bluuebunny/crossref_metadata_2025_split huggingface dataset:
GIBBERELLIN ANTAGONISM BY MATERIAL FROM A BROWN ALGA
Authors: JENNINGS R. C. 
Published: May 2006

SummaryThe ethyl acetate‐soluble, acidic fraction extracted from sporophytes of Ecklonia radiata contains material inhibitory to the growth of dwarf maize plants treated with gibberellic acid, but which did not affect the growth of maize plants not treated with gibberellic acid. Saturation concentrations of gibberellic acid did not overcome the inhibition. It is concluded that the inhibitory material was functioning as a specific antagonist to gibberellin‐controlled growth in maize and that a non‐competitive component was present.The inhibitory extract was shown to reduce the growth of gametophytes of Ecklonia when applied to cultures at physiological concentrations. This suggests an endogenous growth regulatory function for the active material, perhaps as a gibberellin antagonist. Higher levels were extracted from blade tissue than from stipe plus transition region tissue.
THE ECOLOGICAL DISTRIBUTION OF MYCORRHIZA OF BEECH
Authors: MEJSTRIK V. , DOMINIK T. 
Published: May 2006

SummaryThe following conclusions may be drawn from the determination of mycorrhizal spectra on beech at eight localities in Czechoslovakia. Altogether thirty‐three sub‐subtypes of ectotrophic mycorrhiza on beech were described in Czechoslovakia, of which seven are entirely new, namely: De, Df, Ed, Ee, Ek, Ih and Ik (see Dominik, 1959). Maximum frequencies of ectotrophic mycorrhizas were found down to a depth of 15–30 cm. With increasing depth the number of short roots and mycorrhizas decreased and the mycorrhizal spectrum narrowed. The quantities and types of humus were a decisive factor influencing mycorrhiza formation. Subtype E was the most frequent (20.26%) of all mycorrhizas. The richest mycorrhiza spectrum of four comparable localities was at Albrechtice in the Ore Mountains where fourteen sub‐subtypes of ectotrophic mycorrhiza were found despite a heavy deposition of industrial ash from power plants and a high concentration of SO2 in the atmosphere. No differences were found in the mycorrhiza variety between beech saplings (5–10 years) and older trees (over 100 years), nor was the occurrence of individual mycorrhiza strains characteristic of beech trees of different age.
AN IPSWICHIAN PEAT RAFT IN GLACIAL TILL AT HUTTON HENRY, CO. DURHAM
Authors: BEAUMONT P. , TURNER J. , WARD P. F. 
Published: May 2006

SummaryA peat raft found in a sequence of glacial deposits at Hutton Henry, Co. Durham, is described. The peat contained quantities of Carpinus pollen and is therefore Jpswichian in age. From the position of the peat it is concluded that the Upper Till sheet of eastern Durham is of Weichselian age.
POLLEN DIAGRAMS FROM THE NORTH YORK MOORS
Authors: SIMMONS I. G. 
Published: May 2006

SummaryFour pollen diagrams from the Egton High Moor watershed of the North York Moors are described. Two are from infilled sub‐glacial meltwater channels and two from blanket peat. The channel mires developed from woodland through fen peats (dominated by Thelypteris) to acidic bogs during Post‐glacial times. The uplands started to accumulate peats in late zone VI or early zone VIIa. The stratigraphy suggests that fire as well as paludification was involved in the inception of blanket peat. Clearance phenomena are observed in pre‐Ulmus decline times and some of these are tentatively assigned to Mesolithic activity. In the upper portions of the diagrams massive forest clearance is seen and this is probably due to Bronze Age occupation. The representation of Tilia is discussed in its regional context and the possible significance of the Fagus percentages in the light of Tauber's work is briefly mentioned.
VARIATION IN CERCOCARPUS IN SOUTHERN CALIFORNIA
Authors: SEARCY KAREN B. 
Published: May 2006

SummaryPresent‐day Cercocarptis leaves are compared with fossil leaf impressions from Miocene, Pliocene and Pleistocene floras of California and adjacent states in order to interpret the present pattern of geographic variation in leaf size in southern California. The various taxa described have had separate histories since at least the Miocene, and have remained morphologically stable despite changes in the climate and topography in the region.
ZOSTEROPHYLLUM FROM THE LOWER OLD RED SANDSTONE OF SOUTH WALES
Authors: EDWARDS DIANNE 
Published: May 2006

SummaryThe plant is found in the Senni Beds of the Lower Old Red Sandstone of South Wales (= Siegenian‐Emsian). Details of the morphology and anatomy of both sterile and fertile parts are given, together with an account of the spores. The plant is thought to be closely related to Zosterophyllum fertile erected by Leclercq in 1942, but as this species is known from a single fructification, it is concluded that the new plant, for the moment, should be called Z. cf. fertile.
A NOTE ON TRACE ELEMENTS FOR THE GROWTH OF NIGROSPORA ORYZAE (B. AND BR.) PETCH
Authors: RAWLA G. S. 
Published: May 2006

SummaryOut of sixteen trace elements tested for the growth of this fungus, only Fe, Zn and Mn are found essential whereas the rest of the trace elements are not found essential for its growth. The fungus requires an optimum concentration of 1–10 ppm Fe and Zn and of 100 ppm Mn for its growth. Concentrations of the essential trace elements beyond the optimum level inhibit the growth of this fungus progressively. However, 200 ppm Zn completely inhibits the growth of this fungus.
THE EFFECT OF TEMPERATURE ON THE TRANSLOCATION OF PHOSPHORUS BY RHIZOPUS STOLONIFER
Authors: LYON A. J. E. , LUCAS R. L. 
Published: May 2006

SummaryThe effect of temperature on the rate of phosphorus translocation, on the uptake and metaholism of phosphate and on respiratory rate of Rhizopus stolonifer, has been studied. Over the temperature range 20–30° C the rate of phosphorus translocation is greatest at 20° C and lowest at 30° C. The rate of oxygen uptake is greatest at 25° C. The rate of phosphate uptake does not vary significantly over this temperature range, but the proportion of ahsorhed phosphate present as orthophosphate bears a direct relationship to the rate of phosphorus translocation. These results are consistent with the view that phosphorus may be translocated in the form of orthophosphate.
UPTAKE OF IONS BY ROOTED WILLOW CUTTINGS
Authors: BOVIS C. P. , BRIGGS G. E. 
Published: May 2006

SummaryThe uptake of radioactive ions from solutions into the root, wood and bark of the stem, and leaves of rooted willow cuttings has been investigated. The salts used were Na82 Br, K131 I, 42KCl and 86RbCl. In none of the experiments did the amount of isotope even in the lowest part of the stem reach the value to be expected if its concentration in the water‐free space there was equal to that outside the roots. After 9 days when 520 ml had been transpired hy a plant weighing 34 g the estimated concentration of 86Rb in the water‐free space of the wood was less than one‐seventh of that outside the roots. Transport to the bark appears to be via the wood. For the stems plus leaves the ratio of uptake of an ion to that of water was less than the concentration outside except in one experiment, which was exceptional in other respects. The gradient of concentration in the wood and the contribution of diffusion to uptake are discussed.
THE UPTAKE AND ACCUMULATION OF COPPER BY BECIUM HOMBLEI (DE WILD.) DUVIG. & PLANCKE
Authors: REILLY C. 
Published: May 2006

Summary Becium homblei, a flowering plant of the family Labiatae indigenous to Zambia, has been found to grow on soils contaminated with high levels of copper. The plant is capable of accumulating more than 100 ppm of the metal in its leaves and roots. Serial extraction of the plant tissue with various solvents has shown that much of the accumulated metal is tightly bound within the plant and is not in free solution in ionic form. The finding that increased copper content is accompanied by an increase in total nitrogen suggests that the metal may be bound as a complex with protein in the plant tissue.
THE SIGNIFICANCE OF CLINAL VARIATION IN DACTYLIS MARINA BORRILL†
Authors: BENSON MAUREEN , BORRILL MARTIN 
Published: May 2006

SummaryClinal variation was studied in four populations of Dactylis marina Borrill from the Portuguese coast. Differences in the balance of leaf epidermal characters are found to be associated with differences in climatic conditions. In particular, the presence of epidermal papillae was found to affect the association between frequency of epidermal cells and stomata.The presence of a cline in papillosity, a character known to be recessive, suggests that this type of epidermal cell may play an important physiological role in the life of the plant.The effects of epidermal morphology are discussed, and suggestions made for further study.
STOLON INITIATION AND DEVELOPMENT IN SOLANUM TUBEROSUM L.
Authors: LOVELL P. H. , BOOTH A. 
Published: May 2006

SummaryPlants of cv. Majestic were grown in solution culture in tanks so designed that the development of the normally subterranean stolons could be followed individually by daily observation and measurement. An analysis is made of the pattern of stolon emergence, elongation, branching and tuber initiation. The effects on stolon development of reduced mineral nutrient supply, decapitation of the main shoot apex and exclusion of light from the developing shoot were also examined.
A TAXIMETRIC STUDY OF AN ANGIOSPERM FAMILY: GENERIC DELIMITATION IN THE CHRYSOBALANACEAE
Authors: PRANCE G. T. , ROGERS D. J. , WHITE E. 
Published: May 2006

SummaryThis is an account of how some taximetric techniques were used in a study of generic delimitation in the Hirtelleae, one of the two tribes of an Angiosperm family, the Chrysobalanaceae. It is probably the first account of a study in which the use of such techniques has formed part of an original monographic study of a sizable group of higher organisms above the species level.A preliminary study based on an examination of herbarium material of all 254 species suggested considerable departures from previously accepted generic concepts, chiefly involving the splitting of Parinari into four, possibly as many as eight, smaller, more clearly defined units. The character‐states of twenty‐one characters were recorded for all species (140) for which the material was sufficiently complete. These data were subjected to four taximetric analyses—two principal component analyses and two clustering analyses—which are described and discussed. All four clearly confirmed the heterogeneous nature of Parinari. Most of the tentative groupings were confirmed by all or most of these analyses. Accordingly the following segregates from Parinari are recognized: Bafodeya, Cyclandrophora, Kostermanthus, Exellodendron, Maranthes and Neocarya. For a few species the results obtained by the taximetric analyses are less unanimous; the reasons for this are discussed. Indecisive results were obtained for only two species.All four analyses yielded taxonomically meaningful results and provided insights into the taxonomic situation, though to different degrees. The Wirth, Estabrook and Rogers model gave the most useful results and displayed them in the most informative way. Since much confusion exists concerning the aims and methods of taximetrics, we have attempted to explain our own position. Rather than expect the reader to take on trust our statements concerning the contribution of taximetrics to our study, we have given a full account of the history of the problem and of our tentative taxonomic conclusions before the analyses were done, and have shown how they were confirmed or modified in the light of the results of the different methods.
SUCCINATE METABOLISM IN RELATION TO TUBER STORAGE AND TUBER DEVELOPMENT IN SOLANUM TUBEROSUM
Authors: LOVELL P. J. , BOOTH A. 
Published: May 2006

SummaryFreshly‐cut slices of mature tubers liberated little 14CO2 from [2–3 14C] succinate even when sprouting after 9 months storage at 5° C. Output from 24‐hour washed slices was considerable; it increased in amount with increasing length of storage period and was enhanced when light was excluded during washing and incubation in succinate.A comparison was made between non‐tuberizing stolon tips and young tubers taken within a day or so of tuber initiation. The fresh stolon tips released an appreciable quantity of CO2 from succinate, much less after washing. Fresh young tubers liberated much less 14CO2, slightly more after washing. Although this indicated that the tricarboxylic acid‐ (TCA‐) cycle block might arise soon after initiation, the qualitative distribution of the label in tissue extracts showed stolon tips and young tubers to be similar to each other and distinct from mature tuber tissue.
MERISTEMS AND GROWTH CONTROL IN ASCOPHYLLUM NODOSUM (L.) LE JOL.
Authors: MOSS BETTY 
Published: May 2006

SummaryFrom a study of young plants of Ascophyllum nodosum raised from fertilized eggs it has been shown that an apical cell differentiates from the basal cell of one of a group of apical hairs. This apical cell builds up an active meristem around itself. This meristem and its subsequent products function throughout the life of the thallus. Generally the apical meristem dichotomizes once a year. Behind it a succession of lateral nodes develop during spring and summer. These originate from the meristoderm in a similar way to the conceptacles. The branches, whether vegetative or fertile, which are produced from the lateral nodes, are superficial in origin.The apical cell of a meristem exerts apical dominance and inhibits the development of branches from nearby lateral nodes. Meristems from lateral nodes will inhibit the development of branches from a wound callus. Lateral branches, gametangia in conceptacles and branches from a wound callus all require some interruption of the dominating effect of the apical cell before they can complete their normal development.
DURATION OF THE MITOTIC CYCLE IN THE APICAL BUD OF RUDBECKIA BICOLOR
Authors: JACQMARD A. 
Published: May 2006

SummaryDuration of the mitotic cycle and its component phases is estimated in the different regions of the apical bud of Rudbeckia bicolor by means of pulse‐labelling with tritiated thymidine and autoradiographic techniques. The average length of the mitotic cycle is around 30–33 hours in all regions of the bud, except in the central zone where it is far longer.
SHADE TOLERANCE IN TREE SEEDLINGS
Authors: LOACH K. 
Published: May 2006

SummarySeedlings of five tree species of different shade tolerance were raissed in 100, 44, 17 and 3% of natural daylight. Growth analysis was carried out on data obtained from two harvests during the growing season. The net assimilation rates (E) of the more tolerant species were little higher in 100% daylight than in slight shade (44% daylight), but thereafter E decreased as shade increased. The intolerant species had greatest E in 100% daylight, but this high E fell sharply with increasing shade, and in Populus tremuloides was negative in 3% daylight. Even in this deep shade, however, the intolerant Liriodendron tulipifera had as high a net assimilation rate as the shade‐tolerant species. Decreased E was offset by increased leaf area ratio (leaf area/plant weight), but in contrast to previous studies with herbaceous species, the magnitude of this increase gave no indication of the relative shade tolerance of the different species. In L. tulipifera and Acer rubrum, the increased leaf area ratio resulted from an increase in the proportion of assimilates diverted into leaf production (i.e. increased leaf weight ratio), together with a relatively greater increase in specific leaf area (leaf area/leaf weight). The more tolerant Fagus grandifolia and Quercus rubra showed less increase in specific leaf area, and leaf weight ratio increased only in the deepest shade. No clear‐cut distinction can be drawn between tolerant and intolerant species on the basis of the relative size or efficiency of their photosynthetic systems in low light; factors other than those relating to carbohydrate economy in shade, also play a role.
AN ELECTRON MICROSCOPE STUDY OF EXOGENOUSLY DORMANT SPORES, SPORE GERMINATION, HYPHAE AND CONIDIOPHORES OF ALTERNARIA BRASSICICOLA
Authors: CAMPBELL RICHARD 
Published: May 2006

SummaryFreeze‐etching and chemical fixation techniques were used to study exogenously dormant spores, spore germination, hyphae and conidiophores of Alternaria brassicicola (Schw.) Wiltshire. Dormant spores have very thick, heavily pigmented, mclanized walls with plugged septal pores. The small amounts of endoplasmic reticulum and the few mitochondria lie near the plasmalemma. The germ‐tube walls arise from the inner layers of the spore walls; lomasomes and endoplasmic reticulum vesicles are probably concerned with this wall formation. During germination mitochondria and ribosomes increase in numbers, first in the germinating cell and then in the germ tube. As the hyphae age they produce lipid droplets and vacuoles; the latter finally fill most of the cell as the cytoplasm degenerates. Conidiophores have a similar structure to mature hyphae except that they have, after spore production, a pore in the tip and an annulus.
A BASIC STAINING MATERIAL ASSOCIATED WITH THE PENETRATION PROCESS IN RESISTANT AND SUSCEPTIBLE POWDERY MILDEWED BARLEY
Authors: EDWARDS H. H. 
Published: May 2006

SummaryA possible mechanism for resistance has been observed in powdery mildewed barley (Erysiphe graminis f. sp. hordei on Hordeum vulgare). A substance which stains with basic protein staining procedures occurs in papillae of susceptible and resistant powdery mildew infected barley. It is first detectable after the infection peg penetrates the host cell wall. In susceptible host cells this substance is confined to the papilla, whereas in resistant host cells this substance spreads throughout the penetrated cell and to adjacent mesophyll cells beneath the infected cell. The spread of this substance correlates with the expression of resistance in the host cells.
OBSERVATIONS ON THE STRUCTURE AND BIOLOGY OF HAPLOMITRIUM AND TAKAKIA, HEPATICS WITH ROOTS
Authors: GRUBB P. J. 
Published: May 2006

SummaryThe gametophytes of certain species of Haplomitrium and of Takakia have organs that may be called roots. These normally grow downward, are almost colourless and, unlike flagella‐shoots, have no leaf rudiments. They may have up to two orders of branching; they have no root‐caps but are covered by mucilage if grown in dry conditions.The axes of most species have a central cylinder of elongated cells. In the aerial shoots these cells generally appear ‘empty’ like the hydroids of mosses. The leaf cells have an outer layer which is relatively impermeable to water and solutes. Shoots of Haplomitrium mnioides are able to maintain their water balance more effectively than those of Plagiochila asplenioides under marginally drying conditions. The endohydric habit of Haplomitrium and Takakia appears to confer little advantage in the field because it is not coupled with a protoplasmic resistance to desiccation.
PHOTOINDUCED CHANGES IN RICE SHOOT APEX
Authors: MISRA G. , KHAN P. A. 
Published: May 2006

SummaryA late‐winter variety of indica rice was subjected at the age of 28 days to one to twelve consecutive cycles, each of 8 hours natural daylength plus 16 hours darkness. Changes in the shoot apex in its transition from the vegetative to the reproductive condition under each photo‐inductive cycle were noted. Seven consecutive photoinductive cycles played the master role and brought about panicle initiation 50 days earlier and panicle emergence 61 days earlier than in the controls grown under natural daylengths in the open field.
STUDIES IN THE VEGETATIONAL HISTORY OF MID‐WALES
Authors: MOORE P. D. 
Published: May 2006

SummarySediments of Late‐glacial origin from the Elan Valley in Cardiganshire have been subjected to close‐interval pollen, spore and macrofossil analysis. From the results of this analysis an attempt has been made to reconstruct contemporary plant species assemblages and to follow the changes in these communities during the climatically unstable Late‐glacial period. Conventional zonation required some modification for adequate representation of the dynamic state of both environment and vegetation at the time, hence a series of transitional zones has been constructed. Certain species are found to reach their greatest abundance in these transitional periods and are considered to be relatively thermophilous yet intolerant of competition.Certain of the types found, e.g. Artemisia c.f. norvegica, Linnaea borealis, Tofieldia and Scleranthus perennis are of particular interest, both because of the infrequency with which they have been recorded in British quaternary deposits in the past, and because of their present day disjunct and sometimes anomalous distributions. Their presence in mid‐Wales during Late‐glacial times throws further light upon these distributions.
PERIDERM DEVELOPMENT AND PHELLOGEN ACTIVITY IN THE SHOOTS OF ACACIA RADDIANA SAVI
Authors: ARZEE TOVA , WAISEL Y. , LIPHSCHITZ NILI 
Published: May 2006

SummaryThe origin and the seasonal activity of the phellogen in Acacia raddiana were investigated. The phellogen is initiated from collenchyma cells of one of the three outermost layers of the cortex. The first phellogen persists for several years. The activity is periodic and slow. The phelloderm consists of several crystal‐containing cell layers, which eventually become sclerified. The activities of the phellogen and of the cambium were found not to be correlated.
EFFECTS OF ASPERMY VIRUS INFECTION ON THE WATER STATUS OF TOMATO LEAVES
Authors: TINKLIN R. 
Published: May 2006

SummaryThe effect of aspermy virus infection on the water status of tomato leaves was studied. Infected leaves had a higher relative water content than controls, the increase being related to inoculum concentration. This was shown to be caused by an inability to take up water rather than a truly higher water content. It is suggested that this may be the result of a reduction in the permeability of cell membranes.
THE QUALITATIVE AND QUANTITATIVE PHOTO‐PERIODIC RESPONSE OF INDIAN POTATO VARIETIES
Authors: PUROHIT A. N. 
Published: May 2006

SummaryPlants of Solanum tuberosum L. vars. Kufri Sindhuri, Kufri Shakti, EM/B‐1399 and OT‐No. were grown under short day (SD) and long day (LD) (continuous light) at identical temperature and humidity. Observations on haulm growth, number and shape of leaves, and number of tubers produced per plant and their fresh weight were recorded.Plants grow taller under LD in all the varieties. The early maturing varieties (Kufri Shaki and EM/B‐1399) die earlier, but more or less simultaneously under SD and LD conditions, whereas the growth period of the other two varieties is lengthened considerably under LD conditions. The heteroblastic development of leaves is considerably influenced by photoperiod.All the four varieties are quantitative long‐day with respect to floral initiation but in all of them floral buds drop before they open into flowers. One of the four varieties, OT‐No., is quantitative whereas the others are qualitative short‐day in tuber initiation. Yield per plant is considerably influenced by the photoperiod. Long days during tuber enlargement increase the yield.The significance of these results in evaluating the seasonal and regional adaptability of potato varieties and the mechanism of tuberization is discussed in the light of available literature on the subject.