Description and Model of the Architecture of Four Genotypes of Determinate Autumn-sown White Lupin (Lupinus albus L.) as Influenced by Location, Sowing Date and Density

The structure of four new autumn-sown determine genotypes ofwhite lupin, grown with a combination of sowing dates and plantdensities at four locations in France was studied in 1990/91and 1991/92. Plant architecture was characterized in terms ofthe number of first-order branches produced and the distributionof leaves on these branches and how they varied with the numberof mainstem leaves and the position of the branch on the mainstem. The variation in the number of mainstem leaves on determinegenotypes was satisfactorily described by an earlier model developedfor indeterminate genotypes using the intensity of vernalizationrelative to accumulated temperature above 3°C as input.However the architecture of the first-order branches, definedby their number and the total number of leaves per branch ateach subtending position on the mainstem, differed and was influencedby genotype, location and sowing date. In four determinate genotypes,these two characters were positively correlated, and correlatedwith the number of leaves on the mainstem. Increasing densityfrom 10 to 40 plants m^-2 reduced the number of branches andtheir total number of leaves. Pruning 15 leaves from the mainstemat the beginning of stem elongation did not influence the developmentof the first-order branches. There appeared to be a functionalrelationship between the number of leaves on the mainstem andthe number of branches established very early in the growingseason. The profiles of number of leaves on the first-order brancheson the mainstem with branch position were modelled using twosub-models, one describing the mean number of leaves on thebranches actually present, and the second describing the frequentlyof occurrence of a branch at a particular position on the mainstem.Of the five model parameters, one, representing the minimalnumber of branches present on the plant, was correlated withthe number of first-order branches. Genotype, location, sowingdate and density affected the shape of the profiles.Copyright1993, 1999 Academic Press While lupin, Lupinus albus L., determine growth, architecture, model, branch     

Stability of the Nitrogen Concentration of Inoculated White Lupins during Pod Development

The general pattern of decrease of the 'critical' plant N concentration(i.e. minimum concentration required for maximum growth rate)during growth has been described for several C₃ non grain-legumespecies, and this can be used as a reference curve for diagnosisof N nutrition in these species. The present study was undertakento investigate changes of N concentration during growth of agrain legume, in different conditions of N nutrition. Whitelupin (Lupinus albus L.) was grown for six crop seasons in fieldtrials in which inoculation with Rhizobium lupini, nitrogenfertilizer rate, cultivar and plant density were density weremanipulated. The yield and dry matter production of noninoculatedplants were lower than, or at the best similar to, those ofinoculated plants, whatever the level of N supply. From anthesisto the beginning of seed filling, the N concentration of shootsof inoculated plants was found to be remarkably stable betweenyears, N fertilization regimes, cultivars, and for individualplants within a plot. Nitrogen concentration only varied withplant density. By contrast, the N concentration of noninoculatedplants was highly variable and generally lower than that ofinoculated plants, whatever the level of N supply. The highand stable N concentration of inoculated plants did not appearto be necessary for maximum growth rate but seemed to be requiredfor maximum production of seed dry matter and N. The potentialuse of these results to diagnose, in any white lupin crop, aninefficiency of the lupin-R. lupini interaction is evaluated.Copyright1993, 1999 Academic Press Lupinus albus L., white lupin, N₂ concentration, inoculated plants, non-inoculated plants, N₂ fixation efficiency, diagnosis     

Density Studies on Lupins. II. Components of Seed Yield

Components of seed yield of cv. Ultra (Lupinus albus L.) andcv. Unicrop (L. angustifolius L.) were measured when grown atthree densities. The low density (10 plants m^–2) Unicropyield (34 g seed per plant) was 1.8 times that of Ultra as ithad more branches, pods and seeds per pod. Ultra seeds (310mg per seed) were heavier than Unicrop seeds (180 mg). The branchingpattern of Ultra was less dependent on plant density, henceat 93 plants m^–2 it gave a higher per plant yield (7.4vs 6.4 g) than Unicrop at lower densities (83 plants m^–2).Density had most influence on pod formation and only small effectson seeds per pod and seed weight. Yield components on the main-steminflorescence were influenced less by density than componentson branch inflorescences. Later formed, higher order generationsof inflorescences were most affected by increased inter- andintra-plant competition. Pod numbers on the main-stem were similarfor both species. Pods formed at higher flower nodes in Unicrop,but the lower flower nodes were less fertile than those in Ultra.Node position of flowers had no influence on seed set in main-stemUnicrop pods, but pods from higher nodes in Ultra formed fewerseeds. Seed weights in Unicrop were similar among main-stemnodes but in Ultra seed weights tended to increase at highernodes. Lupinus spp, lupins, seed yield, planting density     

Branch development in Lupinus angustifolius L.#I. Not all branches have the same potential growth rate

Although the basal and uppermost lateral branches of Lupinus angustifolius L. frequently grow and contribute to yield, buds formed in the axils of leaves 6-12 (referred to as middle buds) rarely grow. This may be due to an inherent limitation of these buds, or some form of apical dominance or competition imposed by the plant. The hypothesis that middle buds have the full capacity to grow, but remain suppressed on intact plants was tested. The main stem apex and buds from the axils of leaves 1 and 8 (bud 1 and bud 8) were excised and cultured on sterile agar. The buds were removed from culture and weighed every 2-3 d for 21 d. The growth rate of apices from the main stem was approximately 5.8 mg d^-1, compared to 2.4 mg d^-1 for bud 1 and 0.9 mg d^-1 for bud 8. Buds in the axils of leaves 6-10 on intact plants were painted six times with a synthetic cytokinin, benzylaminopurine, from 40 d after sowing. This promoted rapid elongation and thickening of these buds, visible as early as 5 d after painting began. The rapid growth of these branches was associated with a reduction in the length of the remaining branches on the plant. However, excision of lower branches did not increase the growth of the middle buds. It is concluded that buds 6-12 of Lupinus angustifolius L. have a partial potential to grow. This potential appears to be limited by innate factors in the bud, and may be structural and/or hormonal. The limitation appears to develop very early in the plant, and potential growth is not modified by subsequent nutrition of the plant.     

Influence of Position and Number of Nodal Roots on Outgrowth of Axillary Buds and Development of Branches in Trifolium repens (L.)

The implications of the presence of a root, either at the parentnode or at neighbour nodes, on branch formation of Trifoliumrepens (white clover) was investigated. Plants were freely rootedor rooting was restricted to every sixth or every twelfth nodealong the parent axis. The absence of a root at the parent nodehad little influence on the probability of the subtending axillarybud forming a branch but, on average, delayed the outgrowthof the bud. The probability that an axillary bud, emerging froma non-rooted parent node, developed to a lateral branch (branchwith elongated internodes) decreased with decreasing proximityof the parent node to a rooted node. Lateral branches emergingfrom non-rooted parent nodes which were two nodes distal toa rooted node had a higher rate of node appearance, a greatermean internode length and area per leaf, and were more branchedthan lateral branches emerging from other non-rooted parentnodes. The dry mass of each single root and of branches grownat rooted parent nodes were significantly higher in plants withrestricted rooting than in freely rooted plants. Restrictionin the number of rooted nodes per plant increased the numberof inflorescences. It is concluded that the whole plant responseto restricted root formation was continuous growth of the parentaxis and compensatory growth of the branch at the rooted node.In general, growth was slow for axillary buds whose developmentwas dependent on the basipetal movement or cross-transport withinthe stolons of resources exported from roots. Trifolium repens (L.); white clover; axillary bud outgrowth; branch development; clonal growth; nodal root     

Growth Context and Fate of Axillary Meristems of Young Peach Trees. Influence of Parent Shoot Growth Characteristics and of Emergence Date

The relationship between several growth components of a shootand the fates of the axillary meristems (developing in the axilsof the leaves) borne by that shoot were studied, on first-ordershoots of young peach trees. A comprehensive picture of thoserelationships was obtained by a discriminant analysis. Shootgrowth at meristem emergence date was characterized by internodelength, leaf-production rate and leaf-unfolding duration. Allpossible fates of axillary meristems at the end of the growingseason (i.e. blind nodes, single vegetative or flower bud, budassociations, sylleptic or proleptic shoots) were considered.Shoot-elongation rate determined meristem fates quantitatively.The number of buds produced by a meristem increased when theshoot-elongation rate increased. Qualitatively, the fate of axillary meristems was related tothe balance between shoot-growth components. If the subtendingleaf unfolded slowly, sylleptic or proleptic shoots were morelikely to develop than bud associations, for high shoot-elongationrates; and flower buds were more frequent than vegetative buds,for low shoot-elongation rates. Compared to flower buds, blindnodes appeared for similar shoot-elongation rates but longerinternodes and lower leaf-production rates. The emergence dateslightly modified the relation between shoot growth and axillary-meristemfates, but the main features held true throughout the growingseason. The relationships between shoot growth and meristem fates mayresult from competitive interactions between the growing subtendingleaf and the developing axillary meristem. Growing conditionsmight also influence both shoot growth and meristem fates byfavouring either cell enlargement or cell division.Copyright1995, 1999 Academic Press Peach tree, Prunus persica (L.) Batsch, axillary meristem, meristem fate, branching, flowering, shoot growth, discriminant analysis, exploratory analysis     

Growth Dynamics and Morphology of Annual Shoots, According to their Architectural Position, in Young Cedrus atlantica (Endl.) Manetti ex Carriere (Pinaceae)

The influence of shoot architectural position on growth andbranching pattern of young Cedrus atlantica (Endl.) Manettiex Carrière trees were studied. Extension growth andtype of axillary products (lateral bud, sylleptic short or longshoots) of annual shoots of increasing branching order (mainstem, branches and branchlets) were recorded weekly during the1993 growing season. Annual final shoot length, duration ofextension, and maximum extension rate decreased with increasingbranching order. Sylleptic axillary shoots occurred only onannual shoots of the main stem and branches and were producedwhen extension rate was at its highest. Differences in growthrate and final length of annual shoots, according to their architecturalposition, were related to differences in the total number anddiversity of types of sylleptic axillary shoots produced. Itis suggested that types and numbers of sylleptic axillary shootsproduced are linked with threshold values for both final lengthand extension rate of the parent shoot. Copyright 1999 Annalsof Botany Company Atlas cedar, extension growth, sylleptic branching, tree architecture, morphology.     

The Effects of Temperature and Other Variables on the Contribution of Lateral Branches to Yield in Phaseolus vulgaris L.

At low temperatures (15/15 °C day/night) in controlled environmentsthe growth of lateral branches at the cotyledonary node ofPhaseolusvulgarts L is suppressed The suppression can be overcome byraising the temperature of the buds by approximately 6 °Cwith small electric heaters In order to test the practical significanceof the induction of branching for yields of the commercial crop,seedlings were raised in contrasted regimes and then transplantedto the field The effects of pretreatment regime on final yieldwere small, changes in the yield from axillary branches tendedto be balanced by compensatory changes in the yield from themain stem In another field experiment, synthetic growth substanceswere applied in order to suppress or enhance branching Changesin the amount of yield carned on branches were again offsetby compensatory changes in the yield from the main stem Compensatoryeffects between branches and main stem were also found in avariety trial However, in an experiment on a single cultivarand various levels of N fertilizer, compensatory effects werenot found, here, branch and main stem yields were positively,rather than negatively, correlated These results are discussedin relation to the intrinsic factors that govern yield in Pvulgaris Phaseolus vulgaris L, dwarf bean, axillary branches, correlative inhibition, temperature, growth substances, plant density, yield     

Winter Growth of Autumn-sown White Lupin (Lupinus albus L.) Main Apex Growth Model

The winter growth of winter white lupin (cv. Lunoble) was investigated.Over three consecutive years, 1987–1989, it was sown atdifferent times at Lusignan (France) and in 1989, at nine differentlocations with various sowing times. The production of primordia,the vernalization requirements and the final number of leaveson the main stem were related to field measurements of dailymaximum and minimum temperatures. A statistical model for the main apex growth with a system oftwo equations was developed, with a threshold level for leafprimordia production at 3 °C. The number of leaf primordiaproduced by a vegetative apex (y) in terms of the cumulativesums of temperature over 3 °C (x) followed the curvilinearregression y = 4.76 + 00268x + 00000156x². The upper and lowertemperature limits for vernalization were estimated as 14 andI °C respectively. The vernalization requirements of a vegetative apex (y) decreasedwhen the number of initials produced (x) increased accordingto the negative exponential regression y = exp (7.2 + 002626.x). The two equations were used for the prediction of the finalnumber of leaves of a lupin crop. The predictive accuracy ofthe model was checked against independent data. The agreementbetween observed and predicted final leaf number was often close,but some deviations did occur with low leaf number. The modeldescribed most of the growth phenomena which occur during thephase sowing to floral initiation of the main stem of a winterlupin crop, and its possible uses are discussed. Lupinus albus L., white lupin, growth, model, vernalization, primordia, apex, thermal time     

The Distribution of Nine Elements in Shoots of Lupinus albus L. and Lupinus angustifolius L. Compared with that of Silicon as a Measure of Passive Transport

The Ca, Mg, K, Na, P, Fe, Mn, Zn, Cu and opaline-Si contentsof leaves, stems and inflorescences from each order of shootaxis was determined in Lupinus albus L. and Lupinus angustifoliusL. The distribution of Si was used as a base for passive transportin the transpiration stream. All of the elements investigatedwere redistributed among the leaves, stems and inflorescencesof either L. albus or L. angustifolius. Most of the elementsinvestigated were enriched in the inflorescences and depletedin either the leaves or the stems. Sodium was enriched in thestems whereas Ca and Mn were redistributed only in L. albus.The pattern of element redistribution was similar in each ofthe lateral shoot axes except for the youngest. For the elementsenriched in the inflorescences, more than half was suppliedby redistribution. Calcium redistribution was similar to thatfor K, which is regarded as phloem mobile, but a mechanism forCa redistribution is uncertain. Lupinus albus L., Lupinus angustifolius L., mineral transport, leaves, inflorescences, transpiration, silicon, calcium     

Density Studies on Lupins: I. Flower Development

In an August-sown experiment the pattern of flower developmentwas followed for cv. Ultra (Lupinus albus L.) and cv. Unicrop(L. angustifolius L.) grown at low (10 plants m^–2) andhigh (93 and 83 plants m^–2, Ultra and Unicrop respectively)densities. Dry weight increase of flowers on the main-stem inflorescenceand first lateral below the main-stem were compared at differentfloral stages. Maximum flower weight was reached just priorto the open flower stage and remained constant or declined untila pod formed or abscission occurred. The time period betweenmaximum flower weight and pod formation or abscission was upto 10 days. Emergence of the inflorescence was earlier and thefirst flower of Ultra opened 10 days before Unicrop. Developmentof each terminal raceme (inflorescence) was acropetal, withpods having formed on lower flower nodes when terminal flowerswere still quite immature. Laterals forming the next generationof inflorescences grew from axillary leaf buds below an inflorescencewhile it was in full flower. Sources of competition from connectedreproductive and vegetative metabolic sinks are discussed. Lupinus spp., lupins, flower development, planting density     

Effect of Light Quality (Red:Far-red Ratio) at the Apical Bud of the Main Stolon on Morphogenesis of Trifolium repens L.

A controlled environment experiment investigated whether thered:far-red (R:FR) ratio of light at the apical bud of the mainstolon could alter plant morphogenesis in clonal cuttings ofwhite clover (Trifolium repens L.) The apical bud included theapical meristem, five to six developing leaf primordia withassociated axillary bud primordia and stipules and the firstemerged folded leaf until development was greater than 0·3on the Carlson scale. Three light regimes were imposed on theapical bud by collimating light from R or FR light-emittingdiodes so that the R:FR ratio of light incident at the apicalbud was set at 0·25, 1·6 or 2·1, withoutsignificantly altering photosynthetically active radiation.The effect of these light regimes on white clover seedling growthwas also tested. At a low R:FR ratio seedling hypocotyl and cotyledon lengthswere significantly longer. However, with the cuttings, the lighttreatments did not alter node appearance rate or internode lengthof the main stolon, petiole length, area of leaves or totalshoot dry matter. There was one significant photomorphogeneticresponse in the cuttings, a delay of 0·5 of a phyllochronin the appearance of branches from axillary buds in the lowR:FR ratio treatment relative to the other treatments. Wherebranch appearance was delayed plants had fewer branches. Thisdifference could be ascribed solely to a delay in branch appearanceas there were no significant treatment effects on either theinitiation of axillary bud primordia within the apical bud,the probability of branching or on the rate of growth of branchesafter appearance. Because treatment of the apical bud inducedonly one of the many previously observed responses of whiteclover to a decrease in the R:FR ratio of light, we concludethat other plant organs must also sense the quality of incidentlight.Copyright 1994, 1999 Academic Press White clover, Trifolium repens, apical bud, light quality, red:far-red ratio, light-emitting diode, branching, axillary buds, photomorphogenesis     

The Rate of Morphogenesis of Embryos and Seeds in Four Species of Grain Legumes

Comparative embryo development has been studied histologicallyin Lupinus albus, Lupinus mutabilis, Vicia faba, Pisum sativumand Latkyrus latifolius. The detailed histology of the stagesof embryo formation up to the early differentiation of tissuesof the seed is reported. The rate of embryogenesis has beentimed through 15 stages of development from anthesis and comparativerates of tissue formation established between the species. Themain observation was the slow rate of morphogenesis of embryosand seeds in Lupinus albus in comparison with the very rapidrate observed in Pisum sativum. A long period at the globularembryo stage, when embryo morphogenesis was inactive contributedto the extended development time of embryos and seeds in Lupinusalbus. Slow differentiation of reproductive tissues in L. albusdetermines late maturity in seeds and pods. Lupinus albus, white lupin, L. mutabilis, tarwi, Vicia faba, faba bean, Pisum sativum, pea, Lathyrus latifolius, everlasting pea, embryo development     

Winter Growth of Autumn-sown White Lupin (Lupinus albus L.) Main Apex Growth Model

The winter growth of winter white lupin (cv. Lunoble) was investigated.Over three consecutive years, 1987–1989, it was sown atdifferent times at Lusignan (France) and in 1989, at nine differentlocations with various sowing times. The production of primordia,the vernalization requirements and the final number of leaveson the main stem were related to field measurements of dailymaximum and minimum temperatures. A statistical model for the main apex growth with a system oftwo equations was developed, with a threshold level for leafprimordia production at 3°C. The number of leaf primordiaproduced by a vegetative apex (y) in terms of the cumulativesums of temperature over 3°C (x) followed the curvilinearregression y = 4.76+ 0.0268x + 0000015 6x². The upper and lowertemperature limits for vernalization were estimated as 14 and1°C respectively. The vernalization requirements of a vegetative apex (y) decreasedwhen the number of initials produced (x) increased accordingto the negative exponential regression y = exp (7.2— 0.02626.x). The two equations were used for the prediction of the finalnumber of leaves of a lupin crop. The predictive accuracy ofthe model was checked against independent data. The agreementbetween observed and predicted final leaf number was often close,but some deviations did occur with low leaf number. The modeldescribed most of the growth phenomena which occur during thephase sowing to floral initiation of the main stem of a winterlupin crop, and its possible uses are discussed Lupinus albus L, white lupin, growth, model, vernalization, primordia, apex, thermal time     

Modelling of quinolizidine alkaloid net flows in Lupinus albus and between L. albus and the parasite Cuscuta reflexa: new insights into the site of quinolizidine alkaloid synthesis

The present work reveals new and completely different conclusionsabout the alkaloid economy of symbiotically fed Lupinus albusand L. albus parasitized by Cuscuta reflexa in the study periodof 43–55 d after sowing of lupin. Net flows of alkaloidswithin lupin and between host and parasite were calculated usingthe molar ratio of alkaloid nitrogen: total nitrogen combinedwith known net flows of nitrogen in the transport fluids andanalysing alkaloid accumulation in plant organs by HRGC. Incontrast to previous studies, quinolizidine alkaloids were predictedto be synthesized mainly in the root of L. albus and to be predominantlytransported via xylem to the apical plant shoot organs. Parasitismby C. reflexa for 12 d induced a decline of alkaloid contentin the host L. albus up to 53% compared to control plants andalkaloid synthesis was halved—apparently due to a shortageof the precursor lysine. In spite of an additional decreasein nitrogen levels at the second harvest, the host-parasitesystem showed a1.3-fold higher alkaloid content than the controlplants, 63% of the total alkaloids being attracted by Cuscuta.This indicates (a) restriction of catabolic processes withininfected lupins, (b) a massive shift of nitrogen metabolismin the direction of alkaloids and (c) an enormous sink potentialof Cuscuta for nitrogenous compounds. Although xylem was foundto be the main translocation system for alkaloids, the modellingof alkaloid flows predicts Cuscuta to derive only 4.5% of itstotal alkaloid supply from the xylem and 95.5% from the phloem.By analogy with nitrogen flows, this finding requires xylemphloemtransfers which were assumed to occur within the stem axis oflupin. A similar proportion regarding the contribution of xylemand phloem to the supply of Cuscuta was obtained for the netflows of two selected alkaloids, lupanine and 13     

Thermosensitivity in Spring White Lupin

Spring morphotypes of white lupin (Lupinus albus L.) are veryresponsive to cool temperatures during seedling developmentas expressed in a number of subsequent developmental characters.Thermosensitivity was examined in a number of studies whereseedlings were incubated at various stages of development andat differing temperatures. Plants were scored for thermosensitivity,as expressed by the number of mainstem and first order lateralvegetative nodes, at flowering. The stages of radicle emergenceand split seed coat were observed to be the developmental stageswhen mainstem and first-order lateral meristems were most sensitiveto incubation temperature. These data show that the optimumwindow for cold treating spring lupin seed is very narrow andoccurs prior to seedling emergence. Seedlings at radicle emergencestage were incubated at temperatures ranging from 1 to 27 °Cfor 0 to 14 d in 2 d increments. For temperatures less than12 °C, mainstem node number decreased curvilinearly withduration of incubation. For temperatures between 12 and 17 °C,mainstem node number decreased linearly with duration of incubation.However, mainstem node number increased linearly with durationof incubation at temperatures greater than 17 °C. The datashow that 'warm' temperatures during early seedling developmenthave a profound influence on subsequent plant morphology. Responseto 'warm' temperatures is greater than to 'cool' temperaturesand it is suggested that the differential response to warm vs.cold incubation temperatures could account for morphologicaland phenological differences observed within genotypes in fieldstudies among sites and years. The lack of temperature responsein one genotype, 'Start' may indicate thermoneutrality in thisgenotype.Copyright 1995, 1999 Academic Press Lupinus albus L., lupin, vernalization, thermosensitivity, vegetative development     

A Biochemical and Cytochemical Study of the Cuticle-associated Peroxidases in Lupinus

A biochemical and cytochemical study of peroxidases (EC 1.11.1.7 [EC] )associated with the outermost cell layers of Lupinus albus hypocotylshas been performed. Cytochemical investigations showed thatin the epidermis of lupin hypocotyls, peroxidatic activitiescould be detected mainly at the level of the endoplasmic reticulum,Golgi apparatus, ground substance of the cytoplasm, intercellularspaces between adjacent epidermal cells, and in the cuticlelayer. No peroxidatic reactions were seen at the level of eitherthe radial or the tangential walls. The cuticle peroxidaticreaction was due to two acidic isoperoxidases, also found incell walls of vascular tissues, and was further characterizedthrough a study of its catalytic activities. These studies showedthat cuticle-associated peroxidases were able to oxidize genistein,but unable to oxidize ascorbic acid. These results suggest thatextracellular peroxidases associated with the outermost celllayers of lupin hypocotyls are involved more in the metabolismof isoflavones of the cuticle layer than in the growth responsesof the whole organ. Epidermal cell, cuticle, peroxidase cytochemistry, genistein oxidation, Lupinus albus     

Effect of Severity of Defoliation on the Viability of Reproductive and Vegetative Axillary Buds of Trifolium repens L.

This glasshouse experiment was performed to assess the effectsof a range of constant defoliation regimes applied to cuttingsof a single large-leaved genotype ofTrifolium repens L. on theviability of its axillary buds. Plants were established to comprisea single main stolon (axillary branches were removed) and defoliationtreatments were applied by removing the older (basal) leavesuntil leaf complements of 1·0, 1·5, 2·0,2·5, 3·0 or all leaves (control) remained. Basalleaves were subsequently removed as necessary to maintain thetarget leaf complements. Only severe defoliation (leaf complements of 1·0 and1·5) induced a loss of viability in axillary buds. Lossof viability was greatest in reproductive buds present withinthe apical bud when the treatments were first imposed. Althoughthe most severe treatment (leaf complement 1·0) resultedin death of half the plants, in plants surviving that treatment,death of vegetative axillary buds was restricted to 21% of thevegetative buds at the three youngest node positions withinthe apical bud at the time of treatment application. No othertreatment induced any loss of viability of vegetative buds.There was no loss of viability of axillary buds at nodes formedafter the treatments were imposed. The frequency of initiationof inflorescences at nodes formed after treatments were imposeddecreased as defoliation severity increased. Severe defoliation resulted in marked changes in plant morphologyindicative of a sharp decrease in availability of intraplantresources. It was concluded that under severe defoliation: (1)the potential for vegetative growth (as represented by viablevegetative axillary buds) was maintained at the expense of reproductivegrowth; and (2) that the loss of viability of axillary budswas associated with the sudden changes in physiological processesinduced by defoliation as there was no loss of viability inbuds formed after plants had adjusted their phenotype to oneof smaller size. Trifolium repens L.; white clover; defoliation; axillary buds; viability; inflorescences     

Influence of Bud Position and Plant Ontogeny on the Morphology of Branch Shoots in Pea (Pisum sativum L. cv. Alaska)

The morphology of axillary shoots of pea plants (Pisum sativumL. cv. Alaska) was analysed as a function of the position ofthe bud on the plant axis and the stage of plant developmentwhen the buds began to grow. Buds from the three most basalnodes were stimulated to develop by decapitating the main shootwhen buds were still growing (4 d plants), shortly after budsbecame dormant (7 d plants) or after the initiation of floweringon the main shoot (post-flowering plants, about 21 d after sowing).Branch shoots were scored for node of floral initiation (NFI),shoot length, and node of multiple leaflets (NML), a measureof leaf complexity. Shoots that developed spontaneously fromupper nodes (nodes 5-9) on intact post-flowering plants werescored for NFI. NFI for basal buds on 4 and 7 d plants variedas a function of nodal position and ranged from 5 to 6·7nodes. NFI on these plants was not influenced by bud size orwhether a bud was growing or dormant when the plant was decapitated.NFI for shoots derived from basal buds on decapitated post-floweringplants and upper nodes on intact post-flowering plants was about4. Reduced NFI on post-flowering plants may be due to depletionof a cotyledon-derived floral inhibitor. Basal axillary shootson 4 d plants were about 20% longer than those on 7 d plantsand about five times longer than those on post-flowering plants.These differences may be due to depletion of gibberellic acidsfrom the cotyledons. NFI and NML for the main shoot and forbasal axillary shoots were similar under some experimental conditionsbut different under other conditions, so it is likely that eachdevelopmental transition is regulated independently.Copyright1995, 1999 Academic Press Apical dominance, bud development, garden pea, initiation of flowering, Pisum sativum L., shoot morphology     

Development and Growth Potential of Axillary Buds in Roses as Affected by Bud Age

The effect of axillary bud age on the development and potentialfor growth of the bud into a shoot was studied in roses. Ageof the buds occupying a similar position on the plant variedfrom 'subtending leaf just unfolded' up to 1 year later. Withincreasing age of the axillary bud its dry mass, dry-matterpercentage and number of leaves, including leaf primordia, increased.The apical meristem of the axillary bud remained vegetativeas long as subjected to apical dominance, even for 1 year. The potential for growth of buds was studied either by pruningthe parent shoot above the bud, by grafting the bud or by culturingthe bud in vitro. When the correlative inhibition (i.e. dominationof the apical region over the axillary buds) was released, additionalleaves and eventually a flower formed. The number of additionalleaves decreased with increasing bud age and became more orless constant for axillary buds of shoots beyond the harvestablestage, while the total number of leaves preceding the flowerincreased. An increase in bud age was reflected in a greaternumber of scales, including transitional leaves, and in a greaternumber of non-elongated internodes of the subsequent shoot.Time until bud break slightly decreased with increasing budage; it was long, relatively, for 1 year old buds, when theysprouted attached to the parent shoot. Shoot length, mass andleaf area were not clearly affected by the age of the bud thatdeveloped into the shoot. With increasing bud age the numberof pith cells in the subsequent shoot increased, indicatinga greater potential diameter of the shoot. However, final diameterwas dependent on the assimilate supply after bud break. Axillarybuds obviously need a certain developmental stage to be ableto break. When released from correlative inhibition at an earlierstage, increased leaf initiation occurs before bud break.Copyright1994, 1999 Academic Press Age, axillary bud, cell number, cell size, pith, shoot growth, Rosa hybrida, rose