Effects of Gibberellic Acid and Naphthaleneacetic Acid on Petiole Senescence and Subtended Peduncle Growth of Cyclamen persicum Mill

Removal of the blade from the leaf subtending the first flowerbud on Cyclamen persicum ‘Swan Lake’ plants causedthe petiole of that leaf to senesce, but had no effect on thegrowth of the flower peduncle in the debladed petiole's axil.A 10 mg NAA l^–1 application generally had no effect onpetiole senescence, peduncle elongation or flowering date whenapplied to the cut end of the petiole after blade removal. A25 mg GA₃ l^–1 application or a combination of 25 mg GA₃l^–1 application or a combination of 25 mg GA₃ l^–1plus 10 mg NAA l^–1 delayed petiole senescence and enhancedpeduncle elongation and subsequent flowering. No treatment significantlyaltered peduncle length at the time of flowering. Cyclamen persicum Mill, ‘Swan Lake’, tissue receptivity, flowering, GA₃, NAA     

The Uptake and Distribution of Copper in Some Forage Grasses as Affected by Nitrate-nitrogen Supply in Flowing Solution Culture

The effect of changes in nitrate-nitrogen supply on the absorptionand distribution of copper was examined in grasses grown inflowing solution culture with a maintained concentration ofcopper. Absorption by roots (µg Cu g^–1 dry root)decreased markedly when nitrogen had been depleted or was maintainedat 0.1 mg l^–1 N, but there was an immediate increase whennitrogen was maintained at 1.0 or 10.0 mg l^–1. There werealso large increases in the concentration of copper in the shootsof plants grown with 1.0 and 10.0 mg 1^–1 N. The rootsof plants grown with 0.1 or 1.0 mg 1^–1 N retained similarproportions of uptake, but a lower proportion was retained whenthe plants were grown with 10.0 mg 1^–1. Although a lowerproportion of the copper was associated with cell walls in theplants grown at 10.0 mg 1^–1 N this was the result of alower content of cell walls rather than an effect on copperitself. In a longer-term experiment in conventional solutionculture with a range of nitrogen concentration, the concentrationof copper in shoots was largely determined by shoot growth. Dactylis glomerata, Festuca arundinacea, Lolium perenne, cell walls, copper absorption, copper distribution, flowing solution culture, nitrate-nitrogen     

In Vitro Regeneration from Seedling Organs of Brassica oleracea var. italica Plenck cv. Green Comet I. Effect of Plant Growth Regulators

The calabrese cultivar Brassica oleracea var. italica cv. GreenComet was used in a study of the effects of exogenous hormoneson the growth and differentiation of seedling organs in vitro.Four types of explants were tested: hypocotyl segments, rootsegments, primary leaf discs and cotyledon discs. These explantswere incubated on media containing factorial combinations ofBAP x IBA, BAP x NAA, KN x IBA and KN x NAA (all at 0, 0.1,10 and 10.0mg l^–1). Hypocotyls were the most regenerativeexplants; shoot production was favoured by cytokinin: auxinratios greater than one and was decreased by IBA at 10 mg l^–1when callus was produced. Shoot formation from root explantsoccurred either in the absence of hormones or with low concentrations;no shoot was produced when any hormone was present at 10 mgl^–1. In contrast, shoot production from primary leaf diseswas favoured by high concentrations of both auxin and cytokininwith the combination of BAP and IBA the most effective. Shootproduction from cotyledon discs was sporadic with no consistentresponse on any auxin/cytokinin combination. After further experimentson the optimization of hormone concentration, the followingcombinations were chosen as allowing reliable regeneration:0.1 mg l^–1 BAP+0.1mg l^–1 IBA for hypocotyl segments,0.075 mg l^–1 KN +0.025 mg l^–1 IBA for root segments,and 5.0 mg l^–1 BAP+5.0 mg l^–1 IBA for leaf discs. Brassica oleracea var. italica, calabrese, tissue culture, seedling, auxin, cytokinin     

Somatic Embryogenesis from Clonal Leaf Tissues of Cassava

Leaf lobes were isolated from palmate leaves of clonal cassava(Manihot esculenta Crantz) material growing in vitro or in glasshouseconditions and subjected to a two-stage culture procedure involvingincubation on Murashige and Skoog (MS2) basal medium supplementedwith 2–12 mg l^–1 2,4-D for 20 d (Stage I) beforetransfer to MS2 basal medium supplemented with 0.01 mg l^–12,4-D and 0.1 mg l^–1 6-benzylamino purine (BAP) (StageII medium). Embryogenetic tissues, foliose structures and somatic embryosdeveloped from leaf lobes at all Stage I 2,4-D concentrations,except on those explants isolated from shoot-tip cultures incubatedon MS2 basal medium supplemented with 0.1 mg l^–1 NAA and1.0 mg l^–1 BAP. Leaf lobes isolated directly from glasshouse plants showed optimalembryogenetic competence when subjected to a Stage I cultureperiod of 17 d, although foliose structure initiation was optimalwith shorter Stage I durations. Leaf lobes of 2–4 mm lengthand those isolated from phyllotaxic leaf numbers 4 and 5 showedthe greatest embryogenetic competence. Manihot esculenta, cassava, somatic embryogenesis, tissue culture, morphogenetic competence     

Somatic Embryogenesis and Its Hormonal Regulation in Tissue Cultures of Freesia refracta

Somatic embryogenesis can be induced in tissue cultures of Freesiarefracta either directly from the epidermal cells of explants,or indirectly via intervening callus. These two pathways ofsomatic embryogenesis can be controlled and regulated by varyingthe combinations and levels of exogenous hormones. When younginflorescence segments were cultured in vitro on modified N₄(MN₄) medium supplemented with 2 mg l^–1 indoleacetic acid(IAA) and 3 mg l^–1 6-benzylaminopurine (BAP), some ofthe epidermal cells began to exhibit the features of embryogeniccells. These cells produced embryoids and developed into newplants through direct somatic embryogenesis. If the same explantswere placed on Murashige and Skoog's (MS) medium containing2 mg l^–1 IAA, 05 mg l^–1 BAP and 05 mg l^–1naphthaleneacetic acid (NAA), pale-yellow translucent nodularcalluses appeared on the surface of the explants. When thiskind of callus was transferred to MN6 medium with 2 mg l^–1IAA and 3 mg l^–1 BAP, embryoids formed which further developedinto plantlets. The regenerated plants were morphologicallynormal and possessed the normal diploid chromosome number of2n = 22. A similar result has also been obtained with youngleaf explants of this plant. The early segmentations of embryogeniccells and the development of embryoids were studied using histologicaland scanning electron microscopic techniques, and the resultshave been discussed in association with the ontogeny and originof the embryoids. Freesia refracta Klatt, somatic embryogenesis, plant regeneration, exogenous hormones     

Regeneration of Lasiurus scindicus from Tissue Culture

Embryogenic callus cultures were initiated from mature embryosof Lasiurus scindicus on Murashige and Skoog's medium supplementedwith 6 mg l^–1 2,4-Dichlorophenoxyacetic acid (2,4-D).These cultures were maintained on 2 mg l^–1 2,4-D. Plantletswere regenerated via somatic embryogenesis when the calli weretransferred onto hormone-free MS basal medium. Young plantswere successfully transplanted to pots and grown to maturityin a greenhouse. Grass, Lasiurus scindicus, Thar Desert, drought tolerant, somatic embryogenesis, plant regeneration     

The Effect of Inorganic Nutrients on the Hormonal Requirements of Normal, Habituated, and Crown-gall Tissue 4

The addition of Braun and Wood's inorganic supplements (845mg l^–1 KCl, 1800 mgl^–1 NaNO₃, 300 mg l^–1 NaH₂PO₄.2H₂O,790 mg l^–1 (NH₄)₂SO₄) to White's medium caused markedincreases in the growth of normal tissues of Helianthus annuus,Nicotiana rustica, Daucus carota, and Vinca rosea and crown-galltumour tissues of H. annuus. However, no evidence was obtainedwhich suggested that the presence of these extra salts markedlyinfluenced the essential requirements of normal callus for auxinsand kinetin. In contrast their presence significantly influencedthe hormonal requirements of certain habituated cultures ofH. annuus and V. rosea. These habituated cultures had specificauxin requirements on White's medium while either an auxin orkinetin was sufficient on high-salts medium. These results arediscussed in relation to previous reports which suggested thatthe biosyntheses of auxins and other growth factors in normaland crown-gall cultures are specifically activated by certaininorganic ions.     

Shoot and Plantlet Formation in Organ and Callus Cultures of Albizzia lebbek Benth

Plantlets were produced in vitro from root and hypocotyl explantstaken from seedlings of the tree legume, Albizzia lebbek. Theseexplants formed shoots when cultured with 5.0 mg l^–1 kinetinand 1.0 mg l^–1 IAA in MS medium. Shoots were also inducedin large numbers from callus treated with benzylaminopurine.About 20 per cent of the shoots rooted and were grown into plants. Albizzia lebbek Benth, tree legume, hypocotyl, root, in vitro cultures, shoot-plantlet induction     

Differentiation of Shoot Buds in vitro in Tissue 1Sisymbrium irio L.

Shoot bud formation was induced in the stem callus of Sisymbriumirio L., a Cruciferous plant. The callus was established onMurashige and Skoog medium with IAA (1?0 mg l^–1) and kinetin(0?5 mg l^–1). The effect of three purines (kinetin, 6-benzylaminopurine,and 6-methylaminopurine) incorporated singly along with IAAin MS medium was investigated. It was found that kinetin orMAP (3–5 mg l^–1) along with IAA (0?5 mg l^–1)were the most effective in inducing shoot bud formation. Adeninesulphate (10 mg l^–1) with kinetin (1?0 mg l^–1) alsoinduced bud differentiation. The morphogenetic potential of the callus to differentiate shootbuds was seemingly lost in 2 year old callus cultures. However,on successively subculturing on a regeneration medium shootbuds differentiated and the number of buds formed improved onfurther subculture. Two types of meristematic outgrowths were recognized: (i) arisingfrom superficial cells and (ii) arising from deep-seated cellsin the vicinity of tracheidal elements. However, both typesformed meristematic nodules on the surface of which shoot budsdifferentiated. Some embryoids were also recognized arisingsuperficially.     

Atmospheric ozone affects carbohydrate allocation and winter hardiness of Pinus halepensis (Mill.)

Fumigation of 2 year-old Aleppo pine (Pinus halepensis Mill.)trees with episodes of O₃ (up to 120 nl l^– as comparedto 25 nl l^–) throughout two summer seasons produces tallerplants with greater stem diameters but reduced root:shoot ratios.Both light and electron microscopy of current year needles carriedout at mid-summer reveal extensive accumulations of starch,particularly in the endodermis, and crushing of the phloem sievecells. Parallel measurements of starch levels also reveal anon-mobilizable component. All these features probably indicatethat episodes of high summer O₃ detrimentally affect the normalability of Aleppo pines to withstand severe water stress andthis may account for their reduced vitality in Mediterraneanregions. By autumn, however, the amounts of starch are similarto those in low O₃-grown trees and no evidence of the phloemsieve tube crushing remain although plastids do show increasednum bers of plastoglobull. Similar summer high level O₃-fumigatedneedles also show enhanced winter hardiness in the autumn whichis unusual for conifers. Key words: Pinus halepensis, Aleppo pine, amyloplasts, ozone, plastoglobuli, starch     

Effect of Growth Regulators and Light on Pollen Germination and Pollen Tube Growth in Pinus roxburghii Sarg

Pine (Pinus roxburghii) pollen grown in suspension cultureswas used to study the effects of growth regulators and lightconditions on germination and pollen tube growth. Indol-3-ylacetic acid, gibberellic acid, ethylene, abscisic acid and cyclicAMP (cAMP) at low concentrations (1–10 mg 1^–1) promotedgermination and tube growth. Addition of 1 and 10 mg 1^–1cAMP to any of the growth regulators had a promotory effect.Pollen tube growth decreased in white light as compared to thedark, and was increased in red light. Far-red light counteractedthe effect of red light. The effect of growth regulators incausing the enhanced tube growth appears to be manifested throughsubstances such as cAMP, and phytochrome seems to be involved. Pinus roxburghii, pine, pollen germination, pollen tube growth, growth regulators, cyclic AMP, phytochrome     

Callus Culture of Sainfoin (Onobrychis viciifolia) and Plant Regeneration through Somatic Embryogenesis

Callus of sainfoin (Onobrychis viciifolia Scop.) was initiatedfrom stem and root explants which were obtained from seedlingsgrowing in vitro, on Linsmaier Skoog (LS) medium supplementedwith 1 mg l^–1 2, 4-D and 1 mg l^–1 BA or only 1 mgl^–1 BA, and the Vacin and Went medium without hormones.Somatic embryos were formed on LS medium containing 1 m l^–1BA. Embryos developed into complete plants on filter paper saturatedwith hormone-free LS medium. Onobrychis viciifolia, somatic embryogenesis, callus culture, plant regeneration     

Micropropagation of Betula celtiberica

Plantlets were successfully regenerated from shoot segmentsof Betula celtiberica excised from young seedlings. Initiationand elongation of multiple shoot-buds were obtained after 20d culture in MS-modified medium plus BAP 0.6 mg l^–1 followedby 20 d culture in the same medium in the presence of a reducedBAP concentration (0.1 mg l^–1). Rooting was achieved 7d after having transplanted the isolated shoots to fresh medium,supplemented with IBA (0.2 mg l^–1). Betula celtiberica, birch, micropropagation, organogenesis     

Somatic Embryogenesis in Cassava: The Anatomy and Morphology of the Regeneration Process

Anatomical and morphological studies demonstrated that somaticembryos developed similarly on mature seed and clonal leaf explantsof cassava (Manihot esculenta Crantz) cultured for 20–24d on Murashige and Skoog (MS2) basal medium supplemented with4.0 mg l^–1 2,4-D (Stage 1) before transfer to MS2 basalmedium supplemented with 0–01 mg l^–1 2,4-D and 0–1mg l^–1 6-benzylaminopurine (Stage II medium). Within 7d of inoculation onto Stage I medium, cell divisions occurredin the adaxial tissues of cotyledon-piece and leaf-lobe explants,and associated with this was the development of embryogeneticprotusions and ridges on the adaxial surface. Foliose structuresand somatic embryo initials developed from these tissues oncotyledon, embryonic axis and leaf-lobe explants and, when cultureswere transferred to Stage II medium, further somatic embryodevelopment occurred. Somatic embryos apparently originatedfrom groups of cells and were identified by the presence ofa closed root axis, a shoot axis and cotyledons of similar shapeand venation to those of zygotic embryos. Somatic embryos hadno vascular connection with parental cultures. Manihot esculenta, cassava, somatic embryogenesis, tissue culture, anatomy, morphology, morphogenesis     

In Vitro Micropropagation of Delphinium malabaricum (Huth) Munz.--a Rare Species

A micropropagation technique was developed for Delphinium malabaricumusing nodes from inflorescence stalks Maximum shoot proliferationwas obtained on Murashige and Skoog's medium supplemented with2-1P (10 mg l^–1) and inositol (100 mg l^–1) Fromthe sixth passage onwards, shoots could be multiplied by omissionof inositol and reduction of 2-1P (0.5 mg l^–1) concentrationBest rooting response was obtained with a 24-h pulse treatmentof shoots with 0.5 mg I^–1 IBA in the dark, transfer oftreated shoots to hormone-free half-strength MS medium and incubationunder 24-h light. Regenerated plants were established successfullyin the field Cytological examination of root tips of in vitroand control plants showed identical chromosome number (2n =16) Delphinium malabaricum (Huth) Munz, micropropagation, tissue culture, rare plant     

Effect of External Supply of Growth Substances on Axillary Proliferation and Development in Dioscorea bulbifera

Bulbil development in cultured nodes of D. bulbifera proceededin the absence of growth substances from the medium. When IAAwas incorporated into the medium at the concentrations of 5mg l^–1 and 10 mg l^–1 the cultured nodes producedlarger bulbils than in its absences. When the concentrationof IAA was increased to 15 mg l^–1, however, the culturednodes produced a callus instead of a properly organized bulbil.The dry weight of bulbils increased when kinetin was added tothe medium at the concentrations of 0.05, 0.5, and 2.5 mg l^–1.The greatest increase was with 0.5 mg l^–1 kinetin. Onincreasing the concentration of kinetin in the medium to 5.0mg l^–1 the tissue produced had smaller dry weight thanthose produced in the absence of growth substances. Additionof different combinations of IAA and kinetin to the basal mediumresulted in the production of normal bulbils, roots, and shootsin some instances (suitable combinations) and in the productionof callus and abnormal shoots in others (non suitable combinations).     

Egg size and clutch size in two Daphnia species grown at different food levels

The effect of three different Scenedesmus food concentrations(0.04, 0.2 and 1 mg C l^–1) on maternal investment wasstudied in two cladoceran species of similar size, Daphnia pulicariaand D.hyalina. It was observed that as food concentration decreased(between 1 and 0.2 mg C l^–1), there was an increase insize, protein content, lipid content, carbon and mass of theegg, while, at the same time, the clutch size of the femalesbecame smaller. Such an increase in ‘per offspring investment’was reflected in an increase in body length, body carbon andbody mass of neonates as the food available for females decreased.However, in D.pulicaria this tendency was not maintained downat 0.04 mg C l^–1 in which there was a decrease of theegg characteristics mentioned above. Although, there are notavailable all the egg and neonate parameters of D.hyalina at0.04 mg C l^–1, the body length of the neonates was largerthan at 0.2 and 1 mg C l^–1. These results show that, asfood diminishes, these two cladoceran species are able to respondby decreasing clutch size, but increasing the size of egg, therebyincreasing the probability of neonate survival. This tendencyis probably maintained until the food concentration is too lowand the females have to reduce the energy allocated for reproduction.     

Density and distribution of bacterioplankton and planktonic ciliates in the Bering Sea and North Pacific

The total number of planktonic bacteria in the upper mixed layerof the Bering Sea during the late spring-early summer periodranged between 1 and {small tilde}4 x 10⁶ ml^–1 (biomass10–40mg C m^–3). In the northern Pacific, along 47–52⁶N,the corresponding characteristics of the bacterioplankton densityin the upper mixed water layer were: total number 1–2x 10⁶ cells ml^–1 and biomass 15–46mg C m^–3Below the thermocline at 50–100 m, the density of bacterioplanktonrapidly decreased. At 300 m depth, it stabilized at 0.1–0.2x 106 cells ml^–1. The integrated biomass of bacterioplanktonin the open Bering Sea ranged between 1.2 and 3.6 g C m^–2(wet biomass 6–18 g m^–2) Its production per dayvaried from 2 to 23 mg C m^–3 days^–1 in the upper0–100 m. The numerical abundance of planktonic ciliatesin this layer was estimated to be from 3 to l0 x 10³ cells l^–1,and in the northern Pacific from 0.4 to 4.5 x 10³ l^–2.Their populations were dominated by naked forms of Strombidium,Strombilidium and Tontonia. In some shelf areas, up to 40% ofthe total ciliate population was represented by the symbioticciliate Mesodinium rubrum. The data on the integrated biomassof basic groups of planktonic microheterotrophs are also presented,and their importance in the trophic relationships in pelagiccommunities of subarctic seas is discussed.     

Somatic Embryogenesis and Plant Regeneration from Inflorescence Culture of Java Citronella: (Cymbopogon winterianus)

Embryogenic callus was induced from immature inflorescence segmentsof Java citronella (Cymbopogon winterianus) and maintained for2 years on Murashige and Skoog's medium supplemented with 2,4-D(l mg l^–1). The callus cells retained the original chromosomenumber of 2n = 20. The somatic embryos germinated into plantletson MS basal medium or medium with IAA, NAA, BAP or KN individually(l mg l^–1). The regenerated plantlets developed a goodroot system on full strength solid MS inorganics medium withIAA (1 mg l^–1). The regenerated plants were similar tothe donor plant in morphology and had the same chromosome number,but showed some variation in the essential oil content. Java citronella, Cymbopogon winterianus, somatic embryogenesis, regeneration, inflorescence culture     

Phytoplankton and nutrients in the waters north-west of Spitsbergen in the autumn of 1979

Phytoplankton biomass, primary production rates and inorganicnutrients were measured in the uppermost layer of the ice-edgeregion and in open water and compared with environmental factorsduring a three-week cruise in September – October 1979.Biomass and production values were low (maximum 2.2 µgchl a l^–1, 2.5 mg C m^–3 h^–1). A post-bloomcommunity of diatoms, consisting mainly of representatives ofChaetoceros, Leptocylindrus, Nitzschia and Thalassiosira, waspredominant. Concentrations of phosphate were quite low (maximum0.55 µM I^–1). Nitrate and silicate ranged from nomeasurable quantities to 5.7 µM l^–1 and 3.8 µMl^–1, respectively. The possibility of light and nutrientlimitation on phytoplankton growth is discussed.