Effects of stem girdling on cone yield and endogenous phytohormones and metabolites in developing long shoots of Douglas-fir (Pseudotsuga menziesii)

Stem-girdling treatments were applied in early spring to stimulate cone formation in two genotypes of interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco). After girdling treatments, male cone yield increased significantly in the next growing season. The increase was 14-fold in genotype 9137. In genotype 9550, more than 8,700 male cones were induced from each tree whereas no male cones were found in controls. Female cone yield was zero in controls and low for girdled trees in both genotypes. Multiple phytohormone-related compounds, including gibberellins (GAs), cytokinins, indole-3-acetic acid (IAA), abscisic acid (ABA) and their selected metabolites, were analyzed in developing long shoots after girdling treatments by high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC?CESI?CMS/MS) in multiple reaction monitoring mode. Concentrations of GA₄ were slightly higher at week 2 following girdling treatment, whereas at week 8 lower GA₄ concentrations were found in girdled samples. Stem girdling did not affect concentrations of IAA and major cytokinins, such as zeatin riboside and isopentenyl adenosine. Concentrations of ABA differed two-fold between the genotypes. Although girdling treatment did not cause differences in ABA concentrations, it generally resulted in higher concentrations of ABA glucose ester. Concentration increase of 7??-hydroxy ABA by girdling was only found in genotype 9550 at week 8. Girdling caused little change in concentrations of phaseic acid in both genotypes.     

In situ forcing of pollen maturation in Jack pine and Japanese larch male cones

Paper bags equipped with a polyethylene window were placed on branchlets 6 and 9 weeks before the time of pollen dispersal of Japanese larch and Jack pine, respectively. This technique produced a localized greenhouse effect around the branchlets, accelerating male cone development. For Jack pine trees, buds in bags with the window oriented upward had the shortest maturation time. In fact, it was possible to collect these pollen cones about 11 days before the unbagged control without decreasing the production of pollen. The mean germination rate of the pollen from the bags with the window pointed upward, however, was significantly lower than the control, by about 15%. Buds in bags with the window oriented downward had an accelerated development of about 9 days (compared to the control) but did not experience a decrease in pollen production or quality. This same technique caused the abortion of male cones of the Japanese larch trees. Thermal probes in the bags enabled us to follow the progression of temperature inside and outside the bags during the development of the male cone in each species. They revealed that the bags increased mean temperature, daily temperature range, and degree-day accumulation, and that this effect was most pronounced for Jack pine, when the polyethylene window was oriented upward.     

Response of Japanese red pine to inoculation with a blue stain fungus,Ceratocystis piceae

To confirm the pathogenicity of a blue stain fungus,Ceratocystis piceae (Münch) Bakshi to the Japanese red pine (Pinus densiflora Sieb. et Zucc.), the responses of healthy young pine trees and stressed trees which were girdled by the half-circumferential girdling technique were investigated by the fungal inoculation test. Although neither of the pine trees inoculated withC. piceae in the non-girdled treatment nor the controls died, mortality of the trees girdled and inoculated withC. piceae was 28.6%. In the pine trees inoculated withC. piceae, the mean area of the necrotic lesion of the sapwood was significantly larger than that of the controls, and the mean of the water pressure potential of the xylem decreased, regardless of the girdling treatment. TheC. piceae was reisolated from the wood pieces near the inoculation points on the inoculated trees, but not from the controls. These results suggest that under strongly stressed conditions, the Japanese red pine trees might have been killed by heavy infestations ofC. piceae carried by bark beetles. A part of this paper was presented at the 103rd Annual Meeting of the Japanese Forestry Society (1992).     

Viability of thinning sessile oak stands by girdling

The effects of girdling were analysed in a sessile oak (Quercuspetraea Matts. Leibl.) forest with an 80-year-old coppice withstandard structure in northern Spain. The study evaluated theviability of girdling as an alternative to felling trees duringcrown thinning. Eighty-four direct competitors of selected futurecrop trees were girdled by double notching and peeling. Threeyears after girdling, 100 per cent of the treated trees haddied. Approximately half of the girdled trees did not resprout.The occurrence of basal sprouting was very low, and more than35 per cent of the sprouts had very low vigour. No correlationwas found between sprouting and the diameter of the girdledtrees or the distance to their nearest neighbour. A negativerelationship between the diameter of the girdled tree and thestage of decline was recognized. Girdling is an economic alternativeto non-commercial thinning in oak stands and can be seen asan effective structural enrichment treatment.     

Stem girdling manipulates leaf sugar concentrations and anthocyanin expression in sugar maple trees during autumn

To better understand the effects of sugar accumulation on red color development of foliage during autumn, we compared carbohydrate concentration, anthocyanin expression and xylem pressure potential of foliage on girdled versus non-girled (control) branches of 12 mature, open-grown sugar maple (Acer saccharum Marsh.) trees. Half of the study trees were known to exhibit mostly yellow foliar coloration and half historically displayed red coloration. Leaves from both girdled and control branches were harvested at peak color expression (i.e., little or no chlorophyll present). Disruption of phloem export by girdling increased foliar sucrose, glucose and fructose concentrations regardless of historical tree color patterns. Branch girdling also increased foliar anthocyanin expression from 50.4 to 66.7% in historically red trees and from 11.7 to 54.2% in historically yellow trees, the latter representing about a fivefold increase compared with control branches. Correlation analyses indicated a strong and consistent relationship between foliar red coloration and sugar concentrations, particularly glucose and fructose, in both girdled and control branches. Measures of xylem pressure potentials confirmed that girdling was a phloem-specific treatment and had no effect on water transport to distal leaves. Results indicate that stem girdling increased foliar sugar concentrations and enhanced anthocyanin expression during autumn in sugar maple foliage. Native environmental stresses (e.g., low autumn temperatures) that reduce phloem transport may promote similar physiological outcomes.     

Variability of the seeds and cones and key taxonomic charactersselection of Larix in Northeast China

IntroductionLarisoIgensiSHenryandLarisgmeIinii(Rupr.)Rupr.areboththenativetreespeciesinChina,buttheirdiStributingcentersarenotwithintherangeofChina.LarisoIgen$isismainlydistributedinNoFthKoreaandadjacentNortheastChinaandRussia(Dylis1961).lnChina,itsdistributingcenterisintheChangbaiMountains.Nevertheless,LarisgmeliniiismainlydistributedintheFar-EastandEastSiberiaofRussiaandNortheasternChina.ItsdistributingcenterinChinaisintheDaxing'anMountains.Thecharac-tersofthesexuaIreproduction…     

Timing of shedding seeds and cones, and production in different stands of Scots pines at Abernethy Forest, Scotland

A study was carried out over 11 seed years on the timing ofshedding of seeds and cones, and annual seed fall and cone productionin three stands of native Scots pinewood and a Scots pine plantationin Abernethy Forest, Scotland. Peaks in seed fall took placemainly in May, and cones were shed mainly between June and August.There were few residual seeds remaining in shed cones. Synchronizedpeaks in seed fall and cone production (mast years) took placeat 3-year intervals across the different stands. The differencebetween cohorts of high and low cone production ranged fromfactors of 5 to 20 among sites. Coefficients of variation forcone production ranged from 62 to 84 per cent among sites. Therewere no significant differences in cone production among sites,but there were site-related differences in seed fall. The largercanopy cover in the plantation probably accounted for the higherseed fall per square metre there, though variations in the amountof seed eaten by birds and mammals may also have been important.Canopy cover needs to be considered when converting cone densitiesunder crowns to cone density per unit of woodland area. A similarcalculation is difficult for seeds because they are lighterthan cones and many fall outside the area under the crowns.The results are discussed in relation to the potential for treeregeneration and the availability of food for birds and mammalsprior to seed dispersal.     

Variability of the seeds and cones and key taxonomic characters selection ofLarix in Northeast China

The paper presents the results of biometrical study of the seeds and cones of larch taxa from Northeast of China. Fourteen characters are considered and their analyses showed that the seeds and cones of the larch taxa were relative greatly variable. Cluster analysis and principal component analysis for all 6 larch taxa were made. The analysis results proved that the dominant larch population in Toudao Farm fell within the range of variation ofLarix olgensis. The key taxonomic characters are the length of seed wing, length of cone, length of seed, the length/width ratio of seed and number of scales. This research was supported by Natural Science Foundation of Heilongjiang Province.(C9515) Responsible Editor: Chai Ruihai     

落叶松球果花蝇种团生物学特性与危害特点的补充

该文对落叶松球果花蝇种团Strobilomyia spp.的危害特点、延长滞育及不同经营条件下种子园内的发生情况及以前获得的一些未报道的数据进行了补充，调查发现，球果产量高时，受花蝇危害率较低，第2年花蝇的延长滞育率则高；球果产量低时，受花蝇危害率较高，第2年花蝇的延长滞育率则低，并对球经蝇目前的各种防治措施进行了探讨。     

Bole girdling affects metabolic properties and root, trunk and branch hydraulics of young ponderosa pine trees

Effects of trunk girdling on seasonal patterns of xylem water status, water transport and woody tissue metabolic properties were investigated in ponderosa pine (Pinus ponderosa Dougl. ex P. Laws.) trees. At the onset of summer, there was a sharp decrease in stomatal conductance (g(s)) in girdled trees followed by a full recovery after the first major rainfall in September. Eliminating the root as a carbohydrate sink by girdling induced a rapid reversible reduction in g(s). Respiratory potential (a laboratory measure of tissue-level respiration) increased above the girdle (branches and upper trunk) and decreased below the girdle (lower trunk and roots) relative to control trees during the growing season, but the effect was reversed after the first major rainfall. The increase in branch respiratory potential induced by girdling suggests that the decrease in g(s) was caused by the accumulation of carbohydrates above the girdle, which is consistent with an observed increase in leaf mass per area in the girdled trees. Trunk girdling did not affect native xylem embolism or xylem conductivity. Both treated and control trunks experienced loss of xylem conductivity ranging from 10% in spring to 30% in summer. Girdling reduced xylem growth and sapwood to leaf area ratio, which in turn reduced branch leaf specific conductivity (LSC). The girdling-induced reductions in g(s) and transpiration were associated with a decrease in leaf hydraulic conductance. Two years after girdling, when root-to-shoot phloem continuity had been restored, girdled trees had a reduced density of new wood, which increased xylem conductivity and whole-tree LSC, but also vulnerability to embolism.     

杉木球果和种子发育节律的研究初报

杉木为我国南方主要造林树种,研究也较充分,但对球果和种子发育的研究比较薄弱。蒋恕(1980年)和华中农学院植物教研组(1975年)等从解剖学角度研究过杉木的受精过程。中国科学院林业土壤研究所(1973年)和唐午庆等(1964年)从物候学角度报告过杉木球果的大小和重量变化。我们则想从种子生产角度观察球果,特别是种子的发育过程,了解不同季节的种子品质变化,以便为最适采种期找到一些客观指标,并为种子园适时管理提供一些依据。     

Estimating seed quantity and quality in shortleaf pine (Pinus echinata Mill.) cones from natural stands

The quantity and quality of seeds were studied in 886 shortleaf pine cones collected from 48 trees in each of two 15-ha natural stands in western Arkansas, USA. The number of seeds per cone ranged from 0 to 102, and averaged 34.6 and 38.0 in the two stands. Between 30 and 50 percent of the seeds were sound. Overall mean values for total number and total sound seeds compare with previous work. However, the wide variation between individual trees in a stand needs to be considered when evaluating cone abundance and estimating potential seed yields. For the stands observed in this study, a sample of 65 to 85 cones would be needed to estimate the number of sound seeds per cone (within ±3 seeds) with 95 percent probability. Sampling 1 or 2 cones from each of about 3 trees per ha would provide a reliable estimate of sound seed contents.     

Girdling decreases photosynthetic electron fluxes and induces sustained photoprotection in mango leaves

Girdling has been suggested as a way to improve earliness and intensity of flowering in mango (Mangifer indica L.). However, the accumulation of carbohydrates associated with girdling may result in a decrease in photosynthesis. We assessed the long-term effect of branch girdling during the prefloral period on leaf net photosynthesis (A(n)) of 3-year old mango trees, cv. Cogshall, growing on La Réunion island. Leaf gas exchange and chlorophyll fluorescence parameters were measured monthly from March to August 2004 on recently matured leaves on girdled and non-girdled branches. Within 28 days after girdling, A(n) was reduced by 77% and remained at about 2 micromol CO(2) m(-2 ) s(-1) until the beginning of flowering. The decrease in photosynthetic electron transport rate (J) and sustained photoprotection (reflected by the decrease in predawn maximal efficiency of photosystem II) effectively protected leaves on girdled branches from photodamage, as shown by the vigorous recovery of A(n) and J observed immediately after the appearance of inflorescences. These increases in A(n) and J were unaccompanied by a decrease in leaf carbohydrate concentration during the first month following the onset of flowering, indicating that there are carbohydrate-dependent and carbohydrate-independent mechanisms of sink regulation of photosynthesis. It is concluded that girdling does not necessarily lead to irreversible damage, even in the presence of a fourfold increase in leaf starch concentration and in the absence of any sink activity. However, the decrease in leaf nitrogen concentration indicates that there may exist long-term negative effects of branch girdling on photosynthetic capacity. A modified version of the biochemical model of A(n) is presented that takes account of the effect of leaf starch concentration on J.     

Girdling effects on fruit set and quantum yield efficiency of PSII in two Citrus cultivars

Girdling effects on fruitlet abscission, leaf chlorophyll, chlorophyll a fluorescence and carbohydrate concentration in various flowering and vegetative shoots were studied during natural fruit drop in two Citrus cultivars. Irrespective of shoot type, girdling delayed fruitlet abscission, but only fruitlets borne on leafy shoots had increased final fruit set. Chlorophyll a fluorescence analysis revealed differences in quantum yield efficiency of photosystem II of light adapted leaves (Phi(PSII)) among shoot types and in response to girdling. In young leaves of vegetative shoots, girdling decreased Phi(PSII), whereas Phi(PSII) increased from Day 30 after girdling in young leaves of leafy flowering shoots; however, Phi(PSII) did not change in mature leaves during fruit set in either control or girdled trees. Girdling altered leaf carbohydrate concentrations and the photosynthetic performance of the various shoot types. Our results indicate that, in Citrus, several carbohydrate-based regulatory mechanisms of photosynthesis coexist during carbohydrate accumulation brought about by girdling. It is concluded that the delay in fruitlet abscission and the increase in Phi(PSII )observed in girdled leafy flowering shoots are the mechanisms underlying the enhancement of fruit set after girdling.     

New observation of cone flies attacking cones of Picea obovata andLarix sibirica in central Siberia

lntroductionConeniesofgenusStfObilOmwiMichelsen(=LasiOmmaSteinAuct-partim=ChorthOPhil8Macquart=HtwiaRobineau-Desvoidy,DiPtera:Anthomyiidae)arewidespreadpestsdamagingconesandseedsofconifers(Roquesetal1996)-SpeciesofthisapparentIymonophyleticgenusoccurmainlyintheborealandMontanapartsoftheHoIartic,wherelarvaIinstarsdevelopexclusivelyintheconesofvariousgroupsofPinaceaeexceptthepinespecies(Michelsen,1988).AtotalOf19SbobiIOmyisspecieswereidentified(TUrgeonetal1994;Roquesetal1996),moStof…     

马尾松开花结实规律的初步研究

马尾松开花结实习性及球果丰歉规律,是良种生产的主要研究内容之一。例如幼林期初始开花结果年龄、雌雄球花的比例;成林期的结实数量、年度之间的差异以及球果在树冠层的分布情况;立地条件对林木开花结实的影响等问题,无论是实生种子园还是无性系种子园甚或采种母树林,都应当有所了解,掌握规律以指导园地管理与种子采收。探明这些问题不仅对于良种生产,同时在杂交育种等科研工作方面也是必不可少的。为此,我们对实生马尾松开花结实规律进行了初步研究,现总结如后。     

Impact and control of the cone tortricid Pseudococcyx tessulatana (Staudinger), damaging the cone crop of a selected clone of cypress (Cupressus sempervirens L.) in Italy

The green cypress (Cupressus sempervirens) is of great interest for ornamental, reforestation and windbreak use in the whole Mediterranean basin. In Italy, seed material selected for resistance to the fungus Seiridium cardinale is produced in seed orchards by controlled crosses of parent trees. The insect pest showing the highest impact on seed cone production is Pseudococcyx tessulatana (Lep.; Tortricidae), which attacks cones during the initial growth period as well as full-grown cones. The impact on the seed cone crop of the tortricid was estimated on a clone patented for its resistance to cypress canker (Agrimed 1). The attack was inversely related to the cone crop, as it concerned 36.7?% of cones in 1999 (high crop year) and the 66?% in 2000 (low crop year). In both years, about 90?% of the surveyed branches revealed cones attacked by P. tessulatana by the 1^st life-cycle larvae, whereas only 40?% of branches were also attacked by the larvae of the 2^nd life cycle. The highest attack rate per branch was always observed on branches bearing a low number of cones. The potential of two control methods against P. tessulatana to protect cones which result from crossing a mother tree “Agrimed 1” with selected father trees was also evaluated in 2000. The protection given by a sleeve surrounding the branch was almost complete (0.4?% cone mortality), whereas a cone mortality of 24.3?% was observed on branches treated by the insecticide diflubenzuron. Sleeves appear to be useful to protect branches on which special crosses were done, but are expensive and time-consuming and may favour the attack of the mealybug Planococcus vovae inside the sleeve. The insecticide application may represent a valid alternative, especially when protection should be directed toward a high number of branches.     

华北落叶松与日本落叶松杂交试验

通过华北落叶松与日本落叶松的杂交,在22个控制授粉杂交组合中,球果长在1.74 cm~2.92 cm之间,球果径在0.98 cm~1.46 cm之间;在30个组合中,单粒球果质量介于0.52 g~1.63 g之间;球果种鳞数在23枚~47枚之间;种子连翅长在0.75 cm~1.07 cm之间;种子千粒重在2.6 g~5.0 g之间。     

Effects of gibberellin A(4 + 7) and bark-ringing on cone initiation in mature Picea sitchensis grafts

Large numbers of cones (strobili) were induced in a 10-year-old plot of mature grafts of Picea sitchensis (Bong.) Carr. All trees injected with 20 mg GA(4 + 7) in June initiated female and male cones in the same year. This treatment increased the number of female cones per plant 12-fold above the controls, more than doubling the percentage of cones that were female. Complete bark-ringing (done in May of the previous year) showed an additive effect with GA on the number of female cones formed, but a negative interaction on the number of male cones induced. Ringing promoted male cone production most when used alone. Treatments, singly or combined, also increased the proportion of cones that were lateral, compared with the preponderance of terminal male cones in the controls. The effects were apparently not directly associated with alterations in vegetative vigor, although these occurred causing a reduction in the proportion of buds containing vegetative shoots the following year. The clones differed in most characteristics, but both sparse and prolific clones were induced to reproductive activity. Viable seed yields per tree, and notional production from seed-orchards were enhanced almost 10-fold by GA injection, and about 4-fold by bark-ringing and GA + bark-ringing.     

Seed production of western larch in seed-tree systems in the southern interior of British Columbia

A series of surveys and experiments were conducted on four sites to identify constraints to seed production and natural regeneration in western larch seed-tree systems in the southwestern interior of British Columbia, Canada. These surveys included pollen monitoring, a cone analysis to evaluate seed production potential, seed trapping to estimate seed rain and the installation of field germination trials to assess the effects of germination substrate and seed losses due to bird and rodent predators. Pollen shedding was found to be adequate for moderate seed production with filled seed counts ranging from 9 to 30 per cone (10–34% of all seeds/cone). No significant differences in seed yields per cone and cone characteristics were observed between uncut control stands and seed-tree stands. Seed rain was generally good in 1995, ranging from 70,000 to 4.6 million seed/ha. For the four seed-tree stands, the average filled seed percentage of the trapped seeds ranged from 9–30%. Seed rain and seed quality were much reduced in 1996. Field germination trials showed western larch seeds germinated and survived best (15–70%) on mineral soil but rodent and/or bird predation reduced germination success significantly. Germination/germinant survival on undisturbed forest floor, covered with predator exclusion screens, was intermediate.