bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Time of Nitrogen Application on Amino‐Nitrogen Composition of Roots and Xylem Sap of Apple
Authors: TROMP J. , OVAA J. C.
Published: April 2006

Apple rootstocks M.7 were given a nitrogen application either in the spring or in the preceding autumn. At the time of the spring application some rootstocks were ringed. During the 50‐day experimental period from bud‐break, shoot growth and the amount of nitrogen incorporated into the new shoots were slightly reduced in the spring‐treated trees and strongly reduced in the ringed trees of both treatments. Roots of unringed autumn‐fertilized trees showed higher levels of total and amino nitrogen than those of similar trees in the spring treatment; to a lesser degree, the reverse held for xylem sap from the stem. Ringing increased the amino‐nitrogen level in the roots, which suggests a reduced translocation rate.

The nitrogen treatments led to marked differences in the percentage composition of the amino‐nitrogen fraction of roots and xylem sap. The distribution of amino acids and amides in the roots and that in xylem sap of the same trees was divergent, but arginine and asparagine often were the most important constituents. Aspartic acid was rather abundant in xylem sap. Ringing did not affect the composition of the amino‐nitrogen fraction in the roots quantitatively but increased the proportion of arginine in the sap.

The possible relationship between the composition of xylem sap and soluble nitrogen in the roots is discussed. It is argued that especially in spring‐fertilized trees appreciable amounts of nitrogen must be translocated via the phloem in addition to the transport in the xylem.
La perception géotropique dans la coiffe des racines de Lentille
Authors: PERBAL GÉRALD , PERBAL PATRICK
Published: April 2006

Geoperception in the Lentil Root Cap.— Previous analysis showed that, in its initial phase, the geotropic response of Lens culinaris L. roots cannot be explained by a simpleaction by sliding, pressure or contact of amyloplasts on a sensitive surface located along the longitudinal wall. In this study another mode of action is tested by considering the following parameters as functions of the roots inclination: (1) the distance (d) which the amyloplasts move; (2) their number of contacts (c̃) with parietal cytoplasm; (3) the variable (sin α) of the transversal component of the statolith weight (M̄×g sin α). It is shown that the initial rate of curvature (V̄), at the various angles, is related to the sedimentation of the amyloplasts by the equation V̄=a log bd̄c̄ sin α (where a and b are constants). The results obtained prove that the geotropic stimulation is dependent upon the sine of the angle (α) of the root inclination and explain the sine rule deviation. The role of statoliths is discussed in the light of recent literature on growth inhibitors which are involved in the geotropic reaction.
Light Control of Anthocyanin Biosynthesis in Zea Seedlings
Authors: DUKE STEPHEN O. , NAYLOR AUBREY W.
Published: April 2006

Evidence for involvement of two non‐photosynthetic pigments in photoinduction of anthocyanin biosynthesis in the roots and mesocotyls of Zea mays L. seedlings is presented. Short (5 min), low energy (4.5 × 103 J m−2) fluences of red light neither induced anthocyanin synthesis nor enhanced phenylalanine ammonia‐lyase activity in dark‐grown maize seedlings. Little anthocyanin synthesis and no enhancement of phenylalanine ammonia‐lyase activity was induced by continuous far‐red light. Continuous white or blue light induced both anthocyanin synthesis and enhanced phenylalanine ammonia‐lyase activity. These results show that phytochrome alone cannot induce anthocyanin synthesis in maize seedlings. However, a strong phytochrome mediation of white light induced pigment synthesis was demonstrated. This effect was not demonstrable with white light enhanced phenylalanine ammonia‐lyase activity, indicating that phytochrome controls another step in anthocyanin biosynthesis.
Differential Foliar Sensitivity of Soybean Cultivars to Ozone Associated with Differential Enzyme Activities
Authors: TINGEY DAVID T. , FITES ROGER C. , WICKLIFF CARLOS
Published: April 2006

Soybean [Glycine max (L.) Merr.] cultivars Dare and Hood were exposed to ozone (980 μg/m3) for 2 h to determine if differences in cultivar sensitivity were associated with differential activation of selected enzymes. The first trifoliate leaves of the cultivars were in similar stages of development (14 days from sowing) when exposed. The ozone treatment increased the activities of glucose 6‐phosphate dehydrogenase, phenylalanine ammonia lyase, polyphenol oxidase and peroxidase above the control in both cultivars within 30 h after exposure. However, the activity of all these enzymes increased several hours sooner in Dare (sensitive) than in Hood (tolerant). Our data suggest that the differential sensitivity of these two cultivars to ozone could be based on the differential ozone induced activation of the enzymes involved in the lesion formation process.
The Growth Physiology of Coleoptiles in Continuous‐Record Vessels: Anomalous Kinetics of Cycloheximide Action on Auxin‐Controlled Growth
Authors: BLACK M. , DHEIDAH M.
Published: April 2006

The interacting effects of auxin and cycloheximide upon the growth of Triticum coleoptiles depends upon the incubation conditions. In the growth vessel developed by Evans and Ray (1969) the action of cycloheximide is severe and the growth kinetics show a rapid nullification of auxin action by the inhibitor; hormone action is also totally prevented by a relatively short period of pre‐treatment with cycloheximide. The kinetics of response to the two substances are quite different when coleoptiles are floating on the test solutions; here, cycloheximide is much less severe in its action. These differences are due to a heightened sensitivity to cycloheximide induced by exclusion of the air bubble from the coleoptile cylinder in the Evans and Ray chamber. The outer surface of the coleoptile wall is a less efficient respiratory surface than the inner one. When coleoptiles are filled with a stagnant solution insufficient oxygen can be taken up through the inner surface and the tissue therefore suffers oxygen deprivation. This exacerbates the action of cycloheximide as a potent respiratory inhibitor. The results raise questions concerning the use of conditions in which coleoptile sections are filled and submerged, which is a feature of recently introduced continuous‐record growth vessels. In particular, interpretation of the interactions between cycloheximide and auxin under such conditions must be made cautiously.
Effects of NaCl Salinity on Nitrogenous Compounds and Proteases during Germination of Vigna sinensis Seeds
Authors: PRISCO JOSÉ TARQUINIO , VIEIRA GUSTAVO HITZSCHKY FERNANDES
Published: April 2006

Serido bean (Vigna sinensis (L.) Savi) seeds were sown in water and in NaCl solution of —4.3 bars water potential. Total, insoluble and soluble proteins as well as soluble amino nitrogen and proteolytic activity of cotyledons were studied after 0, 1, 3, 5, 7, and 9 days of germination. Protein breakdown and turnover was delayed by the NaCl treatment as compared to the control. This was not due to the total amount of proteolytic activity, which was unchanged by salinity; even though the specific activity decreased due to the delayed breakdown of proteins under salt stress. The inhibitory effects of salinity on seed protein reserve mobilization may be due more to inhibition of translocation of hydrolysis products than to inhibition of protease activity.
Multiphasic Hexose Uptake in Chlorella
Authors: NISSEN PER
Published: April 2006

The model proposed by E. Komor and W. Tanner for hexose proton cotransport in Chlorella (Planta 123: 195–198. 1975) is shown to be incorrect. Their data cannot represent hexose uptake via a protonated and a deprotonated form of the carrier, but may be precisely represented by a single bi‐ or triphasic mechanism.
Further Characterization of Nitrate and Nitrite Reductases from Chlamydomonas reinhardii
Authors: BAREA J. L. , MALDONADO J. M. , CÁRDENAS J.
Published: April 2006

The enzymes responsible for nitrate reduction in Chlamydomonas reinhardii, namely NADH‐nitrate reductase and ferredoxin‐nitrite reductase, have been further characterized. The first activity of the nitrate reducing complex, NADH‐diaphorase, is protected by FAD against thermic inactivation. This fact suggests an important structural and functional role for this nucleotide in the first moiety of the nitrate reductase complex. The effect of p‐hydroxymercuribenzoate on the diaphorase activity and the protection by NADH against its inactivation indicate that some—SH groups participate in the electron transfer mediated by diaphorase.

Radioactive labelling of nitrate reductase with 99Mo and 185W as well as competition experiments between Mo and W indicate that molybdenum is an essential component of terminal nitrate reductase activity. Iron seems to participate in the redox processes mediated by both nitrate and nitrite reductases as suggested by experiments performed at physiological level. Finally a tentative mechanism for the whole process of nitrate assimilation in Chlamydomonas is proposed.
The Effects of Increased Illumination and Shading on the Low‐Light‐Induced Decline in Photosynthesis in Cotton Leaves
Authors: NAGARAJAH S.
Published: April 2006

An experiment was carried out to study whether low‐light‐induced damage to the photosynthetic system in leaves of cotton (Gossypium hirsutum cv. Deltapine) which are below the compensation point in the canopy can be arrested and reversed by increased illumination. In addition it was intended to find out whether the photosynthetic system in leaves of shade plants show a greater resistance to low‐light‐induced damage than leaves of plants from more exposed habitats.

The plants were grown at high density, and increased illumination to the shade leaves in the canopy was achieved by thinning the stand. Thinning was carried out at two stages and its effects on the decline in the photosynthetic capacity of the 4th leaf were followed. An early thinning was carried out shortly after the 4th leaf dropped below the compensation point and a late thinning 2 weeks later. Comparison was also made between the low‐light‐induced damage to the photosynthetic capacity of the 4th leaf in plants grown under two light regimes during the progressive increase in self‐shading of the 4th leaf within the canopy.

It was observed that both types of thinning arrested the low‐light‐induced damage to the photosynthetic system in shade leaves. The decline in photosynthetic capacity of the 4th leaf was stopped after both early and late thinning. The dry weight of the shoot system in the early and late thinned plants was not significantly different. It was double that of the control plants. The plants thinned early did not have higher shoot weight than the late thinned plants since there was a rapid shedding of flowers and fruits after early thinning. The 4th leaf in the early thinned plants showed a 30% increase in chlorophyll content and dry weight per unit leaf area. It is suggested that shedding of flowers and fruits, and increases in chlorophyll and dry weight per unit leaf area in the early thinned plants were caused by a change in the hormonal balance of the plants.

The photosynthetic system in leaves of shade plants showed a greater resistance to damage by low light intensity than the photosynthetic system in leaves of plants grown at higher light intensities.
The Effect of Zinc on the Formation of Ribulose Diphosphate Carboxylase in Phaseolus vulgaris
Authors: JYUNG WOON H. , CAMP MARY E.
Published: April 2006

The effect of Zn on the formation of ribulose diphosphate carboxylase (RuDPCase was investigated in the leaf discs from Zn‐deficient Sanilac navy bean plants (Phaseolus rulgaris L.). The incorporation of 14C‐leucine into the partially purified RuDPCase was found to be a quantitative equivalent of the level and activity of the enzyme. Zn as ZnSO4 at 10 uM stimulates the formation of RuDPCase by at least 2‐fold. Neither CuSO4 nor CdSO4 at the same concentration substitutes for ZnSO4. The enhancement of RuDPCase formation by added Zn is greater with increasing severity of Zn deficiency, suggesting that Zn is a limiting factor in this system. Suppression of the Zn‐stimulated formation of RuDPCase by actinomycin D and cycloheximide suggests that the Zn‐mediated formation of RuDPCase most likely represents de novo synthesis. Also, the possible site(s) of action of Zn is discussed.
Effect of Water Deficit on the Growth of Squash Fruit
Authors: COCUCCI S. , COCUCCI M. , TRECCANI C. POMA
Published: April 2006

The growth of squash fruit was followed in the field under normal and drought conditions. The following phenomena were observed: a) under drought conditions the fruit growth is normal in the night while it becomes more and more reduced with progress of time in the daylight period; b) the decrease of growth capacity in the daylight period does not correspond to a dehydration of the fruit tissues and it is accompanied by a conversion of polysomes to monosomes; c) the water deficit also causes a decrease of RNA and protein content in the fruit tissues, but this situation does not affect the rate of growth in the night. The data suggest that under conditions the fruit growth is controlled by water availability through protein synthesis; under ample water supply, water availability or some other factor, rather than RNA and protein level, is limiting the fruit growth.
An Electrical Analogue to Simulate the Oxygen Relations of Roots in Anaerobic Media
Authors: ARMSTRONG W. , WRIGHT E. J.
Published: April 2006

The paper describes the construction and the theory underlying a simple electrical analogue which may be used to simulate the internal oxygen relations of roots in the wetland condition. The model represents an unbranched root lying within an oxygen sink and consists of twenty circuit units linked in series. Each unit which can be programmed independently, represents the major oxygen diffusion paths, impedances and sinks recognizable in a centimetre‐long segment of root/wet soil system. Simplicity has been achieved by specifying constant radius for the root (0.05 cm), constant potential activity for the external sink, by expressing respiration and radial oxygen loss as a function of root surface area, and by the non‐inclusion of oxygen storage capacity.
Localization and Activity of a Carboxypeptidase in Germinating Seeds of Scots Pine, Pinus sylvestris
Authors: SALMIA M. AULIKKI , MIKOLA JUHANI J.
Published: April 2006

Extracts prepared from the endosperm of germinating seeds of Scots pine, Pinus sylvestris L., hydrolysed two typical carboxypeptidase substrates, Z‐Phe‐Ala and Z‐Phe‐Phe, with pH optima at 4.2 and 5.0. The activities were completely destroyed by diisopropylfluorophosphate. Identical heat inactivation curves and elution patterns in gel chromatography on Sephadex G‐200 suggest that the two activities are due to a single enzyme.

In resting seeds very low carboxypeptidase activity was present in both the endosperm and the embryo. During germination on agar gel at 20°C in the dark the activities, expressed as enzyme units per seed, increased in the seedling and particularly in the endosperm up to the stage when the reserves of the endosperm were completely depleted. The time of rapid increase of activity in the endosperm did not coincide with the onset of storage protein mobilization. On the contrary, the major part of the increase occurred after the bulk of endosperm nitrogen had already been transferred to the seedling.

The results suggest that the carboxypeptidase does not play a major role in the mobilization of storage proteins in germinating pine seeds. On the other hand, it probably functions in the proteolytic reactions associated with the senescence of the reserve‐depleted endosperm.
The Effects of Agitated Liquid Medium on in vitro Cultures of Hevea brasiliensis
Authors: WILSON H. M. , EISA M. Z. , IRWIN S. W. B.
Published: April 2006

The initiation and prolonged growth of callus, from stem explants of young plants of Hevea brasilienies on solid medium yielded a heterogeneous callus, with areas which are the result of compact growth interspersed with brown necrotic tissue and soft white tissue formations. Subculturing this callus (O callus) to agitated liquid medium and returning it to solid medium resulted in the production of a homogeneous friable and rapidly growing callus (Rl callus) The two established lines O and Rl have remained stable over one year in culture and differ in gross morphology, anatomy, growth and auxin content. Both were maintained on Murashige and Skoog's medium, with 2 mg/1 2,4‐D and 0.5 mg/I kinetin. R 1 but not O showed enhanced growth at the lower 2,4‐D level of 0.2 mg/l: both lines failed to continue growing when 2,4‐D was omitted.

It is suggested that the changes resulting from subculture in agitated liquid medium are related to those undergone by callus cultures which become habituated. Thus the Rl callus line is regarded as partially habituated. Subculture in agitated liquid medium also resulted in the production of large numberr of polyploid cells but these did not persist over the long periods of subsequent growth on agar medium, Enhanced auxin production by the establihed Rl callus line was thus observed in the absence of a detectable level of polyploidy.
Influence of Cotyledon Excision and Sucrose on Root Formation in Pea Cuttings
Authors: VEIERSKOV BJARKE , HANSEN JÜRGEN , ANDERSEN ARNE SKYTT
Published: April 2006

Sucrose was supplied to stock plants of Pisum sativum L. cv. Alaska grown at different levels of irradiance. There was no significant effect on the rooting of the cuttings by sucrose supply to intact plants regardless of the irradiance. However, an increase in the number of roots per cutting was obtained at increasing concentrations of sucrose when the stock plants had been grown at 4 W m−2 and their cotyledons had been removed two days before the cuttings were excised.

Cotyledons were removed from stock plants at different times before the excision of cuttings with the intent to regulate the endogenous supply of carbohydrate. The number of roots per cutting was reduced by removal of the cotyledons and this reduction was correlated to the number of days the stock plants had grown without cotyledons as well as to the irradiance pre‐treatment. A greater reduction occurred in cuttings from plants grown under 4 W m−2 than from those grown under 38 W m−2.

The growth of the stock plants and the subsequent stem growth of the cuttings was determined by the irradiance to the stock plants and by the time of removal of the cotyledons. Exogenous supply of sucrose had no effect on the stem growth of the cuttings.
Kinetic Studies of (Mg2+)ATPase in Oat Roots
Authors: CHRISTIANSEN J. L. , LINDBERG S.
Published: April 2006

Kinetic studies on a microsomal fraction from oat roots (Arena sativa) indicate that the MgATP complex is the primary substrate for the ATPase. Free ATP was a weak competitive inhibitor. Free Mg2+ appeared to be either a competitive or noncompetitive inhibitor.
Phase‐Locked Loop Technique to Record Resonance Frequency of Plant Tissue
Authors: AXELSSON P. , JOHNSSON A.
Published: April 2006

An apparatus based on the phase‐locked loop technique has been developed in order to record automatically the resonance frequency of a mechanically vibrating plant specimen. Hereby changes in the elasticity of the plant material can be continuously recorded.

In order to demonstrate the use of the apparatus, elasticity changes of Avena coleoptiles due to exchange of the root medium were continuously recorded.
Carbohydrate Metabolism and Frost Hardiness in Pine and Spruce Seedlings Grown at Different Photoperiods and Thermoperiods
Authors: ARONSSON ARON , INGESTAD TORSTEN , LÖÖF LARS‐GÖRAN
Published: April 2006

Large changes occur in carbohydrate contents of pine (Pinus silvestris L.) and spruce (Picea abies (L.) Karst.) seedlings cold‐hardened by photoperiod or by combined photo‐ and thermo‐period. The largest change is in sucrose content, which is almost doubled after six weeks short‐day (6/18 h) treatment; and more than doubled (spruce) or more than tripled (pine), when also temperature is lowered (10/5°C). Development of frost hardiness is strongly correlated with the change in carbohydrate contents. At dehardening, the carbohydrate content decreases rapidly, especially in pine, and the raffinose formed during the rest period disappears within 2–4 weeks. Frost hardiness decreases in parallel.

The content of soluble carbohydrates may thus play a role in frost hardiness, although it is not the only factor. Bud formation at cold acclimation is not directly correlated with the changes in carbohydrate content and hardiness.
The Physiology of Rooting Populus Cuttings
Authors: OKORO O. O. , GRACE J.
Published: April 2006

The changing levels of carbohydrates and the rates of photosynthesis in rooting Populus cuttings are described. The cuttings were planted in a sand medium, in controlled environment conditions. There was no evidence to support the view that failure to root in P. tremula was caused by insufficient carbohydrate reserves. In leafless hardwood cuttings, the carbohydrate levels were initially very high (14–19%) but fell rapidly (to 5–10%) as roots, callus or shoots developed. In leafy softwood cuttings, a steady accumulation of carbohydrate reserves was observed, rising from 5–10% on planting to 15–25% when roots had developed. One of the differences between the easy‐to‐root P. × euramericana and the hard‐to‐root P. tremula was the apparent downward transport of assimilates in P. × euramericana softwood cuttings.
Kinetic Studies of a (Na++ K++ Mg2+) ATPase in Sugar Beet Roots
Authors: LINDBERG SYLVIA
Published: April 2006

Kinetic studies of a dithiothreitol treated membrane ATPase fraction from sugar beet roots led to the following conclusions: 1) In the presence of MgATP, Na+ and K+ stimulate the ATPase activity in different ways following simple Michaelis‐Menten kinetics. Thus separate sites for Na+ and K+ are suggested. 2) In the absence of K+, Na+ acts as an uncompetitive modifier raising the apparent Km and Vmax for MgATP. 3) In the absence of Na+, K+ activates non‐competitively with respect to MgATP. Thus K+ increases Vmax but does not affect the apparent affinity constant. 4) K+ and Na+ double the rate constants. 5) In the presence of Na+ or K+, Mg2+ in excess acts as a weak inhibitor to Na+ and/or K+ activity. 6) The temperature‐activity dependence in the 5–40°C interval shows biphasic Arrhenius plots with the transition point between 15–18°C. The activation energy is lowered at temperatures > 18°C.
Changes in the Reactivity of the Photosynthetic Apparatus in Heterotrophic Ageing Cultures of Scenedesmus obliquus
Authors: KULANDAIVELU G. , SENGER H.
Published: April 2006

Cultures of Scenedesmus obliquus when grown heterotrophically for 10 or 30 days without addition of fresh medium showed 85 and 98% loss of their photosynthetic capacity respectively. This loss in photosynthetic capacity was accompanied by an increase in quantum requirement.

No major changes in the pigment amounts or types were detected which would explain the decay in photosynthetic capacity.

Partial reactions mediated by photosystem II or I showed a more or less constant decay over a period of 30 days. Photosystem II reactions appeared less stable than those of photosystem I, decaying by 95% as compared with 70%, over this time period.

The results of comparative studies on aged cells for their potential of cytochrome f photooxidation, fluorescence kinetics, 520 nm absorbance change and the variable influence of 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea and 2,5‐dibromo‐3‐methyl‐6‐isopropyl‐p‐benzoquinone on the photosynthetic capacity of such cells, suggest that it is the inherent ability of the cells to photooxidize plastohydroquinone which is affected primarily.

In addition, secondary changes were noted in the activity of reactions on the water‐splitting side of photosystem II and in the P700 — plastocyanin — cytochrome f complex.
Changes in the Reactivity of the Photosynthetic Apparatus in Heterotrophic Ageing Cultures of Scenedesmus obliquus
Authors: KULANDAIVELU G. , SENGER H.
Published: April 2006

Ultrastructural changes of the chloroplast which occur parallel to the decay of photosynthetic capacity during the heterotrophic ageing of Scenedesmus cells have been studied. A gradual disappearance of the starch grains took place as the nutrients in the growth medium were depleted. Accompanying this change was a deterioration in the structure of the cytoplasm coupled with a concomitant granular appearance. At the same time thylakoid structures were not only well preserved but accumulated more material. This resulted in an increasing number of stacked thylakoids and a thickening of the membranes.
Nitrate Uptake during Recovery from Nitrogen Deficiency
Authors: JACKSON W. A. , KWIK K. D. , VOLK R. J.
Published: April 2006

Two‐week‐old nitrogen‐deficient wheat plants attained a high rate of nitrate uptake on the first day of exposure to nutrient solutions supplemented with KNO3. Ammonium uptake from similar solutions supplemented with NH4NO3 was also high during the first day of exposure, but nitrate uptake from this solution was lower than from the KNO3 treatment. During the next two to three days there was a progressive decrease in uptake of both nitrogen ions. A steady increase in uptake then occurred as the plants fully recovered from the nitrogen‐deficient state.

The transient low nitrate uptake after three or four days of exposure to KNO3 was not due to an excessive accumulation of nitrate in the tissue, nor to a failure in nitrate reduction as indicated by the rate of nitrate accumulation relative to the uptake rate. Nitrogen supplied as 15N‐nitrite during the low uptake period was effectively incorporated into organic forms and effectively translocated to the shoots. Failure of the root tissue to increase in soluble carbohydrates during illumination was characteristic of the low uptake period. This contrasted with an increase in root soluble carbohydrates in the light during rapid uptake associated with full recovery from the nitrogen‐deficient state. It is concluded that carbohydrate translocation to the root system was insufficient during the intermediate recovery period for optimal nitrate uptake, although it was sufficient for effective reduction and translocation of nitrate and reduced nitrogen.

Ammonium uptake from NH4NO3 was restricted during darkness by the third day whereas there was little difference between light and dark periods in nitrate uptake from KNO3 until about the sixth day of recovery. The extent to which ammonium restricted nitrate uptake increased progressively for two or three days following which a lessening influence seemed evident, and the effects were not directly associated with the rate of ammonium uptake.
Promotion of Flowering in the Pinaceae by Gibberellins
Authors: ROSS STEPHEN D. , PHARIS RICHARD P.
Published: April 2006

Flowering was significantly promoted in 4‐year‐old grafts of mature coastal Douglas‐fir (Pseudotsuga menziesii (Mirb.) Franco) clones by exogenous gibberellins (GAs) A4 and A7 (as a mixture) applied alone and in combination with A5 and A9. Biweekly applications of 400 μg GA4/7 per branch between late March and late June gave a 5‐fold increase in ovulate and 3‐fold increase in staminate strobilus production over untreated controls. 6N‐benzyladenine and 2,3,5‐triiodobenzoic acid applied in combination with GAs had no consistent effect on strobilus production. Non‐destructive branch girdling, ineffective by itself as a cultural treatment, enhanced the GA benefit to flowering. Exogenous application of GA4/7 is effective and appears to be a practical method for promotion of early and enhanced flowering in grafted Douglas‐fir seed orchards.
Factors Influencing the Growth and Division of Pea Mesophyll Protoplasts
Authors: von ARNOLD SARA , ERIKSSON TAGE
Published: April 2006

High yields of viable protoplasts were produced from pea leaves provided that only leaves of the same age were used in each preparation. The conditions under which the pea plants were grown and the age of the plants were also important. The protoplasts were cultured in a medium supplemented with 1 mg/1 2iP and 1 mg/1 2,4‐D. They were able to regenerate cell walls within two days. After 5 days cell divisions were apparent and sustained divisions led to callus formation. Special emphasis has been given in this paper to the choice of leaf material for protoplast isolation.
Effects of Salt Stress on Growth, Nodulation and Nitrogen Fixation in Cowpea and Mung Beans
Authors: BALASUBRAMANIAN V. , SINHA S. K.
Published: April 2006

The effects of salt stress on growth, nodulation, and nitrogen accumulation in cowpea (Vigna sinensis) and mung beans (Vigna aureus) were studied in sand culture.

Salinity (NaCl) retarded the growth of leaves, stem and roots of both the crops. Root growth of mung beans was more sensitive to the increase in salt stress than that of cowpea. The relative growth rates of stressed plant parts declined initially but were subsequently higher than those of control for a period, suggesting that the plants tended to adapt to unfavourable environment even while being stressed. The total nodule number, weight and nitrogen content per plant decreased due to salt treatment, which interfered with the initiation of nodules but not with their further development. There was a considerable fall in the nitrogen fixation efficiency of mung beans under saline environment; it was not so in cowpea.
Incorporation of 5‐Aminolevulinic Acid in the Chlorophyll‐Protein Complexes of the Moss Ceratodon purpureus
Authors: VALANNE NIINA , ARO EVA‐MARI
Published: April 2006

After one month of cultivation in the dark in inorganic medium the chloroplasts of protonemata of Ceratodon purpureus have larger grana than chloroplasts from light‐grown cultures. Incubation of dark‐grown material with ALA increases the chlorophyll content and chlorophyll a/b ratio. On polyacrylamide‐gel electrophoresis, a préferential labelling of chlorophyll‐protein complex I is obtained after treatment with (3H) ALA in darkness. In contrast, in light, much higher activity is found in chlorophyll‐protein complex II. The free pigment zone is highly labelled in both environments.
Pigment Degradation in Discs of the Thermophilic Cucumis sativus as Affected by Light, Temperature, Sugar Application and Inhibitors
Authors: VAN HASSELT Ph. R. , STRIKWERDA J. T.
Published: April 2006

Chlorophyll degradation in Cucumis leaf discs was measured at different temperatures between 1 and 25°C in the light and in darkness, and in the presence or absence of sucrose. Two different processes of chlorophyll degradation could be distinguished, a light‐requiring process operating at 1 and 5°C and another, light and sucrose enhanced degradation process which was evident at 25°C. Degradation of leaf pigments at low temperatures was of a photo‐oxidative nature since there was no degradation in the dark. The chlorophyll a/b ratio was decreased, carotene was degraded at a faster rate than chlorophyll, and 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (DCMU) and triphenyltetrazolium chloride (TTC) which prevent photo‐oxidation, protected against chlorophyll degradation. The light and sucrose enhanced chlorophyll degradation at 25°C was of an enzymatic nature since it occurred in the dark as well as in the light. The chlorophyll a/b ratio was not affected, and carotene and chlorophyll degradation occurred at the same rate. Since DCMU completely inhibited the light enhancement at 25°C and experimentation in a low oxygen atmosphere also protected chlorophyll against the effect of light and sugar application, it is suggested that the enhancement of chlorophyll degradation by light and sucrose at 25°C may be due to increased sugar uptake of the chloroplasts and consequently excessive starch formation in the organelles.
Auxin Transport in Tendril Segments of Passiflora caerulea
Authors: JUNKER STEFFEN
Published: April 2006

The movement of auxin through tendril segments of Passiflora caerulca L. has been investigated using IAA‐2‐14C. It has been shown that (1) flux of IAA through the segments is strongly polarized basipetally: (2) the amount of 14C recovered in the basal receiver blocks increases linearly within a transport period of 6 h; (3) velocity of basipetal transport is 14.5 mm h−1; (4) at least 70% of the radioactivity in the receiver blocks is confined to the IAA molecule: approximately 55% of 14C from methanolic extracts of the segments is IAA: (5) at low temperatures (2–4°C) the basipetal transport is abolished; (6) white light promotes basipetal transport, and this effect is abolished in a CO2‐free atmosphere; (7) no difference could be detected in 14C content between dorsal and ventral halves of tendril segments nor among individual dorsal and ventral receiver blocks.
Regeneration of Plants from Cell Suspensions Frozen at −20, −70 and −196°C
Authors: BAJAJ Y. P. S.
Published: April 2006

Cell suspensions of carrot, Datura, tobacco and soybean subjected to −20°C, −70°C and −196°C in the presence of a suitable cryoprotective agent, and stored for various lengths of time have been revived. After revival these cells divided to form callus masses. Direct immersion in liquid nitrogen invariably killed the cells, whereas cooling at the rate of 1 or 2°C/min, or pre‐freezing briefly at −20 and −70°C, followed by freezing at −196°C retained the viability. Depending on the plant species up to 70% of the cell clumps could withstand ultra‐cooling. Tobacco and Datura cell suspensions were more sensitive to cold treatment than were those of carrot. Actively growing cell suspensions containing small cell‐clumps revived rapidly, while filtered cell‐suspensions of free cells only occasionally survived. Calli of tobacco and carrot obtained from frozen suspensions have been regenerated into plants.
Effect of Spruce Root Constituents on Extracellular Enzymes of Fomes annosus
Authors: JOHANSSON MARTIN , POPOFF THOMAS , THEANDER OLOF
Published: April 2006

Fractions of acetone extracts from heartwood, sapwood and wood from the reaction zone in roots of Norway spruce, attacked by Fomes annosus, were tested concerning their effect on the activity of cellulase, polygalacturonase, aryl‐β‐glucosidase and laccase, obtained from culture filtrates of the same fungus. A specific inhibition of polygalacturonase was recorded with the resinous fractions. The hydrolysing enzymes were more inhibited by the lignans of the reaction zone in the presence of fungal laccase than in the absence of laccase. The pH dependence of the inhibiting effect of phenols varied among the enzymes. The four enzymes were inhibited by partly different lignan fractions, and synergistic effects between minor compounds were indicated. The phenolic fractions inhibited weakly the biosynthesis of the enzymes. It was obvious that results from enzyme inhibition studies in vitro do not reflect the complicated mutual interrelationships between production and activity of the extracellular fungal enzymes and the chemical constituents of the host in vivo.
Similarities between l‐Phenylalanine and m‐Fluorophenylalanine as Substrates for l‐Phenylalanine Ammonia‐Lyase
Authors: ORKWISZEWSKI JOSEPH A. J. , KOROLY MARY J. , DIMICHELE LEONARD , WEBER DANA M.
Published: April 2006

The ability of l‐phenylalanine ammonia‐lyase (E.C. 4.3.1.5) to metabolize dl‐m‐, dl‐o‐ and dl‐p‐fluorophenylalanine in Avena sativa has been examined. Although all three amino acid analogues served as substrates for this enzyme, there was a marked difference in the behavior of the meta isomer from that of the para and ortho species. The Michaelis constant for the meta analogue was similar to that obtained for the natural substrate, l‐phenylalanine, but distinct from the kinetic data for the para and ortho isomers. In addition, in vivo analyses demonstrated that both l‐phenylalanine and the meta‐fluoro‐derivative served to protect against chlorogenic acid loss, whereas previous studies have shown that the para and ortho species depressed levels of this phenolic derivative. Finally, treatment of coleoptile apices with either the meta isomer or l‐phenylalanine reversed dl‐p‐fluorophenylalanine stimulated growth and attendant reduction in chlorogenic acid content. These findings provide further clarification of the effects of fluorophenylalanines upon l‐phenylalanine ammonia‐lyase mediated biosynthesis of low molecular weight phenols in Avena.
Water Potential and Leaf Elongation in Radiata Pine and Wheat
Authors: SANDS R. , CORRELL R. L.
Published: April 2006

The rate of leaf elongation in radiata pine (Pinus radiata) and wheat seedlings was closely related to the osmotic potential of the rooting solution. Sudden stress application and removal treatments caused immediate changes in the leaf elongation rate and a new steady‐state rate independent of the old was quickly established. The osmotic potential in the active elongation zones of a leaf differed from that of the remainder of the leaf and was considered more appropriate for deriving turgor pressure to be related to leaf elongation. Shifts in elongation rate were associated with corresponding shifts in total leaf water potential in both species and with corresponding shifts in turgor pressure in wheat.

There was a linear correlation between the pitch of the helical thickenings in the protoxylem of radiata pine needles and their elongation rate. A record of elongation rate is, therefore, preserved in the needle. Developmental aspects of the deposition of the helix are discussed.
Galactose‐induced Ethylene Evolution in Mung Bean Hypocotyls: A Possible Mechanism for Galactose Retardation of Plant Growth
Authors: COLCLASURE G. CRAIG , YOPP JOHN H.
Published: April 2006

Galactose has long been known to inhibit growth in certain plant systems and more recently to promote abscission. These same systems are similarly affected by ethylene. The mung bean (Phaseolus aureus Roxb.) hypocotyl system was employed to ascertain whether the inhibitory effects of galactose might be regulated through ethylene. Galactose alone (at 10 and 100 mM) of the many carbohydrates tested elicited high rates of ethylene evolution (1.5–4.0 nl/g fresh weight x h) as determined by gas chroma‐tography. Hook opening, pigment formation, and hypocotyl elongation were inhibited by this resultant ethylene. Galactose and auxin were found to act synergistically with respect to ethylene induction. Use of an auxin antagonist and auxin transport inhibitor revealed that galactose‐induced ethylene formation is auxin dependent. Time course studies indicate that this effect may be auxin‐sparing. Methionine appears to be the substrate of galactose‐induced ethylene. since a methionine antagonist [L‐2‐amino‐4‐(2′‐amino ethoxy)‐trans‐3‐butenoic acid] abolished the induction. Potential interrelationships between galactose and ethylene synthesis are discussed.
Regulation of Apical Dominance by Ethephon, Irradiance and CO2
Authors: ANDERSEN A. SKYTT
Published: April 2006

Apical dominance of intact pea plants (Pisum sativum L. cv. Alaska) was found to be diminished by high irradiance and by increasing the CO2 content of the air. Ethephon treatment of young plants resulted in an outgrowth of laterals, but this was significant only when the apical dominance already was weakened by high irradiance and/or CO2.
Some Environmental and Nutritional Factors Affecting Growth and Sporulation of Aspergillus tamarii Associated with Mouldy Cocoa Beans in Nigeria
Authors: OLUTIOLA P. O.
Published: April 2006

Aspergillus tamarii Kita grew and sporulated best at 30°C. The best pH for growth and sporulation were 5.5 and 6.5, respectively. Among the carbon sources employed, glucose supported the highest growth and sporulation. Best growth was obtained with sodium nitrate as nitrogen source and best sporulation with ammonium tar‐tarate. When glucose was used as carbon source, the carbohydrates found in the mycelium included myoinositol. dulcitol, fructose, arabinose and ribose.
Production of a Cellulase Complex in Culture Filtrates of Aspergillus tamarii Associated with Mouldy Cocoa Beans in Nigeria
Authors: OLUTIOLA P. O. , COLE O. O.
Published: April 2006

Aspergillus tamarii Kita grown in media that contained single soluble or insoluble cellulosic sources of carbon, released a complex of cellulolytic enzymes into the medium. The complex was separated into thirteen components by gel filtration followed by ion exchange chromatography. Eight of the components had a high molecular weight and five had a low molecular weight. One of the high molecular weight components, designated Ab, had the character of C1 cellulase enzyme. In a few cases there was synergism between the components, since in combination they liberated more glucose than when alone.
Flower Bud Atrophy in Baccara Roses
Authors: ZIESLIN N. , HALEVY A. H.
Published: April 2006

The activity of various growth substances in the upper leaves of Baccara roses was compared between flowering and non‐flowering shoots. Flowering shoots had a higher level of gibberellins, auxins and cytokinins. The changes in level of these growth substances during different stages of shoot development were more marked in flowering than in non‐flowering shoots. The level of inhibitors was higher in leaves of “blind” shoots. At least two inhibitors are present; one of them was identified as abscisic acid, while the other appears in the neutral fraction.
Flower Bud Atrophy in Baccara Roses
Authors: ZIESLIN N. , HALEVY A. H.
Published: April 2006

Changes in gibberellin content and of the production of ethylene in the two upper shoots of roses were measured as affected by decreasing temperature and light intensity, factors which encourage flower atrophy. Decreases in temperature or light intensity to the whole plant reduce the endogenous content of gibberellin in the leaves of the two shoots. The decrease is more rapid and occurs earlier in leaves of the second shoot from the top, where “blindness” is more common. There was also a drop in the gibberellin content, when individual shoots were shaded, although the decrease was more moderate. A lowered light intensity reduced the production of endogenous ethylene by the two shoots, but in the second shoot this production increased after a number of days, before atrophy of the flower bud took place. It is suggested that gibberellin participates in the endogenous control of rose flower development, and the possibility is discussed that it acts by directing the translocation of metabolites to the flower bud.
Factors Affecting Dalapon Absorption and Translocation in Johnsongrass
Authors: McWHORTER C. G. , JORDAN T. N.
Published: April 2006

The factors affecting the absorption and translocation of 14C‐dalapon (2.2‐dichloropropionic acid) in johnsongrass were studied. Johnsongrass [Sorghum halepense (L.) Pers.] was first pot‐grown in a greenhouse and then treated and placed in controlled‐environment chambers.

Absorption of 14C‐dalapon into johnsongrass leaves and subsequent translocation occurred continuously within the plant during a 48‐h period after treatment. Gas chromatographic analysis of johnsongrass extracts showed that the dalapon molecule was translocated intact. Absorption and translocation of 14C‐dalapon increased as the droplet volume of the diluent was increased from 0.2 to 5.0 μl per treated spot.

At 21 and 32°C, translocation of 14C‐dalapon from a 2‐cm treated leaf section into the plant was greater at 100% than at 35% relative humidity. At 38°C, translocation was greater at 35% than at 100% relative humidity. The addition of 0.5% surfactant to the dalapon solution increased translocation under all environmental conditions studied. The addition of 0.1 M KH2PO4 to dalapon‐surfactant solutions increased 4‐dalapon translocation under high temperature (38°C), especially at 35% relative humidity.
Nuclear Deoxyribonucleic Acid Metabolism and Membrane Fatty Acid Content Related to Chilling Resistance in Germinating Cotton (Gossypium barbadense)
Authors: CLAY WILLARD F. , BARTKOWSKI EDMUND J. , KATTERMAN FRANK R. H.
Published: April 2006

Chilling damage was examined in the chilling‐sensitive plant Gossypium barbadense. Between 30 and 36 h of germination at 34°C, the seedlings are extremely sensitive to temperatures below 10°C. The initiation of chilling damage by exposure to 2°C for 5 h during the sensitive period resulted in a large reduction in DNA synthesis. The reduction was correlated with a reduced efficiency of nuclear DNA polymerase activity. Comparing a more chilling resistant genotype to a more sensitive variety indicated that the resistant genotype nuclear DNA polymerase activity is more efficient when exposed to a chilling stress. Resistance was also correlated with a higher degree of unsaturated fatty acid content in the nuclear membranes of the resistant variety.
Purification and Properties of Rape Alcohol Dehydrogenase
Authors: LEBLOVÁ SYLVA , STIBOROVÁ MARIE
Published: April 2006

Germinating seeds with the highest specific activity (24 hour germination) were used for isolation of alcohol dehydrogenase, ADH, from rape (Brassica napus L. cv. Třebičská). The rape ADH was purified by fractionation with ammonium sulphate, desalting on Sephadex G 25, chromatography on DEAE cellulose and gel filtration on Sephadex G 150. Using this isolation procedure, enzyme with a specific activity 85.6 times higher than that of the crude extract was obtained. The molecular weight of the enzyme obtained is 66.000. The enzyme is a metallo‐enzyme containing sulfhydryl groups as evidence by the inhibitory effect of chelating compounds and thiol reagents. The optimum pH for the oxidation of ethanol is 8.5 and for reduction of acetaldehyde 7.0. The enzyme exhibits a relatively wide substrate specificity towards alcohols. Dimethyl‐sulphoxide (DMSO), some amides and oximes and some intermediates of the carbohydrate metabolism act as ADH inhibitors, ATP as analogue of NAD also exhibits an inhibitory effect. The inhibitory effect of heterocyclic substances (pyrazol, imidazol, pyridine) is similar to the effect on liver alcohol dehydrogenase.
Photoactivation of Oxygen‐evolving System in Dark‐grown Spruce Seedlings
Authors: OKU TATSUO , TOMITA GIITI
Published: April 2006

Plastids prepared from dark‐grown spruce seedlings showed a negligible activity of photosystem II, and no fluorescence variation was observed during actinic illumination. The photosystem II reaction centre, however, was present in primary thylakoids. Exposure of such seedlings to continuous light induced the development of photosystem II activity via three stages (rapid, lagged and gradual), and the variable fluorescence appeared. The rapid development of photosystem II may be attributed to the activation of the oxygen‐evolving system, possibly the manganese‐catalyzing site, and the lagged and gradual developments may be closely related to the formation of thylakoid membranes and their assembly to grana.
Changes in Gibberellin‐Like Substances and Indole‐3‐Acetic Acid in Picea abies during the Period of Shoot Elongation
Authors: DUNBERG ARNE
Published: April 2006

Grafted clones of Picea abies (L.) Karst. were used for the study. A very rapid and conspicuous rise in the content of gibberellin‐like substances chromatographically similar to gibberellin A1, and of indole‐3‐acetic acid, occurred during the brief period of most rapid shoot elongation. A few days later, when the shoot growth had terminated, very small amounts of both compounds could be detected. The changes in the qualitative pattern of gibberellin‐like substances were consistent with a suggested interconversion pathway leading from non‐polar to increasingly polar compounds