bluuebunny/crossref_metadata_2025_split huggingface dataset:
Residual effects of High Temperature Pre‐Treatments on the Germination of Celery Seeds (Apium graveolens)
Authors: BIDDINGTON N. L. , THOMAS T. H. 
Published: April 2006

AbstractCelery seeds (Apium graveolens L.) were allowed to imbibe in the dark for different periods at 28. 32. 37 or 41°(the high temperature pre‐treatmem or HTP) prior to transfer to 15, 17, 19.5 or 22°C in white light (the low temperature treatment or LTT). The effect of HTP's at 28. 32 and 37°C was to lower the upper temperature limit for germination and this effect increased with increase in the temperature and duration of the HTP. Increasing exposure to an HTP of 41 °C, however, did not appear to lower the upper temperature limit for germination but reduced the viability of the seeds. This trend of increased inhibition of germination caused by increasingly higher temperatures was reversed when the transfer was to a 22°C LTT after a 4 day HTP at 37°C.When the temperature of (he HTP was relatively low and transfer was to a low LTT. or if the HTP was of a brief duration, the rate of germination was increased as compared to seeds not given an HTP. However, when the temperature and duration of the HTP were increased, the rate of germination became slower than that of seeds not given an HTP, i.e. the time taken for the seeds to recover from the HTP‐induced dormancy increased with the temperature and duration of the HTP. The decrease in the germination rate was caused by a delay in the start and not a slowing of the rate of embryo elongation within the seed.
Effects of Sulphur Dioxide on Sugar and Free Amino Acid Content of Pine Seedlings
Authors: MALHOTRA S. S. , SARKAR S. K. 
Published: April 2006

AbstractTreatment of jack pine (Pinus banksiana Lamb.) seedlings with gaseous SO2 resulted in a shift between the reducing and non‐reducing sugars. Increasing concentrations of gaseous SO2 caused an increase in reducing sugars and a decline in the non‐reducing sugars, suggesting a conversion from the latter to the former at high SO2 concentrations. The total amino acid content of the intact tissues also increased with increasing concentrations of gaseous SO2. Gas‐liquid chromatographic analyses of the amino acids indicated that SO2 (1. 34 mg · m‐3 for 96 h) resulted in an increase in the content of alanine, valine, glycine, isoleucine, leucine, threonine, aspartic acid tyrosine, lysine, and arginine, and a decrease in the content of serine and glutamic acid. The enzymatic and other implications of such changes are discussed.
Protein Synthesis in Dormant and Non‐Dormant Cocklebur Seed Segments
Authors: SATOH SHIGERU , ESASHI YOHJI 
Published: April 2006

AbstractUsing the axial and cotyledonary segments of lower cocklebur (Xanthium pensylvanicum Wallr.) seeds, protein synthesis as shown by incorporation of radioactive leucine was examined in relation to their dormant status. During the first 9 h of water imbibition, the protein synthesis was higher in the dormant axes than in the non‐dormant, after‐ ripened ones. When imbibed for more than 12 h non‐dormant axes had a higher activity than dormant ones. This was also the case with the cotyledonary segments.Cyctoheximide, an inhibitor of protein synthesis, blocked protein synthesis in the axial tissue regardless of its dormant status, and thereby inhibited germination of the non‐dormant seeds. In the dormant seeds, however, cycloheximide at 3 mM slightly stimulated germination without stimulating the C2H4 production. Based on these results, it is suggested that in cocklebur seeds there may be some proteinaceous system which is involved in the maintenance of dormancy.
The Effect of Calcium on the Uptake and Distribution of Sodium in Excised Barley Roots
Authors: NEIRINCKX L. , STASSART J. M. 
Published: April 2006

AbstractThe total uptake and relative distribution of Na+ along the root was investigated in excised barley roots (Hordeum vulgare L. cv. Union) of 6‐day‐old plants cultured on 0.25 mM CaSO4. One technique involved cutting the roots at harvest time after different uptake periods into different segments each 2 cm long. These segments were ashed and sodium was measured by flame photometry. For each experiment two treatments were done, one containing calcium in the uptake solution and one without calcium. A second technique involved the measurement of sodium transport, using labelled 22Na+ solution. Although no significant differences could be found between the calcium containing and the calciumless treatments at 24 h, there were clearcut differences for the first 6 to 8 h. The effect of calcium on the first stages of the sodium uptake was a large accumulation of sodium in the part close to the apex with a translocation close to nil; whereas the sodium taken up in the absence of calcium did not accumulate in such large amounts in the apex region but was immediately transported basipetally.
The Influence of Light and Oxygen on Nitrogenase Activity in the Lichen Stereocaulon paschale
Authors: HUSS‐DANELL KERSTIN 
Published: April 2006

AbstractThalli of the lichen Slereocaulon paschale (L.) Fr. were prctreated in the light (light activated) or in the dark (dark starved). In short‐time experiments with both light activated arid dark starved thalli, the nitrogenasc activity was higher in the light than in the dark, Light activated thalli had a very much higher rale of C2H2 reduction than dark starved thalli, both in the light and in the dark. The dark starved lhalli showed increasing nilrogenase activity when incubated in the light.Either light or oxygen was necessary for nitrogenase activity in light activated thalli. and up to about 10kPa oxygen they showed additive effects. Both in the light and in the dark the nitrogenase activity decreased when the oxygen partial pressure was lower than in normal air. The experimental data thus showed a short‐term effect of light on nilrogenase activity by provision of ATP and reductant, and a long term effect probably by build up of reserves that were later utilized. Any immediate effect of photorespiration on nitrogenase activity could not be found in light activated thalli.
Origin of Cytokinins Transported in the Phloem
Authors: VONK C. R. 
Published: April 2006

AbstractThe origin of cytokinins in the exudate of Yucca inflorescences has been studied. A decrease in nucleotides of both isopenlenyladenine and zeatin was observed after removal of leaves as measured over a three day period. Removal of roots and the greater part of the rhizome resulted in a transient decline of isopenlenyladenincand zeatin nucleotides during 24 h. after which an increase took place. The results strongly indicate that the latter increase is due to cytokinins originating from the leaves.
Apparent Three‐Site Kinetics of Cs+‐Uptake by Yeast
Authors: DERKS W. J. G. , BORST‐PAUWELS G. W. F. H. 
Published: April 2006

AbstractThe concentration dependence of the uptake rate of Cs+ in yeast at low pH is described by a cubic rate equation rather than by a quadratic rale equation. This points to the involvement of three sties in the translocation of Cs+ across the yeast cell membrane. The possibility that one of the three sites is only apparent due to interaction of Cs+ with the electrical double layer of the yeast cell membrane is also considered.
Metabolism of Auxin in Pine Tissues: Naphthaleneacetic Acid Conjugation
Authors: RIOV JOSEPH , COOPER RAYMOND , GOTTLIEB HUGO E. 
Published: April 2006

AbstractIncubation of sections of various tissues of Pinus pinea L. and Pinus halepensis Mill, with α‐naphthaleneacetie acid‐1‐14C (NAA) resulted in two metabolites which proved to be l‐O‐(α‐naphthylacetyl)‐β‐D‐glucose (NAGlu) and α‐naphthylacetylaspartic acid (NAAsp). NAGlu was purified by means of insoluble polyvinyl‐polypyrrolidone (Polyclar AT) column chromatography and preparative thin layer chromatography and identified by its ‘H‐nuclear magnetic resonance and mass spectra. NAAsp was partially purified by means of preparative thin‐layer chromatography and identified by co‐chromatography with a synthetic standard and hydrolysis to the parent compounds. NAA and L‐aspartic acid. Needles and shoot bark rapidly converted NAA mainly to NAGlu. In contrast, woody roots and shoot wood showed a much slower rate of conjugation with the formation of both NAGlu and NAAsp. Preincubation of wood sections in NAA increased the formation of NAGlu, whereas the formation of NAAsp was almost unaffected.
Resistance to Water Transfer in Desert Shrubs Native to Death Valley, California
Authors: SANCHEZ‐DIAZ MANUEL F. , MOONEY HAROLD A. 
Published: April 2006

AbstractDifferences in plant resistance to water flow, patterns of water transport through stems, and stomatal behavior were studied on three species native to the exceptionally hot and dry habitat of Death Valley, California (—, and Larrea divaricata).Dawn xylem water potentials in July for Atriplex were — 27.5 bar under natural conditions. Corresponding values for Tidestromia and Larrea were respectively — 8.0 bar and ‐32.0 bar (natural) and — 7.5 bar and — 18.0 bar (irrigated). Recovery of xylem water potential in covered field plants of an irrigated transplant garden reached a maximum value in July of — 9.5 bar in Atriplex, — 5.7 bar in Tidestromia and — 7.0 bar in Larrea.Resistance to free‐energy transfer was used to study resistance to water transport through the plants. Under field conditions irrigated Atriplex plants gave a whole plant resistance of 20.70 × 106 s cm‐1, as compared lo 18.37 × 106 s cm‐1 for Larrea and 10.01 × 106 s cm‐1 for Tidestromia. Plant resistance to water How computed by this method on Atriplex plants grown under laboratory conditions gave a value of 3.73 × 106 s cm‐1 at 35C.Paths of water flow in field plants as investigated with injected acid fuchsin indicated a sectorial straight type vessel.The relationship between transpiration rates and xylem water potentials in Atriplex hymenelytra was linear between transpiration 1.28 μg cm‐2 s‐1 and 2.35 μg cm‐2 s‐1 at 35°C. These results indicate that according to the Van den Honert model for water transport, plant resistance to water flow remained rather constant at this temperature. In Atriplex grown under laboratory conditions there was an adjustment of plant resistance so change in water flux at 9.5°C and 25°C.When laboratory‐grown plants of Atriplex and Tidestromia were subjected to water stress by withholding water. Tidestromia closed stomata and reduced transpiration rates at higher water potentials than in Atriplex.The ratio of vapor pressure gradients of leaf/air to leaf diffusion resistance was proportional lo transpiration rates.It is suggested that Atriplex hymenelytra is a species that combines strong regulation of water loss by stomata with low efficiency of the water transport system. These plants are unable to prevent depression of plant water potential as transpiration increases. On the other hand. Tidestromia oblongifolia has little stomatal regulation of transpiration and a highly efficient water transport system. These plants sustain very high rates of transpiration without significant decrease in plant water potential.
Influence of Nitrogen Form and Nitrogen Absence on Utilization of Assimilates for Growth and Maintenance in Tops and Roots of Lolium multiflorum
Authors: HANSEN G. K. 
Published: April 2006

AbstractUtilization of assimilates for growth and maintenance of tops and roots of Lolium multiflorum was determined for plants supplied with either nitrate or ammonium. Carbon dioxide exchange rates were measured continuously for tops and roots separately. Three‐day periods were applied for two irradiation levels. On the last day of each three‐day period no nitrogen was supplied to the two treatments. In the nitrate treatment, the coefficient of utilization for converting assimilates into constructive growth (YG) remained unaffected in absence of nitrate. However, in absence of nitrate the maintenance respiration (M) for both tops and roots was only one third of that in presence of nitrate. In the treatment with ammonium the maintenance respiration of the plants was not influenced by the absence of ammonium. However, especially for the tops YG increased in absence of ammonium. In both the treatments, growth respiration of the roots was inefficient compared to that of the tops. Only in the case of absence of nitrate, maintenance respiration of the roots was similar to that of the tops.
Photosynthate Partitioning and Enzymes of Sucrose Metabolism in Sugarbeet Roots
Authors: SILVIUS JOHN E. , SNYDER FREEMAN W. 
Published: April 2006

AbstractPopulations of sugarbeet (Beta vulgaris L.) plants that differed in taproot/leaf weight ratio and in photosynthate partitioning between taproots and fibrous roots did not differ in root/shoot ratio as indicated by relative dry weight distribution. Based on the hypothesis that dry weight distribution is influenced by the metabolism of imported sucrose, we examined the relationships between the activity of the enzymes of sucrose metabolism and dry weight distribution as a function of genotype and ontogeny.A decreased specific activity of acid invertase in taproots was associated with increased taproot/fibrous root weight ratio at 21 and at 28 days post‐emergence. Alkaline invertase activity was negatively correlated with taproot/fibrous root weight ratio at 28 days. Sucrose synthetase specific activities of taproots were not correlated with dry matter distribution. Acid invertase may influence photosynthate partitioning between the taproot and fibrous roots via regulation of sucrose levels in the region of fibrous root initiation.
Inertness of horseradish peroxidase to 2,4‐dichlorophenoxyacetic acid
Authors: PAUL K. G. , ÖHRMAN B. 
Published: April 2006

AbstractThe possibility of mutual effects of 2,4‐D and horseradish (Armoracia lapathifolia L.) peroxidase on each other has been explored by four procedures. (i) Compounds I, II, and III of horseradish peroxidase (HRP) and H2O2 were exposed to 2,4‐D. (ii) Extracts from batchwise operations of HRP + H2O2 and 2,4‐D were analyzed for oxidation products by means of thin layer chromatography. (iii) The velocity of the IAA oxidase reaction with HRP as catalyst, and (iv) Km and Vs of the overall peroxidation of guaiacol by HRP + H2O2, were determined in the absence and presence of 2,4‐D.The results failed to show any effect of 2,4‐D; only at very high concentrations did 2,4‐D slightly inhibit the oxidation of IAA by one isoperoxidase. It is concluded that 2,4‐D does not promote growth in plants by hampering a peroxidase‐catalyzed IAA oxidation. It seems probable that 2,4‐D perturbs the isoperoxidase pattern by acting at some step prior to the release of the enzyme from its site of synthesis.
Aspects of DNA, RNA and protein synthesis during somatic embryogenesis in a carrot cell suspension culture
Authors: FUJIMURA TATSUHITO , KOMAMINE ATSUSHI , MATSUMOTO HIDEAKI 
Published: April 2006

AbstractChanges in DNA, RNA and protein content, incorporation of 3H‐thymidine, 14C‐uridine and 3H‐leucine and template activity of chromatin were investigated in the early process of somatic embryogenesis in a carrot (Daucus carota L. cv. Kurodagosun) cell suspension culture using a synchronous system. An embryogenetic culture in a medium containing 10‐7M zeatin was compared with a non‐embryogenetic culture in a medium containing 10‐7M zeatin and 5 x 10‐7M 2,4‐D. DNA was synthesized very actively prior to and during the formation of globular embryos in the embryogenetic culture. The RNA and protein content per tube increased at an almost constant rate in both cultures, while the rate of incorporation of labelled precursors of RNA and protein rose much more prior to active DNA synthesis in the embryogenetic culture than in the non‐embryogenetic culture. Template activity of chromatin was high in the early stage of embryogenesis in the embryogenetic culture. The results obtained here showed that synthesis and turnover of RNA and protein became active prior to active DNA synthesis in the early stage of embryogenesis, and that these changes at macromolecular levels may play important roles in embryogenesis.
Additive and nonadditive effects of serial applications of gibberellic acid on sugarcane internode growth
Authors: MOORE PAUL H. 
Published: April 2006

AbstractSugarcane (Saccharum spp. hybrids) plants were exogenously supplied with, 0, 1.0, 1.5, and 2.0 mg gibberellic acid (GA3) per stalk in single and multiple applications. Increases in stalk fresh weight, total stalk length, and lengths of individual internodes were primarily a function of the interval between applications. Applications produced additive growth responses at 15‐ and 30‐day intervals but not at 0‐ and 45‐day intervals.
Control of K+ (Rb+) influx and transport with changed internal K+ concentration and age in two varieties of barley
Authors: JENSÉN PAUL 
Published: April 2006

AbstractThe influx of Rb+ into the roots of two barley varieties (Hordeum vulgare L. cv. Salve and cv. Ingrid) from a K+‐free 86Rb‐labelled nutrient solution with 2.0 mM Rb+, was checked at intervals from day 6 to day 18. The control plants were continuously grown in complete nutrient solution containing 5.0 mM K+, while two other groups of plants were grown in K+‐free nutrient solution starting on day 6 and between day 6 and day 9, respectively. The pattern of Rb+ influx was similar for both varieties, although their efficiencies in absorbing Rb+ were different. The relationship between Rb+ influx and K+ concentration of the root could be interpreted in terms of negative feedback through allosteric control of uptake across the plasmalemma of the root cells. Hill plots were bimodal, but in the opposite direction. The Hill coefficients, reflecting the minimum number of interacting allosteric binding sites for K+ (Rb+), were low (≤–3.0). It is discussed whether the threshold value, that is the breaking point in the Hill plot, is indicative of a changed efficiency of transporting units for K+ (Rb+) transport to the xylem. Moreover, feedback regulation might be involved in transport of K+ between root and shoot. The variation in K+ concentrations in the roots and shoots of control plants were cyclic but in phase opposition despite an exponential growth. The average K+ concentration varied only slightly with age.
Enhancement of pollen embryo formation in Datura innoxia by charcoal
Authors: TYAGI AKHILESH K. , RASHID A. , MAHESHWARI S.C. 
Published: April 2006

AbstractIn recent years liquid medium has been shown to be better than agar‐gelled medium for production of haploids by anther culture. However, on addition of charcoal to agar medium the anther response in Datura innoxia Mill, increases dramatically and is better than in liquid medium. For anthers with pollen at the premitotic stage, the best result was observed with 1% charcoal in Difco agar and 1.5% in Normal agar. The effect is possibly due to adsorption of substances inhibitory to androgenesis and emanating from anthers, as well as to substances present in the nutrient medium and agar.
Effects of repeated application of water stress on water status and growth of wheat
Authors: SIONIT NASSER , TEARE IWAN D. , KRAMER PAUL J. 
Published: April 2006

AbstractThe effects on water status and growth of controlled cycles of water stress applied at various stages of development were studied on a semi‐dwarf spring wheat (Triticum aestivum L.). The plants were grown in controlled environment chambers of the Duke University Phytetron at 24/18°C with a 12‐h photo‐period at about 600 μE m−2 s−1. Groups of plants were subjected to severe water stress by withholding irrigation, beginning at the 7th leaf, early anthesis, or early dough stages of development. A second cycle started 9 to 13 days after termination of the first cycle and maintained until the flag leaf water potential reached –25 bars at each of the growth stages.The lower leaves showed sign of wilting as indicated by curling in the first drying cycle at –7 bars and in the second cycle at –9 bars of leaf water potential during all stages of growth. Although these leaves recovered completely upon rewatering, onset of senescence was accelerated by three days in stressed plants. A preliminary drying cycle did not increase the ability of the plants to withstand subsequent stress because of severity of stress. Water stress of –25 bars at all three stages of growth reduced seed yield. The reduction was greater when a second stress cycle was also applied. Stress applied during early anthesis stage produced the smallest and the least number of seeds. The lack of osmotic adjustment probably was due to very rapid and severe development of water stress.
CO2 effects on apical dominance in Pisum sativum
Authors: PAEZ A. , HELLMERS H. , STRAIN B. R. 
Published: April 2006

AbstractAlaska pea plants (Pisum sativum L.) were grown at 0.10 vol% and 0.035 vol% CO2 to determine the effects of high CO2 concentration upon plant growth and apical dominance. The results showed that a 0.10 vol% CO2 atmosphere significantly increased the rate of lateral branch, flower bud, flower and fruit development over an environment with 0.035 vol% CO2. At plant maturity, however, there were no significant differences in the number of branches or fruits produced at the different CO2 levels. Thus, no evidence was obtained for the loss of apical dominance at the CO2 concentrations tested. Root dry weight was significantly greater in plants grown at 0.10 vol% CO2 than in those grown at 0.035 vol% CO2 and leaf dry weight was significantly lower. However, no significant differences were found in total plant dry weight production at plant maturity.
Perception et réaction géotropiques de l'épicotyle d'Asparagus officinalis
Authors: PERBAL GÉRALD , RIVIERE SIMONNE 
Published: April 2006

Abstract Geoperception and georeaction in Asparagus officinalis epicotyls The location and the role of the statenchyma were investigated in Asparagus officinalis epicotyls 1, 2 or 3 cm in length. The statocytes represent a monocellular sheath which comprises the outer layer of the pericycle. Three phases of differentiation (S1, S2, S3) of the statocytes may be distinguished by criteria of cell length, the state of vacuolisation and the sedimentation of amyloplasts and nuclei with respect to gravity. The statenchyma was found to be located only in the first 10 mm of the epicotyl 1, 2 or 3 cm in length; in effect the oldest statocytes (S3) differentiate into sclerenchyma beneath this level.The geotropic curvature of the epicotyls begins with a positive (downward) curvature and the negative (upward) response is only realized after 15–30 min of geotropic stimulation. The upper limit of the bending is located in the zone containing the mature statocytes (S3), while the lower limit is located much closer to the base of the epicotyl.Experiments on decapitation of the epicotyls have indicated that the S1 and S2 statocytes do not play an important role in the perception of gravity. However, with S3 statocytes, it has been demonstrated that there is a statistical correlation between the initial rate of curvature of the epicotyls and the length of their sheaths. Thus, the longer the sheath, the more the epicotyls curve.From the results obtained it is proposed that the statocytes are responsible for the geotropic perception of Asparagus officinalis epicotyls.