The Effect of Scion Water Potential on Graft Success in Sitka Spruce (Picea sitchensis)

The effect of scion storage on graft success in Sitka sprucehas been examined. Scions kept in cold store for up to 7 d werefound to graft successfully to active rootstocks in about 95%of cases. From 7 d, however, there was a marked decline in successuntil, after 14 d of storage prior to grafting less than 40%of grafts survived. Scion leaf-water potential decreased continuouslyduring storage and fell dramatically during the first 3 d aftergrafting. In successful grafts, scion water potential then recovered,reaching a stable level after 3 weeks. No recovery occurredin grafts, which eventually failed. The relationship betweenscion leaf water potential and graft success rate is discussedwith reference to the role of callus development in graft formation. Picea sitchensis, water potential, graft success     

The effects of localized heating and disbudding on cambial reactivation and formation of earlywood vessels in seedlings of the deciduous ring-porous hardwood,Quercus serrata

Background and Aims

The networks of vessel elements play a vital role in the transport of water from roots to leaves, and the continuous formation of earlywood vessels is crucial for the growth of ring-porous hardwoods. The differentiation of earlywood vessels is controlled by external and internal factors. The present study was designed to identify the limiting factors in the induction of cambial reactivation and the differentiation of earlywood vessels, using localized heating and disbudding of dormant stems of seedlings of a deciduous ring-porous hardwood, Quercus serrata.

Methods

Localized heating was achieved by wrapping an electric heating ribbon around stems. Disbudding involved removal of all buds. Three treatments were initiated on 1 February 2012, namely heating, disbudding and a combination of heating and disbudding, with untreated dormant stems as controls. Cambial reactivation and differentiation of vessel elements were monitored by light and polarized-light microscopy, and the growth of buds was followed.

Key Results

Cambial reactivation and differentiation of vessel elements occurred sooner in heated seedlings than in non-heated seedlings before bud break. The combination of heating and disbudding of seedlings also resulted in earlier cambial reactivation and differentiation of first vessel elements than in non-heated seedlings. A few narrow vessel elements were formed during heating after disbudding, while many large earlywood vessel elements were formed in heated seedlings with buds.

Conclusions

The results suggested that, in seedlings of the deciduous ring-porous hardwood Quercus serrata, elevated temperature was a direct trigger for cambial reactivation and differentiation of first vessel elements. Bud growth was not essential for cambial reactivation and differentiation of first vessel elements, but might be important for the continuous formation of wide vessel elements.     

Induction of cambial reactivation by localized heating in a deciduous hardwood hybrid poplar (Populus sieboldii x P. grandidentata)

BACKGROUND AND AIMS: The timing of cambial reactivation plays an important role in the control of both the quantity and the quality of wood. The effect of localized heating on cambial reactivation in the main stem of a deciduous hardwood hybrid poplar (Populus sieboldii x P. grandidentata) was investigated. METHODS: Electric heating tape (20-22 degrees C) was wrapped at one side of the main stem of cloned hybrid poplar trees at breast height in winter. Small blocks were collected from both heated and non-heated control portions of the stem for sequential observations of cambial activity and for studies of the localization of storage starch around the cambium from dormancy to reactivation by light microscopy. KEY RESULTS: Cell division in phloem began earlier than cambial reactivation in locally heated portions of stems. Moreover, the cambial reactivation induced by localized heating occurred earlier than natural cambial reactivation. In heated stems, well-developed secondary xylem was produced that had almost the same structure as the natural xylem. When cambial reactivation was induced by heating, the buds of trees had not yet burst, indicating that there was no close temporal relationship between bud burst and cambial reactivation. In heated stems, the amount of storage starch decreased near the cambium upon reactivation of the cambium. After cambial reactivation, storage starch disappeared completely. Storage starch appeared again, near the cambium, during xylem differentiation in heated stems. CONCLUSIONS: The results suggest that, in deciduous diffuse-porous hardwood poplar growing in a temperate zone, the temperature in the stem is a limiting factor for reactivation of phloem and cambium. An increase in temperature might induce the conversion of storage starch to sucrose for the activation of cambial cell division and secondary xylem. Localized heating in poplar stems provides a useful experimental system for studies of cambial biology.     

Changes in the localization and levels of starch and lipids in cambium and phloem during cambial reactivation by artificial heating of main stems of Cryptomeria japonica trees

Background and Aims

Cambial reactivation in trees occurs from late winter to early spring when photosynthesis is minimal or almost non-existent. Reserve materials might be important for wood formation in trees. The localization and approximate levels of starch and lipids (as droplets) and number of starch granules in cambium and phloem were examined from cambial dormancy to the start of xylem differentiation in locally heated stems of Cryptomeria japonica trees in winter.

Methods

Electric heating tape was wrapped on one side of the stem of Cryptomeria japonica trees at breast height in winter. The localization and approximate levels of starch and lipids (as droplets) and number of starch granules were determined by image analysis of optical digital images obtained by confocal laser scanning microscopy.

Key Results

Localized heating induced earlier cambial reactivation and xylem differentiation in stems of Cryptomeria japonica, as compared with non-heated stems. There were clear changes in the respective localizations and levels of starch and lipids (as droplets) determined in terms of relative areas on images, from cambial dormancy to the start of xylem differentiation in heated stems. In heated stems, the levels and number of starch granules fell from cambial reactivation to the start of xylem differentiation. There was a significant decrease in the relative area occupied by lipid droplets in the cambium from cambial reactivation to the start of xylem differentiation in heated stems.

Conclusions

The results showed clearly that the levels and number of storage starch granules in cambium and phloem cells and levels of lipids (as droplets) in the cambium decreased from cambial reactivation to the start of xylem differentiation in heated stems during the winter. The observations suggest that starch and lipid droplets might be needed as sources of energy for the initiation of cambial cell division and the differentiation of xylem in Cryptomeria japonica.     

Development and Structure of Unusual Xylem Elements During Graft Union Formation in Picea sitchensis L.

Electron microscope studies of Sitka spruce have been undertakento observe the sequence of cellular development following grafting.Observations at the graft interface reveal a recovery and regenerationsequence associated with union formation. Xylem elements differentiateddirectly from the vascular cambia of the rootstock and scionare different from elements arising from parenchymatous callusderived from ray parenchyma, which may be produced in an attemptto establish a connecting water conducting system as rapidlyas possible. Failure to form such a system may be a primarycause of graft failure. Grafting, Picea sitchensis, xylen elements     

Effects of Waterlogging on Water Relations of Actively-growing and Dormant Sitka Spruce Seedlings

Two-year-old Sitka spruce [Picea sitchensis (Bong.) Carr.] seedlings,either actively growing or dormant, were waterlogged in a growthroom at 15 °C. Shoot and root growth, transpiration andleaf water potential were observed. In actively-growing plants shoot extension continued after waterlogging,though at a reduced rate, and shoots of dormant plants brokebud and extended during the waterlogging period. Root growthwas suppressed by waterlogging in both types of plant. The 22day waterlogging treatment eventually killed the actively-growingplants but plants which were dormant at the time of waterloggingwere more tolerant. Changes in plant water relations after waterloggingwere entirely different depending on the condition of the plantswhen the soil was flooded. Dormant plants showed a gradual reductionin transpiration and increased water stress over the waterloggingperiod; after the soil was drained leaf water potential increasedto equal the value of control plants which had been maintainedin a freely drained condition, but transpiration did not increaseuntil root growth began. Actively-growing plants exhibited amore complex behaviour, characterized by a very rapid reductionin transpiration after waterlogging, accompanied by a briefperiod of water stress, followed by a period of increasing transpirationrate in the absence of water stress. Finally a second reductionin transpiration occurred and water stress increased as theseedlings died. The importance of the stage of activity of theroot system to the response of plants to waterlogging is discussed. Picea sitchensis (Bong.) Carr., Sitka spruce, waterlogging, water relations, dormancy, transpiration, water potential     

Experimentally Synthesized Plant Chimeras 2. A Comparison of In vitro and In vivo Techniques for the Production of Interspecific Nicotiana Chimeras

In vitro and in vivo techniques were compared for synthesizingchimeras between Nicotiana glauca Grahm and N tabacum L Interspecificchimeral callus, produced from mixed callus cultures in vitro,was placed on media which favoured only N tabacum shoot formationNone of the 474 regenerated N tabacum shoots incorporated Nglauca cells into their meristems When chimeral callus was regeneratedunder hormonal conditions favouring simultaneous organogenesis,of 397 shoots, only non-chimeral shoots of both species aroseIn vivo, reciprocal splice grafts between species were decapitatedjust above the graft union and treated with or without auxin—lanolinpastes Auxin increased callus formation but inhibited adventitiousshoot formation Three of 209 adventitious shoots arising fromthe graft union were interspecific mericlinal chimeras whichwere later stabilized as periclinal chimeras All three chimerasformed when N glauca was the understock Two of the chimerasarose on untreated shoots which produced no visible callus,indicating that excessive callus formation may be unnecessaryfor multiple cell origin of adventitious shoots to occur Chimeras, tobacco, Nicotiana glauca, Nicotiana tabacum, tissue culture, graft chimeras, callus cultures     

Structural Changes in the Vascular Cambium of Pinus strobus L. during an Annual Cycle

The changes in the ultrastructure of cambial cells of easternwhite pine (Pinus strobus L.) during an annual cycle are observedand recorded as are relationships of cambial cells during dormancyand at resumption of cambial activity. Cambial activity wasresumed late in March or early in April, when a few cells dividedpericlinally. Cambial activity reached a maximum during thelatter part of May with 15 to 20 undifferentiated cells present.In July it declined markedly, and the number of undifferentiatedcells equalled that of the dormant period. The xylem and phloemtissue cells produced late in the annual cycle overwinteredat varying developmental stages. In October cambial cells structurallyresembled dormant cells. The number of dormant cells in easternwhite pine cambium varied from 6 to 10. Active cells were characterizedby a large central vacuole, by an abundance of all cell organelles,and by thin cell walls. Dormant cells were characterized bynumerous small vacuoles, by structurally and quantitativelymodified cell organelles, and by relatively thick cell walls.     

Graft establishment between compatible and incompatible Prunus spp

Graft compatibility has been studied in apricot (prunus armeniacaL.) grafted on Prunus cerasifera Ehrh. Two apricot cultivars,one compatible and one incompatible on this rootstock, wereselected for this study. In these species incompatibility isonly manifested by tree breakdown at a late phase of the tree'slife. The process of graft union formation was observed forthe first month following grafting. No differences were foundeither in the process of healing or in its kinetics. Thus, callusproliferation, callus differentiation and vascular connectionsare established in the same way and at the same time in bothcompatible and incompatible grafts. However, clear differencesexist in the level of differentiation of the callus produced.While in compatible grafts, callus quickly differentiates intocambium and vascular tissue, in incompatible grafts this differentiationis not complete and a portion of the tissue evolves into a parenchymatoustissue that coexists with the differentiated vascular tissue. Key words: Graft, Prunus, compatibility     

Relationship between the earlywood-to-latewood transition and changes in levels of stored starch around the cambium in locally heated stems of the evergreen conifer <Emphasis Type="Italic">Chamaecyparis pisifera</Emphasis>

Key message

We observed the formation of latewood tracheids with narrow diameters and thick walls and the disappearance of stored starch around the cambium on the locally heated region of stems in evergreen conifer Chamaecyparis pisifera during winter cambial dormancy.

Abstract

Wood formation is controlled by cambial cell division, which determines the quantity and quality of wood. We investigated the factors that control cambial activity and the formation of new tracheids in locally heated stems of the evergreen conifer Chamaecyparis pisifera. Electric heating tape was wrapped around one side of the stem, at breast height, of two trees in 2013 and two in 2014. Pairs of stems were locally heated in winter, and small blocks were collected from heated and non-heated regions of stems. Cambial activity and levels of stored starch around the cambium were investigated by microscopy. Cambial reactivation and xylem differentiation occurred earlier in heated than in non-heated regions. New cell plates were formed after 14–18 days of heating. After a few layers of tracheids with large diameters and thin walls had formed, cell division and cell enlargement during differentiation were inhibited. Tracheids with narrow diameters and thick walls, defining those as latewood, were formed near the cambium, and finally, four to six layers of tracheids were induced. After cambial reactivation, amounts of stored starch started to decrease and starch disappeared completely from phloem and xylem cells that were located near the cambium during the differentiation of heated regions. Our results suggest that an increase in temperature induces the conversion of stored starch to soluble sugars for continuous cambial cell division and earlywood formation. By contrast, a shortage of stored starch might be responsible for inhibition of cambial activity and induction of the formation of latewood tracheids.

     

The Anatomical Relationship Between Cambial Regeneration and Root Initiation in Wounded Winter Cuttings of the Apple Rootstock M.26

Root primordia differentiate remote from the existing vasculartissue of split- or incision- wounded winter cuttings. Thisis preceded by heavy callusing of the wounds and basal cut surface.Most of the callus is cortical in origin but callus is alsoformed as a result of damage to the cambium. In the incisiontreatment a new cambium differentiates within the cambial callusfrom the undamaged cambium on either side so as to form an outward-pointingsalient enclosing randomly orientated xylem. Two such salientsare formed in the split base treatment since each resultanthalf behaves like a separate cutting. The salients are subdividedhorizontally into finger-like projections due to the dispositionof the rays at the edges of the wound. Once a root primordiumforms, differentiation of procambium-like tissue between itand one or more projections proceeds rapidly, followed by outgrowthof the root. Roots emerge from the basal callus and in verticalfiles from the wound callus. The split base treatment increases16-fold the number of rooted cuttings over controls, while incisionwounds increase rooting four-fold; this is associated with thefact that more rhizogenic (salient-forming) sites are formedby splitting the base. The physical and anatomical factors involvedin cambial regeneration are discussed. Anatomy, apple, callus, cambium, cambial regeneration, M.26 rootstock, Malus pumila L., rooting, root initiation, wound response     

Variations in the Lengths of Fusiform Cambial Cells and Vessel Elements in Kalopanax pictus

Samples of a mature specimen of Kalopanax pictus, a ring-poroushardwood, were studied to compare the respective lengths offusiform cambial cells and vessel elements in the stem. Thelengths of dormant and reactivated fusiform cambial cells weremeasured with a confocal laser scanning microscope in tissuethat had been macerated by digestion with pectinase and in thicktangential sections. The lengths of early wood and late woodvessel elements were measured in tissues that had been maceratedby Franklin's method. The vessel elements and fusiform cambialcells varied considerably in length within individual samples.The mean length of early wood vessel elements corresponded tothat of fusiform cells in the dormant cambium but not in thereactivated cambium. Significant differences were observed betweenthe mean lengths of dormant and reactivated fusiform cambialcells, between those of reactivated fusiform cambial cells andearly wood vessel elements, between those of reactivated fusiformcambial cells and late wood vessel elements, and between thoseof early wood and late wood vessel elements. The frequency distributionsof lengths of cambial cells were bimodal and differed from thoseof vessel elements, which more closely resembled a normal distribution.The proportion of shorter lengths was higher in the reactivatedcambium than in the dormant cambium, the early wood and thelate wood vessel elements. Our results do not suppot the hypothesisthat the lengths of early wood vessel elements in ring-poroushardwoods change during differentiation. The similar rangesof recorded lengths suggest that short and long vessel elementsmight be derived directly from short and long cambial cells,respectively. Copyright 1999 Annals of Botany Company Kalopanax pictus, cambium, vessel element, confocal laser scanning microscopy, maceration, cell length.     

Cambial reactivation in locally heated stems of the evergreen conifer Abies sachalinensis (Schmidt) Masters

A study was made of cambial activity, the localization of storage starch around the cambium, and the localization and occurrence of microtubules in cambial cells from dormancy to reactivation in locally heated (22–26 °C) stems of the evergreen conifer Abies sachalinensis. Heating induced localized reactivation of the cambium in the heated portions of the stem. Erect ray cambial cells resumed cell division 1 d prior to the reactivation of fusiform cambial cells and procumbent ray cambial cells. The re-initiation of the division of fusiform cambial cells occurred first on the phloem side. During the heat treatment, the amount of storage starch decreased in procumbent ray cambial cells and in the phloem parenchyma adjacent to the cambium but increased in fusiform cambial cells. Preprophase bands of microtubules, spindle microtubules and phragmoplast microtubules were observed both in erect ray cambial cells and in procumbent ray cambial cells. By contrast, no evidence of the presence of such preprophase bands of microtubules was detected in fusiform cambial cells. The results suggest that the localized heating of stems of evergreen conifers might provide a useful experimental model system for studies of the dynamics of cambial reactivation in intact trees. Received: 25 May 2000 / Accepted: 12 July 2000     

Relationships between cambial activity,cell differentiation and the localization of starch in storage tissues around the cambium in locally heated stems of<Emphasis Type="Italic"> Abies sachalinensis</Emphasis> (Schmidt) Masters

A study was made, in a cool-temperate zone, of the extent of cell division in the cambium, the extent of differentiation of cambial derivatives, and the localization of storage starch around the cambium in locally heated (22–26°C) stems of the evergreen conifer Abies sachalinensis (Schmidt) Masters during cambial dormancy and immediately after natural reactivation of the cambium. In locally heated regions of stems during cambial dormancy, heating induced localized reactivation of the cambium. However, the cells in the heated and reactivated cambium stopped dividing soon after only a few cells had been generated. In addition, no differentiation of the xylem and the disappearance of starch from storage tissues around the cambium were observed. In regions of stem that had been locally heated after natural reactivation of the cambium, cell division continued in the cambium and earlywood tracheids with a large radial diameter and secondary walls were formed, with abundant starch in the storage tissues around the cambium. Our results suggest that the extent of both cell division in the cambium and cell differentiation depends on the amount of starch in storage tissues around the cambium in the locally heated stems of an evergreen conifer growing in a cool-temperate zone.     

Predicted changes in the synchrony of larval emergence and budburst under climatic warming

Summary The impact of climatic warming on the synchrony of insect and plant phenologies was modelled in the case of winter moth (Operophtera brumata) and Sitka spruce (Picea sitchensis) in the Scottish uplands. The emergence of winter moth larvae was predicted with a thermal time requirement model and the budburst of Sitka spruce was predicted from a previously published model (Cannell and Smith 1983) based on winter chilling and thermal time. The date of emergence of winter moth larvae was predicted to occur earlier under climatic warming but the date of budburst of Sitka spruce was not greatly changed, resulting in decreased synchrony between larval emergence and budburst. The general question of how a change of climate might affect phenological synchrony and insect abundance is discussed.     

Cambial sensitivity to rising temperatures by natural condition and artificial heating from late winter to early spring in the evergreen conifer Cryptomeria japonica

Differences in the timing of cambial reactivation and the initiation of xylem differentiation in response to the sum of daily maximum temperatures were studied in two Cryptomeria japonica trees with cambium of different ages under natural and locally heated conditions. In addition, we observed the effects of low temperature on cambial activity. The timing of cambial reactivation and of the initiation of xylem differentiation differed between 55- and 80-year-old cambium under natural conditions. In the 55-year-old cambium, cambial reactivation occurred when the cambial reactivation index (CRI), calculated on the basis of daily maximum temperatures in excess of 10°C, was 94 and 97°C in 2007 and 2008, respectively. In 80-year-old cambium, cambial reactivation occurred when the CRI, calculated on the basis of daily maximum temperatures in excess of 11°C, was 69 and 71°C in 2007 and 2008, respectively. After cambial reactivation in 2007, normal cell division was evident in the cambium even though the minimum temperature had fallen between −2 and −3°C. Under natural conditions, xylem differentiation started 38–44 days after cambial reactivation. In heated stems, the time between cambial reactivation and the initiation of xylem differentiation ranged from 14 to 16 days, a much shorter time than under natural conditions, indicating that continuous exposure to an elevated temperature had induced earlier xylem differentiation. Our observations indicate that the sensitivity to reactivation inducing stimuli of the cambium depends on both the stage of dormancy and tree age of the cambium.     

Seasonal Rhythms of Structure and Behaviour of Vascular Cambium in Ficus rumphii

Cambial structure and activity of Ficus rumphii Blume vary withthe changes in local climate. The cambial cells start swellingearly in April prior to the onset of periclinal divisions whichare most frequent in August. Cell division stops in October.During the growth season, initiation as well as cessation ofthe phloem production precedes that of xylem. A moderately hightemperature is correlated with the cambial reactivation. Onceinitiated, the activity continues at relatively low temperatures.Hot and dry environment favours the phloem production, whereashot and moderately humid conditions induce xylogenesis. Thesize and relative proportion of cambial initials also changewith season. Fusiform initials are shorter and broader duringthe rainy season (July–September) than for the rest ofthe year. Multiseriate and triseriate rays, as also the tallrays, outnumber the other types of rays throughout the year. Ficus rumphii, vascular cambium, phenology, climatic variation     

Prevention of auxin-induced vascular differentiation in wound callus by surface-to-surface adhesion between calluses of stock and scion in cactus grafts

The relationship between formation of CVB, which connects vascularcut ends of stock and scion, and the condition of tissue whereCVB is expected to be induced was studied using a cactus graftcombination of Notocactus submammulosus var. pampeanus youngseedlings on Hylocereus trigonus plants. When a scion with its basal part removed by a transverse cutwas put onto a transverse cut surface of a stock with a distanceof 1 mm between the vascular cut ends of both graft components,CVB was formed in only 13% of the grafts in the callus massmade by adhesion between calluses of stock and scion. The percentagearose to ca. 100% when 100 ppm NAA was applied to the scionapices. This promotive effect of NAA decreased with increasingtime from grafting to NAA application. When wound calluses of stock and scion were prevented from contactonly at the portion between the vascular cut ends of stock andscion by introducing a piece of aluminium foil into the graftunion, CVB was formed in 80% of the grafts in the callus ofthe stock without NAA application. In the case where the scionwas grafted at right angle onto an additional longitudinal cutsurface made 1 mm from the vascular bundle of the stock withremaining intact parenchyma between this cut surface and thevascular bundle of the stock, CVB was not formed even when NAAwas applied. These results suggested that wound response wasa prerequisite for CVB differentiation and that surface-to-surfaceadhesion of calluses inhibited CVB formation by making calluscells differentiate into quiescent parenchyma cells rapidly.The mechanism of this phenomenon is discussed. (Received September 29, 1977; )     

The Effect of Explant Type on the Establishment of Sitka Spruce [Picea sitchensis (Bong.) Carr.] in Culture

Five different types of shoot tip explant from three-year-oldand 13-year-old Sitka spruce trees were established on a rangeof media and shoot growth was recorded. While Schenk and Hildebrandtmedium gave the greatest shoot elongation, Webb and Street mediumproduced the healthiest-looking shoots. Poorest growth was recordedfor the explants cultured without the crown or any vasculartissues from the previous year's growth. [¹⁴C]sucrose tracerstudies indicated that poor uptake was not responsible for thereduced growth and it was suggested that damage due to inadequatewater uptake may be responsible. Results demonstrated that peelingthe protective scales from resting buds and trimming the shoottissues below the crown to a wedge shape and excluding the barkwas a reliable method of explant preparation for establishingmature and juvenile Sitka spruce in culture. Picea sitchensis, Sitka spruce, mature, juvenile, crown, [¹⁴C]sucrose, micropropagation