bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE MODE OF ACTION OF KINETIN IN MAINTAINING THE PROTEIN CONTENT OF DETACHED TROPAEOLUM MAJUS LEAVES
Authors: MIZRAHI YOSEF , AMIR JACOB , RICHMOND AMOS E. 
Published: May 2006

SummaryKinetin maintains the protein content of detached leaves, but the reason is not clear. This work attempted to find out whether the effect arises from maintenance of protein synthesis or retardation of protein breakdown. Protein synthesis and degradation in detached Tropaeolum majus leaves were estimated by measuring the incorporation into amino acids and protein of photo‐synthetically fixed 14C, and by determining the total amounts of amino acids and protein present in ageing leaves. Protein synthesis in kinetin‐treated leaves kept in darkness was higher than in the control. Rough calculation showed, however, that enhancement of protein synthesis by kinetin cannot directly account for the higher protein level found after this treatment. It seems to result from decreased degradation rather than from the maintenance of protein synthesis.
A TAXONOMIC STUDY OF LABIATAE AND RELATED GENERA
Authors: EL‐GAZZAR A. , WATSON L. 
Published: May 2006

SummaryExtensive comparative anatomical and morphological observations have been made on 400 species (138 genera) of Labiatae and Verbenaceae sensu lato. Two computational analyses, very different and calling for different coded interpretations of the data, gave essentially similar classifications. These analyses and subsequent taxonomic consideration result in an arrangement which does not reflect the present family boundary. Four of Bentham's eight tribes of Labiatae (Ocimoideae, Satureieae p.p., Monardeae, Nepeteae) seem distinctly different from the rest which come closer to Verbenaceae. Of ten subfamilies and tribes sampled, only Ajugoideae and Verbenoideae emerge intact. In terms of this sample, forty‐seven genera gain support but twenty‐five are heterogeneous in that species form groups not conforming with present generic boundaries.
RESPONSE OF ADAXIAL AND ABAXIAL STOMATA TO LIGHT
Authors: TURNER NEIL C. 
Published: May 2006

SummaryThe response to light by adaxial and abaxial stomata was measured with an aspirated diffusion porometer in normal and inverted leaves of sorghum (Sorghum bicolor (L.) Moench) and tobacco (Nicotiana tabacum L.). The adaxial stomata, normally exposed to bright light, closed at 2000 ft‐candles in both sorghum and tobacco whereas the abaxial stomata, normally in dim light, closed at approximately 1000 ft‐candles in sorghum and 200 ft‐candles in tobacco. The greater sensitivity of the abaxial stomata to light in both the monocotyledon, sorghum and the dicotyledon, tobacco, indicates that the phenomenon is widely distributed and occurs irrespective of differences in stomatal density. Further, the narrowing of the adaxial stomata which occurred upon leaf inversion suggests that the level of carbon dioxide within the intercellular spaces of the leaf does not control stomatal apertures.
REGULATION OF THE GROWTH POTENTIAL OF DOUGLAS FIR SEEDLINGS DURING DORMANCY
Authors: LAVENDER D. P. , HERMANN R. K. 
Published: May 2006

SummaryThe three experiments indicated that individual buds were the receptors for the growth stimulus produced by extended photoperiods during the autumn and winter. No evidence of transport of growth stimulatory materials from active to dormant bud was noted. Buds whose chilling requirements were fully satisfied initiated growth in response to favourable temperatures rather than to long photoperiods.Initiation of activity by lateral cambia required material exported from both expanding buds and mature foliage.No significant correlation between shoot and root growth was found. Although neither active buds nor applications of exogenous IAA or GA stimulated roots growth, both root elongation and initiation were found to be dependent upon some substance or substances, presumably hormones or carbohydrates, exported from mature foliage.Findings indicated that seedling physiology during the dormant period may be controlled by a changing balance in growth inhibitors and promoters.
A VIRESCENS MUTANT OF PHASEOLUS VULGARIS; GROWTH, PIGMENT AND PLASTID CHARACTERS
Authors: DALE J. E. , HEYES J. K. 
Published: May 2006

SummaryA slow‐greening mutant growing at a slower rate than control plants is described. Mutant plants produce less chlorophyll than control plants, and their rate of production of pigment is lower. There is some evidence that chlorophyll is broken down in the mutant under high light conditions. Plastid numbers per leaf cell are similar in control and mutant, but a reduction in leaf cell number in the mutant results in their containing fewer plastids per leaf. The slow accumulation of chlorophyll by plastids of the mutant is correlated with a slow development of plastid fine structure, in particular in stacking of grana, as seen by electron microscopy.
TRISTYLY IN LYTHRUM JUNCEUM *
Authors: DULBERGER RIVKA 
Published: May 2006

Summary Lythrum junceum was found to be tristylic in Israel. The three floral forms differ in style length, stamen length, pollen size, presence or absence of starch in the pollen and in stigma size. In the majority of natural populations examined, the three forms were represented in roughly equivalent numbers. The results of an artificial pollination programme demonstrate that the trimorphism is accompanied by physiological incompatibility, typical to tristylic plants. Self‐pollinations were sterile. Intra‐form and inter‐form pollinations between anthers and stigmas at different levels were also sterile. The inhibition of pollen tubes occurs in the style. Inter‐form pollinations between anthers and stigmas at equivalent level resulted in seed production, the most fertile form being the mid‐styled one; these differences were lost in open‐pollinated plots. Tristyly in L. salicaria with 2n= 30 is recorded. A comparison is made between tristyly in L. junceum and L. salicaria and it is suggested that tristyly in the latter has evolved later than in the former.
EUTRIPLOID FACULTATIVE AGAMOSPERMY IN TARAXACUM
Authors: RICHARDS A. J. 
Published: May 2006

SummaryDiploidy is reported in the species Taraxacum brachyglossum, T. subcyanolepis and in the T. punctatum/austriacum complex. In each case, diploids are found in company with triploids of the same species, which are shown in the case of T. brachyglossum to be facultative agamosperms. These have regular pollen and show incomplete seed‐set in the absence of cross‐pollination. Triploids in T. subcyanolepis and T. punctatum/austriacum are similar and are also thought to be facultative agamosperms. This is the first report of eutriploid, facultative agamospermy in Taraxacum.Diploid sexuals may be recognized by regular pollen and no seed‐set in insect‐free conditions. Obligate agomosperms have highly irregular pollen, large regular pollen or no pollen and set good seed.It is shown that sexual diploids can give rise to triploids apparently as a result of fertilization by incompletely reduced pollen in triploids. Some triploids can give rise to diploids, perhaps through reduction in the female meiosis, which is synaptic, followed by fertilization with haploid pollen.Suggestions are made as to the mechanism controlling facultative agamospermy in disomic triploid and eutriploid individuals. Critical phases seem to be the course of the female meiosis and the timing of autonomous embryony.
THE BREAKDOWN OF PAINT SURFACES BY ENTEROMORPHA SP.
Authors: MOSS BETTY , WOODHEAD P. 
Published: May 2006

Summary Enteromorpha is the dominant alga associated with the fouling of large ships. Using the electron scanning microscope on germinating zoospores and on young plants which had been raised in culture it has been shown that the primary and subsequent rhizoids which are produced by the plant penetrate the substrate and so cause physical breakdown of a paint surface.Among the algae causing severe fouling of large ocean‐going ships, Enteromorpha is the most common. It sometimes occurs in such extensive growths as to slow a tanker down to about one‐third of its normal speed. Anti‐fouling paints have been designed mainly to resist or to repel the settling larvae of barnacles and other animals and since they do not prevent the growth of algae attention is now being focused to this problem. While studying the settlement of Enteromorpha swarmers on paint surfaces we looked at the method of attachment and the damage to the paint which resulted from their germination and growth. Observations were made with an electron scanning microscope so that the germinating zoospores could be seen in situ growing on a painted surface.
A VIRUS OF BLUE‐GREEN ALGAE FROM FRESHWATER HABITATS IN SCOTLAND
Authors: DAFT M. J. , BEGG J. , STEWART W. D. P. 
Published: May 2006

SummaryA virus which is pathogenic to certain blue‐green algae belonging to the genera Plectonema, Phormidium and Lyngbya has been isolated from a variety of freshwater habitats in Scotland and has been detected over a 12‐month period in one of these habitats. The virus (D‐1) is a cyanophage, has an isohedral head and a short tail and is morphologically and serologically related to the LPP‐1 virus isolated from the United States and the GIII virus isolated from Israel by other workers. The partially purified virus has an absorption spectrum characteristic of a nucleoprotein with a maximum at 260 nm and a minimum at 243 nm. D‐1 is temperature sensitive being inactivated on heating at 60°C for 6 minutes. Its multiplication rate is fast, increasing from an initial titre of 103 to 1012PFU/ml within 40 hours. The lysis of the host cell results in a rapid loss of the phycobilin and chlorophyll pigments.
THE MORPHOLOGY AND COMPOSITION OF ISOLATED PLANT CUTICLES
Authors: BAKER E. A. 
Published: May 2006

SummaryThe morphology of the inner and outer surfaces of cuticular membranes of mono‐ and dicotyledonous leaves and fruits was studied with the scanning electron microscope. Variations in surface structure are related to differences in thickness and composition of the membranes. Delicate leaf membranes have fine ridges and simple stomata, well‐developed membranes, thick V‐shaped ridges and heavily cutinized stomata. Fruit membranes show deep ridges and extensive secondary cutinization. The most heavily cutinized structures occur in membranes which yield high proportions of 10,16‐dihydroxyhexadecanoic or 9,10,18‐trihydroxyoctadecanoic acid which suggests that the membrane thickness and the complexity of the structural features are associated with the degree of hydroxylation of the constituent cutin acids. The relationship between the structure and composition of the cuticular membrane and the type and growth habit of the plant is discussed.
EFFECTS OF ENVIRONMENT ON RELATIONS BETWEEN EXTENSION AND CAMBIAL GROWTH OF POPULUS EUPHRATICA OLIV.
Authors: LIPHSCHITZ NILI , WAISEL YOAV 
Published: May 2006

SummaryVariations in the xylem increment and vessel diameter were found among Populus euphratica Oliv. trees from habitats of different water regimes. Vigorous shoot growth under conditions of ample water supply was associated with wide annual xylem rings and diffuse porous wood. Restricted shoot elongation of trees on dry sites was associated with narrow annual rings and ring porous wood. The influence of environmental factors on xylem production appeared to be indirect and to be largely mediated through physiological activity of the shoot system.
CALLUNA, CASSIOPE AND HARRIMANELLA: A TAXONOMIC AND EVOLUTIONARY PROBLEM
Authors: STEVENS P. F. 
Published: May 2006

SummaryLeaf types in Calluna, Cassiope and Harrimanella are described; the so‐called needle leaf of Cassiope lycopodioides and C. mertensiana is shown to be derived from the channelled leaves found in the majority of species of Cassiope, possibly via an intermediate stage such as C. redowskii, which has leaves like the finger of a glove. The needle leaves of C. palpebrata are superficially different from the other leaf types of the genus, as are those of Harrimanella. A considerable number of differences justifying the maintenance of Cassiope and Harrimanella as separate genera are listed. The relationship of Cassiope and Harrimanella to the Rhododen‐droideae and Vaccinioideae are discussed, and although these two genera are very isolated in the Ericaceae they are closer to the Andromedeae than to any other group. With Calluna they have little in common apart from characters occurring sporadically throughout the family; although Cassiope and Calluna are similar in a number of points Harrimanella and Cassiope differ in these characters. The evidence suggests that Calluna is a member of the Ericoideae, although separable as a monotypic tribe; Cassiope and Harrimanella are not at all close to the Ericoideae. It is concluded that leaf type is a character which must be used with caution in establishing relationships within the Ericaceae; the evolutionary significance of the rather frequent conflict between relationships suggested by leaf type and those suggested by floral characters is briefly discussed.
THE ADVANCEMENT INDEX AND TROPICAL RAIN‐FOREST
Authors: SPORNE KENNETH R. 
Published: May 2006

SummaryThis is a reply to a suggestion that the characters used for assessing the relative primitiveness of dicotyledon families are merely adaptations to life in tropical rain‐forest and are not, therefore, reliable indicators of primitiveness. Arguments are put forward that rain‐forest plants should be expected to be primitive, regardless of the place of origin of angiosperms. Recent findings of palynologists are shown to give strong support to advancement index calculations.
NITROGEN METABOLISM IN LICHENS
Authors: KERSHAW K. A. , MILLBANK J. W. 
Published: May 2006

SUMMARYNitrogen fixed by, and secreted from, the blue‐green algal component of Peltigera aphthosa to the thallus has been shown to be utilized almost exclusively by the fungal component. After allowance for the proportions of fungal and green algal components, only approximately 3 % of the expected proportion of secreted nitrogen is accumulated by the green algal cells.The implications of this on the possible theories describing the relationships existing in the lichen symbiosis are discussed.
NUTRITIONAL REQUIREMENTS OF THE EDAPHIC ECOTYPES IN MELILOTUS ALBA MEDIC.
Authors: RAMAKRISHNAN P. S. 
Published: May 2006

SUMMARYThe acidic and calcareous populations of Melilotus alba behave differently when grown in competition than when grown in isolation from each other. Thus, the acidic population which did well in both calcareous and acidic media in competition‐free cultures, showed good growth yield in acidic soils only when in competition with the calcareous population. Further, the differences observed between the two populations in competition‐free experiments became more pronounced when grown mixed. The time of introduction of either of the two populations into the mixture affects the final dry weight yield of the shoot, depending upon the soil type. In mixed cultures of the two populations, the calcareous population grown in an acidic soil and the acidic population grown in a calcareous soil responded by mortality of individuals, especially when the second population in each case was introduced earlier into the mixture.
EFFECTS OF GROWTH REGULATING SUBSTANCES AND WATER POTENTIAL ON THE DEVELOPMENT OF WOUND CALLUS IN FRAXINUS
Authors: DOLEY D. , LEYTON L. 
Published: May 2006

SUMMARYThe rate of growth of wound callus from the cut ends of Fraxinus excelsior L. stems was reduced by lowering the water potential of the culture medium using sucrose and/or polyethylene glycol; the first decrement in potential, from 0 to – 1 bar, had a particularly depressing effect. Gibberellic acid up to 100 mg 1‐1 had no significant influence, whilst indol‐3‐yl‐acetic (IAA) appeared to exert an effect only through its interaction with the water potential. The importance of water potential in tissue development appears to have been frequently overlooked in the use of relatively high sucrose concentrations in tissue culture media, and may account in part for the frequent observation of an optimum sugar concentration for growth. Calluses produced at zero water potential were characterized by active surface growth, relatively little internal differentiation, and a semicircular section. At reduced potentials (–1 bar and lower), the calluses had suberized surfaces and were circular in section; increase in size occurred mainly through the activity of the vascular cambium and a subsurface meristem. More lignified xylem and sclercids were produced in calluses grown at –1 and –2 bars than at zero water potential; at each water potential there appeared to be an optimum IAA concentration for xylem differentiation and this optimum tended to increase as the water potential was increased. Xylem was always associated with a cambium which extended from the subtending twig. Differentiation of vascular tissues, in particular lignified xylem, appears to require physical pressure in addition to a certain concentration of auxin; at zero water potential, sufficient pressure appears to be developed when the callus reaches a certain size, whilst at lower potentials it is induced by suberization of the superficial cells of the callus restraining the expansion of the underlying tissues.
CAVITATION AND OSMOTIC POTENTIALS OF SORDARIA ASCOSPORES
Authors: MILBURN JOHN A. 
Published: May 2006

SUMMARYAscospores of Sordaria fimicola have been separated into two distinct kinds on the basis of colour, structure and physiology, which may represent different degrees of maturation.The osmotic potential of the darker spores has been found to vary considerably (22–45 atm).Cavitation occurs in ascospores and the cavitation potentials of a number of individual spores Were measured. There is considerable variation between different spores even from the same ascus (18–71 atm). Cavitation could neither be detected by vibration techniques depending on electronic amplification, nor could spore recoil be seen when detached spores cavitated under the microscope.Estimates of the permeability coefficients of mature ascospores have been made with respect to water entering the spores osmotically. The osmotic pressure generated in hyphal germ tubes of Sordaria ascospores is discussed.
HORMONAL REGULATION OF NITRATE REDUCTASE ACTIVITY IN LEAVES
Authors: ROTH‐BEJERANO NURIT , LIPS S. HERMAN 
Published: May 2006

SUMMARYThe level of nitrate reductase activity in leaves of tobacco is not determined only by nitrate availability. Kinetin and gibberellin interact, affecting the activity of the enzyme. Kinetin seems to modulate the effectivity of gibberellin on the determination of nitrate reductase activity: the larger the amount of kinetin added the smaller the concentration of GA3 required to obtain maximal activity of nitrate reductase. The effect of both growth substances on the enzyme is not due to a general protein synthesis stimulation.
NATURAL AND EXPERIMENTAL HYBRIDIZATION IN POTENTILLA
Authors: MATFIELD B. , JONES J. K. , ELLIS J. R. 
Published: May 2006

SUMMARYThree natural hybrids have been reported in Potentilla subseries Tormentillae: Potentilla Y. suberecta, P. ×mixta and P. × italica. This paper presents results of morphological and cyto‐logical studies and experimental crosses made to clarify the origins and taxonomy of the hybrids, and to investigate the possibility of introgression.All natural hybrids examined were hexaploid (2n= 42). Experimental crosses confirmed that P. × suberecta is the hybrid between P. erecta (2n= 28) and P. anglica (2n= 56), but the origin of the other hybrids is less clear. It is suggested that the names P. ×mixta and P. ×italica have been applied to different forms of a single variable taxon, and that P. × italica should be regarded as a synonym of P. ×mixta. The origin of this natural hybrid remains uncertain. It is generally considered to be P. reptans (2n= 28) ×P. anglica, but numerous attempts to hybridize these species have failed, although one unpublished, successful hybridization is cited. Experimental crosses have indicated an alternative origin for P. ×mixta, by hybridization between P. reptans and P. erecta, in which the former either contributes an unreduced gamete or occurs as an autopolyploid cytotype.Vigorous backcross progenies were raised from both P. ×suberecta and P. ×mixta and the importance of backcrossing and introgression in natural populations is discussed.
PLANT GROWTH RESPONSES TO VESICULAR‐ARBUSCULAR MYCORRHIZA
Authors: MOSSE B. , HAYMAN D. S. 
Published: May 2006

SummaryThe benefits of mycorrhizal infection were compared in four irradiated and unsterilized soils containing little soluble phosphorus. Mycorrhizal infection was produced in onion seedlings by pre‐planting in a heavily infected soil and transplanting into the test soil, or by sowing in situ on a cushion of Endogone inoculum. In all soils, irradiated or not, mycorrhizal seedlings grew very much better than non‐mycorrhizal ones. In two of the soils natural infectivity was very low and most uninoculated seedlings remained non‐mycorrhizal even after 16 weeks. In the other two soils most plants became mycorrhizal in the unsterilized soils. In one of them the indigenous mycorrhizal fungi aided phosphorus uptake of the host plant, in the other they did not. Infections produced by the indigenous fungi in the two soils were anatomically different, though both were typical VA mycorrhiza.It is concluded that inoculation may have practical significance in some low phosphate soils containing either few indigenous mycorrhizal fungi or ineffective strains.
STOMATAL RESPONSE TO CHANGING LIGHT BY FOUR TREE SPECIES OF VARYING SHADE TOLERANCE
Authors: WOODS DAVID B. , TURNER NEIL C. 
Published: May 2006

SummaryStomatal opening and closing was followed with a diffusion porometer in beech (Fagus grandi‐folia Ehrh.), maple (Acer rubrum L.), oak (Quercus rubra L.) and yellow poplar (Liriodendron tulipifera L.) in a situation where illuminance could be changed by placing shades over the trees. In all four species the stomata opened quicker than they closed. The time to reach an equilibrium stomatal resistance was constant for a species but varied between species, for all changes in illuminance greater than 3000 ft‐candles. To open to a constant leaf resistance took from 3 minutes in beech to 20 minutes in yellow poplar; oak and maple were intermediate at 12 minutes. Beech required 12 minutes to close to a constant leaf resistance, maple 18, oak 20, and yellow poplar 36 minutes. When the change in illuminance was less than 3000 ft‐candles, the stomata took longer to reach a new equilibrium in all species except yellow poplar. Also beech stomata opened and closed in dimmer light than yellow poplar. The rates of stomatal opening and closing correlated well with the known shade tolerance of the species.
BIOLOGICAL EFFECTS OF SURFACTANTS
Authors: ERNST ROBERT , ARDITTI JOSEPH , HEALEY PATRICK L. 
Published: May 2006

SummaryRelative phytotoxicity of purified, biodegradable surfactants was determined by observing their effects on the growth of orchid seedlings in vitro. Pronounced phytotoxic effects occurred on culture media containing high concentrations of surfactants. Concentration of ionies above 100 ppm were most damaging and also caused a 90% or greater reduction of interfacial tension. Nonionic ethoxylates reduced growth and viability at lower concentrations than ionies, but larger percentages of seedlings survived at 1000 ppm levels of these agents, which were less efficient in reducing interfacial tension. No correlation was found between biological effects and surface tension data but a coincidence may exist between interfacial tension reduction by ethoxylates and increased phytotoxicity.A number of purification procedures for surface active agents are presented as an Appendix.