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Leo Lok is a practitioner and independent scholar of Chinese medicine. As a native speaker of multiple Chinese languages and a fluent reader of premodern texts, he is passionate about transmitting ancient knowledge and perspectives to a modern audience which he does through his online platform, Voices of Our Medical Ancestors. In this interview, recorded in April 2024, Leo talks with the editor of the Journal of Chinese Medicine, Daniel Maxwell, about aspects of textual transmission, acupuncture styles, needle retention and how to make progress along the path of Chinese medicine. [ABSTRACT FROM AUTHOR]

Needle abscission in balsam fir has been linked to both cold acclimation and changes in lipid composition. The overall objective of this research is to uncover lipid changes in balsam fir during cold acclimation and link those changes with postharvest abscission. Branches were collected monthly from September to December and were assessed for cold tolerance via membrane leakage and chlorophyll fluorescence changes at −5, −15, −25, −35, and −45 °C. Lipids were extracted and analyzed using mass spectrometry while postharvest needle abscission was determined gravimetrically. Cold tolerance and needle retention each significantly (p < 0.001) improved throughout autumn in balsam fir. There were concurrent increases in DGDG, PC, PG, PE, and PA throughout autumn as well as a decrease in MGDG. Those same lipids were strongly related to cold tolerance, though MGDG had the strongest relationship (R2 = 55.0% and 42.7% from membrane injury and chlorophyll fluorescence, respectively). There was a similar, albeit weaker, relationship between MGDG:DGDG and needle retention (R2 = 24.3%). Generally, a decrease in MGDG:DGDG ratio resulted in better cold tolerance and higher needle retention in balsam fir, possibly due to increased membrane stability. This study confirms the degree of cold acclimation in Nova Scotian balsam fir and presents practical significance to industry by identifying the timing of peak needle retention. It is suggested that MGDG:DGDG might be a beneficial tool for screening balsam fir genotypes with higher needle retention characteristics. [ABSTRACT FROM AUTHOR]

BACKGROUND: Dry needling (DN) is commonly used to treat myofascial trigger points (MTrPs). OBJECTIVE: To compare the effect between DN with and without needle retention in the treatment of MTrPs in the upper trapezius muscle. METHODS: Fifty-four patients who had active MTrPs in the upper trapezius muscle were randomly allocated into the DN group or the DN with retention group. The DN group received DN only, while the DN with retention group received DN with needle retention for 30 minutes. The visual analogue scale (VAS) and pressure pain threshold (PPT) were recorded both before and after 7 and 14 days of the treatment sessions. RESULTS: Both groups showed a significant decrease of the VAS at 7 and 14 days (mean difference DN group &lowbar;53.0, DN with retention group &lowbar;57.0, p < 0.001). The PPT was also significantly improved in both groups (mean difference DN group 109.8 kPa, DN with retention group 132.3 kPa, p < 0.001). However, there were no significant differences in the VAS or PPT between the groups. CONCLUSIONS: Both DN and DN with retention had significant improvement of pain intensity in the treatment of MTrPs in the upper trapezius muscle at 14 days. However, pain reduction was not significantly different between the interventions. [ABSTRACT FROM AUTHOR]

Increasing resistance against foliar diseases is an important goal in the Pinus radiata D.Don breeding program in New Zealand, and screening for resistance has been in place for some time, since the late 1960s. The current study presents results of four progeny trials within the breeding program to investigate whether multiple disease resistance could be detected against three different needle diseases in P. radiata: Dothistroma needle blight (DNB) caused by Dothistroma septosporum, Cyclaneusma needle cast (CNC) caused by Cyclaneusma minus, and red needle cast (RNC) caused by Phytophthora pluvialis. Four progeny trials in the North Island of New Zealand were available to estimate heritabilities and between-trait genetic correlations. Two of the trials were assessed for DNB, involving 63 full-sib families. A third trial was assessed for CNC, involving 172 half-sib families, and a fourth trial was assessed for RNC, involving 170 half-sib families. Disease resistances had moderate estimates of heritability (0.28–0.48) in all trials. We investigated the potential for multiple disease resistance to the three foliar diseases by estimating genetic correlations between disease resistances using a spatial linear mixed model. The correlation between DNB and CNC resistance was favorable and strong (0.81), indicating that genotypes that are highly resistant to DNB also have a high resistance to CNC. These results suggest that selection based on resistance to DNB could allow for simultaneous indirect selection for resistance to CNC, usually only expressed at a later age. This would allow selections to be made earlier due to the earlier expression of DNB than CNC and reduce the number of expensive disease assessments being undertaken. Conversely, genetic correlation estimates for RNC with DNB and CNC were close to zero, and very imprecise. As such, later-age assessments for this disease would still be required.

Increasing resistance against foliar diseases is an important goal in the Pinus radiata D.Don breeding program in New Zealand, and screening for resistance has been in place for some time, since the late 1960s. The current study presents results of four progeny trials within the breeding program to investigate whether multiple disease resistance could be detected against three different needle diseases in P. radiata : Dothistroma needle blight (DNB) caused by Dothistroma septosporum , Cyclaneusma needle cast (CNC) caused by Cyclaneusma minus , and red needle cast (RNC) caused by Phytophthora pluvialis. Four progeny trials in the North Island of New Zealand were available to estimate heritabilities and between-trait genetic correlations. Two of the trials were assessed for DNB, involving 63 full-sib families. A third trial was assessed for CNC, involving 172 half-sib families, and a fourth trial was assessed for RNC, involving 170 half-sib families. Disease resistances had moderate estimates of heritability (0.28–0.48) in all trials. We investigated the potential for multiple disease resistance to the three foliar diseases by estimating genetic correlations between disease resistances using a spatial linear mixed model. The correlation between DNB and CNC resistance was favorable and strong (0.81), indicating that genotypes that are highly resistant to DNB also have a high resistance to CNC. These results suggest that selection based on resistance to DNB could allow for simultaneous indirect selection for resistance to CNC, usually only expressed at a later age. This would allow selections to be made earlier due to the earlier expression of DNB than CNC and reduce the number of expensive disease assessments being undertaken. Conversely, genetic correlation estimates for RNC with DNB and CNC were close to zero, and very imprecise. As such, later-age assessments for this disease would still be required. [ABSTRACT FROM AUTHOR]

Objective: To observe the clinical curative effect of filiform needle retention with red-hot needling therapy in treating stenosing tendosynovitis of the radial styloid. Methods: 60 cases of stenosing tendosynovitis radial styloid patients were divided into a treatment group and control group according to sequence of doctors' office visits, 30 cases in each group. For the treatment group, filiform needle retention with red-hot needling therapy was applied. For the control group, local block therapy was applied. VAS score was used to evaluate the degree of easement of pain immediately after the first treatment. The VAS score was also used to evaluate the clinical curative effect at the one-week follow-up after observing one treatment course, and at the following three-month follow-up. Results: After the first treatment, the VAS score of both groups decreased. Comparison of decreasing extent indicated that the difference was not statistically significant (P > 0.05). It showed that both therapies had comparative effects on extent of easement of pain. After one treatment course, the total effective rate in each was 93.33% in the treatment group, and 90.00% in the control group. Comparison between both groups indicated that the difference was not statistically significant (P > 0.05). After one treatment course, the total effective rate was 99.89% in the treatment group, and 75.00% in the control group during the next three-month follow-up. Comparison between both groups indicated that the difference was statistically significant (P > 0.05). Conclusion: The filiform needle with red-hot needling therapy was superior to local nerve block therapy in treating stenosing tendosynovitis of the radial styloid in producing a clinical curative effect. [ABSTRACT FROM AUTHOR]

Postharvest needle abscission in balsam fir varies based on time of harvest, but little is known about the effect of soil and tree nutrition on postharvest needle abscission. From April to November, 18 balsam fir samples were obtained each month and evaluated for postharvest needle abscission characteristics. Soil samples were collected simultaneously and evaluated for moisture, pH, organic matter, cation exchange capacity, and mineral nutrition. Needle tissue samples were also evaluated for mineral nutrition. Many parameters were found to vary based on month throughout the study, but not all were associated with needle abscission. Soil organic matter, cation exchange capacity, Ca, and Mn all had a significant (P < .01) positive relationship with needle retention; soil Al had a significant (P < .01) negative relationship with needle retention. Needle N, Ca, and Fe were also associated with needle abscission. The strongest positive relationship was found between needle Ca and needle retention (R2 > .50), suggesting that higher concentrations of tissue Ca were linked to superior needle retention in balsam fir. Overall, this study provides evidence that changes to soil management, such as the inclusion of organic matter and certain minerals, may improve needle retention in balsam fir. [ABSTRACT FROM AUTHOR]

A field test with 26 provenances of subalpine fir and corkbark fir was established at three sites in Denmark and one site in Iceland in 1999. Survival, growth and Christmas tree quality were assessed after 10 growing seasons in Denmark and 12 in Iceland. Provenances showed significant differences for all measured traits. The western-most subalpine fir provenances from Washington state and British Columbia showed the overall best results in Denmark with the highest survival (after 15 years), fastest growth in height and highest Christmas tree quality and profitability as well as both good postharvest needle retention and high resistance to pests. The corkbark fir provenances also showed high Christmas tree quality and the lowest frequency of fork formation, but corkbark fir provenances also exhibited the poorest postharvest needle retention. In Iceland, the corkbark fir provenances generally showed the highest survival rate and Christmas tree quality. The White River provenance from British Columbia is recommended for use in Denmark. The Mount Taylor provenance from the Cibola National Forest in New Mexico is recommended for use in Iceland. [ABSTRACT FROM AUTHOR]

Key message: Retention of 10-16-year-old balsam fir needles increased significantly with cumulative spruce budworm defoliation. Mean needle longevity on defoliated 50-year-old fir was almost double that for undefoliated 25-year-old fir. Abstract: Conifers experiencing environmental change affecting photosynthetic capacity have been observed to compensate by adjusting foliage longevity and increasing retention of old foliage. Defoliation by spruce budworm [ Choristoneura fumiferana (Clem.)] is one such change, therefore, it was hypothesized that conifers, such as balsam fir [ Abies balsamea (L.) Mill.] may increase foliage life spans to compensate for losses of photosynthetic capacity to defoliation. Understanding foliage longevity is a key component of predicting foliage complement, which is the main driver of effects of defoliation on forest growth and productivity. Defoliation and needle loss were assessed on 16 age classes of foliage on mid-crown branches sampled from 134 mature balsam fir trees near Amqui and Causapscal, Quebec, and related to needle age and cumulative defoliation (summed annual defoliation from 2012 to 2016). A general linear mixed model fitted to the needle survivorship data accounted for 68% of the total deviance. The model interaction term of cumulative defoliation with foliage age indicated that for foliage ages less than about 9 years, increased cumulative defoliation resulted in lower needle survival, possibly because of backfeeding of spruce budworm on 5+-year-old foliage, while in the older age classes, needle survival increased with increasing cumulative defoliation. For the oldest, 11-16-year-old foliage age classes, 10-16% more foliage per age class was retained under severe defoliation than under light defoliation. As a result, median needle age increased from 9.5 to 10.4 years as cumulative defoliation increased from 0 to 500%. Mean needle longevity of 9.5 years for 50-year-old balsam fir with low defoliation observed in this study was considerably higher than the mean of 5.5 years previously observed for 22- to 27-year-old fir in Cape Breton, Nova Scotia. Such differences in needle longevity and retention would cause considerable differences in predictions of tree growth using foliage-based stand growth models. [ABSTRACT FROM AUTHOR]

Postharvest needle abscission in balsam fir varies considerably depending on the season and may be dependent on endogenous hormones of roots or shoots. Samples were obtained from three trees each month from April 2013 to November 2013 and evaluated for retention. In addition, root and needle tissues were analyzed for abscisic acid, cytokinins, auxins, and gibberellins and their conjugates. There was a 3.5-fold increase in time until needle abscission commencement and 1.75-fold increase in time until complete abscission in autumn compared to spring. There were several changes to root and needle hormones with respect to harvest time, but fewer hormones were linked to postharvest needle retention. Among all hormones analyzed, both isopentenyladenine and isopentenyladenosine in roots were strongly linked to needle retention. When isopentenyladenine was present in roots, needle abscission took 114% longer to begin and 58% longer to finish. Isopentenyladenosine in roots was the strongest hormonal predictor of needle retention ( R = 79%). Dihydrozeatin riboside ( R = 37%), trans-abscisic acid ( R = 50%), and isopentenyladenosine ( R = 59%) in the needles were also strong predictors of needle retention. The relative effectiveness of certain hormones in predicting needle retention and speculation pertaining to the roles these hormones could play are discussed. [ABSTRACT FROM AUTHOR]

Several studies have suggested that postharvest needle retention increases in autumn, likely due to cold acclimation. But some of the dynamics of the phenomenon have yet to be studied. The objectives of this study are to (1) describe seasonal changes in postharvest abscission, water uptake, fluorescence, and moisture content of balsam fir, (2) determine the relationship of needle abscission with water uptake, fluorescence, and moisture content, and (3) link the postharvest changes to certain environmental factors. Branches were collected from 18 trees each month and needle abscission, fluorescence, water uptake, and water content were monitored for 12 weeks. Fluorescence, water uptake, and water content were all correlated with needle abscission. Further, all the above factors improved in autumn months compared to spring or summer months and significantly related to changes in photoperiod and temperature. In addition, fluorescence and moisture content are valuable indicators of postharvest quality. [ABSTRACT FROM AUTHOR]

The paper presents results of an assessment of needle age classes in Scots pine partial populations in the period of three and five years after outplanting in a lowland site in relation to conditions created by climatic elements. The method is based on Skuhravý's (1987) description when the state of needle age classes of the third whorl (from the apex) is evaluated just once. Five-year summary of meteorological data was assessed according to the criteria of determination of periods of heat waves and dry spells. Differences in numbers of living needle age classes in the groups of Scots pine populations in the period of three and five years after their outplanting in permanent lowland sites proved the highest total number of living needle classes in the group of local lowland populations. On the contrary, the lowest total number of living needle classes was found out in the group of mountain populations. Critical climatic periods are overlaps of heat waves and dry spells that illustrate the complexity of moisture and temperature conditions of lowland sites. Although the Scots pine is a xerophytic species, it responded to the cumulation of adverse factors by accelerated needle senescence. Its physiological response to heat and dry stress consists in needle shedding, i.e. reduction in the assimilating area. As mountain populations are not usually exposed to heat waves, the impact of this phenomenon on them was the highest. On the other hand, the local (lowland) populations carrying information on the patterns of local climate from the reproduction period do not undergo any marked reduction in needle age classes.

Objectives : The purpose of this study was to compare the effect of acpuncture and electro-acupuncture of low(EA(L)) and high(EA(H)) frequency at Haegye(ST41) on intestinal hypomotility induced with loperamide in rats. Methods : We made suppressed state of intestinal motility with loperamide in rats and carried out needle retention acupuncture, low frequency electro-acupuncture and high frequency electro-acupuncture at ST41 in rats devided into pre-treatment group and post-treatment group. We fed charcoal to them after the treatment and measured the travel rate of charcoal in the gastrointestinal track to analyze which treatment is more effective in state of intestinal hypomotility. Results : None of acupuncture, EA(L) and EA(H) at ST41 had significant influences on intestinal motility of rat in normal state. Needle retention at ST41 did not significantly increase intestinal motility suppressed with loperamide in rats. Pre-treatment of EA(L) and EA(H) at ST41 significantly increased intestinal motility suppressed with loperamide in rats. Post-treatment of EA(L) and EA(H) at ST41 did not have significant influences on intestinal motility of rat in normal state. Conclusions : These results suggest that treatment of EA(L) and EA(H) at ST41 may be effective on gastric disorders such as intestinal hypomotility and its effect had more prevention than cure. Further study is necessary to know more effects of ST41 and electro-acupuncture of low and high frequency.

Balsam fir (Abies balsamea) trees are commonly used as a specialty horticultural species for Christmas trees and associated greenery in eastern Canada and United States. Postharvest needle abscission has always been a problem, but is becoming an even bigger challenge in recent years presumably due to increased autumn temperatures and earlier harvesting practices. An increased understanding of postharvest abscission physiology in balsam fir may benefit the Christmas tree industry while simultaneously advancing our knowledge in senescence and abscission of conifers in general. Our paper describes the dynamics of needle abscission in balsam fir while identifying key factors that modify abscission patterns. Concepts such as genotypic abscission resistance, nutrition, environmental factors, and postharvest changes in water conductance and hormone evolution are discussed as they relate to our understanding of the balsam fir abscission physiology. Our paper ultimately proposes a pathway for needle abscission via ethylene and also suggests other potential alternative pathways based on our current understanding.

Postharvest needle abscission is a major challenge in balsam fir with respect to postharvest Christmas tree quality. It is hypothesized that differences in dehydration rate or ability to rehydrate may contribute to observed differences in needle abscission resistance (NAR). Branches were collected from low and high NAR genotypes and dehydrated for 0, 1, 2, 5, 7, 14, or 21 d before being provided water and evaluated for water content, xylem pressure potential, stomatal conductance, and needle abscission. Fresh branches were 57% water content at −0.5 MPa and rapidly declined over 21 d without water to approximately 28% water content at −7.0 MPa. The ability to rehydrate was different between low and high NAR genotypes; low NAR genotypes could only successfully rehydrate within 2 d of dehydration (51% water content, −2.8 MPa) while high NAR genotypes were able to rehydrate within 7 d of dehydration (36% water content, −4.9 MPa). There was no significant difference in postharvest abscission of contrasting NAR genotypes when dehydrated for up to 2 d, but high NAR genotypes had significantly lower abscission when water was withheld for 5 or 7 d. When dehydrated for 14 or 21 d, no branches were able to recover and abscission occurred rapidly. It was concluded that low NAR genotypes were unable to recover from a similar water content as high NAR genotypes, which contributes to genotypic differences in postharvest abscission rates. [ABSTRACT FROM AUTHOR]

Postharvest balsam fir trees are known to suffer a number of problems that may be linked to abscission rates, such as dehydration or wounding. By definition, postharvest balsam fir trees are also detached from roots and will no longer be supplied certain root derived factors normally translocated via the xylem. Resupplying those root derived factors may delay abscission. The objective of this experiment was to take sap from a root intact species (i.e. Acer saccharum L) and add it to the water supply of balsam fir branches. Further, the effect of reverse osmosis and autoclaving the sap supply will be explored. The experiment was conducted once in spring and again in autumn to examine seasonal changes in needle abscission. The only hormones found in the maple sap were ABA and its metabolites, with PA (163.0 ng g–1) being the primary metabolite present. Needle retention was higher in branches harvested in autumn, as long as they were provided a sap that did not undergo RO. If the sap had undergone RO, then needle retention was slightly decreased in autumn. Needle retention generally decreased as the concentration of maple sap in the water supply increased and this trend was accelerated if the sap had undergone RO. Autoclaving the sap successfully delayed the length of time for water consumption to decrease, but this unexpectedly did not translate into improved needle retention. [ABSTRACT FROM AUTHOR]

Needle retention (number of needle sets) and needle density (number of needle pairs per centimeter of shoot) were surveyed on Scots pines in five forest regions of Slovakia. The Needle Trace Method (NTM) was used to determine needle retention and needle density along the main stem retrospectively for the last four decades. In all forest regions, the values of these indicators varied from year to year. However, in Záhorská lowland, Vtáčnik, Krupinská plain, and High Tatras, the trends of both observed indicators were constant over the time series. The situation was different in the Levočské hills, where the needle retention displayed a decreasing trend and needle density an increasing trend. These trends probably reflected a long-term stress of air pollution on pines in this forest stand.

Balsam fir (Abies balsamea) trees are commonly used as a specialty horticultural species for Christmas trees and associated greenery in eastern Canada and United States. Postharvest needle abscission has always been a problem, but is becoming an even bigger challenge in recent years presumably due to increased autumn temperatures and earlier harvesting practices. An increased understanding of postharvest abscission physiology in balsam fir may benefit the Christmas tree industry while simultaneously advancing our knowledge in senescence and abscission of conifers in general. Our paper describes the dynamics of needle abscission in balsam fir while identifying key factors that modify abscission patterns. Concepts such as genotypic abscission resistance, nutrition, environmental factors, and postharvest changes in water conductance and hormone evolution are discussed as they relate to our understanding of the balsam fir abscission physiology. Our paper ultimately proposes a pathway for needle abscission via ethylene and also suggests other potential alternative pathways based on our current understanding. [ABSTRACT FROM AUTHOR]

Efforts are being made to determine significant biophysical and physiological events related to postharvest needle abscission. It is known that initial postharvest average water consumption is 0.2 mL g day (based on dry shoot tissue), but gradually decreases by up to 75 %. It is hypothesized that some degree of water deficit is manifested through changes in several biophysical and hormonal factors. Parameters including needle loss, water use, relative water content, electrical capacitance, membrane injury, and xylem pressure potential were measured once every 5 days on balsam fir branches collected from a clonal orchard. In addition, needles were sampled at the beginning of the experiment and during peak needle abscission which were then subjected to endogenous hormonal analysis. Peak needle abscission occurred within 24 days. During this time water use decreased by 70 %, relative water content decreased by 23 %, capacitance decreased by 64 %, membrane injury increased by 100 %, needle break strength decreased by 50 %, and xylem pressure potential decreased fourfold. Abscisic acid increased by 32-fold and trans-zeatin riboside increased by fourfold during peak abscission compared to fresh branches. Other cytokinins, such as cis-zeatin riboside, isopentenyl adenosine, trans-zeatin-O-glucoside, and dihydrozeatin riboside all doubled during abscission. Finally, there was a 95 % decrease in indole-3-acetic acid. Observed changes in all biophysical parameters, as well as abscisic acid, could be indicative of a possible postharvest water stress or dehydration. It is possible that dehydration-induced changes in biophysical and hormonal factors trigger and/or modulate postharvest needle abscission. [ABSTRACT FROM AUTHOR]

Seasonal changes in the concentration of abscisic acid (ABA) in current-year needles of two different genotypes (AB-NSD-004 and AB-NSD-184) were monitored in branches collected from 20-year-old balsam fir ( Abies balsamea L. (Mill.)) trees over a period of 11 months. A significant genotype × harvesting time interaction was observed for endogenous ABA levels and postharvest needle retention duration (NRD). A consistent pattern of seasonal variation in ABA concentration was observed in both genotypes, with the highest amount of ABA (7,887 ng g −1 DW) accumulating in April and May. The highest levels of ABA coincided with the lowest postharvest NRD regardless of genotype. Nevertheless, genotypes differed in their ABA concentrations. Branches of genotype AB-NSD-184 sampled during August exhibited 170 days of NRD whereas those collected in May and June registered the lowest NRD of around 40 days. There was a significant negative correlation ( P < 0.05) between endogenous ABA concentrations and postharvest NRD in genotype AB-NSD-184. Also, an inverse relationship was observed between the average daily photoperiod and the postharvest NRD ( R2 = 0.35; P = 0.000) in the same genotype. Together with average daily temperature, the R2 value for this correlation reached the highest (0.75; P ≤ 0.00). Genotypes differed in their physiological responses to environmental cues and thus differed in their postharvest qualities. Average daily photoperiod and maximum daily temperature are strongly linked to the postharvest NRD through modulating endogenous ABA concentration. [ABSTRACT FROM AUTHOR]

Two experiments were conducted to understand the effect of light emitting diodes on postharvest abscission in balsam fir (Abies balsamea L.) branches. In one experiment, branches were pre-exposed to the fluorescent light, LEDs, or darkness for 1, 4, 8, 12, 24, or 48 h. In a second experiment, branches were constantly exposed to fluorescent lights, LEDs, or darkness. The response variable was needle retention duration (NRD). A 48-hour exposure time to red, white, or blue LEDs significantly (P < 0.001) increased NRD by approximately 75, 118, or 127%, respectively, compared to a cool white fluorescent lighting or darkness. Constant exposure to any LED significantly (P < 0.001) improved NRD compared to fluorescent lights or darkness, though white and red LEDs were most effective. It is speculated that LED-promoted needle retention could possibly be due to changes in carbohydrate synthesis similar to those observed during cold acclimation. [ABSTRACT FROM AUTHOR]

Two experiments were conducted to understand the effect of light emitting diodes on postharvest abscission in balsam fir (Abies balsamea L.) branches. In one experiment, branches were pre-exposed to the fluorescent light, LEDs, or darkness for 1, 4, 8, 12, 24, or 48 h. In a second experiment, branches were constantly exposed to fluorescent lights, LEDs, or darkness. The response variable was needle retention duration (NRD). A 48-hour exposure time to red, white, or blue LEDs significantly (P < 0.001) increased NRD by approximately 75, 118, or 127%, respectively, compared to a cool white fluorescent lighting or darkness. Constant exposure to any LED significantly (P < 0.001) improved NRD compared to fluorescent lights or darkness, though white and red LEDs were most effective. It is speculated that LED-promoted needle retention could possibly be due to changes in carbohydrate synthesis similar to those observed during cold acclimation. [ABSTRACT FROM AUTHOR]

Needle loss after harvest is a major problem for Atlantic Canada's Christmas tree and greenery industry. Ethylene is a signal for abscission in balsam fir, but preliminary studies have suggested that the role of ethylene may be influenced by length of exposure. Short-term and long-term ethylene exposure experiments were conducted. Branches were exposed to ethylene for 24 h (short-term) or continuously (long-term) at concentrations of 0 to 1000 ppm. The response variables measured were needle retention duration (NRD), average water use (AWU), and xylem pressure potential (XPP). Short-term exposure to any concentration of ethylene delayed needle abscission by 30 to 40 days. In contrast, long-term exposure to all concentrations of ethylene accelerated abscission, most evident by a 21-day decrease in NRD at 1000 ppm ethylene. There was a 60% decrease in NRD, 160% decrease (more negative) in XPP, and 80% increase in AWU as a result of long-term exposure to ethylene. Overall, our results demonstrate an opposite effect of short-term and long-term ethylene exposure, which suggests that short-term exposure to ethylene might help to precondition balsam fir and delay needle abscission during postharvest handling. [ABSTRACT FROM AUTHOR]

Post-harvest needle abscission is a major challenge for Christmas tree and greenery industries. It was hypothesized that ethylene triggers abscission in balsam fir. Three experiments were conducted to test this hypothesis. In experiment 1, 70 balsam fir branches were collected, placed in water, and ethylene evolution was observed over time. In experiment 2, a 2 × 5 factorial experiment was designed to determine the effect of exogenous ethylene and an ethylene receptor blocker, 1-methylcyclopropene (1-MCP), on needle abscission. In experiment 3, a 2 × 6 factorial experiment was designed to determine the effect of exogenous ethylene and an ethylene inhibitor, aminoethoxyvinylglycine (AVG), on needle abscission. It was found that ethylene evolution was the highest 1–2 days prior to needle abscission, which was consistent in untreated branches and branches exposed to exogenous ethylene. Exposure to exogenous ethylene significantly decreased needle retention by 63%. When ethylene receptors were blocked by 1-MCP, needle retention increased by 147% despite the presence of ethylene and increased by 73% in the absence of ethylene when compared to the respective controls. When endogenous ethylene synthesis was inhibited by AVG, there was no improvement in needle retention in the presence of ethylene, but there was a 113% increase in needle retention in the absence of exogenous ethylene. Ethylene is strongly implicated as the signal triggering abscission in root-detached balsam fir. [ABSTRACT FROM AUTHOR]

The dynamics of six different needle parameters of Pinus sylvestris L. and Pinus ponderosa Dougl. ex P. & C. Laws. were examined retrospectively for a 112-year-old mixed stand in Brandenburg, Germany, using the needle trace method. Similarities were found in needle production, needle loss and needle density. However, needle age, needle retention and total number of needles revealed significant differences between the tree species, with higher values for P. ponderosa. Pinus ponderosa yielded approximately twice as much mean whole-crown needle dry mass as P. sylvestris. Furthermore, different branching systems could be detected between the species, with both pines following "Corner's rule". The results suggest that under identical growing conditions, P. ponderosa exhibits more efficient water use and can therefore maintain a bigger crown (as the basis for increased growth) than P. sylvestris. [ABSTRACT FROM AUTHOR]

Nordmann fir [ Abies nordmanniana (Stev.) Spach.] is a widely used Christmas tree species in northern Europe. In recent years there has also been increasing interest in using Nordmann fir as a Christmas tree in North America. Postharvest quality is a central characteristic for high-quality Christmas trees. To examine the genetic variation in needle retention, a series of experiments was conducted using cut branches from a grafted seed orchard with 23 clones and a progeny trial comprising 19 open-pollinated clonal progenies of the orchard. For both clones and open-pollinated families strong genetic differences were seen in needle retention when branch samples were allowed to dry. Based on one progeny trial, single tree heritabilities were estimated in the range of 0.27–0.31 after 10–15 days of drying. A parent–offspring regression indicated a higher heritability. These results indicate that breeding efforts can be used to improve significantly the postharvest needle retention characteristics of Nordmann fir Christmas trees. [ABSTRACT FROM AUTHOR]

Background: Dry needling (DN) is commonly used to treat myofascial trigger points (MTrPs)., Objective: To compare the effect between DN with and without needle retention in the treatment of MTrPs in the upper trapezius muscle., Methods: Fifty-four patients who had active MTrPs in the upper trapezius muscle were randomly allocated into the DN group or the DN with retention group. The DN group received DN only, while the DN with retention group received DN with needle retention for 30 minutes. The visual analogue scale (VAS) and pressure pain threshold (PPT) were recorded both before and after 7 and 14 days of the treatment sessions., Results: Both groups showed a significant decrease of the VAS at 7 and 14 days (mean difference DN group -53.0, DN with retention group -57.0, p< 0.001). The PPT was also significantly improved in both groups (mean difference DN group 109.8 kPa, DN with retention group 132.3 kPa, p< 0.001). However, there were no significant differences in the VAS or PPT between the groups., Conclusions: Both DN and DN with retention had significant improvement of pain intensity in the treatment of MTrPs in the upper trapezius muscle at 14 days. However, pain reduction was not significantly different between the interventions.

Balsam fir trees are the most popular choice for Christmas trees in Atlantic Canada and a major export commodity, despite postharvest needle abscission challenging the industry's viability. The objective of this study was to determine if any needle or branch biophysical and/or morphological characteristics may be linked with needle abscission resistance (NAR) in balsam fir. A total of 17 different parameters were measured in branches of clones that belonged to low, medium, or high needle abscission resistant groups. Of the parameters measured, branch diameter, initial mass, needle density, break strength, and needle retention duration were significantly (P < 0.05) different between genotype groups. It was found that high NAR genotypes had a 9.1% smaller diameter, 25.0% lower initial mass, 33.2% lower needle break strength, 32.4% lower needle density, and 91% longer needle retention than low NAR clones. Of these factors, needle density was the best predictor for needle retention duration (R²= 47%). Identification of these parameters is an important first step to understand physiological and genetic linkage for development of Christmas trees with high NAR. [ABSTRACT FROM AUTHOR]

Needle retention, xylem pressure potential and overall quality of canaan fir (Abies balsamea var.phanerolepis (L.) Mill.) and fraser fir (Abies fraseri (Pursh) Poir.) Christmas trees were evaluated over a 40-day display period. Cut trees were stored outdoors for 24, 48, or 96 hours, and half the trees had a 2.5-cm section trimmed from the basal portion of the stem, before placement in water at an indoor display room. Controls were placed in water immediately after harvest. Xylem pressure potentials and overall quality were similar for both species except for trees stored 96 hours. Untrimmed canaan fir dried to -2.4 MPa and was rated below average by the end of the display period compared to -1.3 MPa and a good quality rating for fraser fir. Needle retention and color characteristics were excellent across all treatments for fraser fir during the entire display period. Needle loss for canaan fir began relatively soon during display, generally increased across all treatments, and was highly variable. In addition, quality of some canaan fir trees decreased as needles turned brown, but did not shed during the display period. Tree water status alone did not completely account for loss of needles and quality in canaan fir; the need exists to identify seed sources with better postharvest characteristics. [ABSTRACT FROM AUTHOR]

Needle retention is an important step in the acupuncture procedure. How to optimize scientifically the duration of needle retention according to individual case has been considered in the medical circle. In this paper, by collecting the literatures on needle retention from the early Qin dynasty to the contemporary time, the evolution of the needle retention from a short duration to a long one with the productivity improvement was elaborated. On the base of the views of the medical scholars of all dynasties, it was concluded that the ultimate purpose of needle retention is to improve the effects of acupuncture on the premise of ensuring the safety of acupuncture. Hence, the clinical physician should optimize the duration of needle retention cautiously in compliance with the tolerance of patient so as to save the time cost of both physician and patient, avoid the occurrence of tolerable effect of acupuncture and reduce the potential safety hazard of acupuncture induced by the long duration of needle retention.