bluuebunny/crossref_metadata_2025 huggingface dataset:
MOVEMENT OF GROWTH REGULATORS IN PLANTS
Authors: McCREADY C. C. , JACOBS W. P.
Published: May 2006

Summary

The movement of radioactivity added in the form of indoleacetic acid (as the natural hormone) or as 2,4‐dichlorophenoxyacetic acid (as a synthetic growth regulator) was followed in segments cut from petioles of Phaseolus vulgaris.

The movement of 14C added as IAA was strongly basipetally polar, although significant amounts moved acropetally during 24 hours. The velocity of basipetal movement was 6 mm/hour for IAA‐[14C], and was the same for donor concentrations of 5 or 50 μM. The flux increased with increasing concentration in the donor blocks, but a progressively smaller percentage of the applied radioactivity was transported.

2,4‐D‐[14C] was found to have very similar transport properties to those of IAA‐[14C], except that its velocity of basipetal movement was much less, namely 1 mm/hour. After correction had been made for the much slower net loss of 2,4‐D from its donor blocks, the acropetal movement of the 14C from the two substances was essentially the same.
THE LIVING WOOD FIBRES OF TAMARIX APHYLLA AND THE CHANGES OCCURRING IN THEM IN TRANSITION FROM SAPWOOD TO HEARTWOOD
Authors: FAHN A. , ARNON N.
Published: May 2006

Summary

The viability of the fibres of Tamarix aphylla has been examined by various methods. It has been concluded that the wood fibres retain their living protoplasts for the same period as the wood parenchyma and ray cells, i.e. 16–21 years. The first structures to disappear from the fibres, parenchyma and ray cells were the starch grains (seventh to thirteenth growth ring, as counted from the cambium). The fourteenth to eighteenth growth rings were the last to show positive tetrazolium tests. In the last step before final heartwood production (sixteenth to twenty‐first growth ring), the disintegration of the nuclei occurred.
THE EPIGYNOUS GLANDS OF ZINGIBERACEAE
Authors: RAO V. S.
Published: May 2006

Summary

Robert Brown's interpretation of the epigynous glands of Zingiberaceae as derived from two out of the three members of an inner androecial whorl, the third member being the posterior functional stamen, has been held as probably correct for many years. Studies on many members of this family, both Indian and foreign, proved that the epigynous glands in this family are special vascularized upward growths from intramarginal portions of the carpels. These portions more or less correspond to two of the three septa of the ovary. The glands are anterolateral in position. Abnormal flowers of many species confirmed the conclusions drawn from normal flowers.
PLANT GROWTH AND THE AERIAL ENVIRONMENT
Authors: HUGHES A. P. , EVANS G. C.
Published: May 2006

Summary

The analytical methods developed in the earlier papers of this series are applied to the effects of daylength on the pattern of growth under controlled environmental conditions, with particular reference to ontogenetic drifts. Longer days are found to decrease the leaf weight ratio (8–16 hours by 9%, 16–24 hours by 8%), confirming suggestions from the field observations. Unit leaf rate is nearly proportional to daylength, and if allowance be made for respiration, at a fixed light intensity the daily addition of dry weight per unit leaf area is closely proportional to daylength, in spite of changes in plant form and leaf structure. At a fixed total dry weight of plants grown under fixed conditions of temperature and spectral composition, the specific leaf area is found to be much more closely associated with unit leaf rate than with light intensity or total daily light. Apart from ontogenetic changes, the relationship appears to be influenced by daylength, temperature and the spectral composition of the light. The possibilities of a direct causal relationship are discussed, and the consequences of some anomalous observations are considered. Changing daylength produces changes in unit leaf rate, specific leaf area and leaf weight ratio which have compensatory effects on relative growth rate: at a fixed light intensity an increase of the daylength from 8 to 16 to 24 hours produced increases in relative growth rate of about 20 % and 4 % only. The ontogenetic drifts of dry‐matter content of leaf, stem and root follow their characteristic pattern, higher values being associated with higher unit leaf rates.

It is concluded that the growth pattern of the plant is very closely bound up with the rate of accumulation of new material per unit leaf area, over a considerable range of leaf structure. It is noteworthy that Impatiens parviflora was found to make normal growth in constant temperature and humidity conditions with continuous light and flowered normally in 8, 16 or 24 hour days.
THE EFFECT OF AMINO ACIDS ON GROWTH AND SPORULATION OF ASPERGILLUS FLAVUS AND THEIR CARRY‐OVER FOR SUBSEQUENT SPORE GERMINATION
Authors: GROVER RAJENDRA K.
Published: May 2006

Summary

Aspergillus flavus utilized amino nitrogen source better than nitrate, nitrite, or ammonium nitrogen sources. With casein hydrolysate as nitrogen source, optimum growth was obtained at 100 μg N/ml concentration when incubated for 8 days at 24–26° C. Using ten different amino acids singly or in mixture in Czapek's synthetic basal medium at a concentration of 100 μg N/ml, the mycelial yields were higher when the basal medium contained L‐arginine, glycine, DL‐leucine, DL‐methionine or the mixture of ten amino acids, than when casein hydrolysate was used. Abundant sporulation was obtained when the basal medium contained glycine, DL‐leucine or DL‐methionine. Spores harvested from media containing single amino acids germinated very poorly, although spores harvested from media containing casein hydrolysate, when germinated in individual amino acids, showed good germination in β‐alanine, L‐arginine, glycine, DL‐leucine, DL‐methionine and L‐tryptophane. When one of the ten amino acids was omitted from the basal medium, growth response was poor when any of L‐arginine, glycine, DL‐leucine, or DL‐methionine were absent; germination of spores harvested from media devoid of β‐alanine, glycine, DL‐leucine, DL‐methionine or L‐tryptophane was significantly poor. The combination of one or more amino acids did not show any additive effect, but each amino acid seemed to act independently. The carry‐over effects of the amino acids reflected in subsequent spore germination was conspicuous with β‐alanine, glycine, DL‐leucine, DL‐methionine and L‐tryptophane. These five amino acids when used alone or in combination with each other in the basal medium, produced spores which germinated normally; L‐tryptophane seemed to be the most important amino acid among these, as its absence in the medium markedly affected spore germination.
PHYLLOTAXIS AND APICAL GROWTH
Authors: CUTTER ELIZABETH G.
Published: May 2006

Summary

Apical size, phyllotaxis index and the rate of leaf inception were compared in spiral and bijugate specimens of Dryopteris from the same collection and were found to be similar. Apices were laid bare and maintained under observation in the laboratory for periods of up to 9 months; during this time the bijugate specimens became spiral, as previously reported. Exploratory experiments on the bijugate genus Dipsacus indicate that treatment with gibberellic acid leads to increased internodal elongation and a slight increase in the mean angle of divergence. Removal of young developing leaves and leaf primordia leads to an increase in the rates of leaf inception and development. These observations are discussed in relation to the earlier observations and experiments of Snow. The conclusion is reached that while apices with different systems of phyllotaxis may be of similar size and have similar rates of leaf formation and radial growth, progressive changes in various rates of growth may nevertheless lead to changes in phyllotaxis by modifying the relationships between successive leaf primordia. Vertical as well as radial and tangential growth should be taken into account.
THE ANTHROPOGENIC FACTOR IN VEGETATIONAL HISTORY
Authors: TURNER JUDITH
Published: May 2006

Summary

Vertical series of pollen samples from raised bogs at Tregaron, Cardiganshire and Whixall Moss, Shropshire have been analysed and several of the crucial horizons dated by radiocarbon measurements, thus showing some of the vegetational changes which have occurred in the two regions and their approximate duration. These changes are probably the result of human influence during the last few thousand years, and at Tregaron this interpretation is supported by both surface sample analyses and the historical evidence for the changes in the agricultural practices of the area. The different ways and extent to which man modified or determined the vegetation are discussed.
THE INFLORESCENCE OF FAGUS AND CASTANEA, AND THE EVOLUTION OF THE CUPULES OF THE FAGACEAE
Authors: BRETT D. W.
Published: May 2006

Summary

The early ontogeny of the female inflorescences of Fagus sylvatica and Costarica satva is described together with some other features of the inflorescences and flowering shoots.

The mode of ontogeny of the inflorescences in these species suggests that the two types of cupule are exactly comparable, and that the segments of the cupules (free in Fagus, united in Castanea) are referable to the normal cymose branching of the inflorescence. This is also supported by the vascular organization in the cupules of these species and of Nothofagus. It is, therefore, concluded that the cupule segments in these genera are sterile axes of the next higher order in the dichasium above the flowers they enclose. Thus a single flower is enclosed in a cupule consisting of only two segments (Nothofagus, Castanea), three flowers in a cupule of four segments (Fagus with the primary flower absent, Nothofagus, Castanea), and so on.

It has been possible to apply this interpretation to the various forms of cupule occurring throughout the Fagaceae, and by so doing certain important evolutionary trends have been recognized which have suggested a more natural basis for classification and the need to re‐define some genera.

The status of the cupule of Fagus as the primitive type is upheld by a general lack of specialization in this genus as regards secondary xylem, cotyledons, some floral characters, and the manner in which the inflorescences are borne. Geographical distribution is briefly considered in this connection.

General phylogenetic results of this analysis are expressed in the following proposed subdivision of the Fagaceae:

Subfamily I Fagoideae

Subfamily II Castaneoideae

Tribes

i. Castaneae

ii. Lithocarpeae

iii. Pasanieae

iv. Querceae
A BIOCHEMICAL APPROACH TO SOME TAXONOMIC PROBLEMS IN THE GENUS COPROSMA
Authors: TAYLOR A. O.
Published: May 2006

Summary

A limited biochemical investigation of the polyphenols precipitated by lead acetate and present in extracts of Coprosma robusta, C. propinqua var. lattuscula, C. propinqua var. propinqua and interspecific hybrids of these has suggested that:

(1) C. propinqua var. latiuscula may have arisen by repeated back crossings of C. propinqua on hybrids of an original C. robusta × C. propinqua var. propinqua swarm.

(2) Rapid, quantitative analysis of polyphenols, without the identification of components, could prove a great help in the study of hybridization, introgression, species relationships and phylogeny in the genus Coprosma.
PLANT GROWTH AND THE AERIAL ENVIRONMENT
Authors: HUGHES A. P. , EVANS G. C.
Published: May 2006

Summary

A comparison was made between the rooting conditions used previously in this series of investigations (sandy loam with added fertilizers) and a mixture of vermiculite, sand and gravel with culture solution. The principal effect of vermiculite was to increase the leaf weight by 25% for a given total dry weight. This was mainly compensated for by a lower root weight. The specific leaf area of vermiculite plants was 5% lower than for plants of comparable size and unit leaf rate in sandy loam. The overall result was a rise of 20% in leaf area ratio. The unit leaf rate was unaffected by the rooting condition so there was a resultant 20% increase in relative growth rate over that in sandy loam. The second comparison was with Red light from magnesium arsenate tubes (6000–7000 Å). Red light from germination gave excessively spindly plants, but plants grown initially for 10 days in Daylight‐white grew well subsequently in Red. There was no effect of Red light on leaf weight/total dry weight distribution. The specific leaf area and relative growth rate were marginally lower. Red light was converted 20% more efficiently on an incident energy/apparent assimilation basis.
POLLEN ANALYTICAL DATING OF A DERBYSHIRE LANDSLIP: THE COWN EDGE LANDSLIDES, CHARLESWORTH
Authors: FRANKS J. W. , JOHNSON R. H.
Published: May 2006

Summary

An attempt has been made to use the technique of pollen analysis to establish an upper age limit for a geomorphological feature. The results of the analyses are presented and indicate that local geological events can be traced in the pollen diagram against the background of normal ecological development.
SOME FACTORS AFFECTING THE RATE OF ABSORPTION AND UTILIZATION OF IONS BY STEM SEGMENTS
Authors: PALMER J. M. , LOUGHMAN B. C.
Published: May 2006

Summary

When excised epicotyl segments of Pisum are incubated for periods of up to 24 hours in 0.01 M potassium maleate they exhibit a considerable increase in their ability to absorb and esterify phosphate. In comparison, hypocotyl segments of Gossypium and Helianthus subjected to similar treatments show no change in their ability to absorb and esterify phosphate. The difference in response is attributed to differences between the species themselves rather than to their morphological nature. It is possible to reduce the magnitude of the increase in the rate of phosphate uptake occurring in segments of Pisum epicotyls by increasing the phosphate concentration of the outside medium. This reaction closely resembles that which occurs when slices of potato tuber are similarly treated. In contrast to potato slices, the rate of respiration of Pisum epicotyl segments decreased during the incubation period. The increase in the rate of phosphate uptake is accompanied by an increase in the rate of sulphate absorption and protein synthesis. Other results showed that the rate of phosphate absorption by fresh and incubated tissue is limited by different systems. It would appear that the rate of uptake of phosphate by fresh segments is limited by its rate of diffusion into the tissue, whilst that absorbed by incubated segments is limited by the metabolic activity of the segment.
POST‐GLACIAL DEPOSITS AT TARN WADLING, CUMBERLAND
Authors: WALKER D.
Published: May 2006

Summary

The topographic setting and stratigraphy of shallow lake deposits at Tarn Wadling are described. A pollen diagram through the muds indicates their very recent age.
THE AUXIN, 2,4‐DICHLOROPHENOXYACETIC ACID, AS A REGULATOR OF PROTEIN SYNTHESIS AND SENESCENCE IN DETACHED LEAVES OF PRUNUS
Authors: OSBORNE DAPHNE J. , HALLAWAY MARY
Published: May 2006

Summary

Experiments on the hormonal regulation of protein synthesis and senescence in detached leaves of Prunus serrulata are described.

Senescence is associated with a fall in the content of total protein in the leaf, a loss of chlorophyll and an increase in the soluble nitrogenous fractions. Auxins such as n‐butyl ester of 2,4‐dichlorophenoxyacetic acid (2,4‐D) effectively retard these changes when supplied to leaves at particular stages of growth and development. 2,4‐D is found to stimulate oxygen uptake in young and mature leaves, compared with controls, but has little effect upon oxygen uptake of autumn leaves, while protein levels are maintained by the auxin in freshly detached autumn leaves but not in younger leaves, unless they have already been detached for precise periods of time and considerable protein loss has already taken place.

2,4‐D prevents protein loss in autumn leaves by maintaining protein synthesis. The incorporation of [14C] leucine into protein falls by as much as 60% in 7 days in control halves of leaves, but in halves of the same leaves which have been supplied with 2,4‐D, the incorporation of [14C] leucine into protein is sustained at, or above, the original level.

It is proposed that auxins participate in the balance of hormonal factors which regulate the metabolism of protein. They would appear to be essential for maintaining the incorporation of amino acids into protein, and at certain stages of leaf development, they would appear to be limiting for the proper functioning of the processes of protein synthesis.

The results are discussed in connection with known effects of environment on the auxin content of leaves, and with effects of auxins and other plant growth regulators on protein and nucleic acid metabolism.
A DOUBLE SHELL PLANT GROWTH CABINET
Authors: RORISON I. H.
Published: May 2006

Summary

The construction and performance of a plant growth cabinet which stands in an insulated room are described. Its performance does not match that of a closed circuit system, but the uniformity of environmental conditions maintained, despite frequent access, and the ease of access, recommend it to those who need frequent contact with their experimental material. The cost is modest by present‐day standards.
LATE‐QUATERNARY DEPOSITS AT LE MOURA, BIARRITZ, SOUTH‐WEST FRANCE
Authors: OLDFIELD F.
Published: May 2006

Summary

The present paper describes pollen‐analytical and stratigraphic evidence and macroscopic plant remains from Full‐, Late‐ and Post‐glacial deposits at Le Moura, a valley bog near Biarritz, South West France. The last part of the Full‐glacial period probably saw the existence of treeless conditions in the area whilst during the Late‐glacial period, pine (including Pinus uncinata) and tree birches spread into the area and forested episodes alternated with periods of park woodland and steppe‐tundra. In the Late‐glacial deposits at Le Moura, indications of hydroseral and terrestial plant successions intermingle in contrapuntal fashion, and only when a detailed palaeo‐ecological analysis of the evidence was carried out did any satisfactory indication of climatic change during the period emerge. The main Late‐glacial episodes closely parallel those from north‐west Europe, a mild forested phase presumably contemporary with the Allerod (zone II) occurs, preceded and succeeded by less wooded, cooler episodes. A pre‐Allerød climatic oscillation of apparently short duration and narrow amplitude is tentatively detected. Among the Full‐ and Late‐glacial plant records, Armeria sp., Cryptogramma crispa, Centaurea cyanus, Empetrum nigrum, Ephedra cf. distachya, Erica tetralix, Euphorbia amygdaloides, Pinus sylvestris and P. uncinata, Polygonum cf. viviparum and Valeriana dioica may be noted. The Post‐glacial record is incomplete, there being a discontinuity in deposition giving rise to the absence of any records from the whole of the period considered equivalent to British pollen zone VIIb, early zone VIII and late zone VIIa. The dominant woodland species throughout the earlier part of the Post‐glacial period are the oaks and pine, with hazel, whilst alder and beech appear towards the top of the diagram. Other mixed oak forest elements are very scarce. Both the strati‐graphic and pollen‐analytical records show that the end of phase P2 (approximately equivalent to British zone VI) at the site was a relatively dry continental period. Whilst the highest levels of the series include records for recently introduced plants such as maize and a species of cedar, earlier pre‐cultural levels include pollen records of Vitis, Olea, Daboecia cantabrica, Erica vagans and Quercus ilex. The biogeographical significance of the plant records and the palaeo‐climato‐logical reconstructions is briefly discussed.
THE ROLE OF ENDOGENOUS GROWTH SUBSTANCES IN THE FRUITING OF UPLAND COTTON
Authors: DALE J. E. , MILFORD G. F.
Published: May 2006

Summary

Two acidic growth substances, one promoting, the other inhibiting, straight growth of wheat segments were extracted with diethyl ether from cotton fruit of different ages. The changes in concentration of these substances with time were not related to fruit shedding. The addition of the substances to young fruit did not alter either rate, or level, of shedding and it was concluded that these substances are not controlling abscission of fruit, although they may be connected with fruit development.
PHOTOSYNTHETIC AND RESPIRATORY COMPONENTS OF THE NET ASSIMILATION RATES OF SUGAR BEET AND BARLEY
Authors: WATSON D. J. , HAYASHI KEN‐ICHI
Published: May 2006

Summary

The net assimilation rate (E) of a plant population (the mean rate of increase in total dry weight per unit leaf area, measured over a period of 1 or 2 weeks), represents the excess of the rate of photosynthesis of the leaves (P) over the rate of respiration of the whole plants (R), both expressed per unit leaf area (E=P—R). To determine P, photosynthesis was prevented on some days during the experimental period by shading plants, and the effect on E was measured. The plants were held in a controlled environment to ensure that external conditions affecting photosynthesis were the same on all days and effects on change with age in the rate of photosynthesis were avoided by appropriate distribution of the shading days. With these precautions, E was linearly related to n, when n (the number of days when photosynthesis was permitted in an experimental period of 15 days) ranged from 15 to 9. The regression coefficient b of E on n measures the contribution of 1 day's photosynthesis to E, so the photosynthetic component P of EN,the net assimilation rate when photosynthesis is permitted every day in an experimental period of N days, is given by Nb. The respiratory component, R,is estimated by the difference EN—P, or graphically by extrapolating the regression line to n= 0.

This method showed that young sugar‐beet plants had a greater net assimilation rate than barley plants solely because they had a greater rate of photosynthesis of the leaves; the values of the rate of respiration of whole plants for the two species were identical.
PLANT GROWTH AND THE AERIAL ENVIRONMENT
Authors: HUGHES A. P.
Published: May 2006

Summary

The apparent efficiency of conversion of incident light energy (ɛapp/i) by whole plants of Im‐patiens parviflora in a range of natural and artificial light climates has been calculated from growth analysis data. It was found that it ranged from 1.3% in full natural daylight to 7.5% in extreme shade (metal shades transmitting 7% daylight). The corresponding figures for real efficiency, i.e. corrected for respiration losses, ɛtrue/i were 3.0% and 12.5% respectively. In the growth cabinets with light intensities roughly equivalent to 7—15% daylight a combination of two Blue/six De Luxe Warm White fluorescent tubes gave values of ɛapp/i averaging 7.4% for plants grown at 15°C, 5.9% for those at 10°C and 6.5% at 20°C. Four Daylight/four De Luxe Warm White averaged 5.8% at 20°C and Red (magnesium arsenate) at 20°C was highest with 7.7%. Blue tubes gave 6.0% apparent efficiency with plants at 15°C. In all the cabinet experiments and in the extreme shade in natural daylight the plants were small with leaves scarcely overlapping. In more open, natural daylight sites some self‐shading would have occurred. When the efficiency was expressed on a quantum basis, rather than on total energy, and correction for temperature differences applied, there was little difference between Blue, Blue‐white and Red, with Daylight‐white somewhat lower. On the basis of assimilation for a given number of lamps the combinations two Blue/six De Luxe Warm White and four Daylight/four De Luxe Warm White were the best.
THE STRATIGRAPHY AND POLLEN ANALYSIS OF A RAISED PEAT BOG AT LLANLLWCH, NEAR CARMARTHEN
Authors: THOMAS K. W.
Published: May 2006

Summary

Organic deposition commenced at Llanllwch in Zone VI at the site of a Post‐glacial lake. The lake was colonized by reedswamp and succeeded by fen as the lake level was lowered. Before the end of Zone VI a flushing effect of the bog surface allowed Molinietum to develop which was replaced by Callunetum until, in Zone VIIb, probably due to increased precipitation. Sphagnum bog developed. In the raised bog peat a recurrence surface has provided a radiocarbon date of 1200 B.C. Forest destruction began in Neolithic times, and there is evidence for intensive human activity from Norman times to the present.
HEAVY METAL TOLERANCE IN POPULATIONS OF AGROSTIS TENUIS SIBTH. AND OTHER GRASSES
Authors: GREGORY R. P. G. , BRADSHAW A. D.
Published: May 2006

Summary

Populations of Agrostis tenuis can be found growing on a variety of different mine workings in conditions of metal contamination toxic to most higher plants. Samples of such populations together with samples of populations taken from ordinary pastures were tested for tolerance to high concentrations of copper, nickel, lead and zinc by measuring the effect of these metals on the rooting of tillers. The soils in which the populations were originally growing were analysed for each of the four metals and the tolerances of the populations have been related to the levels of the metals in the soils.

In general, the mine populations show remarkable tolerance to the particular metals present in high quantities in the soils of their original habitats: the pasture populations do not show this tolerance. The tolerance is specific, for, except in the case of zinc and nickel, tolerance to one metal is not accompanied by tolerance to any other. There must, therefore, be three specific tolerances in the one species. Individual tolerances can however occur together and this can be related to the occurrence of the two metals together in toxic quantities in the soil.

The tolerances must be genetically controlled but the physiological mechanism involved is not clear. A number of other species were also shown to have populations tolerant to high levels of zinc.
STUDIES IN THE PHYSIOLOGY OF LICHENS
Authors: SMITH D. C. , DREW E. A.
Published: May 2006

Summary

Carbon fixed by photosynthesis in the algal layer can move into the medulla of Peltigera polydactyla within 30 minutes. This movement continues at a steady rate equivalent to 40–50% of the total rate of carbon fixation in photosynthesis, and it can also continue for a time in darkness. Fixed carbon accumulates initially as soluble compounds, especially mannitol, both in the algal layer and in the medulla. Since translocation in the thallus is relatively rapid it follows that the first stage of this process, namely, the transfer of photosynthetic products within the algal layer from an algal cell to its associated fungal hyphae, is also a rapid process.
STUDIES IN THE RESPIRATORY AND CARBOHYDRATE METABOLISM OF PLANT TISSUES
Authors: BARKER J.
Published: May 2006

Summary

Subjecting peas to high pressures of oxygen produced a progressive decrease in CO2 output with accumulation of citrate, pyruvate, alcohol and acetate (Turner and Quartley, 1956; Pritchard, 1961). The present results show that the progressive decrease in CO2 output in high oxygen was also, in general, accompanied by large and continuing decreases in adenosine triphosphate and in the glycolytic intermediates, dihydroxyacetone phosphate, 3‐phosphoglycerate and phosphoenolpyruvate. Fructose diphosphate also decreased more rapidly initially in oxygen than in air in three of the four experiments.

Oxygen poisoning thus appears to ‘block’ partially or completely, certain respiratory pathways, the most important ‘block’ in plant tissues probably being that at aconitase (Pritchard, 1961). The ‘blocks’ are visualized as decreasing both the CO2 output and the rate of formation of adenosine triphosphate. Thus in the present experiments the decreased CO2 output in oxygen was associated with a decrease in content of adenosine triphosphate. The decrease in the content of the latter may in turn reduce the rates of hexokinase and phosphofructokinase phosphoryla‐tion and so cause the observed decreases in contents of fructose diphosphate, and, at late stages, of glucose‐6‐phosphate. The decrease in fructose diphosphate appeared to reduce the rate of glycolysis, as shown by the decrease in the contents of glycolytic intermediates.
CARBOHYDRATE PHYSIOLOGY OF MYCORRHIZAL ROOTS OF BEECH
Authors: LEWIS D. H. , HARLEY J. L.
Published: May 2006

Summary

The presence of several classes of reducing substances in mycorrhizal roots of beech is demonstrated, throwing considerable doubt on the values of ‘easily soluble reducing substances’ which have been used for correlation with degree of mycorrhizal infection by several workers. The soluble sugars of beech mycorrhizas are glucose, fructose, sucrose and trehalose, together with the acyclic polyol, mannitol and two cyclic polyols, myo‐inositol and an unidentified inositol. Trehalose and mannitol are absent from uninfected roots showing their presence to be dependent on fungal infection. Methods for the individual assay of the soluble carbohydrates are presented. The main sugars obtained by acid hydrolysis of the insoluble residue of mycorrhizas are galactose, glucose, mannose, arabinose, xylose, fucose, ribose, rhamnose and a deoxypentose provisionally identified as deoxyribose. The mannose and deoxypentose polymers are absent from beech tissue and deoxyhexose polymers from the fungus. Much of the glucose is derived from fungal glycogen. Mycorrhizas accumulate principally trehalose and glycogen from exogenous glucose and trehalose, and mannitol from fructose and mannitol. The pattern of synthesis from exogenous sucrose is intermediate between glucose and fructose. The results are compared with those obtained for other fungi by other workers and a possible ecologically significant role for mannitol is suggested.
THE DURATION OF THE G1 PHASE OF THE MITOTIC CYCLE AND ITS RELATION TO RADIOSENSITIVITY
Authors: CLOWES F. A. L.
Published: May 2006

The duration of each phase of the mitotic cycle in four regions of the root meristem of Zea mays has been determined by pulse labelling with 3H thymidine. S, G2 and mitosis are similar in length in all the regions, but G1 differs considerably and is largely responsible for the diversity in rates of mitosis. G1 is non‐existent in the cap initials, 151 hours in the quiescent centre, and 2–4 hours in the stele.

These data, together with information on sensitivity to ionizing radiation, suggest that it is the ratio of the lengths of G1 to the rest of the mitotic cycle that decides how resistant a tissue will be to radiation and they lead to a general explanation of the law that rapidly dividing cells are more susceptible than slowly dividing cells. The extreme sensitivity of the cap initials and the high resistance of the quiescent centre are correlated with the brevity of G1, in the former and the prolongation of G1 in the latter. The fraction of the mitotic cycle spent in G1 (when each nucleus has only the 2C amount of DNA) therefore probably determines both radio‐sensitivity and rates of division.
UPTAKE OF 22Na BY INTACT SEEDS
Authors: GIFFORD G. F. , NELSON E. D.
Published: May 2006

When the intact seeds of forty‐two species were exposed to a salt‐isotope solution containing 22Na it was found that about 75% of the different seeds showed signs of accumulation of the 22Na. All halophytes and species associated with halophytes, with one exception, displayed the above‐mentioned pattern. The seeds responded to a 24 hour exposure period by either decreasing, remaining essentially the same, or increasing in uptake of 22Na as compared with an 8 hour exposure period. Surface area of the seeds, as determined for twenty species, had no apparent relationship to 22Na uptake. The time interval to first germination showed a relationship to sodium uptake for grasses only, and this was valid only up to a 48 hour germination period. The two grasses Oryzopsis hymenoides and Secale montanum. were for some reason an exception to the above trend. The per cent total germination of the seeds after 149.5 hours showed no relationship to 22Na uptake.
AN IAA‐INDUCED STIMULATION OF GROWTH OF ROOTS OF VICIA FAB A PREVIOUSLY TREATED WITH COLCHICINE
Authors: DAVIDSON D. , MACLEOD R. D. , TAYLOR JANET
Published: May 2006

Roots of Vicia faba were treated with a 0.02% solution of colchicine for 2 hours. Some roots were also treated, 22 hours later, with 10‐6 M IAA for I day. All beans were grown on for a further 6 days and the total growth of primary and lateral roots was determined.

Primary roots treated with colchicine and then IAA showed significantly greater growth than roots treated only with colchicine. Lateral roots produced by the treated primary roots showed significantly less growth when treated with colchicine and IAA than when treated only with colchicine. Primary‐ roots treated with colchicine and IAA had fewer polyploid cells, in division, than roots treated only with colchicine, indicating that recovery of the diploid condition is related to the rate of root growth.

IAA treatment does not produce an immediate stimulation of growth; no effect was seen for 3 days. Its effect appears to be one of facilitating the normal mechanisms by which an apical meristem recovers from a colchicine treatment. The stimulation of root growth by concentrations of IAA that are normally inhibitory leads us to conclude that one result of a treatment with colchicine is a reduction in the level of natural auxin in a root.
PLANT GROWTH AND THE AERIAL ENVIRONMENT IX. A SYNOPSIS OF THE AUTECOLOGY OF IMPATIFNS PARVIFLORA
Authors: HUGHES A. P.
Published: May 2006

Many features discussed in detail in earlier papers are correlated with particular emphasis on (i) the partition of dry material into leaf, stem and root, (ii) the leaf auxochrone, (iii) the interrelationship of flower opening, leaf number and vascularization, (iv) the extension of the hypocotyl, (v) ontogenetic drifts in specific leaf area, (vi) the relationship between specific leaf area and unit leaf rate, and (vii) a general synopsis in the form of a flow diagram. The flow diagram summarizes the overall autecology of the species and indicates the relative importance of factors affecting dry‐weight distribution, leaf expansion and the inverse relationship between specific leaf area and photosynthesis (as measured by growth analysis), in determining the growth rate of the plant in various conditions.
THE INHERITANCE OF MATING TYPE IN DESMIDS
Authors: BRANDHAM P. E. , GODWARD M. B. E.
Published: May 2006

Fertile cultures of eight species of desmids have been established. Six are homothallic, one is heterothallic and one has homothallic and heterothallic varieties. Two incompatible pairs of mating types have been found in the last species (Cosmarium botrytis). Incompatibility and isolation of mating types in natural habitats may be responsible for the apparent sterility of many species of desmids. Conjugation between two morphologically distinct varieties has been induced. The inheritance of mating type has been studied. A lethal factor affecting this inheritance has been noted in one species. Mechanisms for the inheritance of the lethal factor are suggested.
INTERACTION OF GIBBERELLIC ACID AND INDOLE‐ACETIC ACID IN THE DIFFERENTIATION OF WOUND VESSEL MEMBERS
Authors: ROBERTS L. W. , FOSKET D. E.
Published: May 2006

Summary

Sucrose‐agar media supplemented with indole‐acetic acid (0.05 ppm) and gibberellic acid (0.05 or 0.5 ppm) increased the formation of wound vessel members in transverse tissue slices excised from the second internode of Coletis blumeni (Bentb.) stems. The treated tissue slices showed the initiation of cambial activity, whorls of wound vessel members in the cortex, and adventitious root formation after prolonged incubation. Also, incompletely differentiated secondary xylem cells and wound vessel members were observed which exhibited relatively thin secondary wall striations, and stained weakly with phloroglucinol‐HCl and Safranin O.
THE UTILIZATION OF ACETATE BY NEOCOSMOSPORA VASINFECTA
Authors: BUDD K.
Published: May 2006

Summary

Mycelium of Neocosmospora vasinfecta, harvested during active growth, was incubated for up to 10 minutes in dilute solutions of [1‐14C]acetate or [2‐14C]acetate. Radioactivity in the respiratory CO2 and in identifiable compounds extracted from the mycelium was measured. Closely similar results were obtained with both [1‐14C]acetate and [2‐14C]acetate except for the loss of radioactivity to CO2, which took place much more rapidly from the [1‐14C]acetate. Water‐soluble compounds accounted for over 80% of the radioactivity of the mycelium. With incubation periods of up to 2.5 minutes, most of the radioactivity in the water‐soluble material was associated with organic acids, whereas with longer incubation, the label in basic compounds predominated, Glutamate was consistently the most heavily labelled basic compound, with small amounts of radioactivity in glutamine and aspartic acid. Radioactivity in the organic acid fraction was practically confined to citric acid after 2.5 minutes incubation; succinic, malic and other acids were significantly labelled after 10 minutes. The specific activities of these acids after 10 minutes decreased in the order citrate, succinate, malate, suggesting their involvement in the tricarboxylic acid cycle.

The results are discussed in relation to the importance of the tricarboxylic acid cycle in acetate utilization, nitrogen assimilation and respiration.
THE REPRODUCTIVE CAPACITY OF JUNCUS SQUARROSUS
Authors: WELCH D.
Published: May 2006

Summary

The six attributes which govern the reproductive capacity of Juncus squarrosus have been measured in plants from a variety of habitats at different altitudes, mainly in an area of moorland at the head of Teesdale in the north Pennines.

It was found that about eighty inflorescences per square metre were produced, but this number was reduced in adverse conditions such as at high altitudes in unfavourable seasons, or when there was a spring drought. The average number of florets per inflorescence varied from about six on well‐drained sites and at high altitudes to twenty‐two in moist conditions at lower levels. Up to 60% of the florets ripened into capsules, but in 1962, a very poor summer, less than 10% ripened at 550 m, and in 1963 only 19% ripened at 700 m. Altitude and the seasonal climate also had a marked effect on the number of seeds per capsule, and their viability. In good conditions fifty seeds developed per capsule, and viability approached 100%, but in 1962 at all altitudes, and in 1963 at high levels, values were much lower than this. Normally most of the seeds produced are dispersed, but close to the limit of capsule maturation the capsules may never open.

The total number of viable seeds dispersed was estimated. Even in 1962 about 150 viable seeds per m2 were dispersed at 550 m, and in 1963 the figures varied between 2000 and 13,500 seeds per m2, according to the soil conditions. At the lower levels more seeds may be produced but this is counterbalanced by losses caused by larvae of the moth Coleophora alticolella.
POLLINATION AND BREEDING BEHAVIOUR IN THE TRIFOLIUM RUEPPELLIANUM COMPLEX IN KENYA
Authors: BOGDAN A. V.
Published: May 2006

Summary

The pollination and breeding behaviour of Trifolium baccarinii, T. mattirolianum and of four varieties of T. rueppellianum, all allied taxa constituting the T. rueppellianum complex, were studied at the National Agricultural Station, Kitale, Kenya. T. baccarinii and varieties minimiflorum and lanceolatum of T. rueppellianum have cleistogamous flowers which need no treatment for seed formation similar to var. preussii which, however, opens its flowers during the flowering. Var. rueppellianum does not form seed without tripping which, in the field, is done by bees.

A recessive white‐flowering form was used for assessing the amount of natural cross‐pollination, which was found to be from under 1% to 10%. Two unusual forms: erect and giant were also studied.

T. mattirolianum sets seed only under eross‐pollination and T. rueppellianum may serve as a male parent. F1 crosses of T. mattirolianum×T. rueppellianum form seed without cross‐pollination although tripping is necessary.
THE GERMINATION OF POLYGONUM CONVOLVULUS L.
Authors: TIMSON J.
Published: May 2006

Summary

The dormancy found in fresh nuts of Polygonum convolvulus L., which persists in nuts stored dry in the laboratory, and their germination has been studied. Methods of breaking this dormancy by means of low temperature treatment and by the use of gibberellic acid, thiourea, uracil, thymine, adenine, guanine and cytosine are described. A method of recording germination ability which weights the rapid germination necessary for the establishment of this species in nature has been used. Mechanisms of the dormancy and dormancy‐breaking are discussed.
THE MOVEMENT OF RUBIDIUM ACROSS THE ROOT OF HORDEUM VULGARE (L)
Authors: CROSSETT R. N.
Published: May 2006

Summary

An automatic system is described for the continuous measurement of absorption and translocation of radioactive nuclides by living plants growing in a controlled environment. The system is suitable for studying the behaviour of nuclides emitting β particles in the energy band between 0.5 and 2.5 MeV. The reliability and precision of the system are discussed.

Experiments on the absorption and translocation of 86Rb by 10‐14‐day‐old seedlings of barley are reported. It was found that when 86Rb was absorbed from 10−5 M 86RbNO3 the rate of movement into the shoot (translocation) increased with time, but that when absorption was from a higher concentration of RbNO3 a constant rate of translocation was observed after the initial rise during the first 3 hours. When radioactive seedlings were placed in an inactive 10−5 m RbNO3 solution no loss of 86Rb to the solution was detected, but 86Rb moved to the shoot, the decrease of 86Rb in the root following first‐order kinetics. When radioactive seedlings were transferred to a 10−4 m RbNO3 solution more complex kinetics of decrease in 86Rb in the root were observed. The findings are discussed and found to be compatible with a simple two‐compartment model of the root.
CHANGES IN MITOTIC INDICES IN ROOTS OF VICIA FABA L.
Authors: MacLEOD R. D. , DAVIDSON D.
Published: May 2006

Summary

Roots of Vicia faba were treated with IAA (6.26 × 10−4 m) for 3 hours and fixed immediately or 5, 11 or 23 hours later. Mitotic indices (MI) fell in these treated roots; the decrease was apparent at 5 hours and was significant at 11 and 23 hours, indicating that IAA was inhibiting some interphase processes.

Other V. faba roots were treated with colchicine (0.025%) or IAA (4.7 × 10−4 m) or they were given successive treatments with colchicine or IAA and fixed up to 201 hours later. (a) In roots treated with colchicine, the MI rose for the first 24 hours and then fell to values below 1, where it remained for several days. (b) In roots treated with IAA, a fall in MI was observed within the first 2 days but it eventually returned to normal. This recovery of normal levels of mitotic activity was dependent upon the age of the roots at the time of treatment, the youngest roots died after treatment with IAA while older roots recovered completely. (c) Roots treated with IAA 24 hours after treatment with colchicine showed a decrease in MI in the following 24 hours similar to that found in roots treated only with colchicine. However, the MI of these roots subsequently rose to values that were not significantly different from those of the controls, i.e. there is an IAA induced stimulation of mitotic activity.

Polyploid cells are found in division following treatment with colchicine. Changes in the frequencies of polyploid metaphases occur if roots are also treated with IAA, suggesting, as we have seen above, that IAA affects the duration of mitotic cycles.

These results provide further evidence that a decrease in the endogenous levels of auxins occurs in roots treated with colchicine and this decrease can be partially restored by exogenous auxin. It is suggested that the changes in levels of mitotic activity in treated meristems is due, at least in part, to the colchicine induced fall in endogenous auxins.
THE MANIFOLD EFFECTS OF GENES AFFECTING FRUIT SIZE AND VEGETATIVE GROWTH IN THE RASPBERRY
Authors: JENNINGS D. L.
Published: May 2006

Summary

A mutation found in the raspberry variety Mailing Jewel had bigger fruiting laterals, flowers and fruits than the parent stock. The results of breeding experiments were consistent with the hypothesis that the change was caused by mutation of a single gene from the homozygous to the heterozygous state, and that the gene concerned has functions whose effects are seen at each stage of development. These effects were to depress slightly the amount of vegetative, or first year's, growth and to increase the amount of reproductive, or second year's, growth. It is suggested that genes of similar function may account for differences which distinguish the raspberry from certain related species. The mutant gene is useful for plant breeding purposes. Its possible effects on the physiology of the plant are also discussed.
THE MANIFOLD EFFECTS OF GENES AFFECTING FRUIT SIZE AND VEGETATIVE GROWTH IN THE RASPBERRY
Authors: JENNINGS D. L.
Published: May 2006

Summary

Seedlings with ‘miniature’ fruits or with ‘blind’ fruiting laterals were found to segregate when the raspberry varieties Norfolk Giant and Baumforth's Seedling B, were inbred. It was concluded that in each family both abnormalities were caused by the same recessive gene (l2), which had pleiotropic effects on each stage of growth. Its action was to decrease growth by amounts which increased progressively with each stage of the plant's development. The effects of the gene are compared and contrasted with those of gene L1.