2 m-2 d-1 and 0.31 mg CH4 m-2 d-1, respectively when girdling and adding carbon source. Girdling plants and adding carbon source facilitated the removal of organics and nitrogen. Our study indicated that girdling wetland plants stimulated transformation of organics and nitrogen by net oxygen release from plants, but it could bring a raising greenhouse gas emission, which provided new slights into an improved understanding of wetland plants functioning in greenhouse gas transport and pollutant removal in CWs for wastewater treatment.

Fruit abscission is largely governed by carbohydrate supply, and carbohydrate shortage intensifies fruit abscission. Understanding cues from the starving fruit that activate the abscission zone (AZ) is an intriguing research subject and important for control fruit abscission. In this study, starvation stress generated by girdling and defoliating the bearing shoots was used to explore the cues from the starving fruit that triggers abscission in longan. The starving fruit abscised quickly within 5 days. However, removing the starving fruit induced even faster AZ activation with greater ethylene production in the pedicel. Abscission of the defruited pedicel was strongly suppressed by IAA, slightly by ethylene action inhibitor, silver thiosulfate (STS), but not by GA3 or zeatin. Both IAA and ABA concentrations in the starving fruit and the pedicel were significantly reduced compared with the control. IAA exudation from the starving fruit was significantly lower, while IAA oxidase activity in the fruit was higher. The activity of plasma membrane H+-ATPase (PM H+-ATPase) in the fruit and the pedicel was not significantly affected by carbohydrate starvation, while that of PM Ca2+-ATPase in both organs was significantly reduced by starvation. The results suggested that the starving fruit seems not send abscission-promoting signal e.g. ABA or ethylene, but sends weakened abscission-suppressing signal, IAA, to the AZ. The weakened capacity of starving fruit to export IAA is related to increase in IAA deactivation and reduction in PM Ca2+-ATPase activity. The reduced IAA in the AZ leads to increased sensitivity to ethylene synthesized in situ in the pedicel, which activates the AZ under starvation.

Eggplant seedling production in homestead nurseries of farmers in Jamalpur (Bangladesh) is greatly compromised by damping-off. Therefore, farmers often do not have enough seedlings to transplant. Effective treatments of soil and seed to reduce disease pressure in the nurseries are available but little is known on the relative contributions of soil-borne and seed-borne pathogens to damping-off and on how nursery management can integrate management options under farmers' conditions. A 2-year nursery study was conducted in consecutive seasons, jointly with farmers and using farmers' preserved seed and farmers' nurseries subject to damping-off problems. Year 1 involved a single nursery, Year 2 nine nurseries. The following treatments were tested: Trichoderma harzianum as soil amendment combined with seed treatment using either hot water or Carbendazim and farmers' conventional practice: curative spraying after appearance of damping-off. In Year 1, a control (no intervention) treatment was also included. Emergence of seedlings, incidence of damping-off, seedling performance variables and farmers' appreciation of seedling vigour were recorded. Soil treatment with T. harzianum combined with seed treatment with hot water increased seedling emergence and produced 25–64 percentage points more healthy seedlings than farmers' conventional practice. This combined treatment also improved seedling performance (height, root length, lateral root development), and reduced stem girdling, a symptom associated with disease infection of transplants. To determine the contributions of nursery soil and farmers’ seed to damping-off, blotter and in vitro studies in the laboratory and tray studies in a screen house were performed. Soil proved to be the major pathogen source and treating nursery soil with T. harzianum had the largest positive effect on seedling performance, both reducing damping-off and enhancing seedling growth.

Understanding how soil processes, belowground plant and fungal species composition, and nutrient cycles are altered by disturbances is essential for understanding the role forests play in mitigating global climate change. Here we ask: How are root and fungal communities altered in a mid-successional forest during shifts in dominant tree species composition? This study utilizes the Forest Accelerated Succession ExperimenT (FASET) at the University of Michigan Biological Station (UMBS) as a platform for addressing this question. FASET consists of a 39-ha treatment in which all mature early successional aspen (Populus spp.) and paper birch (Betula papyrifera) were killed by stem-girdling in 2008. Four years after girdling, neither overall fungal diversity indices, plant diversity indices, nor root biomass differed between girdled (treated) and non-girdled (reference) stands. However, experimental advancement of succession by removal of aspen and birch resulted in 1) a shift in fungal functional groups, with significantly less ectomycorrhizal fungi, 2) a trend toward less arbuscular mycorrhizal fungi, and 3) a significant increase in the proportion of saprotrophs in girdled stands. In addition to shifts in functional groups between treated and untreated stands, ectomycorrhizal fungi proportions were negatively correlated with NH4+ and total dissolved inorganic nitrogen (DIN) in soil. This research illustrates the propensity for disturbances in forest ecosystems to shift fungal community composition, which has implications for carbon storage and nutrient cycling in soils under future climate scenarios.

Matsucoccus macrocicatrices Richards (Hemiptera: Matsucoccidae) is the only species within this genus that feeds and reproduces on eastern white pine (Pinus strobus L.), and at the time of its description, was not observed or known to cause serious damage. With eastern white pine dieback occurring extensively throughout the Appalachian Mountains, researchers are now in search of the contributors to this dieback phenomenon. Since its recent discovery (2007) far outside its historical range, M. macrocicatrices, and cankers associated with Caliciopsis pinea Peck, are regularly present on symptomatic trees throughout the range of eastern white pine. Little is known about the relationship between M. macrocicatrices and the fungal cankers commonly found on eastern white pines expressing dieback symptoms. For this study, we evaluated the relationships between both focal organisms and the extent of dieback symptoms on tree seedlings to identify contributing factors affecting symptomatic trees. We assessed the insect-pathogen complex on 270 eastern white pine seedlings from nine states that include the Appalachian Mountain range. There were positive correlations between M. macrocicatrices and seedling dieback, cankers and seedling dieback, and M. macrocicatrices and cankers in both the southern and northern portions of the Appalachians. About 95% of the observed M. macrocicatrices cysts and shells were associated with cankers, especially C. pinea-dominated cankers, which were exceptionally abundant on severely affected seedlings. The most prevalent fungi isolated from cankers without apparent fruiting bodies of C. pinea were in the genus Phaeomoniella. Trials were conducted to test the pathogenicity of C. pinea and other fungal isolates. Of the 15 fungal species tested, C. pinea was the only pathogenic species that formed girdling cankers on eastern white pine seedlings. We postulate that there is a facultative relationship between M. macrocicatrices and C. pinea, forming an insect-pathogen complex that is contributing to eastern white pine dieback and significantly impacting its regeneration dynamics in North America.

In Europe, enhancing the amount of dead wood, and thereby promoting habitats for saproxylic species, is one of the most commonly applied restorative treatments in intensively managed forests. This study examines whether the different tree-level treatments utilized to increase the amount of dead wood (girdling, chainsaw felling, and uprooting) have an effect on the wood-inhabiting fungi in the logs of Scots pine (Pinus sylvestris). We also investigate whether the structure (diversity and composition) of these communities differ from those that occur in pine wood substrates that have been uprooted naturally. The study was conducted within currently protected forests that have been previously managed for timber production. Both fungal DNA (for sequence-based identification) and the presence of sporocarps of polypore fungi were surveyed from the logs. Based on the results, greater number of species were associated with the girdled logs compared to the other types of dead wood. The method of felling the trees (uprooting vs. chainsaw-felling) also resulted in differences in community composition, but this mainly concerned the sporocarp occurrence of polypore fungi. Fungal communities on naturally uprooted dead wood had more variation to the restored logs. Overall, our results suggest that restoration of dead wood can provide substrates for many fungi, including Red Listed polypores, and successfully contribute to achieving some of the restoration targets. However, to capture most of the variation in natural fungal communities, several methods should be used together when artificially increasing the amount of dead wood in forest ecosystems.

Standing dead trees, or snags, represent post-disturbance biological legacies in forest ecosystems, and intentional creation of new snags is increasingly common during forest treatments. The abundance, volume, size, and distribution of snags can affect wildlife communities and stand-level biological diversity. Characteristics such as the wood properties of different tree species, environmental conditions, and cause of tree death (e.g., insects, disease, senescence, wind, fire) can influence decomposition and subsequent use of snags by wildlife. The objectives of this study were to characterize decay patterns in jack pine (Pinus banksiana) snags that had been killed by prescribed fire, topping, and girdling and determine the effects of these treatments on subsequent snag use by subcortical insects and primary cavity-nesting birds. The prescribed fire, topping, and girdling treatments were implemented in 2003, 2004, and 2007, respectively; bird excavations were quantified in 2014 and insect activity was measured in 2016. One-way analysis of variance tests were used to examine any differences among treatments in snag characteristics, decay characteristics, past insect activity, and past use by birds. An information theoretic approach to model selection was then used to rank potential predictors of bird foraging activity and cavities. The topping treatment had unique decay characteristics relative to the other two treatments; topped snags had the highest levels of past insect colonization, were softer, and had higher proportions of loose bark remaining on the boles. Trees killed by prescribed fire had the greatest number of foraging excavations and cavities. Girdled snags had the lowest evidence of past insect colonization and showed different levels of decay and insect use at different vertical positions on the snag bole. Comparison of candidate models showed that a model containing treatment type alone was the highest ranked when predicting foraging by birds, while snag diameter was the highest ranked when predicting the presence of cavities. A model containing treatment and snag density was also a highly ranked for predicting cavity presence. Our findings suggest that different jack pine snag treatments result in unique decay trajectories that may influence snag use by an array of wildlife taxa. Our characterization of three snag creation treatments can also inform options for generating snags, depending on the desired outcome, when management for biological legacies and wildlife habitat is of interest within mixed-pine forests of the Great Lakes region.

There is a strong genetic background control of the content and composition of anthocyanins in grapes, therefore the anthocyanin profile is a suitable parameter for fingerprinting. Anyway, several studies showed how non-genetic factors such as environmental conditions and viticultural practices, can influence the distribution and the concentration of anthocyanins. A statistical analysis performed considering the influence of thinning and girdling alone or in combination on Sugrathirteen ® vines showed how the investigated factors significantly influence various physical-chemical parameters (sugars accumulation, organic acids, etc.) as well as single anthocyanins detected by HPLC. In particular the results show how the treatments were able not only to affect total polyphenols and anthocyanin concentration, but moreover it was possible an analysis of anthocyanins profile variation in relation to the agronomical treatments performed at different timing (berry set and veraison).

Long-distance movement via vascular tissues is an essential step for systemic infection by plant viruses. We previously reported that pre-treatment of Nicotiana benthamiana with acibenzolar-S-methyl (ASM) both suppressed the accumulation of plantago asiatica mosaic virus (PlAMV) in inoculated leaves and delayed the long-distance movement to uninoculated upper leaves. These two effects occurred independently of each other. However, it remained unclear where and when the viral long-distance movement is inhibited upon ASM treatment. In this study, we found that ASM treatment restricted the loading of GFP-expressing PlAMV (PlAMV-GFP) into vascular tissues in the inoculated leaves. This led to delays in viral translocation to the petiole and the main stem, and to untreated upper leaves. We used cryohistological fluorescence imaging to show that ASM treatment affected the viral localization and reduced its accumulation in the phloem, xylem, and mesophyll tissues. A stem girdling experiment, which blocked viral movement downward through phloem tissues, demonstrated that ASM treatment could inhibit viral systemic infection to upper leaves, which occurred even with viral downward movement restricted. Taken together, our results showed that ASM treatment affects the loading of PlAMV-GFP into the vascular system in the inoculated leaf, and that this plays a key role in the ASM-mediated delay of viral long-distance movement.

Plant growth is related to the amount of nutrients that it can acquire and it can be limited by poor root development and nutrient uptake, and low efficiency of nutrient use. Nutrients are not distributed evenly throughout the soil around roots, causing plants to put in action the functioning of the various local and systemic signaling pathways to coordinate adaptative responses to the most diverse types of stresses, among them nutritional limitation. A coordinated array of long-distance signaling mechanisms integrates the communication between shoots and roots, which provide photoassimilates and nutrients, respectively. The use of techniques to study signaling among the most diverse plant species has gained prominence. The main techniques for studying nutrient signaling between shoots and roots are split-root, grafting and girdling. The split-root system is characterized by separating a single root system in two independent compartments, with a common shoot. Split-root has been used for analyzing transcriptional, biochemical, and physiological changes in roots in response to nutritional challenges. Grafting has stood out as an important method concerning signaling mechanisms studies. It still follows the basic principle of cutting and fitting two parts (scion = bud and rootstock = root) from different plants, which merge, grow and develop as a single plant. Most recent studies have been in detecting long-distance signals, their transport, and the factors involved in signaling mechanisms, with particular attention to the role of phytohormones, RNAs, peptides, and proteins. Girdling is an important technique widely used in fruit trees. It consists of the removal of a strip of bark from branches or trunk, affecting different stages of reproductive growth, including flowering and fruiting, development, ripening, and nutritional quality of fruits. The increase in the amount of carbohydrates above the cut induces the expression of genes involved in the metabolism of carbohydrates, favoring the respiratory potential of the stem and branches, as well as the leaf mass per area. The techniques reviewed here allow the monitoring and study of long-distance signaling and relate it to plant development through simple, efficient, and reproducible approaches. They permit researchers to make inferences about the existence, direction, and intensity of the cross-talk between long-distance signaling and nutrients, suggesting that mobile signals and their interactions with individual nutrients exist.

Structural complexity enhancement (SCE) is a forest restoration approach aiming to maintain or increase biodiversity in managed, secondary forests. Whether the diversity of wild bees also benefits from such restoration measures in temperate forests is not well studied. We conducted a restoration experiment in secondary spruce forests on twelve 50 × 50 m plots in the Black Forest National Park in Baden-Wurttemberg, Germany. SCE was carried out on half of the study plots (six) in 2016 comprised create deadwood through girdling and uprooting of 20 spruce trees per plot and thus initiating small gaps. The other six plots were used as control plots with no SCE. Wild bees were sampled in June 2018 and 2019 using coloured pan traps. We hypothesized that creation of deadwood influences bee abundance and richness, especially of aboveground-nesting bees, and thus would also change bee community composition at the plot scale. Furthermore, we assessed the influence of bilberry (Vaccinium myrtillus L.) cover in the plots and areas of meadows and roads of the intermediate surrounding on wild bees. Estimated species richness was higher on restored plots than on control plots. Deadwood originating from restoration increased the number of aboveground-nesting, solitary and cuckoo bee individuals. In particular standing deadwood had a positive impact on bee individuals. Increased bilberry cover and nearby meadow areas increased abundance and richness of the bee community. We conclude that creation of deadwood in coniferous forest is a promising restoration measure to promote solitary, aboveground-nesting bees. Increased light availability through restoration, which promotes bilberry flowering, is also beneficial for bees.

Understanding tree mortality after fires can be used to improve planning of prescribed burning and post-burning salvage logging. This study aims to assess the effects of burning season, fire severity and tree size on the evolution of post-burning mortality of pine species with different fire resistance traits. In 2013, two paired plots (1 ha each) were burned, one in spring and the other in fall, in two mixed-stands of P. sylvestris and P. nigra, and the fire severity and tree size variables were measured. Mortality was assessed individually in a total of 933 pines during the following 3 years post-burning. We modeled the initial (1 year post-burning) and delayed (3 years post-burning) tree mortality using Firth logistic regression and Conditional Inference trees. The probability of dying after burning was lower in P. nigra than in P. sylvestris confirming that P. nigra has higher fire-resistance compared to the moderate fire-resistance of P. sylvestris . Initial mortality was slightly higher for pines burned in spring than for those burned in fall; however, after 3 years the proportion of pines that had died after the fall burns was higher than that after the spring burns. Nevertheless, for the two periods modeled, the likelihood of a pine dying was significantly higher in spring than in fall given a certain level of crown scorch. This suggests that pines with damaged crowns were more likely to die when burning occurred during periods of active growth. However, the higher fire severities at the base of the trees that occurred during the fall burns compared to the spring burns are probably the cause of the higher rates of delayed tree mortality. Higher likelihood of mortality in trees burned in fall, with higher percentages of white ashes in the stem base suggest basal stem girdling as a cause of delayed pine mortality. We can conclude that crown damage is more detrimental when burning occurs during the growth season, while longer combustion times during fall burns may have caused the higher delayed pine mortality in comparison with spring burns.

Cross-pollination increases the number of seedy fruit in a wide range of Citrus cultivars including self-incompatible cultivars such as ‘Nadorcott' mandarin, thereby diminishing the commercial value of the crop. Isolated block planting and whole tree net-covering are some of the techniques applied to increase seedlessness of cross-pollinated varieties. However, in net-covered trees a reduction in yield has been reported. The purpose of this work was to study the spatial distribution of seedy fruit at different distances from other pollen sources, and to evaluate the effect of different fruit set promoting techniques applied to covered trees under commercial field conditions. To this aim, four experiments were carried out in a commercial orchard of ‘Nadorcott' mandarin to assess: a) the spatial distribution of seed number per fruit and seedy fruit under open-pollinated conditions; b) the effect of girdling and gibberellic acid (GA 3 ) application on fruit set and seedless fruit in net-covered trees; and c) seedless fruit number in open pollinated trees treated with GA 3 and consecutive copper sulphate (CuSO 4 ) sprays. A gradual reduction in the percentage of seedy fruit from the pollen source up to 140 m away from where the seedless fruit presented a spatially randomized pattern. Net-covered trees reduced the number of seedy fruit and the number of seeds per fruit, whereas the number of fruits was reduced by 66%. Under nets, single GA 3 spray, but not girdling, impaired fruitlet drop. Six consecutive 25 mg per liter or 50 mg per liter sprays of CuSO 4 reduced the number of fruit per tree, the 50 mg per liter dose increased fruit seedlesness. Single GA 3 25 mg per liter sprays or combined with CuSO 4 reduced the number of seedy fruit with the reduction in fruit per tree.

Leaf chlorosis often develops in low-fruiting (“off”) trees of healthy, severely alternate bearing ‘Nadorcott’ mandarin (Citrus reticulata Blanco) trees in commercial orchards in South Africa, whereas leaves of heavily-fruiting (“on”) trees maintain a healthy green colour. This study investigated the role of fruit load and leaf carbohydrate content on the development of leaf chlorosis in “off” trees under a broad spectrum of source/sink relationships. Leaf chlorosis in “off” trees was mediated by low sink activity, and leaf total chlorophyll content strongly correlated with leaf starch content [r2 = (−)0.74 (P

The early culmination of maximum radial growth (RG) in late spring has been found in several coniferous species in a dry inner Alpine environment. We hypothesized that an early decrease in RG is an adaptation to cope with drought stress, which might require an early switch of carbon (C) allocation to belowground organs. To test this hypothesis, we experimentally subjected six-year-old Norway spruce saplings (tree height: 1.35 m; n = 80 trees) to two levels of soil water availability (watered versus drought conditions) and manipulated tree C status by physically blocking phloem transport at three girdling dates (GD). The influence of C availability and drought on tree growth (radial and shoot growth; root biomass) in response to girdling was analyzed in both treatments. Non-structural carbohydrates (NSCs, soluble sugars and starch) were measured in the stem, root and current leader to evaluate changes in tree C status due to girdling. The main finding was a significant increase in RG of the girdled trees compared to the controls above the girdling zone (UZ). At all girdling dates the RG increase was significantly more intense in the drought-stressed compared with watered trees (c. 3.3 and 1.9-fold higher compared with controls in the drought-stressed and watered trees, respectively), most likely indicating that an early switch of C allocation to belowground occurs as an adaptation to maintain tree water status under drought conditions. Reactivation of the cambium after the cessation of its regular activity was detected in UZ in drought-stressed trees, while below the girdling zone no xylem formation was found and the NSC content was strikingly reduced. Irrespective of water availability, girdling before growth onset significantly reduced the progression of bud break (P < 0.05) and the length of the current leader shoot by −47% (P < 0.01) indicating a reduction in xylem hydraulic conductance, which was corroborated by significantly reduced xylem sap flow (P < 0.001). Based on our findings, we conclude that during the growing season drought stress prioritizes an early switch of C allocation to the root system as an adaptation to maintain adequate tree water status in drought-prone environments.

When an invasive organism targets a dominant tree species, it can trigger unprecedented shifts in forest plant communities. Emerald ash borer (EAB; Agrilus planipennis Fairmaire), an invasive insect that kills by girdling trees, represents a significant threat to North American Fraxinus (ash) species. EAB has already decimated many Fraxinus populations and threatens loss of overstory cover in Great Lakes region wetland forests dominated by Fraxinus nigra (black ash). Canopy treatments, such as clearcutting and group selection, are being evaluated to promote regeneration of non-EAB-host tree species. Studies suggest clearcutting may raise water tables, lower tree regeneration, and shift the composition of woody and herbaceous ground-layer plant communities. However, no empirical research to date has examined the effects of canopy treatments on ground-layer plant communities in F. nigra wetlands. We used a large-scale field experiment in northern Minnesota F. nigra wetlands to examine the response of the woody and herbaceous ground-layer to four overstory treatments: clearcutting, group selection, F. nigra girdling, and unharvested forest. Our objectives were to determine: (1) to what extent established regeneration of associated tree species could be expected to contribute to overstory maintenance under EAB- and management-induced canopy changes; (2) the impact of canopy changes on the composition of the overall woody ground-layer; and (3) the effect of canopy treatments on the herbaceous layer. We found density of established tree regeneration was significantly higher in the clearcut treatment than in the group selection, girdle, and control. Fraxinus nigra had the highest seedling density in all treatments, while Ulmus americana (American elm) was the most abundant non-EAB-host tree species across treatments. Regeneration density of associated tree species varied by treatment and fell short of seedling stocking guidelines. Background variation in experimental blocks exerted a greater influence than treatment on overall woody community composition. Treatment influenced herbaceous layer height, but did not significantly impact total cover. Herbaceous species richness and diversity increased in all treatments, with the clearcut and group selection moving toward greater graminoid cover, while the control and girdling treatment increased in wetland indicator species. Our findings suggest artificial regeneration, combined with herbaceous and shrub competition control treatments, will be necessary to restock F. nigra forests following EAB invasion. Sites with lower abundance of shrub species and higher established tree regeneration should be prioritized for management activities.

The relative importance of belowground and aboveground energy inputs for the decomposer communities in soil remains largely unknown. In particular, no research has been done on the significance of root-derived resources for nematode communities in boreal forests. In two spruce stands in the taiga zone, we set up a field experiment in which girdling of spruce trees and clipping of dwarf shrubs was performed. Root-derived resources were hypothesized to be highly important; accordingly, we expected to observe a suppression of the nematode community after experimental manipulations. To obtain information on the nature of changes in the soil food web, nematode community structure indices were applied. In partial confirmation of our hypothesis, spruce girdling decreased mycorrhizal hyphae biomass as assessed via in-growth mesh bags, as well as the abundance of fungivorous nematodes, mostly of the Aphelenchoides and Filenchus genera. The enrichment index (EI) value decreased, indicating reduction of organic matter inputs into the soil food web, whereas nematode channel ratio (NCR) index value increased, indicating a shift towards domination of the bacterial energy channel. Total nematode abundance, genera richness, and abundance of herbivores, omnivores, and predators did not change in response to spruce girdling. Clipping of dwarf shrubs decreased fungal and bacterial PLFA biomarkers, but did not affect nematode communities. Thus, the resources channeled in soil by the roots of canopy trees are of different relative importance for nematodes having different trophic habits. Fungivorous nematodes are at least partly dependent on root-derived resources, suggesting feeding on ectomycorrhizal mycelium. Rhizodeposits of understory vegetation are likely of low importance for nematodes.

Girdling is a widespread agronomic technique to increase the fruit quality characteristics (e.g. size, solid soluble content [SSC] and colour). However, the information on the fruit metabolic changes related to this practice still remains unclear and fragmentary. Moreover, girdling duration and application time may greatly affect the plant/fruit metabolic responses producing sometimes counterproductive results. Fruit quality, metabolomic and antioxidant analyses were conducted to characterise the effects of two different girdling dates (4- and 2-weeks before the harvest, 4 W and 2 W, respectively) in skin and pulp of red-fleshed plum (Prunus cerasifera var. pissardii). Overall, the pulp metabolism was altered in both 4 W and 2 W Girdling by inducing accumulation of sugars (sucrose and trehalose), sugar alcohols (inositol and xylitol), organic acids (especially some TCA cycle intermediates such as α-ketoglutaric, citric, isocitric, fumaric and malic acid), amino acids (s-alanine and L-proline), anthocyanins and other phenols. In the skin only girdling 4 W showed major significant differences compared to the control increasing the fruit quality characteristics (size, SSC, dry matter and red colour) and showing greater metabolic changes with respect to the controls. Furthermore, the total antioxidant activity was also increased in both skin and pulp respect to other treatment only in Girdling 4 W. This approach could be used with both P. cerasifera plums as well as other red-fleshed fruit species in order to ensure red-fleshed fruits production with a uniform red colouration and higher content of bioactive compounds.

This study aimed to examine the effects of girdling on tomato (Solanum lycopersicum L.) plant growth and fruit development, and identify appropriate girdling time on tomato. Girdling was carried out on tomato main stems at four different girdling time: 0 days after anthesis of the last truss (0 DAA), 7 DAA, 14 DAA, and 21 DAA, respectively. Tomato plants that were not treated with girdling served as the control. Girdling altered carbohydrate allocation to different organs. With more carbohydrates partitioned to fruits, girdling significantly increased the fruit weight and yield, and advanced the commercial harvest time by approximately 10 days in comparison to the control. Due to a lack of carbohydrate supply, root biomass and carbohydrate concentration reduced in the girdled plants. No evident sink feedback inhibition of photosynthesis was observed in leaves after girdling. Considering plant growth and fruit development, the appropriate girdling time was approximately 2–3 weeks after anthesis of the last truss. Our results have demonstrated that the application of girdling on tomato plants can increase fruit size and accelerate fruit development, which provides an effective approach to regulate carbohydrate partitioning in tomato production.

Litchi ( Litchi chinenis Sonn.) is a woody mycorrhizal fruit tree. Hypha and root hairs are the most important structures for nutrition and water absorption in litchi. Girdling is an important technique in litchi cultivation. However, the effects of girdling on arbuscular mycorrhiza (AM) colonization and root hair development remain unknown. To understand the effects of girdling on AM and root hairs in litchi, the carbohydrate content, enzyme activities related to sucrose metabolism, AM colonization, and length and density of root hairs were measured under girdling, wounding and control conditions in the roots of one-year-old seedlings. Results showed that sufficient carbohydrates were available for AM and root hairs in the mycorrhizal roots of litchi in the wounding and control groups. Girdling significantly decreased the concentrations of glucose at 3 days (3D), 1 week (1W), 2 weeks (2W), 1 month (1M) and 2 months (2M) after treatment, of fructose at 3D, 1W, 2W, 1M and 2 M after treatment, of sucrose at 1W, 2W, 1M and 2M after treatment, and of starch at 2W, 1M and 2M after treatment. Consistent with its effects on carbohydrates, girdling significantly reduced arbuscular colonization (1M and 2M) and root hair length (1M). The correlations of arbuscular colonization and root hair length with concentrations of carbohydrates (fructose, sucrose and starch) were significant only under girdling treatment. Under conditions of hexose starvation caused by girdling, litchi seedlings exhibited significantly upregulated neutral invertase activity in sucrose-cleaving parts and downregulated sucrose phosphate synthase and sucrose synthase (synthesis direction) in sucrose synthesis parts. The correlations of arbuscular colonization with levels of sucrose-cleaving enzymes (neutral invertase and acid invertase) and root hair length with levels of sucrose-cleaving enzymes (neutral invertase and acid invertase) were also significant only under girdling treatment. Our findings indicated that AM colonization was more sensitive to carbohydrates than root hair length in litchi seedlings. Furthermore, girdling likely affected AM colonization and root hair length by decreasing the carbohydrate contents and regulating the activities of sucrose-metabolising enzymes.

The defense of conifers against phytophagous insects relies to a large extent on induced chemical defenses. However, it is not clear how induced changes in chemical composition influence the meal properties of phytophagous insects (and thus damage rates). The defense can be induced experimentally with methyl jasmonate (MeJA), which is a substance that is produced naturally when a plant is attacked. Here we used MeJA to investigate how the volatile contents of Scots pine (Pinus sylvestris L.) tissues influence the meal properties of the pine weevil (Hylobius abietis (L.)). Phloem and needles (both weevil target tissues) from MeJA-treated and control seedlings were extracted by n-hexane and analyzed by two-dimensional gas chromatography-mass spectrometry (2D GC-MS). The feeding of pine weevils on MeJA-treated and control seedlings were video-recorded to determine meal properties. Multivariate statistical analyses showed that phloem and needle contents of MeJA-treated seedlings had different volatile compositions compared to control seedlings. Levels of the pine weevil attractant (+)-α-pinene were particularly high in phloem of control seedlings with feeding damage. The antifeedant substance 2-phenylethanol occurred at higher levels in the phloem of MeJA-treated than in control seedlings. Accordingly, pine weevils fed slower and had shorter meals on MeJA-seedlings. The chemical compositions of phloem and needle tissues were clearly different in control seedlings but not in the MeJA-treated seedlings. Consequently, meal durations of mixed meals, i.e. both needles and phloem, were longer than phloem meals on control seedlings, while meal durations on MeJA seedlings did not differ between these meal contents. The meal duration influences the risk of girdling and plant death. Thus our results suggest a mechanism by which MeJA treatment may protect conifer seedlings against pine weevils.

Table grapes need of substantial water supply for achieving commercial requirements. Viticulture practices such as girdling (G) and gibberellic acid (GA) application, as well as water supply, can improve table grape quality. The study, which was conducted in two consecutive seasons (2010–2011), aimed to assess the counterbalance effect of these viticulture practices on yield and quality parameters and flavonoids composition in case of a significant and unusual irrigation water reduction (40%) applied to a table grape variety. The data from the two-way ANOVA and PCA analyses indicated that viticulture practices were clearly related to anthocyanins and flavonols variations whereas water management appeared mainly involved in the yield parameters variability. Specifically, the reduced water supply (RWS) decreased the grape yield (−20%) with respect to full water supply (FWS); by contrast GA, G, and G × GA treatments determined an increment of grape production ranging from 10 to 23%, independently from irrigation strategy. Moreover, G, in particular applied to RWS grapes, was able to improve the total soluble solids over titrable acidity (TSS/TA), a ratio strictly related to the quality perception by the consumer. Total anthocyanins were found positively linked to FWS whereas flavanols content was indifferent to water management. Instead viticulture practices seemed to have a greater impact on anthocyanin composition, considering that in RWS grapes under GA condition, higher contents of malvidin and peonidin (mainly responsible for the color stability of the skins) were revealed. Furtheremore, catechins and rutin appeared significantly enhanced by G and G × GA, and GA, respectively. From gathered findings, it can be concluded that suitable viticulture practices can allow a sensible reduction of water supply during table grape growth cycle without detrimental effects on yield and quality.

Trees with root systems established well below grade due to deep planting or soil disturbance are common in urban landscapes, yet the long term effects of buried trunks and subsequent remediation strategies, such as root collar excavation are poorly documented. We evaluated the consequences of deep planting over a 10-year period on tree growth and stability, with and without root collar excavation, for red maple [Acer rubrum L. Red Sunset® (‘Franksred’)] and Northern red oak (Quercus rubra L.) planted at grade or 30-cm below grade. Sleeves to prevent soil-trunk contact were installed around trunks on a subset of deep trees. Root collar excavations were made during the 6th growing season for both species and trees were grown for an additional 4 and 3 growing seasons for red maples and Northern red oaks, respectively. Within two weeks of root collar excavations, pulling tests compared the effect of treatments on stability of red maples. Deep planting generally slowed growth of red maple but had no clear effect on Northern red oak. Root collar excavation had no lasting effect on growth of either species. Approximately 55% of deep red maples and 33% of deep Northern red oaks had roots crossing and in intimate contact with buried trunks, suggesting a potential for future girdling roots. Approximately 25% of deep maples had substantial adventitious rooting. All deep Northern red oaks had new roots emerging just above the first original structural roots but none were clearly adventitious. Trunk sleeves had no effect on growth for either species. Neither deep planting nor root collar excavation resulted in a loss of tree stability compared to trees planted at grade, although failure patterns varied among treatments. Overall, the biggest long term concern for deep-planted trees is the potential for girdling root formation.

Information about reproductive behavior of the olive trees (Olea europaea L.) in regions with lower occurrence of cold is fundamental to the expansion of its economic cultivation. Researches studding the adequacy of management techniques in order to promote flowering in these regions are important. Thus, this research was conducted to evaluated water restriction, girdling and paclobutrazol on flowering and production of olive cultivars. Three experiments were conducted in Federal University of the Jequitinhonha and Mucuri Valleys in Diamantina, Minas Gerais, Brazil. In the first experiment, ‘Arbequina’ olive trees were subjected to water restriction and two environmental conditions. In the second experiment, the girdled branches in different times on flowering and nutritional behavior of ‘Grappolo 541’ and ‘Barnea’ olive trees were evaluated. And in the third experiment, the application of paclobutrazol (PBZ) and the water restriction were studied in the vegetative growth and flowering of ‘Ascolana’ olive trees. The flowering of ‘Arbequina’ olive tree occurred with the averages of minimum temperatures varied from 8.4 to 11.7 °C, in autumn and winter. The girdling at different times did not influence the production of olive trees ‘Barnea’ and ‘Grappolo 541’. The girdled branches had a higher nutrient levels in leaves.The application of paclobutrazol in the soil promoted the reduction in vegetative growth of ‘Ascolana’ olive trees, with increase of flowering and fruiting. The water restriction did not favor the flowering of ‘Arbequina’ and ‘Ascolana’ olive trees and it reduced the effect of PBZ in ‘Ascolana’.

Snag retention is increasingly being incorporated into forest management guidelines. Questions remain, however, in northern hardwood systems regarding factors affecting retention in actively managed stands, the effectiveness of snag creation, and the net effects of snag creation and timber harvesting on snag numbers and sizes. To address some of these questions, we examined the dynamics of natural and created snags within mature, even-aged northern hardwood forests under seven different management scenarios: three Harvest Only treatments, three Harvest Plus (created) Snags treatments, and one untreated Control. We found tree diameter, tree species, and stand treatment status (i.e., managed or Control) to be related to the retention of natural snags, created snags, or both. Snags were less likely to remain standing if they had smaller diameters, were species with relatively rapid decay rates, or were found in stands that had been logged. We found girdling trees to be an effective method of dead wood creation, although trees took longer to die than we expected. At least 84% of girdled trees had died in most stands within 4.5 years of girdling, and 30–77% of girdled trees were still standing 5.5 years after treatment. Comparison of net effects of snag creation and timber harvesting among treatments showed that managed stands, on average, experienced net snag losses compared to untreated Controls. These losses were statistically significant for all snag sizes, but not for large snags alone (i.e., dbh ⩾25.4 cm). Active management prescriptions that included snag creation demonstrated the potential to mitigate snag losses, with the extent of mitigation varying with the type of management. Surprisingly, mitigation was primarily driven by significantly greater natural snag recruitment in Plus Snags treatments, potentially due to competition from girdled trees that had not yet died. Our results may help inform the development of snag management guidelines in even-aged, second-growth northern hardwood systems for forest managers who are interested in enhancing the structural complexity of these forests.

Tree canker diseases are mainly caused by necrotrophic fungal pathogens, which induce canker lesions, wilting, or dieback in many species. We hypothesized that canker-associated canopy dieback is related to functional failure of the phloem and cambium, carbon starvation and/or hydraulic failure. Using a girdling and inoculation system, we evaluated gas exchange and hydraulic parameters, concentrations of non-structural carbohydrates (NSCs), leaf characteristics, stem phenotyping and symptoms of 6-month-old poplar saplings with Botryosphaeria or Valsa canker disease. Pathogen inoculations inhibited callus formation and phloem regeneration and altered the physiological parameters, water potential, NSC content in stems, and symptoms on leaves and stems, while the girdling-only control did not. Results suggest that the functional and structural integrity of the phloem and cambium play crucial roles in the pathogenesis of canker disease. Botryosphaeria canker decreased photosynthetic rate (−54% to −75%), stomatal conductance (−71% to −80%) and transpiration rate (−58% to −66%), while Valsa canker decreased photosynthetic rate (−53% to −83%), stomatal conductance (−71% to −87%) and transpiration rate (−53% to −76%) at 20, 25, and 30 days after inoculation. Results suggest that the two fungal pathogens induce carbon starvation by inhibiting photosynthesis. The leaf water potential was higher and the change in specific hydraulic conductivity was smaller in the canker region than in the adjacent regions, while the NSC content was lower in the region below cankers than above them, suggesting that the fungal pathogens caused poplar canopy dieback by initially inducing carbon starvation, not hydraulic failure.

Flower induction in iron walnut (Juglans sigillata) is a complex and highly regulated process involving multiple signal pathways to ensure flower bud formation in the subsequent year. However, the underlying molecular mechanism of the induction remains unknown. Girdling is an effective method for inducing flower bud formation in iron walnut. In this study, comparative transcriptome profiles between girdled (G) and ungirdled (unG) materials on the same tree were used to identify the signal pathway involved in flower bud induction by girdling in iron walnut. The results showed that genes related to starch and carbohydrate metabolism, photosynthesis, and hormone signals, including pectinesterase (PAE), trehalose 6-photosphatase (TPP), α-aminolase (α-AL), atpF, and auxin response factor ARF9, participated in the induction process after girdling. Expression pattern of genes related to sugar metabolism revealed that sugar was the initial signal for flower induction and that photosynthesis increased after girdling, influenced by the carbon source–sink relationship. Hormone signalling networks including auxin, abscisic acid (ABA), and brassinolide also contributed to flower bud induction of iron walnut. Auxin played an important role in tissue regeneration and flower induction after girdling. ABA directly participated in flower induction. Gene expression pattern similarities between ABA and sugar metabolism signals indicated that ABA may also be involved in sugar regulation, in turn regulating floral induction. In summary, flower induction after girdling in iron walnut is mainly regulated by a polygenic network centred on sugar and hormone signals.

Under non-inductive environmental conditions longan trees (Dimocarpus longan Lour.) were subjected to potassium chlorate (KClO3) applications, solely or in combination with shoot girdling or defoliation treatments, to induce flowering. Treated trees showed visible flower buds four weeks after treatment, while untreated reference trees remained vegetative. Trees treated with KClO3 solely and in combination with apical shoot defoliation flowered terminally at the shoot apex. KClO3 treatment in combination with girdling caused flowering exclusively at the lateral buds immediately below the girdle. Results from histological and hormone analyses are integrated with longan flowering gene expression data to build a comprehensive time course model for chemical flower induction in longan. The increased cytokinin concentration in shoot apex tissues, likely due to de novo biosynthesis and translocation, corresponds with transient up-regulation of the flower promoting gene Dimocarpus longan FLOWERING LOCUS 1 (DlFT1) in mature leaves after KClO3 treatment. Both occur during the presumed period of flower induction approximately at 10 days after treatment. Subsequently, and with some delay floral homeotic genes Dimocarpus longan APETALA 1 (DlAP1) are up-regulated in the buds indicating flower bud development, which coincides with visible floral meristems in histological specimen. The specific cytokinin accumulation and flowering gene expression pattern suggest a tight orchestration of hormonal and genetic pathways in chemically induced longan.

Chestnut blight cankers caused by the fungal pathogen Cryphonectria parasitica on infected American chestnut trees can be invaded by hypoviruses that infect C. parasitica mycelia. Hypoviruses lower pathogen virulence (i.e. hypovirulence) and decrease the probability of stem girdling. Cankers also are susceptible to invasion by non-C. parasitica fungi; however, the influence of invading fungi on disease severity is unknown. Fungi may antagonize C. parasitica growth and combine with hypovirulence to further reduce the probability of stem girdling. We conducted a survey to investigate how spatial and temporal dynamics of the fungal community within cankers correlate with canker severity and the likelihood of girdling. Cankers from six American chestnut populations were monitored from 2012 to 2016. We found that the spatial distribution of the fungal community within a canker resembled a mosaic that increased in fungal diversity over time. Cankers with increased fungal diversity were not associated with higher stem survivorship over time, compared to cankers with abundant hypovirulence in recovering chestnut populations. Fungal communities also were unstable, and cankers on surviving trees containing hypovirulence consistently were invaded by non-C. parasitica fungi. Our results suggest that canker communities are not stable, and volatility of the fungal community indicates that cankers can change quickly from less severe to more severe cankers through loss of hypovirulence. Non-C. parasitica fungi may facilitate canker expansion through greater inhibition of hypovirulent C. parasitica relative to virulent C. parasitica, which may permit virulent C. parasitica to escape hypovirus infection and resume rapid canker expansion.

Pre-harvest growing conditions during the development of fruit have impacts on fruit quality at the time of harvest and during storage. These impacts may result in differences in the skin properties of the fruit and some sub-surface cellular structural changes, which have potential effects on postharvest fruit quality and storability. Optical coherence tomography (OCT) is a non-destructive imaging method that enables acquisition of three-dimensional (3D) images of sub-surface structures of semi-transparent and turbid objects. This technology is a potential tool to provide new information about the structural nature of horticulture products. This work used five commercial kiwifruit cultivars, ‘G3’, ‘G9’, ‘G14’, ‘Hort16A’ and ‘Hayward’, where ‘Hayward’ was also manipulated with different orchard management practices (crop load and girdling), to investigate the properties of the layers of structures immediately underneath the periderm. Fruit samples were harvested at commercial maturity and then 3D OCT images of the skins were captured prior to fruit quality assessment. An automated image processing protocol was established to enable visualisation and characterisation of larger near skin cellular structures in the outer parenchyma tissue. There was no obvious differentiation between the observed large cells and the stone cells that are present in Actinidia chinensis cultivars. Significant differences in the microstructures of the sub-surface cells were found amongst five commercial kiwifruit cultivars. In general ‘G3’, ‘G14’ and ‘Hayward’ had larger and greater numbers of large sub-surface cells than ‘G9’ and ‘Hort16A’. The volume fraction of large cells in the near skin tissue was lower for the yellow-fleshed cultivars (‘G3’, ‘G9’ and ‘Hort16A’) in comparison to the green-fleshed cultivars (‘G14’ and ‘Hayward’). Low crop load increased maximum large cell length. However, no other effects of crop load and girdling were observed on the microstructures of the large cells in ‘Hayward’. Overall, OCT was an efficient non-destructive technique that can be utilised to reveal the structures of skin and sub-surface cellular layers with high resolution. The developed image processing protocol was suitable for the processing of large data sets with acceptable accuracy. However, more work should be carried out to overcome image artefacts caused by surface lenticels and trichomes. Limitations caused by low penetration depth should also be improved to allow better representation of the whole fruit structure. publisher: Elsevier articletitle: Characterising kiwifruit (Actinidia sp.) near skin cellular structures using optical coherence tomography journaltitle: Postharvest Biology and Technology articlelink: http://dx.doi.org/10.1016/j.postharvbio.2015.08.021 content_type: article copyright: Copyright © 2015 Elsevier B.V. All rights reserved. ispartof: Postharvest Biology and Technology vol:110 pages:247-256 status: published

To investigate the climate impacts on the different components of ecosystem respiration, we combined soil efflux data from a tree-girdling experiment with eddy covariance CO2 fluxes in a Mediterranean maritime pine (Pinus pinaster) forest in Central Italy. 73 trees were stem girdled to stop the flux of photosynthates from the canopy to the roots, and weekly soil respiration surveys were carried out for one year. Heterotrophic respiration (RH) was estimated from the soil CO2 flux measured in girdled plots, and rhizosphere respiration (RAb) was calculated as the difference between respiration from controls (RS) and girdled plots (RH). Results show that the RS dynamics were clearly driven by RH (average RH/RS ratio 0.74). RH predictably responded to environmental variables, being predominantly controlled by soil water availability during the hot and dry growing season (MayeOctober) and by soil temperature during the wetter and colder months (NovembereMarch). High RS and RH peaks were recorded after rain pulses greater than 10 mm on dry soil, indicating that large soil carbon emissions were driven by the rapid microbial oxidation of labile carbon compounds. We also observed a time-lag of one week between water pulses and RAb peaks, which might be due to the delay in the translocation of recently assimilated photosynthates from the canopy to the root system. At the ecosystem scale, total autotrophic respiration (RAt, i.e. the sum of carbon respired by the rhizosphere and aboveground biomass) amounted to 60% of ecosystem respiration. RAt was predominantly controlled by photosynthesis, and showed high temperature sensitivity (Q10) only during the wet periods. Despite the fact that the study coincided with an anomalous dry year and results might therefore not represent a general pattern, these data highlight the complex climatic control of the respiratory processes responsible for ecosystem CO2 emissions. © 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Emerald ash borer, Agrilus planipennis Fairmaire , has become the most destructive forest insect to invade North America. Unfortunately, tactics to manage A. planipennis are limited and difficult to evaluate, primarily because of the difficulty of detecting and delineating new infestations. Here we use data from a unique resource, the SL.ow A.sh M.ortality (SLAM) pilot project, to assess whether treating a small proportion of trees with a highly effective systemic insecticide or girdling ash ( Fraxinus spp.) trees to serve as A. planipennis population sinks can result in discernable effects on A. planipennis population growth or ash mortality. Components of the SLAM pilot project included an extensive inventory of ash abundance across a heterogenous area encompassing >390 km 2 , treatment of 587 ash trees with a highly effective systemic insecticide, and girdling 2658 ash trees from 2009 to 2012. Fixed radius plots were established to monitor the condition of >1000 untreated ash trees throughout the area from 2010 to 2012. While only a very small proportion of ash trees in the project area were either treated with insecticide or girdled, both tactics led to detectable reductions of A. planipennis densities and protected ash trees in areas surrounding the treatments. The number of trees treated with the systemic insecticide reduced larval abundance in subsequent years. In contrast, the area of phloem in the insecticide-treated trees had no discernable effect on A. planipennis population growth, indicating that the number of treated trees was more important than the size of treated trees. Significant interactions among girdled trees, larval density, and the local abundance of ash phloem indicate girdling trees has a positive, but complex potential as a management tactic.

This paper examined the route of water supply into soybean nodules through the new visualization technique of time of flight secondary ion mass spectrometry (Tof-SIMS) cryo system, and obtained circumstantial evidence for the water inflow route. The maximum resolution of the Tof-SIMS imaging used by this study was 1.8 μm (defined as the three pixel step length), which allowed us to detect water movement at the cellular level. Deuterium-labeled water was supplied to soybean plants for 4 h and the presence of deuterium in soybean nodules was analyzed by the Tof-SIMS cryo system. Deuterium ions were found only in the endodermis tissue surrounding the central cylinder in soybean nodules. Neither xylem vessels nor phloem complex itself did not indicate any deuterium accumulation. Deuterium-ion counts in the endodermis tissue were not changed by girdling treatment, which restricted water movement through the phloem complex. The results strongly indicated that nodule tissues did not receive water directly from the phloem complex, but received water through root cortex apoplastic pathway from the root axis.

Accidental (strimmer, mower) or malicious girdling of ornamental trees is a frequent and underestimated problem in urban landscapes. No guidelines exist for landscape managers on the likelihood of fatal damage according to time of girdle, i.e., season (spring, winter) and extent of girdling. This report investigated the effect of stem girdling (0%, 25%, 50%, 75%, 100%) performed either during winter or spring on semi-mature birch ( Betula pendula Roth.) and English oak ( Quercus robor L) trees over a five-year period. 1. All English oak survived any amount of girdling irrespective if girdled in spring or winter. Silver birch was more sensitive to girdling with 100% and 40% mortality recorded after a 100% winter and spring girdle, respectively. 2. Tree vitality (leaf chlorophyll fluorescence, leaf chlorophyll content, crown leaf yellowing, nitrogen content) and growth (girth increment, die-back, number of epicormics above and below the girdle) of both tree species was not detrimentally affected following a 25% and 50% girdle. 3. Epicormic production was more pronounced in English oaks compared to silver birch. 4. Spring girdled oak typically had lower tree vitality and growth values than winter girdled trees indicating an influence of time of girdling. Such a response was not recorded in silver birch where time of girdling induced similar effects on tree growth and vitality. 5. Growth and vitality measurements of surviving trees of both species were, in virtually all cases, statistically comparable with non-girdled trees by the end of the third growing season. Such a result indicates girdling >50% influences growth and vitality of both English oak and silver birch for three years.

Litchi ( Litchi chinensis Sonn. cv. Hong Huay) is one of the most economically important fruit products in Thailand, especially in the highlands of Chiang Mai where litchi can have natural off-season flowering even during the rainy season (June to August). The off-season production of litchi is not a common practice in the region because the physiological responses of litchi trees to flower induction techniques are still unclear. Therefore, we aim to use Random Forests (RF) as a tool to understand the effects of horticultural techniques on plant hormone dynamic or generative shoot development. A field experiment was conducted considering four horticultural treatments, namely (1) control, (2) girdling, (3) foliar spraying with 1% of monopotassium phosphate (0-52-34) and ethephon 800 mg/l, and (4) combination of girdling and foliar spraying. The girdling was applied at the end of leaf development stage. Foliar spray was applied three times at 7-d intervals from 14 days after girdling. Random Forests (RF) was applied to compute the percentage of flowering from plant hormone concentrations observed on 0, 7, 21, 35, 49, 56 and 63 days after the treatment, and to evaluate variable importance to illustrate physiological responses to horticultural treatments. In the field experiment, the three horticultural techniques could induce off-season flowering, while untreated trees had no flower, but leaf flushing. The RF model showed fair performance for modelling the percentage of flowering. The variable importance illustrated the effects of plant hormones in different tissues (i.e. wood, bark, leaves and apical bud) and timing (i.e. sampling dates). The variable importance of the total cytokinins and zeatin/zeatin riboside were observed to be high in wood, leaves and apical bud, while the importance of auxin in bark, wood and apical bud was found to be low on day 35. The RF model could present additional information for a deeper understanding of plant hormone dynamics in plant tissues and critical timing required for flower induction, which can be used for better and improved farmers’ management and practices in the future.

Sprouting is recognized as an important genet persistence strategy for clonal woody plants, but the role of sprouting may differ between species and between sexes, depending on physiological integration. We tested the effect of physiological integration on the mortality, recruitment and growth of the sprouting male and female ramets of two closely related dioecious shrubs of Lindera, in a field experiment using girdling manipulation. Although between-sex differences observed were obscure, we found between-species differences in the sprouting patterns. The rates of ramet mortality and recruitment were significantly lower for L. praecox than L. triloba. In L. praecox genets, the ramet production was low, and the main ramets might actively translocate assimilates towards the small sprouted ramets, which then facilitates high ramet growth and survival (sprout-nursing strategy). Meanwhile, in L. triloba genets, although many ramets were recruited, assimilate translocation from the main ramets to the sprouted ramets might be less abundant, which causes high ramet mortality (sprout-turnover strategy). For a more general knowledge of the various sprouting strategies in clonal plants, our study demonstrated that inter-specific comparisons using girdling experiments at the whole-plant level could reveal the role of physiological integration on the link between the sprouting pattern and above-ground structures of clonal plants.

The skin is the physical barrier between the fruit and the environment in which it develops. Environmental conditions during fruit development have a large influence on fruit quality, both at the time of harvest and during subsequent storage. It is hypothesized that some features of the skin and sub-epidermal tissues could provide information about the past growing conditions to which the fruit was exposed and therefore be of predictive value for storage quality. In this study, five commercial kiwifruit cultivars (‘Hayward’, ‘Hort16A’, ‘G3’, ‘G9’ and ‘G14’) were studied, and ‘Hayward’ fruit were manipulated during growth with different light or cultural practices. After harvest at horticultural maturity, X-ray micro computed tomography (µCT) was used to investigate features of the skin and the immediate parenchyma tissue. Despite orchard management practices (crop load and girdling) being observed to effect macro fruit quality parameters (mass, firmness, SSC, and DM), differences in microstructure (e.g. porosity) caused by these practices were not observed. However, porosity and pore size were found to be highly variable between cultivars. The thickness of dense sub-epidermal tissue could be readily measured and the 3-D distribution of raphide bundles was visible as high density particles distributed within the parenchyma. Overall, µCT was found to be a powerful technique to explore fruit epidermal and sub-epidermal structures in three dimensions at a micro level. However, the length of time required for data capture and analysis and the large number of samples required to overcome natural variation within horticultural products need to be considered. Future work may define the impact of differences in porosity or sub-epidermal anatomy on kiwifruit physiology (e.g. firmness change or sensitivity to low oxygen storage atmospheres). With this information, µCT could be used as a screening tool during plant breeding, or to determine the response to agronomic treatments, without conducting lengthy storage trials. publisher: Elsevier articletitle: Microstructural characterisation of commercial kiwifruit cultivars using X-ray micro computed tomography journaltitle: Postharvest Biology and Technology articlelink: http://dx.doi.org/10.1016/j.postharvbio.2014.01.012 content_type: article copyright: Copyright © 2014 Elsevier B.V. All rights reserved. ispartof: Postharvest Biology and Technology vol:92 pages:79-86 status: published

Sugars accumulated in fruits are synthesized in leaves and translocated into the fruits. Quantitative measurement of phloem sap flow would enhance our understanding of the phenomenon and would facilitate efforts to ensure the production of high-quality fruits. The influence of girdling, which cuts off phloem, on sap flow rate determined using the heat balance method, was investigated in citrus. The present study aimed to measure the flow rates in phloem and xylem sap separately and to investigate the effect of gauge temperature on gauge output accuracy. When the gauge temperature was kept constant, the flow rate was consistent with the amount of water transpired from the branch. Immediately after girdling, the sap flow rate increased in a non-bearing branch, but decreased in a bearing branch. We conclude that the phloem sap flowed basipetally in the non-bearing branch and acropetally toward the fruits in the bearing branch. Regression lines for the sap flow before and after girdling were almost parallel, and the difference in the intercept of the two regression lines can be regarded as the flow rate change caused by girdling. Our results indicate that it is possible to determine separate flow rates for phloem and xylem sap by combining the heat balance method with girdling.

Girdling practice gained attention as a mean to increase crop yields particularly for alternate bearing plants. Data published for ligneous are controversial and mechanisms by which girdling regulates plant growth and photosynthesis for olive tree are still not well elucidated. The physiological modifications induced by shoots girdling, and their effects on the mobilization of assimilates, on the gas exchanges and on antioxidant activity were studied in olive leaves of Meski, Picholine, Chetoui and Koroneiki cultivars. From each ‘ON’ and ‘OFF’ trees, six shoots were selected, 3 of them were girdled and 3 were used as control. Total carbohydrates, alcoholic (Mannitol) and soluble (Glucose, Fructose and Sucrose) sugars, photosynthesis parameters, total protein and antioxidant activities in leaves of ‘ON’ and ‘OFF’ trees were analyzed. In girdled shoots a reduction of photosynthetic rate and a greater accumulation of both carbohydrates and antioxidant activities were observed. Girdling, breaking off the phloematic flow, caused a store of elaborated sap in leaves that inhibited the photosynthetic activity inducing an oxidative stress. Our results confirmed fluctuations in carbohydrates, gas exchanges and antioxidant activities as a direct consequence of girdling and of presence or absence of fruits, and showed clearly how each olive cultivar responds differently to girdling evidencing that the girdling effects are cultivar dependent.

In Australian macadamia ( Macadamia integrifolia Maiden and Betche, M . tetraphylla Johnson and hybrids) orchards, trees are generally side-hedged in early spring to maintain the inter-row for efficient orchard management. Hedging at this time increases fruit abscission and decreases yield due to competition for carbohydrates between fruit and post-pruning shoot growth, and to the loss of photosynthetic area. Girdling increases fruit set in many crops and the possibility that girdling might mitigate the effect of pruning on fruit abscission and yield was investigated in this study. Girdling was also investigated for its potential to control shoot growth and tree size. In the first experiment, in early spring around anthesis, trees were pruned (P), pruned and girdled (PG), or were left as unpruned and ungirdled control trees. Fruit per raceme over time, percent of racemes with fruit at 20 weeks post anthesis, fruit number per tree, nut weight, yield, and the shoot length and number of the post-pruning flush were measured. In a second experiment, trees were pruned (P) or pruned and girdled (PG) in autumn, and the shoot length and number of the post-pruning flush were measured. In a third experiment, trees were girdled at anthesis in 3 years over a 4-year period and shoot growth, tree height, yield, fruit number and nut weight were compared with ungirdled control trees. Girdling mitigated the effect of pruning on fruit abscission and yield but the mitigation was slight with PG trees producing 28% less yield than unpruned control trees. Girdling reduced shoot length and number but more so on unpruned branches (26% and 28%, respectively) than on pruned branches (10% and 14%, respectively). The tree height increment in girdled trees was around half that of ungirdled trees. In the 4-year study, girdling increased yield by around 10% in two out of four seasons, and decreased it in one season. Cumulative yields were similar for girdled and ungirdled trees. This study has shown that girdling was not useful in mitigating the effect of pruning on yield. However girdling was effective in controlling shoot growth and tree size, with no reduction in cumulative yield, and may be useful as a tree size control strategy. Further monitoring of long-term effects of repeat girdling is required to confirm this.