Showing papers on "Shoot published in 1968"

Enzymic Mechanism of Starch Breakdown in Germinating Rice Seeds I. An Analytical Study

Abstract: Time-sequence analyses of carbohydrate breakdown in germinating rice seeds shows that a rapid breakdown of starch reserve in endosperm starts after about 4 days of germination. Although the major soluble carbohydrate in the dry seed is sucrose, a marked increase in the production of glucose and maltooligosaccharides accompanies the breakdown of starch. Maltotriose was found to constitute the greatest portion of the oligosaccharides throughout the germination stage. α-Amylase activities were found to parallel the pattern of starch breakdown. Assays for phosphorylase activity showed that this enzyme may account for much smaller amounts of starch breakdown per grain, as compared to the amounts hydrolyzed by α-amylase. There was a transient decline in the content of sucrose in the initial 4 days of seed germination, followed by the gradual increase in later germination stages. During the entire germination stage, sucrose synthetase activity was not detected in the endosperm, although appreciable enzyme activity was present in the growing shoot tissues as well as in the frozen rice seeds harvested at the mid-milky stage. We propose the predominant formation of glucose from starch reserves in the endosperm by the action of α-amylase and accompanying hydrolytic enzyme(s) and that this sugar is eventually mobilized to the growing tissues, shoots or roots.

Nitrogen metabolism of Picea glauca. I. Seasonal changes of free amino acids in buds, shoot apices, and leaves, and the metabolism of uniformly labelled 14C-L-arginine by buds during the onset of dormancy

Abstract: Buds, shoot apices, and leaves from terminal shoots of white spruce saplings accumulated high levels of alcohol-soluble nitrogen in spring, late summer, and early winter. Major components, e.g. arginine, glutamine and proline, of the soluble nitrogen showed patterns complementary to each other. These changes represented the storage and mobilization of nitrogenous compounds during the onset of dormancy or the growth of shoots. Leaves contained less total soluble nitrogen than buds or shoot apices. Soluble nitrogen and arginine content of leaves resembled buds in their seasonal patterns but changes in aspartic acid, glutamic acid, and alanine were much greater than in buds, especially in late summer.When the first frost appeared, uniformly labelled 14C-arginine, applied to the apices of buds, readily entered newly synthesized protein, and free arginine was converted to proline via ornithine. Proline with carbon derived from arginine also entered proteins that were metabolized at different rates. A fraction ...

Root and Shoot Initiation in Aspen Callus Cultures

Abstract: INITIATION of organs on cultured callus tissue has been reported for herbaceous species1,2, but similar reports for woody species have been meagre, and the results sporadic. The control of root rather than shoot initiation has been emphasized3–5. I describe here conditions which control either root or shoot formation in callus cultures of Populus tremuloides Michx.

Seasonal Changes in the Distribution of Photo-assimilated 14C in Young Pine Plants

Abstract: Pinus strobus L. plants in their third year of growth were permitted to photoassimilate (14)CO(2) for about 1 hour at monthly intervals between April and October, and the subsequent distribution of (14)C in these plants was determined 8 hours, 1 month, 2 months or 4 months after photo-assimilation. In this way, the fate of (14)CO(2) photo-assimilated during different months of the growing season was observed.In the spring, old needles played a significant role in photo-assimilating (14)CO(2) and exporting current photosynthate to the developing new shoots and roots. By July, the new shoot had replaced the old shoot both as the primary photo-assimilating part of the plant and as an exporter, particularly to the root.The root received current photosynthate from the shoot throughout the entire growing season, although plant analysis only 8 hours after photo-assimilation did not always reveal this. Translocation of recent photosynthate from shoot to root was particularly high in August, September, and October.The amounts of photo-assimilated (14)C lost from the plants over a 4 month interval, principally through respiration and photorespiration, were about one-half of that absorbed during photo-assimilation, with the greatest loss occurring within the first month.

Effect of Trifluralin on Roots of Corn and Cotton

Abstract: Seed of corn (Zea mays L., var. Texas 28) and cotton (Gossy- piitin hirsuttumn L., var. Deltapine smooth leaf) were planted in sand and subsequently drenched with solutions of a,a,a trifluoro-2,6-di- nitro-N,N-dipropyl-p-toluidine (trifluralin). The levels of herbicide used inhibited growth of roots and shoots in both crops, but cotton proved more tolerant than corn. The roots failed to elongate nor- mally, but the lateral growth that continued gave the radicle a "club-shaped" appearance, especially in corn. Stained sections of the roots were mounted as permanent slides for study. The cells at the extreme tip of the treated roots were small and dense; many were nmultinucleate. Immediately behind this region, the cells were ab- normally large, thin-walled, and aberrant. A disorganized type of nuclear division was evident. Cell plate and cell wall formation were apparently rare. Although we found no normal sequence of mitosis in cells of treated roots, all stages of mitosis were seen in the un- treated roots.

Effect of Trifluralin on Growth, Morphology, and Nucleic Acid Synthesis

Abstract: Roots and shoots of corn seedlings (Zea mays L. var. Dixie 18) germinated in trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) solutions are characterized by radial enlargement of the cortical cells and by multinucleate cells in the meristematic regions. Trifluralin inhibits elongation of Avena coleoptile sections at concentrations of 0.1 μm to 10 μm. Synthesis of DNA, RNA, and protein is suppressed in the root tips while no significant effect is noticeable in the shoots of corn germinated in trifluralin. A 32P time-course study of 48, 72, and 96 hours utilizing phenol extraction and MAK column separation of corn root and shoot nucleic acids showed suppression of 32P incorporation in the treated roots; however, the 72 and 96 hour treated shoots incorporated a much greater amount than the control with most of the increased incorporation found in the sRNA and DNA fractions. The increased activity in the DNA may be due to a high G-C type DNA. No selective suppression or enhancement of any particular RNA species was noticed in the treated plants.

d-Glyceraldehyde 3-Phosphate Dehydrogenases of Higher Plants

Abstract: The d-glyceraldehyde 3-P dehydrogenases of spinach leaf, pea seed, and pea shoot were purified. The NADP and NAD-linked enzymes of either spinach leaves and pea shoots could not be separated. Changes in the ratio of NADP- to NAD-linked activity of the spinach leaf and pea shoot enzymes were observed during both purification and storage of crude extracts. The spinach leaf, pea shoot, and pea seed enzymes differ electrophoretically from each other and from the rabbit muscle enzyme. The pea seed and shoot enzymes contain bound nucleotide cofactor, resist proteolytic attack, have similar Michaelis-Menton kinetic constants and are competitively inhibited by d-sedoheptulose-7-phosphate and d-sedoheptulose 1,7-diphosphate. Charcoal removes the bound nucleotide from the pea seed enzyme but not from the pea shoot enzymes. NADP and NADPH were found to inhibit the reductive but not oxidative reaction catalyzed by the charcoal treated seed enzyme. The function of the pea shoot NADP and NAD-linked enzymes in chloroplast metabolism is discussed in regard to their location and catalytic properties. Although the NADP-linked activity can be assigned a primary, if not exclusive function in photosynthesis, the assignment of a distinct metabolic function to the NAD-linked activity cannot be made at present.

The effect of night temperature on tuber initiation of the potato

Abstract: Tuber initiation occurred earlier when the night temperature of the shoot was lowered and earliest when the shoot and root (including stolon) night temperature was lowered. Initiation was also promoted by lowering the night temperature of the underground parts of the plant alone.

The aetiology and development of damage in young fruit trees infested with fruit tree red spider mite, Panonychus ulmi (Koch)

Abstract: SUMMARY Infestations of fruit tree red spider mite, Panonychus ulmi (Koch) altered the growth of young plants of plum and apple. At first, damage to the leaves from mite feeding did not affect their photosynthetic rates. The effects on other processes depended on the density of the infestation. Densities of 1–2 mites/cm2 of leaf decreased the rate of shoot extension of Brompton plum, but about 0.5 mite/cm2 increased it. Less dense infestations apparently caused no damage. The rate of growth of the leaf area of a plant relative to that of the mite population on it determined changes in the mite density, and therefore the effects of infestation. The growth of the root system was decreased before that of the shoots. Later, when some leaves were severely damaged photosynthesis was decreased. The onset and severity of this phase probably depended on the number of mites and days of feeding on individual leaves. The later-formed leaves were smaller, and sometimes fewer on infested plants. Some plants were infested with too low a density of mites to decrease shoot extension, but grew less in dry weight because of decreased photosynthesis later in the season. The initial effects are ascribed to an imbalance in the growth controlling substances caused by feeding. Radioactivity was detected in the growing regions of plants remote from mature leaves on which 14C-labelled mites were confined.

The growth of the lucerne plant after cutting: I. The effects of cutting at different stages of maturity and at different intensities

Abstract: Variation in shoot number, shoot size, and yield of dry matter occurring in the regrowth from lucerne plants cut at different stages of maturity and at different intensities is reported. The main effects of the treatments arose through variation in shoot number and changes in the time at which each shoot commenced extension growth; a linear regression utilizing this information about the population of shoots accounted for nearly all the variation in yield. Less severe, or later, cutting resulted in greater yields of dry matter in a 4 week period of regrowth. Changes in shoot number and shoot size both contributed to the variation in the yield of regrowth. Shoot size was mainly determined by the time at which the shoot resumed extension growth, and once such growth was resumed the shoot growth rate was apparently independent of the cutting treatment applied. The results are discussed in relation to currently held concepts on the role of "reserves" and of residual leaf area in promoting the regrowth of pasture plants. The development of lucerne adapted to grazing management is also considered.

Proportional Reduction in Shoot Growth of Grapevines With Root Systems Maintained at Constant Relative Volumes By Repeated Pruning

Abstract: Grapevines were established in water culture and shoot length and leaf number were measured after imposing four levels of root-pruning treatment. These levels (control, and 75, 50, and 25% of the control root volume) were maintained for 8 weeks by making weekly checks followed by appropriate pruning. Shoot dry weights were also measured in some plants at fortnightly intervals.

The effect of certain growth substances on asymbiotic germination and development of orchis purpurella

Abstract: Summary The effect of some growth substances on gernnination and development of Orchis (Dactylorchis) purpurella seeds was studied in an attempt to simulate the developmental pattern observed in symbiotic cultures. Gibberellic acid enhanced protocorm survival and caused abnormal elongation of the emergent shoot but did not influence the growth and overall size of the protocorms. Indoleacetic acid impeded germination and caused some elongation of the protocorms. Kinetin, both alone and in conjunction with indoleacetic acid, had a pronounced effect on growth and development and the results suggested that the auxin/cytokinin ratio is important in controlling root and shoot initiation. Adenine appeared to have little effect. The growth factor mixtures used did not have as beneficial an effect on protocorm development as did the presence of either symbiotic fungi or undefined fractions such as potato extract and coconut milk, suggesting that symbiotic fungi also provide other growth substances.

Polar Movement of Indole-3-acetic Acid-14C in Roots of Lens and Phaseolus

Abstract: A critical review of the few papers on IAA-14C movement in roots revealed apparent contradictions, as well as flaws in experimental design that would be apt to cause artifacts. The movement of 14C from IAA-14C was studied in sections of Lens and Phaseolus roots, using a system 20 or more times as sensitive as any previously used. To make sure that our results with roots could be compared validly with published work on petioles and stems, we used the same techniques as we had earlier used for shoot structures. The results with Lens were similar in many ways to those for shoots: net movement into receiver blocks was very strongly polar, followed a linear course for several hours, and showed a velocity of the same order of magnitude as in shoots (and, in fact, very close in absolute value to that found in Coleus stem cylinders). Also, as with shoots, all the radioactivity in receiver blocks ran to the RF of IAA. The time-course of loss of counts from donor blocks was similar to that found in shoots. The 2 most striking differences from shoots were 1) the very low percentage of added 14C that was moved into the receivers (about one-tenth of the values for bean petioles), and 2) the fact that the polar movement was acropetal in roots, rather than basipetal as in shoots. Results with Phaseolus roots were similar to those for Lens, although an additional complication with Phaseolus roots was the indication of a transitory stage of weak basipetal polarity in the first few hours after excising the section. This stage was followed in a few hours by a stronger acropetal polarity.

The Effect of Certain Growth Regulators on Growth and Apical Dominance of Young Apple Trees

Abstract: SummaryUnfeathered maiden trees of apple Stark Earliest (syn. Scarlet Pimpernel) were pruned back in winter to a height of 70 cm. The following spring five shoots were allowed to grow out, the others being removed. When the leading shoots were about 12 cm. long the trees were sprayed once with various concentrations of GA, TIBA, CCC and B.9 (see below), other trees being left unsprayed as controls. Subsequent effects on shoot growth were analysed in terms of leaf number and internode length. Apical dominance was destroyed or greatly reduced by GA (200 p.p.m.), TIBA (200 p.p.m.) and CCC (5,000 p.p.m.) and these substances all increased leaf number on the lower shoots. B.9 (2,000 p.p.m.) had no effect on apical dominance. TIBA, CCC and B.9 reduced mean internode length on all shoots, whereas GA increased internode length on the lower shoots only.CCC caused only a temporary check to growth, but the growth-retarding effects of B.9 and TIBA persisted throughout the growing season. The possible mode of action o...

14C translocation patterns in peach and apricot shoots

Abstract: 14CO2 was supplied under laboratory conditions to the terminal leaves of peach and apricot shoots taken from orchard trees over the period from flowering to fruit maturity. The distribution of 14C assimilates along the shoot, and the patterns of deposition within the developing fruit were recorded on X-ray film. In both peach and apricot shoots, the terminal leaves, soon after emergence, exported assimilates to adjacent fruit which competed successfully with nearby expanding leaves, although isolated leaves (in peach) were capable of importing. At a more advanced stage only the fruits imported assimilates from the terminal leaves, and the labelled substrates were deposited in both flesh and inner seed structures despite the hardened stone. The fruit continued to accumulate 14C photosynthate even when completely ripe. Following fruit removal, export from the terminal leaves on the peach shoot was minimal, and labelled photosynthate was detected only in the main stem; whereas in apricot shoots, mature lower leaves showed extensive import of current assimilates.

The Shoot Apical Cell of Equisetum Arvense, a Quiescent Cell

Abstract: SUMMARYA DNA cytophotometric analysis was carried out on 50 shoot apices of Equisetum arvense, 38 belonging to main stems and 12 to branches. No clear difference in the nuclear conditions of the apical cell was found between the two types of shoot. 38 apical cells showed a greater than 4C nuclear DNA content (polyploidy); the remaining gave a DNA content 4C, corresponding to the DNA post-syntesis phase, or G2, of diploid cells. Neither 2C nor 2C-4C intermediate values were found. Only one apical was found in mitosis (diploid).In 21 apices, 30 segment cells were analyzed; in 20 of them a greater than 4C DNA content was estimated. No division was observed in 100 segment cells belonging to the 50 shoot apices, two per apex.The views of previous workers on the organization and mode of functioning of shoot apices with single apical cells are discussed in the light of the present observations. It is concluded that: i) in established shoot apices of Equisetum — and probably other Cryptogams — the shoot apical ce...

Nutritional control of the correlative inhibition between lateral shoots in the flax seedling (Linum usitatissimum)

Abstract: When the epicotyl of the flax seedling is decapitated one of the two shoots produced at the cotyledonary node tends to inhibit and may completely suppress the growth of the other. By growing the seedlings in sand culture with a controlled mineral nutrient supply it was shown that (a) the inhibiting influence of the dominant shoot was inversely related to the nitrogen level; (b) the inhibited shoot could be released from inhibition by increasing the nitrogen supply; (c) the removal of the dominant shoot was followed within 12 h by an increase in the total nitrogen content of the inhibited shoot; (d) a similar control of inhibition could be obtained by varying the phosphorus supply. These results are consistent with the hypothesis that this form of correlative inhibition is due primarily to competition between the shoots for a limited mineral nutrient supply.When one of the cotyledons was either covered or removed its axillary bud was inhibited by the shoot in the axil of the untreated cotyledon. The degree...

Wheat bulb fly, Leptohylemyia coarctata Fall., and its effect on the growth and yield of wheat

Abstract: SUMMARY In two experiments done in successive years to compare the growth and yield of Cappelle wheat either protected from or exposed to attacks by larvae of wheat bulb fly, the plots were previously fallowed, but egg laying was prevented on half of each plot by using Polythene soil covers. In the first season wheat was sown at the end of October, November and December and in the second season in late October and in early January, when there were two sowings, one with and one without a spring application of herbicide. The infestation rate was 1·1-1·7 million eggs per acre, typical of a moderate attack. Larvae had little effect on the yield of October-sown wheat as the plants had two shoots each when first attacked and few were killed. On plots sown late, yield was decreased by up to 22%, as plants had only a single shoot when attacked and many were killed. The main effect of wheat bulb fly was to reduce the number of ear-bearing shoots by killing plants and restricting the production of new shoots. Surviving plants partially compensated by producing more ear-bearing shoots with heavier ears and slightly heavier seeds than normal. Killed plants were not distributed uniformly but were often in patches several feet across. Wheat on the attacked plots ripened more slowly and unevenly than on the unattacked plots. Weather affects the growth of the plants and activity of the larvae and thus partly determines percentage shoot survival.

Relative Mobility of some Organic Nitrogenous Compounds in the Xylem of Apple Shoots

Abstract: IN the apple, as in many other perennial plants, all the absorbed nitrogen is usually reduced and combined into amino-acids in the youngest roots and is subsequently translocated in the form of such compounds. Xylem sap, which has been extracted from the terminal shoots of mature trees by a vacuum technique, contains nitrogen, largely as aspartic acid and asparagine, but also as arginine, glutamic acid and glutamine. There may be traces of a number of other amino-acids, depending on season and on added fertilizer1,2.

Quantitative changes in gibberellin and rna correlated with senescence of the shoot apex in the ‘alaska’ pea

Abstract: A B S T R A C T Senescence of shoot apices of Pisum sativum L. 'Alaska' as measured by cessation of stem elongation was delayed by removal of flowers and by treatment with gibberellin A3 and was hastened by treatment with AMO-1618 (2 isopropyl4-dimethylamino-5-methylphenyl-1-piperidinecarboxylate methyl chloride). Ontogenetic changes in relative endogenous gibberellin levels and in capability of gibberellin biosynthesis in deflowered and control plants were determined indirectly by studying time-course changes in the sensitivity, as indicated by the growth response, of these plants to applied gibberellin and AMO-1618. The results of these experiments suggest that the endogenous gibberellin level varies directly with the growth rate. Analyses of total RNA and protein in shoot tips of deflowered and control plants revealed that the levels of these substances also vary directly with growth rate throughout ontogeny. It is concluded that decreases in endogenous gibberellin, RNA and protein are factors correlated with senescence of the shoot apex.

The Culture of Gooseberry Shoot Tips for Eliminating Virus

Abstract: SummaryTwo methods are described for the culture of 0·5–1·0 mm. gooseberry shoot tips, which have led to the production of plants apparently free from vein-banding virus. Tips from lateral and terminal shoots were used for cultures but all plants which survived when transferred to pots were from terminal tips.

Leaf Growth and Development in the Young Tobacco Plant

Abstract: The growth of the vegetative shoot of tobacco, Nicotiana tabacum L., and the associated changes in dry weight of the whole plant and its major parts are described. By means of serial reconstruction, the volume changes of successive young leaf primordia are followed, and this information is integrated with the dry weight data for older leaves.

Colchicine-induced tetraploid and cytochimeral roses'

Abstract: A complete tetraploid, a 4-2-2 periclinal chimera, and a normal diploid shoot were isolated from a colchicine-treated diploid rose shoot. The ploidies of the three histogenic layers of the shoot apex were confirmed by the size of stomata and pollen grains and by chromosome number from roots. The experiment showed that colchicine had penetrated into the histogenic layers of the shoot apex in only a very small percentage of the treated axillary buds.

Nitrogen metabolism of Picea glauca. III. Diurnal changes of amino acids, amides, protein, and chlorophyll in leaves of expanding buds

Abstract: In spring, buds of spruce shoots under moisture stress contracted during the day and expanded at night. Increased water supply to roots removed the shrinkage of buds and stimulated rapid expansion. In leaves of buds about to break and under moisture stress, the alcohol-soluble nitrogen, high in arginine content, was maximal at midday, after midnight, and again at noon the next day. As a percentage of the soluble nitrogen, all compounds, except arginine, contributed most at sunset and again at sunrise. Other prominent amino acids included proline, alanine, γ-aminobutyric acid, and the amides glutamine and asparagine. Except for the amides, these and other compounds, present at lower levels, gave diurnal patterns similar on a fresh weight basis to arginine. Values for protein nitrogen were greatest at 2 p.m. followed by an increase of asparagine nitrogen, and again at 4 a.m., followed by an increase of glutamine nitrogen. At night the composition of newly synthesized protein increased significantly in aspar...

The association of carbohydrate changes in the shoot tip of cauliflower with flowering.

Abstract: Changes in levels of sugars and starch in the shoot tip of cauliflower, Brassica oleracea L. var. botrytis D. C. cv. Main Crop were studied during periods of growth which were inductive or non-inductive to flowering. Flowering was induced by growing plants for 2 weeks under 16 hr of light at 5 degrees . During this period of floral induction there was a significant increase in sugar and starch content compared to that in vegetative plants grown at 20 to 26 degrees . Sugar and starch content did not increase and flowering was prevented when light and CO(2) were excluded during growth at 5 degrees . A 3-day dark period at 20 degrees or a high temperature treatment at 33 degrees with light following growth at 5 degrees reduced the carbohydrate level and prevented flowering.