bluuebunny/crossref_metadata_2025 huggingface dataset:
INDUCTION OF FLOWERING IN WILD LETTUCE (LACTUCA SERRIOLA L.)
Authors: PRINCE S. D. , MARKS M. K. , CARTER R. N.
Published: May 2006

Both seed and rosettes of Lactuca serriola L. are naturally vernalized during the winter. The response, measured by reduction in time required to flower, is greatest following vernalization of seed and declines with increasing age of the vegetative rosette. However, seedlings pass through a phase of minimum response to vernalization in the cotyledon stage (52% of seed response) after which it increases (73% at two‐leaf stage) before declining in older rosettes. The significance of the effect of stage of development at the start of vernalization is discussed in relation to control of phenology in the natural environment. Effects of photoperiod and temperature on induction of flowering are considered and comparison made with L. sativa.
INDUCTION OF WILTING BY MANNOSE IN SPINACH BEET LEAVES
Authors: HEROLD A.
Published: May 2006

Mannose, but not glucose, induces loss of turgor in whole plants, detached leaves and leaf discs of spinach beet. There is no comparable effect in leaves of tobacco and geranium. Supply of mannose to spinach beet discs causes an enhanced conductivity in the bathing medium after 8–10 h and this is associated with increased leakage of potassium ions over controls. After 24–36 h, water‐soaking is evidence of intercellular accumulation of water in the tissue. Previous work has established that mannose sequesters orthophosphate as mannose phosphate in leaves of spinach beet but not in those of tobacco and geranium, and the implied changes in cell membrane permeability are probably due to limited availability of Pi for ATP synthesis and turnover of phospholipid membrane components. The rate of cuticular transpiration may also be increased.
INOCULATION OF WHITE CLOVER AND RYEGRASS SEED WITH MYCORRHIZAL FUNGI
Authors: Ll. POWELL C.
Published: May 2006

Summary

Seeds of white clover and ryegrass were pelleted with soil heavily infested with the indigenous mycorrhizal fungi or efficient strains of Glomus tenuis and Gigaspora margarita and laid out on unsterilized pasture soils. Ryegrass plants inoculated with Glomus tenuis produced up to 48% more shoot growth than plants infected with the indigenous mycorrhizal fungi in Dunmore soil in glasshouse conditions. Similar inoculation of clover increased shoot growth by up to 91 % in Te Kuiti soil in the glasshouse and 37% in the field. Inoculation of clover with Gigaspora margarita increased dry matter of shoots by 79 % in Te Kuiti soil in the field.
ULTRASTRUCTURAL CYTOCHEMICAL DEMONSTRATION OF POLYSACCHARIDES AND PROTEINS WITHIN THE HOST‐ARBUSCULE INTERFACIAL MATRIX IN AN ENDOMYCORRHIZA
Authors: SCANNERINI S. , BONFANTE‐FASOLO P.
Published: May 2006

Summary

The host‐fungal arbuscule interfacial matrix in the VA mycorrhiza of Ornithogalum umbellatum L. has been studied at the ultrastructural level by various fixation methods, cytochemical techniques and by selective enzymic digestion. Evidence is produced that the interfacial matrix, though varying in size and infrastructure, irrespective of the arbuscule zone, constantly contains polysaccharides (mainly pectin and occasionally some cellulose) and proteins. Combined morphological and cytochemical results show that this structure is made up of wall material from the host cell.
CULTIVATION OF PINUS STROBUS ROOT‐HYPOCOTYL EXPLANTS FOR SYNTHESIS OF ECTOMYCORRHIZAE
Authors: ANDRE FORTIN J. , PICHE YVES
Published: May 2006

Summary

Different conditions for the cultivation of Pinus strobus root‐hypocotyl explants were studied for the production of ectomycorrhizae in vitro. Moisture content of the culture medium used for growing seedlings before excision was critical and a low level of moisture during this period led to a slow and erratic growth of the explants. During short‐term experiments (6 weeks) no vitamins or inositol requirements could be detected but under the same conditions auxins improved growth significantly whereas kinetin did not. The optimum NAA concentration was about 2 × 10−7 M in the absence of exogenous kinetin. The requirement for a piece of hypocotyl might not be absolute because some evidence was obtained that auxin in the organic medium might, partially, replace it. Whereas virtually no growth took place with 5% sucrose in the organic medium, optimum concentration for root elongation was found to be between 11 and 15%. During the 2 first weeks following excision the rate of growth remained low (1.2 mm week−1) but between the 2nd and the 6th weeks it reached 6.3 mm week−1 before dropping back to 2.3 mm week1 between the 6th and the 10th weeks. Some typical ectomycorrhizae showing mantle and Hartig's net were obtained upon inoculation with ectomycorrhizal fungi, but more research is needed before the method can be recommended for general use in studies on the physiology of ectomycorrhizae.
PHYSIOLOGICAL‐ENVIRONMENTAL INTERACTIONS IN LICHENS. VII. THE ENVIRONMENTAL CONTROL OF GLUCOSE MOVEMENT FROM ALGA TO FUNGUS IN PELTIGERA CANINA V. PRAETEXTATA HUE
Authors: TYSIACZNY M. J. , KERSHAW K. A.
Published: May 2006

Summary

The movement of labelled glucose from the phycobiont of the lichen Peltigera canina v. praetextata Hue., to the mycobiont, has been examined under contrasting environmental conditions of temperature and moisture. The ratio of labelled mannitol : labelled photosynthetic products is used as a relative measure of the rate of transport of glucose and its incorporation into mannitol.

The relative amount of label appearing in mannitol remains fairly constant over a wide range of experimental temperatures, but there is a marked interaction with the level of thallus hydration. At 100% thallus water content by weight, when high rates of photosynthesis are still maintained, only a small proportion of the total label appears in mannitol. It is suggested that this retention of photosynthate at low levels of thallus saturation is essential to supply the basic metabolic requirements of the phycobiont. Conversely the requirements of the fungal partner are satisfied at higher levels of thallus saturation. Thus alternate wetting and drying cycles are essential to maintain the metabolic requirements of each of the bionts and hence the physical integrity of the lichen itself. The results are briefly discussed in terms of the facilitated diffusion of glucose proposed by Smith (1974).
LICHEN WATER RELATIONS UNDER DRYING CONDITIONS
Authors: LARSON D. W.
Published: May 2006

Summary

The loss of water by evaporation in various species of lichens has been examined under a range of controlled windspeed/radiation regimes. Temperate and arctic species both show a type of morphological control of evaporation. Such control varies, however, with the nature of the surrounding environment. Evaporation from those species which show a very low resistance to evaporative water loss such as Bryoria nitidula, Umbilicaria deusta and U. veiled appears to be relatively insensitive to increases in radiant flux. Conversely those species, or specific growth forms, which show a high resistance to evaporative water loss, such as Cladina stellaris and U. muhlenbergii, appear to be sensitive to increases in supply of radiant energy.

These results suggest that the morphological control of evaporation in lichens is significant to the ecology of this group of plants.
APICAL INTRUSIVE GROWTH OF FIBRES FROM THE FLOWERING STEM OF LOLIUM TEMULENTUM L.
Authors: LAWTON J. R. , HARRIS P. J. , LOWRY K. H. , DHANOA M. S.
Published: May 2006

Summary

Extension of the internode below the point of insertion of the flag leaf of Lolium temulentum L. takes place in the lower 10 to 15 mm. Extension of the long epidermal cells also takes place in this region. However, fibre cells show little extension in the lower 10 mm and maximum extension occurs at about 30 mm above the node. Thus, there is extension of fibre cells within that portion of the internode which has ceased extension and is bounded by an epidermis, the cells of which have also ceased elongation. This suggests the occurrence of intrusive growth of the fibres and evidence for this is shown from the measurement of macerated fibres and from electron micrographs.

The walls of fibre cells measured in internodes of different lengths and ages thicken only very slightly in the lower 30 mm and most cell wall thickening occurs between 45 and 90 mm above the node. Thus most cell wall thickening occurs after the fibre cells have ceased to elongate.
CARBOHYDRATE METBOLISM IN AGARICUS BISPORUS: CHAGES IN NON‐STRUCTURAL CARBROHYDRATES DURING PERIODIC FRUITING (FLUSHING)
Authors: HAMMOND JOHN B. W. , NICHOLS ROYSTON
Published: May 2006

Summary

Mannitol, trehalose and glycogen contents of Agaricus bisporus fruit bodies were sampled throughout the 46 day period of production of two crops. Maximum trehalose and glycogen levels were consistently observed in the interflush periods, whilst mannitol production was greatest during the flushes. A correlation exists between the sum of the peak glycogen and trehalose values and the yield of the following flush in the first crop. The possible role of trehalose and glycogen as reserves for fruit body production and in the control of flushing is discussed.
CROSS INOCULATION GROUP SPECIFICITY IN CICER‐RHIZOBIUM SYMBIOSIS
Authors: GAUR Y. D. , SEN A. N.
Published: May 2006

Summary

Cross‐inoculation group specificity in Cicer arietinum L. (chickpea) was studied. Seventy‐one strains of root nodule bacteria of C. arietinum were examined for nodulation on 87 species of legumes. These species represent all the known cross‐inoculation groups and were selected from various tribes and genera of family Fabaceae and Mimosaceae. In a reciprocal cross‐inoculation study, 287 strains of root nodule bacteria from 52 of the 87 species, were examined on various genotypes of C. arietinum.

C. arietinum and its root nodule bacteria did not show cross inoculation affinity with any of the members of the known cross‐inoculation groups: alfalfa, clover, pea, bean, soybean, lupin‐lotus and cowpea miscellany; except for some loose non‐reciprocal kinship with Sesbania, which in its turn has strong affinity with the cowpea miscellany. However, under natural conditions in soil, even the loose non‐reciprocal kinship between Cicer and Sesbania was rare. For practical reasons, it is suggested that C. arietinum and its root nodule bacteria should be considered in a separate cross‐inoculation group.

‘Cross‐inoculation host specificity’ appears to be of some help in the revision of the taxonomy of order Leguminosales and supports the placement of Cicer in a monogeneric tribe Cicereae.
THE DEVELOPMENT OF WATERLOGGING DAMAGE IN YOUNG BARLEY PLANTS IN RELATION TO PLANT NUTRIENT STATUS AND CHANGES IN SOIL PROPERTIES
Authors: Drew M. C. , Sisworo E. J.
Published: May 2006

Summary

When the soil in which 13‐day‐old barley plants were growing was flooded, the concentration of dissolved oxygen in the waterlogged soil declined to < 2 % (in the equilibrium gaseous phase) within 48 h. Within the same time there was injury to seminal roots and a reduction in the rate of leaf extension. The net rates of uptake of nitrogen, phosphate and potassium in shoots were reduced shortly after the onset of waterlogging, and because dry matter accumulation by shoots was initially little affected, the average concentration of these nutrients showed a marked decline after 48 h compared with aerated controls. The concentration of nitrate in shoots was particularly sensitive to waterlogging and after 48 h was about one third of that in controls. Analysis of individual leaves and tillers showed that with waterlogging, nitrogen was accumulated by the younger tissues at the expense of the older leaves. This trend, which was not observed with plants in aerobic soil, preceded the premature breakdown of chlorophyll in the older leaves.

With prolonged anaerobiosis, there were increases in the concentration of potentially inhibitory soil products (ethylene, organic acids, manganese) and a decline in nitrate in the soil solution, but these changes, which mostly occurred after the onset of the characteristic symptoms of waterlogging damage were relatively small and unlikely to have led to injury to shoots. The possible relations between the low concentration of oxygen around roots, the inhibition of ion uptake, the redistribution of nutrients within the shoot, and the premature senescence of leaves are discussed.
ROOT FORMATION IN CUTTINGS OF APPLE IN RELATION TO AUXIN APPLICATION AND TO ETIOLATION
Authors: DELARGY J. A. , WRIGHT C. E.
Published: May 2006

Summary

The inter‐relationship of auxin treatment and etiolation, in their effect on adventitious root formation, was investigated in stem cuttings of the difficult‐to‐root cultivar of apple ‘Bramley's Seedling’. Unetiolated cuttings of the scion variety rooted at a comparatively low level with a range of concentrations of each of six synthetic hormones. Localized etiolation of the shoot, on the other hand, stimulated root formation in proportion to the length of the stem segment treated. Indole butryric acid applied to etiolated cuttings promoted a comparatively small, but still significant, increase in root formation. The effect of etiolation is attributed to a change in the effective level of an active factor, as opposed to a direct stimulation of its synthesis.
SALT TOLERANCE IN THE WILD RELATIVES OF THE CULTIVATED TOMATO: PROLINE ACCUMULATION IN LYCOPERSICON ESCULENTUM MILL., L. PERUVIANUM MILL. AND SOLANUM PENNELLI COR. TREATED WITH NaCI AND POLYETHYLENE GLYCOLE
Authors: TAL M. , KATZ A. , HEIKIN H. , DEHAN K.
Published: May 2006

Summary

The cultivated tomato Lycopersicon esculentum cv. Rhemlands Ruhm and the two wild species L. peruvianum and Solomon pelnnellii which originated in dry habitats were compared with respect to accumulation of free proline, chloride and succulence under NaCl stress, and accumulation of proline and succulence under water stress produced by polyethylene glycole.

Proline accumulation increased in all three species under both types of stress. Increase under salinity stress, however, was smaller in the two wild species which accumulated more chloride and were more succulent. Under water stress, the increase of proline level was greatest in is. pennellii, in which succulence decreased drastically, and smallest in L. peruvianum.

The possible role of salt tolerance in enabling wild tomato species to endure drought, and the difference between them with respect to proline accumulation, are discussed.
INDUCTION OF FLOWERING IN WILD LETTUCE (LACTUCA SERRIOLA L.). II. DEVERNALIZATION
Authors: Marks M. K. , Prince S. D.
Published: May 2006

Summary

Vernalized Lactuca serriola L. seeds (cypselae) are devernalized by 25 ° C for 24 h and complete reversal of the vernalization caused by 28 days at 2 to 4 ° C occurs after approximately 7 days. Seeds can only be devernalized before germination and in the absence of light. Plants cannot be devernalized. The significance of stabilization of the vernalized state by light is discussed in relation to seeds in the natural environment and it is concluded that seeds exposed on the soil surface are unlikely to be devernalized whereas those which do not germinate may pass through repeated cycles of vernalization and devernalization.
THE EFFECT OF TEMPERATURE, SOLAR RADIATION AND MOISTURE ON THE REDUCTION OF ACETYLENE BY EXCISED ROOT NODULES FROM ALNUS GLUTINOSA
Authors: MCNIEL R. E. , CARPENTER P. L.
Published: May 2006

Summary

This study describes the influence of light, temperature, and moisture on N2‐fixing ability of Alnus glutinosa. Diurnal and day by day variations in the rate of acetylene reduction by excised root nodules were observed.

Field‐grown A. glutinosa responded in C2H2‐reducing ability due to fluctuation in solar radiation or temperature or both when the plants were not under moisture stress. When solar radiation and temperature increased during the day, the rate of C2H2 reduction increased. Ample soil moisture was needed for nodules of A. glutinosa to be responsive to solar radiation or temperature.
N2‐FIXATION (ACETYLENE REDUCTION) AND THE MICROBIAL COLONIZATION OF MANGROVE ROOTS
Authors: ZUBERER D. A. , SILVER W. S.
Published: May 2006

Summary

Scanning and transmission electron microscopy were employed to study the microbial colonization of roots of three Florida mangrove species (Rhizophora mangle, Avicennia germinans and Laguncularia racemosa). Observations of ultrathin sections revealed that all three species were colonized in the outer cortical cell layers and that colonization was primarily limited to the mucigel layer and sloughing cells. Interpretation of these observations in relation to biological nitrogen fixation associated with roots of these species of intertidal halophytes is presented.
INTERNAL SPREAD OF FUNGI INOCULATED INTO HARDWOOD STUMPS
Authors: RAYNER A. D. M.
Published: May 2006

Summary

Freshly cut stumps of beech (Fagus sylvatica), birch (Betula pendula) and oak (Quercus robur) were inoculated with wooden plugs permeated by mycelium of wood‐decaying basidiomycetes and treated with 40%(w/v) aqueous ammonium sulphamate solution (AMS), 1.5 % (w/v) 2,4,5‐trichlorophenoxyacetic acid (2,4,5‐T) in paraffin, or water. Successful establishment frequently occurred in water‐treated stumps but internal spread was usually limited. AMS prevented establishment of certain fungi (e.g. Daedaleopsis confragosa in birch and oak), but greatly stimulated internal spread of others especially in wood adjacent to the bark. Here some fungi (e.g. Hypholoma fasciculare, Phlebia meritmoides) were favoured because of their capacity for subcortical mycelial growth. 2,4,5‐T stimulated colonization in beech, but not birch or oak.

Colonization patterns varied for different fungus‐tree species combinations, e.g. Chondrostereum purpureum spread faster initially than any other fungus tested in beech and birch, and was not stimulated by AMS treatment in the former. Longitudinal spread of fungi such as Bjerkandera adusta, Coriolus versicolor and Stereum hirsutum in birch was considerably less after 6 months than in oak, but subsequently accelerated, whilst spread in oak ceased.
SEASONAL EFFECTS OF WOUNDING AND GROWTH SUBSTANCES ON DEVELOPMENT OF TRAUMATIC RESIN DUCTS IN CEDRUS LIBANI
Authors: FAHN A. , WERKER E. , BEN‐TZUR P.
Published: May 2006

Summary

The development of traumatic resin ducts, in response to wounding and to hormone [napthalene acetic acid (NAA) and gibberellic acid (GA)] application at various times of the year was studied in the secondary xylem of Cedrus libani Loud. Resin duct formation was associated with enhanced cambial activity. As a result of wounding or of application of NAA or NAA together with GA3, a system of longitudinally oriented ducts developed around the treated area. In most cases the ducts reached their greatest length above the treated area. Application of GA3 alone did not normally cause the formation of ducts. Wounding and auxin application, at the time of highest cambial activity, led to duct formation shortly after treatment. Ducts did not develop during the period of cambial dormancy. When auxin was applied during dormancy, duct systems developed in the following season of cambial activity, but wounding during the same period produced no ducts or only short ones in the following season.
SECONDARY METABOLISM IN TISSUE CULTURES OF THEOBROMA CACAO
Authors: JALAL M. A. F. , COLLIN H. A.
Published: May 2006

Summary

A synthetic medium was developed for the routine subculture of callus and cell suspensions of cocoa. All growth hormones and the coconut milk (CM) supplement of previous media were replaced by indole butyric acid (IBA) and zeatin, at concentrations of 1 mg 1−1 IBA and 0·05 mg 1−1 zeatin for callus and 10 mg 1−1 IBA and 0·5 mg 1−1 zeatin for cell suspension cultures. During the exponential phase of the growth cycle on this medium, the total phenolics in the callus and cell suspensions declined but then increased at onset of the stationary phase and finally declined again with cell senescence. The flavonoid compositions of the callus and cell suspension were similar and much less varied than that of the original intact cotyledon. Both tissue cultures contained epicatechin, leucocyanidins, caffeic and coumaric acids, all of which are thought to act as flavour precursors when in the intact fermented cotyledon. The methylated purines, theobromine and caffeine, could not be detected in the tissue cultures even in the presence of high nitrate levels in the medium. When precursors of theobromine synthesis such as xanthine, hypoxanthine and 7‐methyl‐xanthosine, were fed to the cells, theobromine was formed only when the cells were incubated with 7‐methyl‐xanthosine and a methyl donor, methionine, suggesting that part of the biosynthetic route to theobromine synthesis is still functional in the tissue culture.
INCORPORATION OF 14C‐LABBLLED SUBSTRATES BY UNINFETED AND VA MYCORRHIZAL ROOTS OF ONION
Authors: LÖSEL DOROTHY M. , COOPER KAREN M.
Published: May 2006

Summary

VA mycorrhizal infection of onion roots with Glomus masseae increases their ability to incorporate carbon from external sources, such as sucrose, acetate and glycerol, as well as from photosynthetic assimilate. Within 20 min of photosynthesis in 14CO2, radioactivity was present in lipid and non‐lipid, soluble and insoluble compounds of roots. After a chase period of 18 h, c.30 % of the radioactivity in mycorrhizal and non‐mycorrhizal roots supplied with [2‐14C]‐acetate and [14C]glycerol and 12 to 20% of that from [14C]sucrose was in the lipid fraction, while c. 5% of the 14C‐labelled photosynthate received by the roots appeared in lipids. Mycorrhizal roots differed from uninfected roots in their significantly higher incorporation of carbon from photosynthate, sucrose and acetate into ethanol‐soluble compounds and insoluble materials, from sucrose into water‐soluble compounds and from acetate into lipids.
BREEDING BEHAVIOUR AND POPULATION DIFFERENTIATION IN THE HEXAPLOID GRASS KOELERIA VALLESIANA (HONCK.) BERTOL.
Authors: CALLOW R. S. , Parker J. S.
Published: May 2006

Summary

In Britain, the hexaploid perennial grass Koeleria vallesiana (Honck.) Bertol. is confined to the western end of the Mendip Hills but is widespread in western Europe. Comparisons of the marginal British populations with continental populations from France indicate that there are no differences in breeding behaviour or genetic variability. There are, however, greater geneti differences in morphological characters between British and French material than between British populations. In addition, the Mendip populations, which are topographically isolated, show significant differences in morphology which are genetic in origin.

Comparisons of floret fertility under different systems of mating indicate that K. vallesiana is a self‐incompatible outbreeder. Florets collected from the wild show low fertility (c. 5%) in common with other outbreeding perennial grasses.
FACTORS INVOLVED IN BREAKING BUD DORMANCY IN VIRUS‐INFECTED STEM CUTTINGS OF EUPHORBIA PULCHERRIMA
Authors: MANDAHAR C. L. , GULATI A. , NATH S.
Published: May 2006

Summary

Euphorbia pulcherrima, a vegetatively propagated ornamental plant, normally grows vegetatively in summer and is dormant in winter. Buds on virus‐infected rooted stem cuttings of this plant grew into leafy branches during the normal dormant period while the buds on similar stem cuttings obtained from healthy stocks remained quiescent or sometimes gave rise to cyathia. Estimations of seasonal variations in the endogenous levels of growth inhibitors (abscisic acid and phenols) and of a growth promoter (gibberellin) together with treatment of stem cuttings with GA3, indicated that the dormancy in virus‐infected stem cuttings may be broken because of their low abscisic acid and phenol levels and high gibberellin levels.
REPRODUCTIVE AND VEGETATIVE PERFORMANCE IN TWO WINTER ANNUAL GRASSES, CATAPODIUM RIGIDUM (L.) C. E. HUBBARD AND C. MARINUM (L.) C. E. HUBBARD
Authors: CLARK S. C.
Published: May 2006

Summary

A combined field and growth‐room experiment was carried out using three populations of Catapodium rigidutn and one of C. marinum grown reciprocally on the soils and at the sites where they occurred and also at sites where neither species occurred naturally. The effect of late emergence on vegetative and reproductive production was also investigated. No plants survived to mature seed on either of the acidic soils in the field and on only one in the growth‐room.

The coastal site was most favourable with least mortality, more vegetative growth in winter, most production and earlier maturation of caryopses. At two of the three sites when there were indigenous and artificially established colonies of the same populations, the indigenous plants were the most productive. Significant differences in productivity between sites were correlated with differences in the level of nutrients at the various sites. No differences between the populations at any one site were detected. There were, however, significant differences in the components of yield between the populations when all the sites were taken together. There were significant differences in the production of caryopses between the replicate colonies of each population at a particular site. The marked heterogeneity within sites indicated by this was probably the reason for failure to obtain evidence for adaptation to a particular site by its indigenous population. Constraints on the production of caryopses in the field operated through caryopsis number and not weight and probably early in the life cycle, since the number of tillers and the number of spikelets per inflorescence were the components of yield most reduced in the field compared with the equivalent treatments in the growth‐room. The results of the growth‐room experiment showed that soil factors and not genetic differences between populations were the main determinants of differences in reproductive performance between sites. There were, however, some significant differences in phenology, vegetative growth and yield of caryopses, between the populations of Crigidutn and between these and the one of C. marinum. The effect of late sowing in the growth room was to shorten the life‐cycle, to reduce the production of caryopses slightly, to increase the variation within treatments and to reduce the effect of soil type on performance.
THE INDUCTION OF A LIGHT REQUIREMENT IN BIDENS PILOSA SEEDS BY LEAF CANOPY SHADE
Authors: FENNER M.
Published: May 2006

Summary

The aim of these experiments was to determine whether exposure to leaf‐canopy shade induces a light requirement for germination in Bidens pilosa seeds.

Seeds of this species were pretreated by placing them in the shade of a natural canopy for 12 days and then setting half of them to germinate in full light and the other half in darkness.

Canopy‐treated seeds acquired a marked light requirement. The pretreatment was more effective if the seeds were imbibed during it. Fresh and old seeds gave similar results.

In a second experiment the effect of time of exposure to canopy shade on the induction of a light requirement was investigated. It was found that only 1 h exposure to leaf‐transmitted light is required to induce an almost complete light requirement in this species. The ecological implications of the results are discussed.
HAWKMOTH BEHAVIOUR AND FLOWER ADAPTATION REDUCING SELF POLLINATION IN TWO LILIIFLORAE
Authors: BRANTJES N. B. M. , BOS J. J.
Published: May 2006

Summary

In experiments with models and a Petunia cultivar a hawkmoth makes its initial approach at about the same level as the flower. In Lilium martagon L., after flower opening, the style curves towards the direction of maximum light intensity. A hawkmoth comes into contact with the stigma at the beginning of its visit. Thereafter, while drinking from the individual nectaries on each petal, the visitor picks up pollen from the anther in front of the petals. During the initial approach to Crinum jagns (Thomp.). Dandy flowers a hawkmoth touches only the stigma, which is in front of the anthers. Anthers contact the visitor's body only during drinking. Then the moth leaves the flower by flying upwards and does not touch the stigma again. Thus there is evidence that in two Lilüflorae, the combination of the moth‐behaviour with the flower structure might reduce self‐pollination.
PHYTOCHROME CONTROL OF NITRATE REDUCTASE ACTIVITY AND ANTHOCYANIN SYNTHESIS IN LIGHT‐GROWN SINAPIS ALBA (L.). DIFFERENTIAL RESPONSES OF COTYLEDONS AND HYPOCOTYLS
Authors: WHITELAM G. C. , JOHNSON C. B.
Published: May 2006

Summary

In 40 h old cotyledons of etiolated Sinapis alba (L.) red/far‐red photoreversibility and the effect of continuous far‐red light were used to demonstrate the involvement of phytochrome in the control of in vivo nitrate reductase activity and anthocyanin synthesis. Over a period of several days during the development of S. alba seedlings, in the light, in vivo nitrate reductase activity and anthocyanin synthesis were determined in the cotyledons and hypocotyls. Seedlings were grown under two light environments; fluorescent white light, establishing an estimated phytochrome photo‐equilibrium, φE, of 0.69, simulating direct sunlight and fluorescent white light with added far‐red light, establishing an estimated phytochrome photo‐equilibrium of 0.26, simulating ‘shade’ or ‘canopy’ light. The time courses of both responses were greatly influenced by these different light qualities. Furthermore, in the case of nitrate reductase activity the cotyledons and hypocotyls showed marked differences in their responses to light quality. In the cotyledons a light source establishing a low photo‐equilibrium was initially more effective in eliciting the response, but with time, a light source establishing a high photo‐equilibrium became the more effective. In the hypocotyls a light source establishing a high photo‐equilibrium was always the more effective. The anthocyanin response showed the crossing over of effectiveness of high and low photo‐equilibrium in both tissues. The results are discussed in terms of the transition from the ‘high irradiance reaction’ of young seedlings to a possible steady state of phytochrome control in the mature plant.
THE RHIZOBIUM REQUIREMENTS OF THE NON‐LEGUME PARASPONIA IN RELATIONSHIP TO THE CROSS‐INOCULATION GROUP CONCEPT OF LEGUMES
Authors: TRINICK M. J. , GALBRAITH J.
Published: May 2006

Summary

Parasponia andersonii was nodulated by thirty four of thirty nine slow‐growing rhizobia isolated from tropical legumes and by R. japonicum and JR. lupini. The nitrogenase activity of nodulated plants within a rhizobial treatment varied widely. Effective associations were obtained with some but not all isolates from Cajanus cajan, Centrosema pubescens, Crotalaria anagyroides, Flemingia congesta, Inocarpus fragiferum, Macroptilium lathyroides, Phaseolus calcaratus, Stizolobium deeringianum and Stylosanthes gracilis. Little or no nitrogen was fixed with rhizobia from Albizia stipulata, Cassia mimosoides, Desmodium microphyllum, Pterocarpus indicus, Uraria lagopoides, and the wide‐host range cowpea Rhizobium strain CB 756. Fast‐growing rhizobia from Leucaena leucocephala, Mimosa invisa, M. pudica, Sesbania grandiflora and Lablab pur‐pur eus nodulated Parasponia with a low level of nitrogen fixation.

Isolates from Parasponia failed to nodulate most of the legumes usually nodulated by slow‐growing rhizobia and when tropical legumes were nodulated, the association was either partially effective or ineffective; only isolate CP 283 was highly effective and promiscuous. Hosts normally nodulated with fast‐growing rhizobia, including Leucaena and Mimosa were not nodulated with isolates from Parasponia.

It was concluded that the Parasponia‐Rhizobium symbiosis is best located in the ‘cowpea miscellany’.
PHOTOSYNTHESIS OF YOUNG ORCHID SEEDLINGS
Authors: HEW C. S. , KHOO S. I.
Published: May 2006

Summary

Adult leaves, protocorms and seedlings of succulent tropical orchids exhibit diurnal fluctuations in acidity. The titratable acidity varied at different stages of growth. The fluctuation in acidity was barely detectable in protocorms but as they grew older, their capacity for acid accumulation increased.

The O2 exchange in orchid protocorms and seedlings was similar to that of adult leaves in their responses to temperature, bicarbonate and light intensity. It is concluded that protocorms and seedlings resemble adult organs in having the characteristics of crassulacean acid metabolism (CAM).
STEROIDAL OESTROGENS AND PLANT GROWTH AND DEVELOPMENT
Authors: HEWITT S. , HILLMAN J. R. , KNIGHTS B. A.
Published: May 2006

I. SUMMARY

The current information regarding the occurrence of steroidal oestrogens and the physiological significance of these compounds in plants is reviewed. Special reference is made to the effects of oestrogens on elongation growth, and results are presented from experiments with Pisum and Phaseolus seedlings.
THE EFFECT OF BENTAZONE ON STOMATAL BEHAVIOUR IN CHENOPODIUM ALBUM L.
Authors: TAYLOR F. ELIZABETH , COBB A. H. , DAVIES L. G.
Published: May 2006

The herbicide bentazone induces stomatal opening in epidermal strips of C. album in a light‐dependent response, over a temperature range of 9 to 29 °C. The relevance of these findings is discussed in relation to stomatal structure and the foliar penetration of the herbicide.
MYCORRHIZAE AND NUTRIENT CYCLING IN NATURAL FOREST ECOSYSTEMS
Authors: FOGEL ROBERT
Published: May 2006

The widespread occurrence of mycorrhizae in nature and their importance in the mineral nutrition of almost all plants has been extensively documented but despite this mycorrhizae have not been included in nutrient cycling studies of forest ecosystems. This neglect may be due to a failure on the part of researchers to recognize the functional differences between mycorrhizae and roots and to the labour‐intensive effort needed to study mycorrhizae.

Biomass or surface area of mycorrhizae must be measured before information on ion absorption by mycorrhizae can be applied to forest ecosystems. A full assessment of the importance of mycorrhizae in nutrient cycling also requires data on mycorrhiza production, senescence, and decomposition. Few mycorrhiza studies have provided such data. Consequently, our information on nutrient cycling is derived from fine root (≥ 5 mm in diameter) data which may or may not include mycorrhizae.

Recent studies have shown that most of the organic input to the decomposition process results from fine root production. Fine root mortality and decomposition is also more important than other mechanisms for returning nitrogen immobilized in vegetation to the soil in both deciduous and coniferous forests. A recently completed study indicates that mycorrhizae account for 50% of the annual throughput of biomass and for 43% of the nitrogen released annually in a Douglas fir ecosystem. These transfers are five times larger than the releases from litterfall or litter decomposition. Clearly, the study of mycorrhizal nutrient cycling is in an embryonic state and considerable additional research is needed.
SHORT‐ AND LONG‐DISTANCE TRANSPORT OF BORIC ACID IN PLANTS
Authors: RAVEN J. A.
Published: May 2006

The molecular weight and ether‐water partition coefficient of boric acid are consistent with a PB(OH)3 in plant cell membranes of at least 10‐6 cm s‐1. This permeability coefficient is high enough to account for the measured magnitude of boric acid fluxes at many plant cell membranes. The use of active transport of boric acid to maintain B distribution across a membrane away from thermodynamic equilibrium is consequently likely to be energetically expensive. The content of m‐diols (with which boric acid can form complexes) in cell walls and inside the cells varies widely between different plant species without any obvious correlation with either total B content or with the B content at which deficiency (in B‐requirers) or toxicity symptoms are manifested. B distribution at the cell level depends on the relative extents of passive permeation, active transport and cisdiol formation; regulations may be in response to total intracellular B rather than free boric acid.

The net uptake of boric acid by intact vascular land plants is influenced by the rate of transpiration; while transport of B within the xylem is probably directly proportional to the rate of transpiration, neither whole plant B uptake nor transfer from root tissue into the xylem exhibit such a simple relationship. Redistribution of B in the phloem from transpirational termini is very limited. This limitation could result from the toxicity of B (which requires a low B concentration in the translocation stream relative to other nutrients and to sink requirements) or to ‘counter‐current distribution’ of B from the phloem to the adjacent xylem stream (low in B) through the B‐permeable sieve‐tube plasmalemma.

The transport of B is discussed in relation to the evolution of multi‐cellular algae and of vascular land plants.
EFFECTS OF ORGAN EXCISION AND HORMONE APPLICATIONS ON LATERAL SHOOT EXTENSION AND INFLORESCENCE DEVELOPMENT IN CHRYSANTHEMUM MORIFOLIUM RAMAT
Authors: MENHENETT ROGER
Published: May 2006

The excision of young inflorescence (flower) buds and young, expanding leaves from lateral shoots of pot‐grown Chrysanthemum morifolium Ramat markedly reduced internode extension. The absence of flower buds in particular restricted growth in length. The removal of more mature leaves on lateral stems had little effect. Defoliation of the main stem did not influence lateral stem length but it did delay flowering.

The application of gibberellic acid (GA) more than compensated for the removal of the flower bud and/or young leaves and promoted the elongation of intact shoots. It also increased the rate of flower bud development. While indol‐3‐ylacetic acid (IAA) promoted internode extension in shoots from which flower buds and young leaves had been excised, it never significantly altered the length of intact stems and tended to delay flowering. The cytokinin 6‐benzyladenine (BAP) supplied alone induced little response. Combinations of GA and IAA, or GA and BAP, decreased internode length compared to GA alone.

The data suggest that of the organs of the shoot, the flower buds and young leaves are sites of production of the hormones necessary for stem elongation and that gibberellins play the major role in promoting this process.
THE EFFECTIVENESS OF VESICULAR‐ARBUSCULAR MYCORRHIZAS IN INCREASING GROWTH AND PHOSPHORUS UPTAKE OF SUBTERRANEAN CLOVER FROM PHOSPHORUS SOURCES OF DIFFERENT SOLUBILITIES
Authors: Pairunan A. K. , Robson A. D. , Abbott L. K.
Published: May 2006

The effect of inoculation, with a VA mycorrhizal fungus on growth and phosphorus uptake of subterranean clover was examined using three phosphorus sources with different solubilities. Mycorrhizas markedly increased growth and phosphorus content of tops at intermediate rates of phosphorus application for all sources.

The effectiveness of phosphorus for plant growth for mycorrhizal plants relative to non‐mycorrhizal plants was the same for a water soluble source (superphosphate) and two insoluble sources (C‐grade Christmas Island rock phosphate and calcined Christmas Island rock phosphate). The effectiveness of phosphorus from each of the three sources for phosphorus uptake by mycorrhizal plants relative to non‐mycorrhizal plants was also independent of the solubilities of the phosphorus sources applied.

At a given phosphorus concentration in tops, non‐mycorrhizal subterranean clover produced more dry matter than mycorrhizal clover supplied with superphosphate. Mycorrhizal and non‐mycorrhizal subterranean clover supplied with C grade rock phosphate had the same dry weight at a given phosphorus concentration in their tops.

VA mycorrhizas increased zinc but not calcium uptake by subterranean clover.
EVOLUTION OF INCOMPATIBILITY SYSTEMS IN PLANTS: ORIGIN OF ‘INDEPENDENT’ AND ‘COMPLEMENTARY’ CONTROL OF INCOMPATIBILITY IN ANGIOSPERMS
Authors: Pandey K. K.
Published: May 2006

Incompatibility is a common means of controlling breeding behaviour among plants, and has been an important factor in evolution. It acts to prevent self‐fertilization, as well as to prevent sterilization of ovules by foreign pollen. Angiosperms have both inter‐ and intraspecific incompatibility, and these are controlled by the same S gene complex. Gymnosperms, however, have only interspecific incompatibility. Observations on incompatibility behaviour in flowering plants have suggested that interspecific incompatibility evolved first among gymnosperms or progymnosperms as a means of protecting their naked ovules from foreign pollen. Duplication and redifferentiation of this ‘primary specificity’ gene in angiosperm precursors subsequently gave rise to ‘secondary specificity’ controlling intraspecific incompatibility.

Today there are three basic types of incompatibility found among the angiosperms: (i) inherently independent control‐each allele independently expresses its individual specificity, shows allelic interaction in the pollen after S gene duplication; (ii) inherently complementary control‐alleles of two or more incompatibility loci co‐operate to produce a single specificity, shows no allelic interaction; and (iii) late complementary control‐alleles of two or more incompatibility loci co‐operate to produce a single specificity, shows allelic interaction. The pattern of distribution of these three types of control has given rise to a controversy over which represents the most primitive type of angiosperm incompatibility.

The present paper examines the factors involved in secondary evolution of incompatibility, and concludes that independent control is in fact more primitive. Complementary control probably developed secondarily and independently several times during angiosperm evolution, the first occurrence, that of ‘inherently complementary’ apparently being among the progenitors of the monocotyledons. While the majority of dicotyledons have the original ‘inherently independent’ control, certain evolutionary lines appear to have switched independently to complementary control, the gametophytic system giving rise to ‘inherently complementary’ control and the sporophytic system giving rise to ‘late complementary’ control. A major factor in favour of complementary incompatibility system as opposed to independent control system is the advantage it confers in colonisation after long distance dispersal. The factors involved in the evolution of complementary control, together with certain genetic characteristics of this system, have probably played a significant role in the evolution and distribution of monocotyledons.
A REVISED TERMINOLOGY FOR THE SPORE‐CONTAINING PARTS OF ANTHERS
Authors: Green J. W.
Published: May 2006

A concise terminology for the spore‐containing parts of anthers is proposed. Based chiefly on the numbers of microsporangia and stomia, it considerably reduces the wide variety of terms in current use and should serve most needs in taxonomic description.
THE REPRODUCTIVE BIOLOGY OF ASCLEPIAS TUBEROSA: I. FLOWER NUMBER, ARRANGEMENT, AND FRUIT‐SET
Authors: WYATT ROBERT
Published: May 2006

An analysis of the inflorescence of the herbaceous perennial milkweed Asclepias tuberosa was carried out by sampling populations in North Carolina and Virginia in 1975 and 1976. Reproductive characters are strongly associated within a given level of comparison (e.g. stems per plant with flowers per plant) but show relative independence between levels (e.g. stems per plant with umbels per branch). Plant size is negatively correlated with fruit production on a proportional basis (fruit‐set) but positively related to the absolute numbers of fruits produced. The invocation of a ‘pollen donor strategy’ to explain the occurrence of large inflorescence displays in Asclepias is unnecessary, as these large plants have a larger female contribution to the next generation, irrespective of their male contribution. Self‐pollination is proposed as a process determining the upper limit of inflorescence size in Asclepias. Experimental pollinations suggest that early competition among ovaries within umbels is very important in determining levels of fruit‐set. Competition among ovaries in different umbels, time of pollination, and location of umbels also exert an effect. Inflorescence architecture likely represents a series of evolutionary compromises between maximization of pollinator attractiveness on the one hand and maximization of fruit maturation on the other.
THE EFFECT OF l‐ARGININE ON THE GROWTH OF HETEROTROPHIC CULTURES OF THE EMERSON STRAIN OF CHLORELLA. III. STUDIES WITH THE STRUCTURAL ANALOGUE CANAVANINE
Authors: Thinh L. V. , Griffiths D. J.
Published: May 2006

Summary

The special role of arginine in controlling cell division in heterotrophic cultures of Chlorella emersonii has been studied using the guanidoxy structural analogue, canavanine. Evidence is presented that competition between the two compounds probably occurs at the site of protein synthesis and that the analogue interferes with the synthesis of proteins essential for cell division and chloroplast development. An experimental system based on the light or dark recovery of previously heterotrophically grown cells has shown that protein synthesis which takes place after DNA replication is particularly sensitive to canavanine, and that the initial stages of recovery are important in countering the inhibitory effect of the analogue. The possibility is discussed that arginine‐proteins may have a general role in controlling cell division in Chlorella emersonii.
THE TEMPERATURE RANGE FOR FREEZING DAMAGE AND ITS RELATION TO HARDINESS
Authors: PEARCE R. S.
Published: May 2006

Summary

Several sets of data suggest that the range of temperatures over which damage or kill due to frost progressively increases (i.e. Δ°C/Δd, where d is % damage or % kill) is correlated with hardiness. The relationship may exist for several species of Gramineae, for alfalfa and for several types of tree and fruit bush. There appear to be exceptions to this generalization. A hypothetical explanation is offered.
ANTHOCYANIN VARIATION IN THE GENUS RUBUS
Authors: JENNINGS D. L. , CARMICHAEL ELEANOR
Published: May 2006

summary

The pigments of Rubus fruits vary in concentration and in the nature of the aglycones and sugars contained in the anthocyanin molecule. Variation in concentration is determined by the genes T, P, Y, Ys, Ycor and possibly Bl and by minor genes. Up to six sugars may be present: one monoglycoside, three diglycosides and two triglycosides. The monoglycoside was present in all the material studied and the presence or absence of the diglycosides rutinose, sophorose, and sambubiose was determined by segregation of the genes R, So and Xy. Synthesis of triglycosides occurred when genes So and R or Xy and R were present together. Cyanidin is the predominant aglycone of raspberries and blackberries, but pelargonidin occurred as traces in raspberries and as the predominant aglycone in R. parviflorus, a species of the sub‐genus Anoplobatus, and in R. pileatus, a species of the sub‐genus Idaeobatus. Knowledge of agenotype's anthocyanin sugars frequently provides evidence of its probable ancestry, but little evidence is available to suggest that any one sugar should be preferred to another.