The Relationship Between the Effects of CCC on Root Growth and Cytokinin Levels in the Bleeding Sap of Vitis vinifera L.

The growth retardant (2-chloroethyl)trimethylammonium chloride(CCC) induced swollen root tips on seedlings of grape vines(Vilis vinifera L.) as well as on plants grown from cuttings.In both cases CCC had to be applied to the growth medium forthe response to be expressed; spraying the shoots reduced stemgrowth without inducing swollen roots. N-dimethylarminosuccinamicacid (B995) was ineffective in causing these root symptoms ongrapes, nor did root swellings appear on five other speciestreated with CCC. On the other hand, kinetin resulted in graperoots which in some respects resembled those treated with CCC. Two regions of cytokinin activity were detected on chromatogramsof bleeding sap from grape-vines grown in serated nutrientculture solutions compared with only one region in sap fromplants grown in soil or other solid media. Activity of a regionof high mobility was increased by CCC applications to the culturesolutions; effects of CCC on a region of low mobility, whichmay be a bound derivative of the other, were variable. Boththe concentration and absolute amounts of cytokinin activityin the sap were increased by CCC, indicating that this retardantprobably affected cytokinin synthesis by the root tip. The effectof CCC on cytokinin levels in the sap diminished during thebleeding period. The results are interpreted to indicate that in grapes, CCCacts directly on the root meristem to increase cytokinin production.Swelling of the tips is probably a consequence of the elevatedcytokinin levels in this region.     

Interaction of Growth Retardants and Temperature in Growth, Flowering, Regeneration, and Auxin Activity of Begonia × cheimantha Everett

Soil application of CCC reduced stem and leaf growth in Begonia plants. This effect was evident with all concentrations tested at 18°C, whereas at 21 and 24°C no growth–retarding effect was observed with 2 × 10^?2 M CCC, and with 5 × 10^?3 M growth was even stimulated. Flowering was promoted by CCC in long day and neur–critical temperature, particularly under low light intensity in the winter. The formation of adventitious buds in leaves of plants grown at 21 and 24°C was stimulated when the plants received 5 × 10^?2 and 2 × 10^?2 M CCC, while 8 7times; 10^?2 M was inhibitory. In plants grown at 18°C bud formation was inhibited by all CCC concentrations. Root formation in the the leaves was usually stimulated by high CCC concentrations, while root elongation was reduced. The level of ether–extractable. acidic auxin (presumably IAA) in the leaves was lowered by CCC treatment of the plants, hut this required higher CCC concentrations at higt than at low temperature. When applied to detached leaves CCC stimulated bud formation at concentrations ranging from 10^?4 to 10^?2 M in leaves planted at 18 and 21°C. At 24°C budding was inhibited by 10^?2 M CCC, the lower concentrations being stimulatory also at this temperature. Root formation and growth were not much affected by CCC treatment of the leaves, but increased with the temperature. Soil application of Phosfon (4 × 10^?4 M) had no effect on growth and flowering, nov did it affect the subsequent regeneration of buds and roots in the leaves. In detached leaves Phosfon stimulated bud formation with au optimum at 10^?6 M. Root formation was stimulated by Phosfon at all temperatures, the optimal concentration being 10^?5 M, whereas root length was conversely affected. Foliar application of B-995 to intact plants and treatment of detached leaves greatly inhibited the formation of buds and had little effect on root formation. B-99D reduced the growth and delayed flowering in the plants.     

植物生长延缓剂对盆栽月季生长发育的影响

采用不同质量浓度的3种植物生长延缓剂多效唑(PP333)、矮壮素(CCC)、缩节胺(DPC),运用叶喷和灌根两种处理方式,通过测定植株的形态指标(株高、节间长、叶片长与宽、花枝长、花梗长、花径及初花期等)和生理生化指标(叶绿素含量、光合速率、蒸腾速率、叶片酶活性及可溶性糖含量等),研究3种药剂对盆栽月季‘世纪之春’生长发育的影响。结果表明:(1)不同药剂的使用浓度和方式对盆栽月季的形态和生理指标有不同程度的影响,适宜浓度和方式处理能缩短植株节间长度来降低株高,使株型饱满,开花正常,提高观赏价值;同时可以增加叶片叶绿素含量,提高光合效率,增加叶片超氧化物歧化酶和过氧化物酶活性及可溶性糖含量,对改善盆栽月季观赏品质有重要影响;(2)叶面喷洒700mg.kg-1 PP333和灌根300mg.kg-1 PP333的调控效果最好,喷洒1 200mg.kg-1CCC和300mg.kg-1 DPC效果次之,均能达到有效降低株高和提高观赏效果的目的。     

Cellular Growth in Roots of a Gibberellin-Deficient Mutant of Tomato (Lycopersicon esculentum Mill.) and its Wild-type

The role of gibberellins in regulating the growth of tomatoroots was investigated by comparing various cellular parametersin cultured roots of the gibberellin-deficient mutant gib-l/gib-lwith those in roots of the near-isogenic wild-type. In addition,wild-type roots treated with 0?1 µM 2S,3S paclobutrazol,an inhibitor of gibberellin biosynthesis, and mutant roots treatedwith 0?1 µM GA₃ were also compared: the former roots constitutea phenocopy of the mutant, whereas the latter roots appear tobe ‘normalized’ and similar to wild-type. The elongationof mutant and phenocopied roots were similar, their maximumelongation rates being about half or two-thirds that of wild-typeor GA₃-treated mutant roots, respectively. These rates wereinterpreted in terms of the numbers and lengths of cells withinthe meristematic and non-meristematic portions of the elongationzone. Mean meristem length tended to be shorter in both themutant and the 2S,3S paclobutrazol-treated wild-type roots thanin the other two types of root. A major difference between thetwo pairs of mutant and normal roots was their mean final celllengths: mean lengths of cortical cells of the mutant and 2S,3Spaclobutrazol-treated roots were, respectively, 39% and 25%shorter than the mean length of wild-type roots. Final celllength in the GA³-treated mutant roots were similar to wild-type.By contrast, the diameters of mature cortical cells of the mutantand phenocopy were about 20% greater than the diameters of equivalentwild-type or ‘normalized’ mutant cells. The meanvolumes of cortical cells in all four types of roots showedno significant differences. Knowledge of the distribution ofcortical cell lengths, widths and volumes along the root axis,together with information about the rate of root elongation,permitted comparisons of the relative elemental growth ratesof each of these three cellular parameters. The available evidence suggests that the level of endogenousgibberellins in mutant roots is lower than in wild-type roots.The present results, therefore, suggest that endogenous gibberellinsare necessary for normal growth of cultured tomato roots andthat they regulate the relative amounts of growth at the longitudinaland transverse walls of the cells which, in turn, affects theshape of the elongating cells. Key words: Cell growth, cultured roots, gibberellin, gib-l mutant, Lycopersicon esculentum, 2S,3S paclobutrazol, relative elemental growth rate, root meristem     

Tuberization in Potato at High Temperatures: Responses to Gibberellin and Growth inhibitors

The responses of potato plants (Solanum tuberosum L., cv. Sebago)to high temperatures (32 day/28 C night or 32/18 °C) andgibberellin are similar, in that they promote haulm growth andsuppress tuber production, whereas low temperatures (22/18 °C)abscisic acid and CCC have the opposite effect, promoting tuberproduction and reducing the growth of the haulms. The inhibitoryeffect of the high temperatures on tuber production, under aphotoperiod of 14 h, was almost completely reversed in theseexperiments by the application of CCC, and partly reversed byABA. Single-leaf cuttings from plants grown at the various temperaturesand chemical treatments responded in the same way as the wholeplant. It is suggested that both haulm growth and tuber initiationare influenced by a common hormonal control, and that temperatureexerts its influence by altering the balance between the levelsof endogenous gibberellins and inhibitors. These substancesapparently act directly on the stolon tip, rather than throughtheir general influence on haulm growth. Solanum tuberosum L., potato, tuberization, temperature response, gibberellin, abscisic acid, 2-chloroethyltrimethylammonium chloride (CCC)     

Growth responses of sunflower hypocotyl disks inoculated with Escherichia coli and Agrobacterium tumefaciens I. Morphological observations

Disks of sunflower hypocotyls 1 mm thick grown in light anddarkness on agar containing mineral salts and sucrose to whichIAA was added in varying concentrations, were inoculated withE. coli, A. tumefaciens or sterile synthetic medium. Light-growndisks inoculated with E. coli proliferated from the lower surfaceand formed numerous long roots but dark-grown disks were usuallyinhibited in comparison with uninfected disks. Inoculation withA. tumefaciens induced proliferation mainly from the upper surfaceand a few short roots were formed. Uninfected disks grown with0.01 ppm IAA proliferated in a manner similar to that of E.coli-infected light-grown disks on simple medium but in thedark similar treatments produced quite different morphologicaleffects. The form of proliferation induced by E. coli underall conditions of growth could not be equated with that inducedby A. tumefaciens or by different concentrations of IAA. (Received December 5, 1967; )     

The Influence of Leaf Water Status and ABA on Leaf Growth and Stomata of Phaseolus Seedlings with Hypoxic Roots

The objective of this study was to assess the relative rolesof leaf water status and root-sourced signals in mediating beanleaf responses to root hypoxia. To do so, the roots of beanplants under varied VPD (0.95 kPa to 0.25 KPa) were made hypoxic.Under all conditions, leaf growth rates and stomatal conductanceswere reduced. There was a transitory decline in leaf water potentialat high VPD which accounted for the initial reduction in leafgrowth rates and stomatal conductance. At low VPD, no waterdeficits were detected. Leaf growth inhibition and reduced stomatalconductance under low VPD treatments were unrelated to leafwater status and must be induced by some other factor. In vitrogrowth of leaf discs was reduced by xylem sap collected fromhypoxic roots. Exogenously applied ABA, at high concentrationsin KCl and sucrose, or at low concentrations diluted in xylemsap from aerated plants, inhibited in vitro growth of leaf discs.Applications of ABA in the transpiration stream reduced stomatalconductance.     

The Effects of Rootzone Salinity and Hypoxia on Shoot and Root Growth in Trifolium Species

The effect of concurrent salinity (0-60 mM NaCl) and rootzonehypoxia (flooding for up to 15 d) on shoot and root growth andshoot ion concentrations of six species of Trifolium (T. subterraneumL., T. fragiferum L., T. michelianum Savi., T. isthmocarpumBot., T. purpureum Lois., and T. repens L.), was studied intwo greenhouse experiments. There was a significant salinityx flooding effect for shoot yield but no significant salinityx flooding x species interaction although individual speciesdiffered significantly (P < 0·001) in their growthresponse to the saline or flooded conditions separately. Concentrationsof Na and Cl in the shoots of all species increased with increasingperiods of saline flooding and there was a significant salinityx flooding interaction. Sodium and Cl concentrations were significantlyhigher (P < 0·001) in T. purpureum, the species inwhich shoot growth was most depressed by saline flooding, thanother species. In T. michelianum, T. fragiferum and T. repens,fresh and dry weight of roots increased with flooding underboth saline and non-saline conditions while in T. subterraneumroot growth decreased. A significant proportion of the increasedroot growth in the first three species occurred as new adventitiousroots. These roots had higher percentages of internal gas spaceswithin the root tissue even in the presence of salinity comparedwith roots from non-flooded conditions. There were also significantlymore gas spaces in the total root tissue in T. fragiferum andT. repens under saline-flooding than in roots of T. subterraneum.Electron micrographs of the root cross sections illustratedthe presence of these gas spaces or aerenchyma. Trifolium fragiferum, T. repens and T. michelianum are morelikely to be suited to growth in soils prone to high salinityand to flooding than are T. subterraneum, T. purpureum and T.ishmocarpum.Copyright 1993, 1999 Academic Press Trifolium subterraneum, Trifolium fragiferum, Trifolium michelianum, Trifolium isthmocarpum, Trifolium purpureum, Trifolium repens, salinity, flooding, hypoxia, adventitious roots, aerenchyma, subterranean clover, white clover, strawberry clover, purple clover, balansa clover     

Inoculation with Azospirillum lipoferum Affects Growth and Gibberellin Status of Corn Seedling Roots

Maize (Zea mays L., hybrid Cargill 147) seedlings, grown inaseptic conditions, were inoculated with three strains of Azospirillumlipoferum (Al op 33, Al iaa 320, and ATCC 29708) or culturedin different concentrations of indol-3-acetic acid (IAA) orgibberellin A₃ (GA₃). After 48 h, root length, root surfacearea, root dry weight, and shoot dry weight were measured inall treatments. Gibberellin content was evaluated in selectedroots of control and Azospirillum inoculated seedlings by gaschromatography-mass spectrometry-selected ion monitoring withthe use of deuterated gibberellins as internal standards. Thethree strains of A. lipoferum, IAA (2 ng ml^–1), and GA₃(40 to 400 pg ml^–1) significantly enhanced root growth.Improvement of root hair growth and density was obtained mainlywith A. lipoferum strain Al op 33 and GA₃ 40 pg ml^–1.GA₃ was identified by gas chromatography-mass spectrometry (byboth, full scan and selected ion monitoring) in a free acidfraction from roots of the seedlings inoculated with A. lipoferum.In the roots of the non inoculated seedlings GA₃ was found afterhydrolysis of a fraction expected to contain glucosyl conjugates. (Received April 26, 1993; Accepted September 27, 1993)     

Morphogenese und Stoffwechsel höherer Pflanzen unter dem Einfluß einiger Herbizide und Growth Retardants

Summary Effects of TIBA, 2,4-D, Flurenol and CCC upon growth, root formation, membrane permeability, content of nucleic acids and stability of the chromatin were investigated. The four substances showed little or no effect on growth of isolated plant segments, but TIBA, 2,4-D and CCC caused 25–30% inhibition of growth of whole pea seedlings even at low concentrations. Root formation is inhibited by TIBA, Flurenol and 2,4-D, but not by CCC. At concentrations >10^-4mol/l all the substances reduced the permeability of the plasma lemma, at lower concentrations only CCC and Flurenol still reduced permeability of the plasma lemma. The ratio RNA/DNA was decreased by TIBA, 2,4-D and Flurenol but it was increased by CCC. The Tm-value of isolated pea-chromatin was lowered by treatment with CCC and elevated by treatment with TIBA, 2,4-D and Flurenol can decrease or increase the Tm of isolated chromatin depending on their concentration. The results have shown that even very low concentrations of herbicides and growth retardants are able to induce metabolic alterations with partly unknown consequences.     

Growth retarding and stimulating effects of CCC on Antirrhinum majus L.

Summary Stimulation of stem growth on snapdragon, Antirrhinum majus, by foliar sprays with CCC has been reported by Halevy and Wittwer (1965). Soil application gave little or no effect on growth. Our results confirm the observations by Halevy and Wittwer on stimulated stem elongation when CCC is applied as a foliar spray. However, growth was significantly retarded when the growth regulator was applied to the roots. At present there is no explanation for these findings.     

Effects of Cytokinins on the Growth of Primary Roots of Zea mays

Intact primary roots of Zea mays seedlings, apical 6-mm segmentsisolated from the intact primary roots and 5-mm detipped segments,prepared from the 6-mm apical segments by removal of the apical1-mm meristematic region, were incubated in potassium-phosphatebuffer that contained various concentrations of kinetin, 6-benzylaminopurine(BAP) or zeatin. These cytokinins inhibited the growth of intactprimary roots but they promoted the growth of both tipped anddetipped apical segments. In other words, they promoted thegrowth of root segments irrespective of the presence or absenceof apical meristematic regions. Detipped segments were stoodvertically, with their apical or basal cutends in contact withan agar plate that contained the abovementioned buffer and variousconcentrations of kinetin, BAP or zeatin so that cytokininswere supplied either from the apical or basal cut-ends. Cytokininssupplied from the top promoted the growth of the segments, whilethose supplied from the base did not. These results indicate that the response of roots to the exogenouslyapplied cytokinins is not influenced by the presence of theroot meristem but is significantly affected by the way in whichcytokinins are supplied. (Received October 17, 1995; Accepted August 28, 1995)     

Gibberellins and the Growth of Excised Tomato Roots: Comparison of gib-1 Mutant and Wild Type and Responses to Applied GA3 and 2S, 3S Paclobutrazol

Clones of excised roots of wild type tomato (Lycopersicon esculentum,Mill., cv. Moneymaker) and a near-isogenic GA-deficient mutant(gib-1/gib-1) were cultured in modified White's medium containing1.5% w/v sucrose. The linear elongation rate of the main axisof the gib-1 mutant was 40% less than that of the wild type.In addition, the main axis of the gib-1 mutant was thicker thanthat of the wild type but main axis volume growth was the samein both genotypes, indicating that the gib-1 allele was affectingthe orientation of root expansion. There was no evidence tosuggest that the gib-1 allele affected either the pattern ofemergence or the density of lateral roots. Elongation rate andthickness of gib-1 mutant roots were restored to those of thewild type by the addition of low concentrations (0.1–1.0µM) of gibberellic acid (GA3). These concentrations ofGA3 caused a slight reduction in extension growth of wild typeroots, indicating that endogenous GAs were not limiting elongationof normal roots in culture. The GA biosynthesis inhibitor, 2S,3S paclobutrazol, at 0.1 µM, significantly reduced elongationof wild type roots and this inhibition was counteracted by 0.1µM GA₃. It is concluded that the difference in growthbetween the gib-1 mutant and the wild type represented GA-dependentgrowth. Low concentrations of 2S, 3S paclobutrazol caused onlya small (5%) reduction in growth of the gib-1 mutant and thisgrowth inhibition was not reversed by GA₃. This observation,and the fact that gib-1 mutant roots grow in the absence ofadded GA₃, suggested that part of root growth was GA-independent.However, the possibilities that the gib-1 mutant is ‘leaky’and that paclobutrazol does not inhibit GA biosynthesis completelycannot be excluded. Key words: gib-1 mutant, gibberellic acid, Lycopersicon esculentum, 2S, 3S paclobutrazol, root growth     

Effects of the Temperature of the Rooting Zone on the Growth and Development of Roots of Potato (Solanum tuberosum)

In solution culture the effect of optimal (20 °C) and supra-optimal(30 °C) root-zone temperatures on root growth and root morphologyof six potato clones (Solanum tuberosum L spp) was studied Growthwas compared with sweet potato (Ipomoea batatas L) and cassava(Manihot esculenta Crantz) Significant genotypical differencesin the responses of potato roots to supra-optimal temperatureswere observed, indicating the potential for selecting heat tolerantpotato clones In both heat tolerant and heat sensitive clones,the size of the root system was reduced by supra-optimal root-zonetemperature This was principally a result of decreased numberand length of lateral roots The first symptom of heat damagewas a reduction in the rate of cell division, followed by cessationof root elongation Bending of the apical root-zone togetherwith the formation of root hairs on the inner (concave) andlateral roots on the outer (convex) side were other symptoms,these coincided with the loss of starch granules in the root-cap Potato, genotypical differences, root morphology, root growth, temperature, Solanum tuberosum L     

Nitrate Assimilation and Growth of Steptoe Barley and one of its Nitrate Reductase Deficient Mutants

Barley (Hordeum vulgare L. cv. Steptoe) and a nitrate reductasedeficient mutant (narla) were grown in a nutrient film systemwith three concentrations of nitrate. Comparisons were madewith respect to growth, yield, activities of enzymes of nitrateassimilation and accumulation of nitrate and total nitrogen.In nutrient film, grain yeild of the wild-type was greater thanthat of narla. for any treatment. Nitrate reductase activitiesof narla, measured in vivo, were higher than might be expectedin an NR-deficient mutant both in leaves and especially in roots.In all treatments, narla accumulated more nitrate than did thewild-type. No significant genotypic differences were observedin nitrite reductase or glutamine synthetase activities. Whenthe two genotypes were grown in soil (i.e. when availabilityof nitrate to the roots was less than in nutrient film) differencesin growth were insignificant. Hordeum vulgare L., mutant, nitrate status, assimilation and accumulation, growth, yield     

The Effect of Phosphorus Nutrition upon the Growth and Morphology of Young Plants of Lolium perenne L.

Genotypes of Lolium perenne were grown in soil of low phosphorusstatus, with and without additional phosphorus. Lack of phosphorusresulted in a great reduction in the number of main roots andin an increase in the length of each individual root. The numberof tillers was also reduced, but to a lesser extent than thenumber of main roots. The dry weight of the root and shoot systemwas reduced to a lesser extent than the numbers of roots andtillers. The effect on root relative to shoot growth variedwith the genotype.     

Morphogenetic Effects on Vegetative Plants of Poa pratensis L. of 6-Azauracil, (2-Chloroethyl)- phosphonic acid, and (2-Chloroethyl) trimethyl-ammonium chloride and their Interaction with Gibberellic Acid

Fresh and dry weights and leaf size of Poa pratensis were reducedwhen treated with 6-azauracil (AzU), (2-chloroethyl)phosphonicacid (CEPA), or (2-chloroethyl)trimethylammonium chloride (CCC).AzU and CEPA inhibited epidermal cell division without inhibitingcell elongation, while CCC inhibited mainly cell elongationand cell division to a small extent. The ratio of blade lengthto sheath length and the blade length/width ratio were reduced,but leaf emergence and tillering were increased by AzU and CEPA.CCC affected only the latter three features. Like GA₃, CEPAinduced stem formation, but internodes were shorter. GA₃ was ineffective in preventing leaf-growth inhibition byAzU, which inhibited Ga₃-induced cell elongation. The inhibitoryeffect of CEPA on leaf growth was apparently reversed by GA₃,but this was due solely to increased cell elongation, the reductionin cell number being unaffected. Ga₃ reversed the effect ofCCC on leaf length, as well as on cell size and number. Simultaneousapplication of the inhibitors produced a complex interactionin reducing leaf length and number and size of epidermis cells.It is postulated that AzU, CEPA, and CCC have different modesof action because they have specific effects on plant growthand different effects on GA₃-induced cell elongation.     

Growth and Development of Young Roots of Barley (Hordeum vulgare L.) Genotypes

Barley (Hordeum vulgare L.) genotypes from countries with aMediterranean climate grown in temperature-controlled glasshousein nutrient solution to determine whether the co-ordinationof root branching and growth found by other workers appliedto a wider of up to 14 genotypes. There was substantial variationin the number of seminal axes produced by the genotypes, rangingfrom about seven for Hoshimasari and Swanneck to about fourfor Gerbel 'B'. The number of nodal axes was linearly relatedto the number of leaves and typically between one and two mainstemleaves were required before nodal axes appeared. There weresmall genotypic differences in the number of axes produced perleaf with values ranging from 1·5 to 2·3. Theproduction and growth of lateral roots were coordinated so thatthe mean length of laterals generally increased with time. Landraces(Arabic abiad and Arabic aswad) produced more lateral rootswith a faster rate extension compared with other genotypes.The length and number of primary and secondary lateral rootswere related linearly, but no genotypic differences in thisrelation were evident. Length of primary lateral roots increasedmore rapidly than that of secondary lateral roots throughoutthe three to five leaf stage. The ratio of root weight to totalplant weight decreased with time but there were only small differenceswithin this range of genotypes.Copyright 1995, 1999 AcademicPress Barley, seminal axes, nodal axes, primary lateral roots, relative extension rates, relative multiplication rates     

Root and Shoot Growth of Plants Treated with Abscisic Acid

Young seedlings of Capsicum annum L., Commelina communis L.and maize (Zea mays L.) were subjected to a mild water-stressingtreatment and/or treated with abscisic acid (ABA). Plants rootedin soil received a soil-drying treatment and their leaves weresprayed with a 10–⁴ M solution of ABA. Plants grown insolution culture were stressed by the addition of polyethyleneglycol (PEG) to the rooting medium and ABA was also added tothe rooting medium, either with or without PEG. The effectsof both treatments on the growth of roots and shoots and theultimate root: shoot dry weight ratio were very similar. Shootgrowth was limited both by water stress and by ABA application;while there was some evidence that mild water stress and/orABA application may have resulted in a stimulation of root growth.More severe water stress reduced the growth of roots but theoverall effect of stress was to increase the ratio of rootsto shoots. Capsicum annum L., Commelina communis L., Zea mays L., water stress, abscisic acid     

The Interaction of (2-Chloroethyl) trimethylammonium Chloride and Gibberellic Acid in Strawberry

Applications of (2-chloroethyl) trimethylammonium chloride (CCC), by foliar spray or to the soil, shortened petioles and decreased top and root growth of strawberry plants. Application of gibberellic acid increased petiole length and fresh weights of tops but not of roots. Applied together gibberellic acid overcame the depression of growth in weight of tops induced by CCC and countered the depression in petiole lengths. Gibberellic acid induced elongation of internodes of the vegetative stem and the elongation was increased substantially by concurrent application of CCC. This synergism in stem growth indicates a lack of antagonism between CCC and exogenous gibberellic acid in strawberry. The implications are discussed.