Showing papers on "Shoot published in 1970"

The Distribution of Dry Matter Growth between Shoot and Roots in Loblolly Pine

Abstract: The allometric relationship, log (y) = a + k·log (x)-where x is one plant organ (e.g., dry weight of roots) and y is another (e.g., dry weight of shoot)-was used to study the relative distribution of growth within loblolly pine seedlings. The relative distribution of growth between shoot and roots or among needles, stem, and roots was unchanged by conditions ranging from full sunlight to one-third of full sunlight. There was an indication that the growth of the shoot was inhibited by soil moisture stress to a relatively greater degree than the growth of the roots, as shown by a decrease in slope of the allometric relationship. These results and data reanalyzed from the literature suggested that the relative growth of shoot to root in pine is surprisingly constant under the usual conditions of culture. The ontogenetic decrease in the ratio of shoot to root seems to be a common trend in woody seedlings, and this pattern can be interpreted as adaptive.

Shoot and tree production from Aspen tissue cultures.

Abstract: A B S T R A C T Trees were produced from firm white callus tissue of triploid quaking aspen (Populus tremuloides Michx.), initiated on a modified Wolter and Skoog defined medium and subcultured monthly for two years. When subcultured to medium without auxin, kinetin or supplements, but containing 0.15 mg/liter BAP (6-benzylaminopurine), multiple stunted shoots appeared on most inocula. However, at 0.05 mg/liter BAP, only a few vigorous shoots per piece were initiated, but seven rooted on the callus: two in the dark with BAP and five in 200 ft-c of light with 0.04 mg/liter 2,4-D. After proliferation of the roots on the medium surface, four shoots elongated and were planted in semi-sterilized soil, then were given 3100 ft-c of light for rapid growth into trees. Both light sources were on for 16 hr/day. Two trees were also grown from stunted shoots excised from the callus and rooted in soil. THE INDUCTION of complete plants from cell and tissue cultures of herbaceous angiosperms and monocots was reviewed by Pillai and Hildebrandt

The morphology of vegetative regeneration in calluna vulgaris

Abstract: Summary Calluna vulgaris, in certain habitats, provides useful grazing for herbivores; management is generally by burning, with the aim of promoting vigorous production of young shoots by vegetative regeneration for the stem base. However, the capacity for such vegetative regeneration declines with age. The general morphology of the plant is described, with particular reference to the sequence of development in a single season's growth and to the stages in resumption of growth after overwintering. On this basis, an interpretation is given of the responses to grazing and burning, with evidence derived from detailed observation of treated plants and from transverse sections of stems. Light grazing at the periphery of the plant causes (i) the growth of a few of the uppermost short shoots into new long shoots, and (ii) the appearance of clusters of shoots from lower, woody, parts of the branches. Heavier or more sustained grazing emphasizes the second of these responses. Vegetative regeneration after burning is also of the second category, confined to undamaged positions near the base of the stem. The clusters of shoots appear at the points of origin of existing or former branches. The conclusion, derived both from morphological observations and from evidence of the deep-seated origin of these new shoots, is that they are derived from persisting dormant buds on the close-packed nodes just below the base of each long shoot. These nodes belonged to the overwintering end-of-season short shoot from which the long shoot developed.

Somatic genetic analysis of the apical layers of chimeral sports in chrysanthemum by experimental production of adventitious shoots.

Abstract: A B S T R A C T Many commercial chrysanthemum cultivars display unusual somatic variability. The 'Indianapolis' family of chrysanthemtum sports was analyzed for the genetic potential for color of each of the three layers in the apical meristem of their shoots. Populations of each cultivar were grown and sectors and off-color plants recorded. The location of the pigment within cells and between tissues was determined by microscopic examination of free-hand sections of fresh petals. Adventitiouis buds were forced from the stems of each cultivar by excising all normal lateral buds. These observations showed 12 of the 16 'Indianapolis' cultivars to be perielinal chimeras. Adventitious shoots often originated from two or more cells, derived from at least two different apical layers, and thuis were themselves periclinal chimeras. While somatic mutation is the ultimate source of the variability in 'Indianapolis' chrysanthemums, the most frequent type of sporting resulted from the loss in mitosis of a chromosome carrying a supressor for the formation of yellow chromoplasts, giving a yellow sector or shoot. Sectors resulting from rearrangement of layers in the

Modification of Pattern of Photosynthate Movement within and between Shoots of Vitis vinifera L

Abstract: During the prebloom and bloom stages, no movement of labeled photosynthates occurred from a shoot of Vitis vinifera L. fed with (14)CO(2), to an adjacent shoot on the same spur. Movement of labeled assimilates into the unfed shoot was induced when this shoot was sprayed with 2.89 x 10(-3)m gibberellic acid during the prebloom stage. During the bloom stage darkening or defoliation of the unfed shoot resulted in the import of labeled photosynthates from the adjacent fed shoot. Similarly, movement of (14)C into an untreated shoot was induced by removing the terminal 7.5 centimeters and deblossoming the fed shoot. During the berry set stage, translocation of labeled photosynthates from a newly exporting leaf was upwards to the shoot tip, but the direction of movement was reversed by removal of the shoot tip or by darkening or removal of the leaves below the fed leaf. Translocation of photosynthates was predominantly basipetal from a fed leaf near the base of the shoot during the berry set stage, but upward movement was induced by darkening or defoliation of the upper part of the shoot.

Apical dominance in long shoots of white pine (Pinus strobus)

Abstract: The roles of auxin and nutrition in determining the expression of dominance within a whorl of current shoots were investigated. It was demonstrated that the removal of shoots from a whorl induces compensatory growth in the remaining shoots. Treatments that block auxin movement (triiodobenzoic acid (TIBA), girdling) or decrease auxin production (defoliation, decapitation) also induce compensatory growth, at the same time inhibiting growth in the treated shoot. On the other hand, capping a decapitated and defoliated shoot with indoleacetic acid (IAA) in lanolin maintains diameter growth in the shoot stump and prevents the occurrence of compensatory growth. It is concluded that the shoots in a whorl compete for dominance by competing for a common supply of nutrients transported from the preceding internode. The quantity of nutrients diverted into a shoot, hence growth, is a function of the shoot's capacity to produce growth substances. Hormone synthesis, as well as shoot length, fascicle number, and number o...

Effect of selection for mesophyll cell size on growth and assimilation in lolium perenne l.

Abstract: Summary Divergent selection for mesophyll cell size (mean cross-sectional area) was made within a population of ‘Veya’ perennial ryegrass. Selection for small mesophyll cells generally resulted in smaller mesophyll cells, heavier seed, and greater yield of shoot dry matter than selection for large cells. Between the third and fifth leaf stage, families from parents with small cells exhibited greater net assimilation rate and lower leaf area ratio than those from parents with large cells. Rate of light-saturated photosynthesis of young leaves was negatively related to cell size in the F1 generation. Greater shoot dry matter in the small, compared with the large, cell selections was accounted for in terms of greater initial seed reserves (heavier seed) and also greater net assimilation rate at some stage prior to full expansion of the third leaf. It was concluded that mesophyll cell size is a useful criterion for selecting for light-saturated photosynthesis in Lolium perenne.

Water potential, temperature, and kinetin effects on seed germination in soil and solute systems.

Abstract: A B S T R A C T Germination of lettuce and wheat in soil is reduced by a decrease in water potential, but a significant temperature-water potential interaction exists for lettuce. At 35 C kinetin permits lettuce germination at 0 and -1.1 bars, and at 25 C and 15 C it enhances germination at lower water potentials, causing 30% germination at -8.0 bars. Wheat germinates well at -8.0 bars, but no germination occurs at -14.9 bars; temperature had little effect on wheat germination. Germination in soil and solute systems was compared to determine the usefulness of solute germination data for predicting germination in dry soil. Total germination of lettuce in polyethylene glycol-6000 may approximate total germination in soil at the same water potential, but germination rates differ widely for the two systems. Kinetin-treated lettuce seeds nearly completed germination in two days in polyethylene glycol solutions, but five days were required for similar germination percentages in the soil. Sucrose is not useful for simulating soil water stress; wheat seeds germinate at -14.9 bars in sucrose but fail to germinate in soil at the same potential, and germination is more rapid in sucrose than in the soil. WATER POTENTIAL and temperature are important ,environmental factors affecting seed germination. Individually, each factor has been studied rather 'extensively, but little is known about the effects of water stress at different temperatures. Conclusions about the effects of water stress at one temperature are not valid at other temperatures if a water stress-temperature interaction exists. This paper reports the results of experiments having a two-fold purpose: to determine (1) the

The effect of temperature of the root medium and of the growing point of the shoot on growth, water content and sugar content of maize leaves.

Abstract: Maize seedlings were grown in nutrient solution under 18-h daylength and the temperatures of the root medium and of the growing points of the leaves were varied independently between 20 degrees and 5 degrees C; leaf growth rate and leaf water content were continuously recorded. The effect of root temperature on leaf growth was influenced by the plant water balance and was subject to osmotic adaptation which proceeded faster and was more complete at favourable growth temperatures.-G.M.H. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Shoot responses of young Red Pine to watering applied over two seasons.

Abstract: Young red pine (Pinus resinosa Ait.) trees were grown under three watering treatments from late summer until early fall and under two watering treatments again the next spring. Size of apical buds, date of bud swell and bud burst in the spring, number of needle fascicles on the new shoots, shoot length, and needle-fascicle spacing were related to the first treatments. Most of these plant responses were correlated with bud size, and the correlations were unaffected by the spring watering treatments. The effect of treatments was on magnitude only, i.e. on mean sizes or mean numbers of the plant organs.In all cases in this experiment watering treatments during elongation had no effect on the results. Therefore in a species such as red pine, with determinate height growth, environment during bud formation played an important role in determining later shoot responses by acting on the bud size.Possibly the relationships reported here are genetically characteristic, unalterable by environment or at least by wate...

14C-Studies on Apple Trees. VI. The Influence of the Fruit on the Photosynthesis of the Leaves, and the Relative Photosynthetic Yields of Fruits and Leaves

Abstract: When paired samples of either intact or detached apple shoots with and without fruits were exposed simultaneuosly to 14CO2, the uptake of 14CO2 of leaf area was found to be greater in the fruit-bearing shoots, often by a factor of 1.5 or more, although the difference tends to be slight or even non-existent when the experiments follow shortly after a previous dark period. The uptake of 14CO2 by photosynthesis in the skin of detached fruits is very slight compared to the simultaneous uptake of 14CO2 by the leaves from the same spur, and can hence contribute only slightly to the development of the fruit compared with the supply of assimilates taking place from the leaves to the fruit.

Germination Control of Johnsongrass Rhizome Buds

Abstract: Field-harvested johnsongrass (Sorghum halepense (L.) Pers.) rhizomes were assayed for bud dormancy and growth po- tential under a number of experimental conditions. Natural dor- inancy was not detected in single-node rhizome pieces harvested at any time of the year. Shoot growth rates were highly variable. Kinetin, benzyl adenine, gibberellic acid, and 2-chloroethylphos- phonic acid were ineffective in enhancing germination or normaliz- ing shoot growth. Scale leaves of rhizomes had no effect on bud growth. Rhizome buds were strongly influenced by apical dom- inance and emerged shoots partially suppressed germination of adjacent buds. The optimum temperature for bud germination an(d shoot growth was approximately 30 C. Bud germination was ssuppressed at 15 C. Johnsongrass rhizomes failed to exhibit cold har(liness at any time in their life cycle.

Physiological and chemical features of magnetically treated winter wheat seeds and resultant seedlings

Abstract: Seed of winter wheat (Triticum aestivum L.), cultivar Kharkov 22 MC, magnetically treated before germination respired more slowly, released less heat energy, and grew faster during the initial 16 hr than similar but untreated seed. Magnetically treated seed absorbed more moisture and contained more reducing sugar during the initial 72 hr of growth than un-treated seed. Addition of oxygen to the seed environment during germination repressed shoot growth and enhanced root growth of magnetically treated wheat but had no effect on untreated seed. Addition of carbon dioxide to the seedling environment suppressed the growth of shoots and roots of treated and untreated wheat seed equally.

Derivation of the springtime starch increase in balsam fir (Abies balsamea)

Abstract: The contents of starch, total sugar, crude fat, and moisture were determined during the spring (late March until mid-June) in needles, bark, and wood of 1-year-old balsam fir shoots variously shaded, defoliated, and girdled in late March. The starch content in control shoots peaked during the first week in June, about the time vigorous current shoot elongation began. Shading reduced the concentrations of both starch and total sugar throughout the experimental period, while defoliation decreased them after about mid-spring. Girdling increased the carbohydrate content during early spring in both shaded and unshaded shoots, but decreased it in defoliated shoots. It is concluded that the bulk of the starch accumulating in conifers during the spring is derived from current photosynthesis, the rest being regenerated from carbohydrates produced during the previous year and stored overwinter. Timing the lifting date to maximize the springtime accumulation of starch might be an important consideration when transpl...

Shoot Growth and Heterophylly in Ginkgo biloba

Abstract: Ginkgo biloba resembles other woody plants with long and short shoots in having variable leaves, and this variability in shape and other characteristics is closely related to the specialization of the shoots. The unlobed or bilobed early leaves of short shoots are preformed in the winter bud, and their nearly synchronous expansion in the spring is not accompanied by stem elongation. The leaves clustered at the base of long shoots are like short-shoot leaves in origin, time of appearance, and form, but they are succeeded by a second set of leaves whose internodes elongate. These multilobed late leaves develop at intervals of several days, and their production sometimes continues throughout the summer. The early and late leaves differ in the circumstances and continuity of ontogeny, and their differences in form originate at an early stage. The similarity of the late leaves to the deeply cut leaves of seedlings appears to be due to a common mode of ontogeny, rather than to any tendency to revert to a juveni...

Epidemiology and control of powdery mildew (Sphaerotheca pannosa) on roses

Abstract: SUMMARY In examinations between September 1966 and December 1968 of 741 specimens of rose species and cultivars, cleistocarps of Sphaerotheca pannosa were found on thirty-two cultivars, mostly ramblers and old shrub roses, and on nine of these they were found in two or three successive seasons. On stem pieces placed on soil in each of the winters 1966-7, 1967-8 and 1968-9 the number of cleistocarps with asci and ascospores decreased during November and December and rose slightly in January, but none showed dehiscence. Cleistocarps on rose bushes examined during the winters of 1967-8 and 1968-9 showed a progressive degeneration of ascospores, and by December none was found. Perennation of S. pannosa in buds was demonstrated by field observations, by inducing bursting of dormant buds on surface-sterilized shoots and by dissection of dormant apical buds. In field studies in 1968 of the development of mildew, infected buds were noted on 22 March but secondary infections did not appear until 17 April, though viable conidia and susceptible leaf tissue were present during this period. Low temperatures appeared to be partly responsible for this lag. On detached leaves in the laboratory the fungus developed from germination to sporulation in 4 days at 20°, 7 days at 15°, 11 days at 10° and 28 days at 3°. Keeping inoculated detached leaves at 0° for 10 days apparently did not affect the viability of the conidia. In both 1967 and 1968 there were two host growth periods, each culminating in flowering, between May and September; mildew did not develop on the shoots until the second growth phase, then the disease increased logarithmically on shoots and blooms during August and September. The disease on the shoots was effectively controlled in the field during 1968 by applications of ‘Benlate’ (benomyl) or dinocap, but not by methy-rimol; these fungicides were less effective in controlling mildew on pedicels. Laboratory tests showed that ‘Benlate’ inhibited sporulation of S. pannosa by deforming the conidiophores.

Genetic analysis of root growth in wheat.

Abstract: The growth characteristics of root systems were studied in the wheat varieties Chinese Spring' Hope and the chromosome substitution lines of Hope into Chinese Spring. The growth patterns varied considerably between the lines and this was due to the fact that the plants formed different numbers of tillers and grew for different periods of time. A correlation existed between the development of the shoot and root systems although some lines differed widely in their shoot root ratios. Differences between the lines in the early stages of growth were small and they reacted uniformly to different levels of phosphorus supply. The relation between shoot and root growth was also shown by the fact that the conclusions from genetical analyses were very similar. These showed that the method of control was largely additive in nature. It was concluded that variations in shoot and root characteristics were markedly influenced by single genes affecting the duration of the vegetative growth period as well as by polygenic systems.

Fruit set in grape vines: the mechanism of the CCC effect.

Abstract: SummaryThe treatment of grape inflorescences with CCC before anthesis increased fruit set, but it did not increase the fertilization of ovules. CCC applied to different parts of a shoot had effects remote from the point of application. The effects included reductions in leaf expansion, internode elongation and rate of leaf emergence. The size of the effects was directly correlated with the amount of tissue treated and was inversely correlated with the amount of fruit set. If shoot tips were removed, CCC treatment was without effect on set. It has not been possible to link the data with changes in chlorophyll concentration. It is suggested that the effect of CCC on fruit set is due to a correlated inhibition of shoot growth whereby organic nutrients are diverted to the developing ovaries.

Growth substances and the relation between phenotype and genotype in Pisum sativum.

Abstract: Reciprocal grafts between plants of the tall variety Alaska and the dwarf Progress No. 9 show that neither roots nor mature leaves determine shoot phenotype. It is demonstrated that differences in stem growth between the two varieties are essentially controlled by a single Mendelian factor, and the effect of this Le locus is not graft transmissible. Combined with published data for gibberellin content this confirms that the Le locus does not control shoot phenotype by regulating gibberellin synthesis. Growth of slender plants (Le la cry (s) ) and early growth of microcryptodwarfs (le la cry (c) lm) is not inhibited by AMO-1618 at concentrations which greatly reduce growth of tall plants. This is consistent with the suggestion that rapid growth in these varieties, in the absence of the inhibitory effect of La and Cry, is not dependent on endogenous gibberellin.

Effects of potassium nutrition on protein and total free amino acids in Zea mays.

Abstract: Corn (Zea mays L.) seedlings were grown in nutrient solutions that ranged in K content from none to sufficient. In comparison with K-sufficient plants, the shoots of K-deficient plants exhibited up to 40% increase in protein concentration while the amount of protein per shoot was much reduced. The concentration of free amino acids was increased by about threefold in extreme deficiency, but was hardly affected by moderate deficiency although growth in the latter case was still much retarded. During the development of K deficiency, the ratio of free amino acids to protein in leaves of two different ages did not increase until growth was retarded; similarly the amount of protein per leaf in the maturing leaf was not affected until growth was substantially reduced. When K was added to deficient plants, to permit their recovery, the ratio of free amino acids to protein in the shoot did not decrease for many hours after K was detected in adequate amounts in the shoots. The ratio decreased only after the added K had induced an increase in growth. This suggests that there was no acceleration of polymerization of amino acids resulting directly from the added K. The specific activities of aldolase and triosephosphate dehydrogenase were some 30% lower in deficient than in sufficient shoots. The level of nitrate reductase in the tissue, however, appeared to be related to the supply of nitrate and not to the K level. These data do not support the contention of K level in deficient plants being low enough to directly limit the polylnerization of amino acids and of a reduced rate of protein synthesis being the primary factor limiting growth of K-deficient plants.

Export of photosynthate affected when leaves are pretreated with growth substances.

Abstract: SEVERAL investigators have shown that cytokinins are strong mobilizing agents1–3. For example, a spot of cytokinin on a leaf can attract such substances as amino-acids from adjacent untreated tissues, and treatment of fruits4,5, shoot tips6, or expanded leaves7 increases movement of photosynthate into the treated area. Gibberellic acid also enhances movement of assimilates into the treated area, but the growth retardant CCC ((2-chloro-ethyl)-trimethylammonium chloride) causes a decrease in the mobilizing power of the treated area4,6. We are not aware, however, that leaves on intact plants have ever been pretreated with growth regulators to study the effect on the export of photosynthate from the treated leaves.

Leaf area development on different shoot types in a young aspen stand and its effect upon production

Abstract: Different shoot types in aspen crowns carried leaves of different ages; leaders continued to produce leaves until early August and always carried some young leaves, whereas short shoots completed d...

Studies on bud development in the rhizome of Agropyron repens. 1. The influence of temperature, light intensity, and bud position on the pattern of development

Abstract: When plants of Agropyron repens L. Beauv. are grown at a low nitrogen level, decapitation of the rhizomes releases the lateral buds from inhibition and results in a well-marked polarity of bud development. This polarity is typically characterized by the restriction of shoot development to the bud nearest the apical end of the rhizome, the production of rhizomes from buds at a greater distance from the apex, and a tendency for the buds at the basal nodes to remain inhibited.It was shown that this pattern of bud development is readily affected by environmental conditions. Increasing the temperature from 15° to 25 °C caused a marked increase in shoot formation at the expense of rhizome production and a small increase in the number of dormant buds. Reducing the light intensity had a similar but much more pronounced effect. The position of the buds in relation to the cut end of the rhizome was relatively less important as a morphogenetic factor than their position on the intact plant.As a working hypothesis, b...