bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of CO2‐Concentration on the Occurrence of a Number of Acids from the Citric Acid Cycle in Tomato Leaves
Authors: MADSEN ERIK 
Published: April 2006

AbstractExamination of the effect of CO2‐concentration and time of day on the content of malic acid, citric acid, aconitic acid, isocitric acid, succinic acid and fumaric acid in tomato leaves, revealed that the total content of these acids will rise with the CO2‐concentration up to 0.10 vol% CO2. In the morning up to 0.22 vol% CO2 was needed for optimal effect.Samples of leaves picked at 1 a.m. showed the lowest content of these acids. At 9 a.m. the content had increased, and at 4 p.m. the increase was considerable. The content of malic and citric acid constituted 36 and 34% of the total acid content. In the afternoon and the night the aconitic acid represented 14% and in the morning 20% of the total acid content. Isocitric acid, fumaric acid and succinic acid occurred only in relatively small concentrations.
Supraoptimal Temperature Effects upon Agrostis palustris
Authors: DUFF D. THOMAS , BEARD JAMES B. 
Published: April 2006

Abstract Agrostis palustris turfs cut weekly at 1.3 cm were subjected to successive four‐week periods with day‐night temperature regimes of 20–10, 25–15, 30–20, 35–25 and 40–30°C. Plants grown at 40–30°C exhibited a growth character distinctly different from those grown at 20–10°C. They were more upright and bristle‐like in growth habit. The percentage dry weight of leaf blade tissue increased 67% and weight per unit area increased 53% between 20–10 and 40–30°C. Reduced leaf blade width was noted first at 30–20°C while leaf blade length reduction first occurred at 35–25°C. Weekly yields were significantly reduced at the supraoptimal temperature regimes of 35–25 and 40–30°C. Chlorophyll content was lowest at 20–10 and 40–30°C, the lowest and highest temperature regimes studied. Shoot density appeared to decrease under the 35–25°C regime, but no dead plants were observed. The apparent decrease in shoot density was attributed to the upright growth habit. Density decreased at 40–30°C upon death of individual plants. A community of grass plants maintained as a turf was found to change in form quite rapidly in response to temperature.
Nitrite Uptake by Nitrogen‐Depleted Wheat Seedlings
Authors: JACKSON W. A. , JOHNSON R. E. , VOLK R. J. 
Published: April 2006

AbstractIntact, 14‐day‐old nitrogen‐depleted wheat (Triticum vulgare cv. Blueboy) seedlings were exposed to solutions of 0.5 mM KNO2, 0.05 mM CaSO4 and 1 mM sodium 2‐[N‐morpholino]‐ethanesulfonate, pH 6.1. Nitrite uptake was determined from depletion of the ambient solution or from incorporation of 15N in the tissue. An initial nitrite uptake shoulder was followed by a relatively slow uptake rate which subsequently increased to a substantially greater rate. This accelerated phase was maintained through 24 h. Nitrite accumulated to a slight extent in the root tissues during the first few hours but declined to low values when the accelerated rate was fully developed, indicating an increase in nitrite reductase activity paralleling the increase in nitrite uptake capacity. About 50% of the nitrogen absorbed as nitrite was translocated to the shoots by 9–12 h.Development of the accelerated nitrite uptake rate was restricted in excised roots, in intact plants kept in darkness, by 400 μg puromycin ml−1 and by 1 mM L‐ethionine. When puromycin and L‐ethionine were added after the accelerated phase had been initiated, their effects were not as detrimental as when they were added at first exposure to KNO2. The two inhibitors restricted translocation more than uptake. The data indicate an involvement of protein synthesis and a requirement for movement of a substance from shoots to roots for maximal development of the accelerated nitrite uptake phase. A requirement for protein synthesis in the transport of soluble organic nitrogen from roots to shoots is also suggested.
Endogenous Growth Substances in Normal and Dwarf Mutants of Cortland and Golden Delicious Apple Shoots
Authors: JINDAL K. K. , DALBRO S. , ANDERSEN A. SKYTT , POLL LEIF 
Published: April 2006

AbstractEndogenous growth substances in the shoots of dwarf mutants of Cortland (Cortland 65–6 and Cortland 65–7) and Golden Delicious (Golden Auvil Spur and Yellow Spur) were investigated in relation to dwarfism. The shoots were extracted at three stages of growth, namely: 1) rapid elongation growth, 2) formation of terminal bud, and 3) cessation of cambial growth. The growth substances were partially separated by thin layer chromatography and bioassayed using the Avena first internode and Lepidium seed germination tests.Shoot extracts from the normal Cortland and Golden Delicious plants contained higher levels of auxins at all stages of growth than those from dwarf mutants. Growth‐promoting activity was found in two zones on chromatograms developed with isopropanol: ammonia: water (10:1:1 v/v/v):Rf 0.4 to 0.5 and Rf 0.8 to 0.9.The Lepidium seed germination test showed the presence of a highly inhibitory zone between Rf 0.3 and 0.4 in the extracts of dwarf and normal plants. However, the peak of germination inhibition activity was sharp for dwarf mutants and less for extracts of normal growing plants at 3 stages of growth. The inhibitory substance(s) was further purified on TLC plates by successive separations in different solvent systems. Two substances which inhibited the Lepidium seed germination were found, one close to the Rf value of synthetic abscisic acid and the other appeared to be similar to xanthoxin in Rf value, biological activity and UV absorption spectra.
Chloroindolyl‐3‐acetic Acid and Its Methyl Ester Incorporation of 36Cl in Immature Seeds of Pea and Barley
Authors: ENGVILD K. C. 
Published: April 2006

AbstractImmature seeds of pea and barley were harvested on plants grown in solutions containing 36Cl−, but no other chlorides. Autoradiography of two‐dimensional thin layer chromatograms (silicagel) of butanol extracts of freeze‐dried seeds showed the presence in both species of several radioactive compounds besides Cl−. One compound, present in pea and probably in barley, cochromatographed with a mixture of 4‐ and 6‐chloroindolyl‐3‐acetic acid methyl esters. Another, detected in pea, but probably not in barley, cochromatographed with a mixture of 4‐and 6‐chloroindolyl‐3‐acetic acids.
Proteinase Inhibitors in Germinating Barley Embryos
Authors: KIRSI MARKKU 
Published: April 2006

AbstractThe activities of trypsin inhibitors and Aspergillus‐proteinase inhibitors have been assayed in barley embryos germinating in different conditions.The Aspergillus‐proteinase inhibitor activity increased about 20‐fold during 6 days at 20°C both in separated embryos germinating on nutrient agar and in the embryos of undissected grains germinating on agar with or without mineral salts. Significant inhibitor activity was also present in root tips at later stages of vegetative growth. Whether any changes occurred in the molecular weight distribution of the inhibitors present in the seedlings was studied by gel filtration on Sephadex G‐75; only minor changes were observed.The trypsin inhibitor activity per seedling remained roughly constant in all cultures. In gel filtration experiments all the activity appeared to be due to the inhibitor species present in resting embryos.
Field Studies of Photosynthesis as Affected by Water Stress, Temperature, and Light in Birch
Authors: HARI PERTTI , LUUKKANEN OLAVI 
Published: April 2006

AbstractThis study continues the investigations previously conducted as laboratory experiments. The results from the present study confirm our earlier observations made on alder seedlings concerning the effect of water stress, temperature and light on the net uptake of CO2.A variable that we could call the physiological water stress is proposed as a measure of the intrinsic factor of photosynthesis during and after drought. A physiological water stress builds up and discharges slowly and interacts strongly with temperature. Our model for the effects of physiological water stress, temperature, and light intensity explains satisfactorily the net uptake of CO2 in birch in the field. Thus, our earlier results concerning the effects of physiological water stress on photosynthesis are not artifacts generated by the unnatural laboratory environment.
Nitrite Uptake Patterns in Wheat Seedlings as Influenced by Nitrate and Ammonium
Authors: JACKSON W. A. , JOHNSON R. E. , VOLK R. J. 
Published: April 2006

AbstractNitrite and nitrate uptake by wheat (Triticum vulgare) from 0.5 mM potassium solutions both showed an apparent induction pattern characterized by a slow initial rate followed by an accelerated rate. The accelerated phase was more rapid for nitrate uptake, was initiated earlier, and was seriously restricted by the presence of equimolar nitrite. The accelerated phase of nitrite uptake was restricted by nitrate to a lesser extent. The two anions seem not to be absorbed by identical mechanisms.Ammonium pretreatments or prior growth with ammonium had relatively little influence on the pattern of nitrite uptake. However, prior growth with nitrate eliminated the slow initial phase and induced development of the accelerated phase of nitrite uptake. A beneficial effect was noted after 3 h nitrate pretreatment and full development had occurred by 12 h nitrate pretreatment. The evidence suggests that a small amount of tissue nitrite, which could be supplied either by absorption or by nitrate reduction, was specifically required for induction of the accelerated phase of nitrite uptake.Cycloheximide (2 μg ml−1) seriously restricted development of the accelerated phase of nitrite uptake, but its effect was not as severe when it was added after the accelerated phase had been induced by prior exposure to nitrite or nitrate. However, translocation of 15N from the absorbed nitrite was sharply decreased under the latter conditions, indicating a difference in sensitivity of the uptake and translocation processes to cycloheximide.Potassium uptake was greater from KNO3 than from KNO2 and in both instances it was enhanced during the early stages of the accelerated phase of anion uptake. Moreover, addition of NaNO3 to KNO2 substantially increased potassium uptake. A coupling between anion and potassium uptake was therefore evident, but the coupling was not obligatory because the accelerated phase of nitrite uptake could occur in absence of rapid potassium uptake.
Action du diméthylsulfoxyde sur l'absorption du 42K et du glucose‐14C (U) par des disques foliaires de Zea mays et Pelargonium zonale
Authors: CHAMEL ANDRÉ , CARLIER GEORGES 
Published: April 2006

Abstract 42K and 14C (U)‐glucose uptake by foliar discs of maize (Zea mays L.) and pelargonium (Pelargonium zonale L.) is inhibited by dimethyl sulfoxide (DMSO) at concentrations of 5 and 10%. This effect increases with the duration of the absorption and appears with varied concentrations in K or glucose. In most cases, this inhibitory effect is less with aged discs than with freshly cut discs. Besides, the DMSO (10%) enhances the exsorption of 42K by foliar discs of maize. The effects of DMSO and two osmotic agents, mannitol and polyethylene glycol 1000, on the uptake and water content of discs are compared. It seems that the effect of DMSO on the uptake is not only an osmotic effect. It may also be related to other actions of this substance in affecting an active uptake.
Properties of Mg2+‐Stimulated and (Na++K+)‐Activated Adenosine‐5′‐Triphosphatase from Sugar Beet Cotyledons
Authors: KARLSSON JAN , KYLIN ANDERS 
Published: April 2006

AbstractSugar beet leaf homogenate contains Mg2+‐stimulated ATPase activity with the highest specific activity in the 25,000–30,000 ×g‐fraction. This fraction also has (Na++ K+)‐activated ATPase activity. Both activities have two pH optima, one stable at pH 7.9 and one variable at lower pH. When optimal conditions of Na+ and K+ were tested with 64 combinations of these ions, at least two mountains of activity were revealed.The (Na++ K+)‐ATPase had a high specificity for ATP. It had lost about 50% of its original activity after 56 days of storage at −85°C. The activity drop was most pronounced at high ionic concentrations in the test medium.The (Na++ K+)‐ATPase shows four peaks of activity when tested at constant ionic strength. The idea is put forward that the four peaks reflect two ATPases, one in the tonoplast and one in the plasmalemma, which undergo conformational changes in relation to the ionic milieu.
Raising the Maximum Permissible Air Velocity in Controlled Environment Plant Growth Chambers
Authors: O'LEARY JAMES W. , KNECHT GEORGE N. 
Published: April 2006

Abstract Phaseolus vulgaris L. plants were grown in two naturally lighted, outdoor controlled environment plant growth chambers. The approach velocity to the plant growing zone was 75 cm s−1 in one chamber and 225 cm s−1 in the other. The lower air velocity represents the presently considered maximum permissible air velocity in controlled environment plant growth chambers. The humidity in both chambers was near saturation. After three weeks' growth in these chambers, there were no significant differences in fresh or dry weights of the plants or any parts thereof. The high air velocity reduced the transpiration rate as predicted by energy budget considerations and significantly lowered the average leaf temperature of the crop by three degrees. The data strongly support the hypothesis that the maximum permissible air velocity in controlled environment plant growth chambers can be raised considerably if the humidity is maintained high.
A Proposal for the Use of Standardized Methods for Chlorophyll Determinations in Ecological and Eco‐physiological Investigations
Authors: LINDER SUNE 
Published: April 2006

AbstractThe various methods for chlorophyll determination, found in the literature, may give chlorophyll values differing by as much as 20%. Not only the choice of solvent and equations but also the routines and conditions for processing of samples can be large sources of errors.In the present paper some recommendations are given concerning sampling and storage of plant material, extraction and determination of chlorophylls.A simple and fast method for chlorophyll determinations is described and recommended as a suitable method for most ecological and eco‐physiological investigations in which chlorophylls are determined. The principle of the method is that the total amount of chlorophylls is determined in a colorimeter calibrated for chlorophyll measurements. Results from a prototype of the “Chlorophyllometer” are presented and compared with spectrophotometric determinations.
Induced Heat Sensitivity of Wheat Roots and Protecting Effect of Ethanol and Kinetin
Authors: SKOGQVIST INGRID 
Published: April 2006

AbstractWheat seedlings were subjected to heat shock for 2 min at 45°C. The seedlings were then incubated at 25°C or higher temperatures (usually 35°C). At 25°C the root tips survived the heat shock, but not at temperatures above 34°C, unless they had been pretreated with ethanol or kinetin, After 1 h in ethanol and after more than 15 h in kinetin the root meristem survived a high incubation temperature after the heat shock. Immediately after heat treatment the glyceride content in treated root tips was higher than in untreated roots. The same was observed after heat treatment of root tips pretreated in ethanol and kinetin. The content of ether extractable lipids was not changed by the heat shock.
Release of Volatile Mercury from Vascular Plants
Authors: SIEGEL S. M. , PUERNER N. J. , SPEITEL T. W. 
Published: April 2006

AbstractVolatile, organic solvent soluble mercury has been found in leaves and seeds of several angiosperms. Leaves of garlic vine (Pseudocallyma alliacium), avocado (Persea americana) and haole‐koa (Leucaena glauca) release mercury in volatile form rapidly at room temperature. In garlic vine, the most active release is temperature dependent, but does not parallel the vaporpressure temperature relationship for mercury. Mercury can be trapped in nitric‐perchloric acid digestion fluid, or n‐hexane, but is lost from the hexane unless the acid mixture is present. Seeds of haole‐koa also contain extractable mercury but volatility declines in the series n‐hexane (90%) > methanol (50%) > water (10%). This suggests that reduced volatility may accompany solvolysis in the more polar media. Gas chromatographic analysis shows that the volatile compound is not dimethyl mercury.
Cytokinins in Xanthium strumarium: A Rapid Response to Short Day Treatment
Authors: HENSON I. E. , WAREING P. F. 
Published: April 2006

AbstractFollowing a single inductive short day, cytokinin activity in extracts of leaf laminae, buds and root exudate of Xanthium strumarium L. (as measured by the soybean callus bioassay) declined to between 10 and 25% of the level detected under long‐day conditions. Additional inductive cycles, up to five, produced little further change. Cytokinin activity of petiole extracts fluctuated and did not decline to the same extent as that of leaf laminae, buds or exudate.
Diurnal Cycling in Root Resistance to Water Movement
Authors: PARSONS LAWRENCE R. , KRAMER PAUL J. 
Published: April 2006

AbstractThe occurrence of diurnal changes in root resistance of cotton was studied by measuring the flow of water through 35‐to70‐day‐old root systems under a pressure of 3.10 bars or a vacuum of 0.88 bar. The volume of exudate obtained under constant pressure or constant vacuum was 2 to 3 times greater near midday than near midnight indicating that the root resistance apparently was 2 to 3 times greater at night than during the day. The salt concentration of the exudate also cycled; the concentration was lowest at midday and highest at night, hence there was little diurnal variation in the total amount of salt moved per hour. The cycle for volume of exduate, salt concentration, and apparent root resistance had a period of 22 to 26 hours at 24°C. The cycle gradually died away 2 to 3 days after removal of the shoots.The diurnal variations appeared to be controlled by signals from the shoots because the phase of the cycles could be reset by changing the light‐dark cycle under which the plants were grown. Cycling was eliminated by exposure to 8 or more days of continuous light before removing the shoots, and cycling could not be entrained by a 6 hour light‐6hour dark cycle. Bubbling nitrogen gas through the nutrient medium stopped cycling. A possible role of ion or growth regulator action is discussed.
Metabolism‐linked Binding of Rubidium in the Free Space of Wheat Roots and its Relation to Active Uptake
Authors: IGHE ULF , PETTERSSON SUNE 
Published: April 2006

AbstractComponents of the initial uptake and active transport of rubidium were studied in potassium‐starved and potassium‐rich wheat plants. A metabolism‐linked component of the initial uptake in the root was identified by means of DNP‐treatment. It was shown that there is a direct proportionality between the magnitude of the metabolism‐linked component of the initial uptake and the rate of active uptake.It is suggested that, in the free space, this metabolism‐linked ion binding represents an initial step of the active ion transport preceding the subsequent carrier‐mediated transport across the plasmalemma.
Iron Deficiency in the Blue‐Green Alga Anacystis nidulans: Changes in Pigmentation and Photosynthesis
Authors: ÖQUIST GUNNAR 
Published: April 2006

AbstractPhycocyanin‐free photosynthetic lamellae (PSI‐particles) were prepared from Anacystis nidulans, grown in complete and iron‐deficient media. French press treatment and fractionated centrifugation were used. Absorption studies of the particles revealed an iron deficiency‐induced shift of the main red chlorophyll a absorption peak from 679 to 673 nm as reported before for whole cells. The shift may reflect a changed distribution between different chlorophyll a forms. Action spectra for photo‐oxidation of mammalian cytochrome c with photosynthetic lamellae revealed an iron deficiency‐induced shift, corresponding to that found in the absorption spectra. As photo‐oxidation of cytochrome c is mediated by PSI, it is believed that chlorophyll a also after the shift towards shorter wavelengths, is active in PSI.A decreased photosynthetic capacity of PSI, due to iron deficiency, was shown by time course studies of photosynthetic oxygen evolution, by photo‐oxidation studies of P700 and mammalian cytochrome c, by photo‐reduction studies of NADP and by combined studies of light‐induced and chemical oxidation of P700. The ration chlorophyll a/700 was also determined for whole cells, lyophilized cells and PSI‐particles. Iron deficiency caused an increased ratio in all studied fractions. The results of this work imply that energy is transferred with less efficiency within the photosynthetic units of PSI in iron‐deficient A. nidulans than in iron‐supplied algae.
Sorbitol in Tracheal Sap of Apple as Related to Temperature
Authors: WILLIAMS M. W. , RAESE J. T. 
Published: April 2006

AbstractThe influence of dormant‐season temperatures on levels of sorbitol was determined in an effort to provide further information on the possible role of sorbitol in dormancy of apple tress (Malus sylvestris Mill.). Two‐year‐old shoots were collected throughout the dormant season; sorbitol and sugars were determined in tracheal sap extracted under vacuum and in ground dried wood extracted in a soxhlet apparatus. Sorbitol and sugar trimethylsilyl derivatives were detected by gas chromatography. Levels of sorbitol in the sap generally increased during subfreezing temperatures and decreased during warm periods throughout the dormant season. Early peak increases in sap sorbitol appeared to coincide with the beginning of leaf senescence. Postharvest levels of reducing sugars, sorbitol, and particularly sucrose in the wood, increased as the temperature decreased during the dormant season, and the sugar levels decreased with warming temperatures in the spring. Our data indicate that sorbitol and sucrose are important reserves of storage carbohydrates in resting apple trees.
Titration of Photophosphorylation, Oxidative Phosphorylation and Glycolysis in Scenedesmus with Desaspidin: Regulation between Pathways and Sites for Photophosphorylation
Authors: KYLIN ANDERS , OKKEH ASSAD 
Published: April 2006

AbstractNarrow concentration intervals were used, covering 10−6– 10−4M desaspidin. The interaction with glycolysis involves three steps, the inhibitor constants (Ki:s) being in turn 2.7 × 10−5M, 1.3 × 10−4M, and high. About 18% of total glycolysis is inhibited in each of the two first steps, and 65% left for the third reaction. After compensation for glycolysis, oxidative phosphorylation may show a sudden jump to about 10% inhibition at 1.5 × 10−5M desaspidin, the possible Ki of the reaction starting here being very high. Correcting for glycolysis, desaspidin affects total Photophosphorylation in two steps, with the Ki values of 7.8 × 10−5M and 4.6 × 10−4M respectively. Inhibition in the first step is about 27% of the total photophosphorylation.By applying 10−6M DCMU[/3‐(3, 4‐dichlorophenyl)‐l, l‐dimethy lurea], one can abolish non‐cyclic photophosphorylation. Desaspidin then reacts in a single step with a Ki of 1.4 × 10−4M. At 5 × 10−5M DCMU, also the pseudocyclic photophosphorylation is abolished. The remaining, true cyclic photophosphorylation has a single Ki of 2.3 × 10−5M for desaspidin.Under non‐cyclic conditions, the true cyclic process contributes about 25% to total Photophosphorylation. Under pseudocyclic conditions, no cyclic photophosphorylation occurs. Under true cyclic conditions, the non‐cyclic and pseudocyclic processes are inoperative. This indicates a regulative system, so that either (1) the (non‐cyclic + true cyclic), (2) only the pseudocyclic, or (3) only the true cyclic systems can be traced, dependent on the level of DCMU applied. There are two sites for non‐cyclic Photophosphorylation, one of them common to the pseudocyclic pathway. Cyclic photophosphorylation has a third site, different from the other two.