Confusion in the use of the taste adjectives 'sour' and 'bitter'

Subjects from Britain and America were tested on their skillat applying the taste adjectives ‘sweet’, ‘sour’,‘salty’, and ‘bitter’ to clearly distinguishablesolutions of sucrose, citric acid, NaCl and quinine sulphate,respectively. The main error that occurred was calling citricacid ‘bitter’ while the tendency to call quininesulphate ‘sour’ was not so common; this is the wellknown sour-bitter confusion. A sour-salty confusion was alsonoted as well as a tendency to call citric acid ‘sweet’.All these confusions were rectified by mere definition usingstandards. Skill at applying taste adjectives was not alwaysfound to be consistent over time. More errors occurred at lowersolution concentrations, even though stimuli were clearly distinguishable;indistinguishability of stimuli may account for some confusionsin other studies. ^*Present address: Department of Psychology, University of Bristol,Bristol BS8 1HH, England.     

The Growth and Carbon Economy of Selection Lines of Lolium perenne cv. S23 with Differing Rates of Dark Respiration: 1. Grown as Simulated Swards During a Regrowth Period

Simulated swards of each of two selection lines of Lolium perennecv. S23 with ‘fast’ and ‘slow’ ratesof ‘mature tissue’ respiration were establishedin growth rooms at 20/15 °C day/night temperatures and studiedover four successive regrowth periods of 46, 30, 26 and 53 daysduration. The ‘slow’ line outyielded the ‘fast’,both in harvestable shoot (above a 5 cm cut) and in root andstubble. Its advantage increased over successive regrowth periodsto 23 per cent (total biomass). Gas analysis measurements onthe entire communities (including roots), during the final regrowthperiod, showed that the ‘slow’ line had a 22–34per cent lower rate of dark respiration per unit dry weight.This enabled it to maintain its greater mass of tissue for thesame cost in terms of CO₂ efflux per unit ground area. Halfthe extra dry weight produced by the ‘slow’ line,relative to the ‘fast’, could be attributed to itsmore economic use of carbon. The rest could be traced to a 25per cent greater tiller number which enabled the ‘slow’line to expand leaf area faster (though not at a greater rateper tiller), intercept more light and fix more carbon, earlyin the regrowth period. Lolium perenne L., ryegrass, respiration, maintenance respiration, tiller production, simulated swards, canopy photosynthesis, carbon economy     

Uptake and Metabolism of Sugars by Suspension cultured Catharanthus roseus Cells

p. 186, right column line 11 ‘27.2 KBq’ change to‘37.2 MBq’ p. 187, left column line 8 ‘27.2 KBq’ change to‘37.2 MBq’ line 10 ‘13.6 KBq’ change to ‘18.6 MBq’ line 11 ‘13.6 KBq’ change to ‘18.6 MBq’ line 21 ‘89%’ change to ‘80%’ right column line 24 ‘CLC-NH₄’ change to ‘CLC-NH₂’ P. 189, Table 1 appeared incorrectly: it should appear as indicated.     

The Nitrogen Content of Plants and the Self-thinning Rule of Plant Ecology: A Test of the Core-skin Hypothesis

The ‘core-skin’ hypothesis postulates that secondarilythickened plants behave energetically as an inert ‘core’covered by an active ‘skin’, the ‘skin’being two-imensional, the ‘core’ three-dimensional.This would explain the ‘self-thinning ‘or‘–3/2’ rule of plant ecology, that is, the tendencyfor log (dry weight per plant) and log (number of plants perunit area) to progress along a straight line relationship, withslope = – 3/2’. The hypothesis was tested as follows. Plant nitrogen contentwas used as an estimate of the mass of ‘skin’ perplant, and dry weight as an estimate of the mass of the ‘core’.As plants mature the slope of the relationship between y = log(mass of nitrogen per plant) and x = log (mass of dry matterper plant) is expected to decline from an initial value of 1.0towards a final value of 0.66. The intercept of the relationshipis expected to reflect the intrinsic content of ‘skin’per unit of ‘core’. Genotypic variation in thisparameter should cause genotypic differences in the maximumattainable yield of biomass per unit area. The expectations were investigated by fitting the function y= p+qx+r exp – x to 30 sets of data on plant nitrogencontent, plant weight and time in 18 different vegetables. Simplelinear regressions of y on x were fitted to more limited setsof data on weights and nitrogen contents of mature trees. Theexpectations were, with some minor exceptions, confirmed. Nitrogen, yield, plant competition, self-thinning     

The Extraction, Solubility, and Characterization of Two Groups of Barley Storage Polypeptides

This paper reports further studies on the characteristics ofthe storage protein fraction (hordein) of barley. Hordein consistsof two groups of polypeptides (termed ‘B’ and ‘C’)coded by two separate but linked loci. Whereas the ‘C’polypeptides are readily soluble and extracted in 60% (v/v)ethanol at room temperature, the ‘B’ group is moresoluble in, and therefore more efficiently extracted by, 50%(v/v) propan-1-ol or 45% (v/v) propan-2-ol at elevated temperaturesand in the presence of 2-mercaptoethanol. However, the mostefficient conditions for hordein extraction (50% propan-1-ol+ 2% (v/v) 2-mercaptoethanol at 60 °C) also extract somecontaminating non-hordein polypeptides resulting in an apparentlyincreased lysine content of the hordein fraction. Amino acid analysis of the purified ‘B’ and ‘C’hordein groups shows that, whereas ‘C’ hordein containsmore glutamate + glutamine, proline, and phenylalanine than‘B’ hordein, it contains only traces of lysine andsulphur amino acids in contrast to ‘B’ hordein whichcontains 0·5% lysine 0·6% methionine, and 2·5%cysteine. Equilibrium sedimentation analyses carried out on the purified‘B’ and ‘C’ groups indicates that thepreparations were reasonably monodisperse with molecular weightsof approximately 32 000 and 52 000 respectively. These valuesare considerably lower than those previously determined by SDS-PAGE.     

Margaret Mee's Amazon. Diaries of an artist explorer. * Margaret Mee. 2003. * Woodbridge Suffolk, UK: Antique Collectors' Club. * {pound}29{middle dot}50 (hardback). 320 pp, 400 colour illustrations

‘Delight’ said CharlesDarwin in his diaries in 1832, ‘is a weak term to expressthe feelings of a naturalist who, for the first time, has wanderedby himself in a Brazilian forest’. These feelings musthave been those which drove Margaret Mee to explore the Brazilianjungles on numerous expeditions between 1958 and 1964, creatingwonderful pictures despite all kinds of difficulties encounteredin this hostile world. And these feelings were also those Ihad when I read this book: delight about her precise drawingsand life-like paintings, which are extremely expressive from     

Homeostasis in Nitrogenous Uptake/Assimilation by the Green Alga Platymonas (Tetraselmis) striata (Prasinophyceae)

When nitrate, ammonium, or urea were the sole nitrogen sourcesfor the growth of Platymonas striata there was a short initiallag period, after which uptake/assimilation occurred at a constantrate. Glycine ‘uptake’ was however non-linear withtime. Addition of ammonium or urea markedly inhibited nitrate‘uptake’ whereas although glycine was initiallytotally inhibitory, nitrate ‘uptake’ recommencedabout 1 h after addition, but at a greatly reduced rate. Ammoniumtotally inhibited urea ‘uptake’, but did not inhibitglycine ‘uptake’. When ammonium, urea, or glycinewere present at the same time as nitrate the total rate of nitrogen'uptake/assimilation was within 40% (or closer) of that of nitratenitrogen ‘uptake’ alone. In the first two casesthis reflected a total switching off of nitrate ‘uptake’whilst the new substrate was assimilated at a rate similar tothe initial nitrate rate, whereas in the case of glycine, bothsubstrates were used simultaneously. Once the concentrationof any of the inhibitory nitrogen sources had been reduced toa low level the ‘uptake’/assimilation of nitraterecommenced. It is suggested that the ability of P. striatato maintain a more or less constant rate total nitrogen ‘uptake’/assimilationirrespective of the mixture of utilizable nitrogen sources presentedto it, is not due to controls at the level of the entry of substrateinto the cell, but to intracellular actions at the enzyme level.The relative constancy of, and high rate of ‘uptake’,irrespective of nitrogen source and over a wide range of extracellularconcentrations, is tentatively considered to be due to saturationof the assimilatory mechanisms under the conditions employed;all the sources lead, either directly or indirectly, to theproduction of amino groupings for entry into nitrogenous metabolism.This homeostasis of nitrogen ‘uptake’/assimilationwould clearly be of considerable benefit to the alga in nature,enabling it to maximize growth in changing environmental conditions. Platymonas striata, nitrogen update, nitrogen assimilation     

Coastal eutrophication: recent developments in definitions and implications for monitoring strategies

The word ‘eutrophication’ has its root in two Greekwords: ‘eu’ which means ‘well’ and ‘trope’which means ‘nourishment’. The modern use of theword eutrophication is related to inputs and effects of nutrientsin aquatic systems. Despite a common understanding of its causesand effects, there is no agreed definition of coastal eutrophication.This communication aims to review recent developments in thedefinitions of coastal eutrophication, all of which focus on‘accelerated growth’, and to discuss the implicationsin relation to monitoring and assessment of ecological status.It is recommended that measurements of primary production, beinga sensitive and accurate indicator of eutrophication, shouldbe mandatory when monitoring and assessing the ecological statusof coastal waters. Written responses to this article should be submitted to KevinFlynn at k.j.flynn@swansea.ac.uk within two months of publication.For further information, please see the Editorial ‘Horizons’in Journal of Plankton Research, Volume 26, Number 3, Page 257.     

The Influence of the Plant Growth-regulator, 2-Methyl-4-Chlorophenoxyacetic Acid, on the Metabolism of Carbohydrate, Nitrogen and Minerals in Solanum lycopersicum (Tomato)

The effects of the foliar application of phytocidal concentrationsof 2-methyl-4-chlorophenoxyacetic acid (MCPA) on change in totaldry weight, and in ‘available carbohydrate’ (starch,‘total’ and ‘reducing’ sugars), totalnitrogen, phosphorus, potassium, calcium, and magnesium of ‘tops’and roots of tomato plants have been followed over a periodof 14 days following spraying. There were two main treatments—‘nutrient’(nutrient supply to roots continued after spraying) and ‘water’(distilled water only supplied to roots after spraying) and‘water’ (distilled water only supplied to rootsafter spraying)—the sub-treatments consisting of ‘MCPA’versus ‘no-MCPA’ for each of the main treatments.Twelve different times of sampling were used. In analysing the present data, the quantity ‘residualdry weight’ (total dry weight less ‘available carbohydrate’),which was originally introduced by Mason and Maskell as a basisof reference for analyses of plant organs in short-period experimentsnot involving appreciable growth, has been used as an estimateof the permanent structure of plant growth. This new use ofthe ‘residual dry weight’ basis has brought outimportant features which were obscured when the data were leftin their primary form (as percentages of total dry weight oramounts per plant). Growth, as measured by increase in ‘residual dry weight’,was greatly inhibited by 2-methyl-4-chlorophenoxyacetic acidshortly after spraying, in both the presence and the absenceof nutrient. In the presence of 2-methyl-4-chlorophenoxyacetic acid, netassimilation rate (estimated as rate of increase in total dryweight per gram ‘residual dry weight’ of the ‘tops’)was greatly diminished while uptake of total nitrogen and ofP₂O₅ (estimated as increase in total nitrogen or of P₂O₅ ofthe whole plant per day per 1 g. ‘residual dry weight’of the roots) appeared to undergo a similar but much smallerdiminution. It seemed probable, however, that in the presenceof MCPA a larger proportion of the carbohydrate actually formedwas utilized for synthesis of aminoacids and protein. In the plant as a whole there was no evidence of actual depletionof ‘available carbohydrate’ as a result of MCPAtreatment, this fraction showing a steady increase in all treatmentsthroughout the experiment. The rate of increase was, however,much reduced by MCPA treatment. The ‘tops’ presentedmuch the same picture as the whole plant, but for the rootsthe situation was quite different. While the roots of the ‘no-MCPA’plants and also of the ‘MCPA-water’ plants showeda steady increase in available carbohydrate, those of the ‘MCPA-nutrient’plants rose only very slightly (from the initial value of 8mg. per plant to about 10 mg.) during the first 2 days, andthen in the next 2 days declined to a value (about 6 mg.) belowthe initial and remained at this low level for the rest of theexperiment. It is suggested that the phytocidal effect of 2-methyl-4-chlorophenoxyaceticacid in the presence of nutrient may be due to depletion ofthe ‘available carbohydrate’ supplies in the roots,which is shown to be brought about, in part, by reduced transportfrom the tops, and partly by the relatively greater utilizationof the carbohydrate present. These results offer an explanationfor the facts that plants showing vigorous growth are more easilykilled by MCPA and that perennial plants, particularly thosewith storage tissues in their roots, are more resistant. Further,they suggest the useful practical application that MCPA treatmentshould be given when the carbohydrate reserves of the rootsare at a minimum. For perennial plants, conditions might beexpected to be optimal for the application of MCPA in late spring,at a time when the first ‘flush’ of growth is slowingdown and before any appreciable new reserves of carbohydratehave been accumulated. It was also shown that 2-methyl-4-chlorophenoxyacetic acid preventedthe net synthesis of starch, but still permitted an appreciablenet formation of sucrose. 2-methyl-4-chlorophenoxyacetic acid appeared to have no effecton the uptake of potassium, calcium, or of magnesium. The lackof effect on potassium is contrasted with the previous observationby Rhodes, Templeman, and Thruston (1950) that sub-lethal concentrationsof MCPA, applied over a relatively long period to the rootsof tomato plants, specifically depressed the uptake of potassium.     

Relative Sensitivity and Tolerance of some Gladiolus Cultivars to Sulphur Dioxide

Five Gladiolus cultivars, namely ‘Aldebaran’, ‘BrightEye’, ‘Illusion’, ‘Manisha’ and‘Manmohan’, were exposed to 1 and 2 µg l^–1sulphur dioxide to test their relative-sensitivity toleranceto the pollutant Plants were fumigated experimentally for 2h daily Foliar injury symptoms were observed first in ‘Manisha’followed by ‘Aldebaran’ and ‘Illusion’at the higher dose Photosynthetic pigments and leaf extractpH were significantly decreased, particularly in ‘Manisha’and ‘Illusion’ Overall disturbances in the plantmetabolism due to SO₂ treatment led to retarded growth of plants,as evident from decreased shoot length and phytomass valuesThe order of sensitivity of the five Gladiolus cultivars toSO₂ was as follows, with the greatest first Manisha, Illusion,Aldebaran, Bright Eye, Manmohan Cultivars, Gladiolus, sensitivity, sulphur dioxide, tolerance     

Factors Affecting the Abscission of Reproductive Organs in Yellow Lupins (Lupinus luteus L.): III. ENDOGENOUS GROWTH SUBSTANCES IN VIRUS-INFECTED AND HEALTHY PLANTS AND THEIR EFFECT ON ABSCISSION

Extracts of small and mature-size lupin pods yielded four substancesaffecting the growth of wheat-coleoptile sections: one acidpromotor (A), two acid inhibitors(B and X), and one neutralinhibitor(Y). Inhibitor B was extremely active, however, coleoptile sectionsshowed no signs of toxic effects; they resumed growth at a rapidrate after rinsing them and adding ß-indolylaceticand (IAA) to the medium. 1 µg of IAA was required to counteractthe effect of ‘B’ extracted from 230 mg. Of tissue.On an equal fresh weight basis the inhibiting action of ‘B’in lupin pods was 500–1,500 times more potent than thatof ‘inhibitor ß’ in etiolated pea seedlings. Small pods of plants infected with pea-mosaic virus yielded3 times the amount of ‘A’ of healthy plants (equivalentto 1 µg. IAA 0.3 µg. IAA per 25 g. of tissue respectively),and approximately the amount of ‘B’. Mature podsof virus-infected plants again yielded more‘A’,but also 2? times more ‘B’ than pods of healthyplants. Healthy pods yielded more ‘A’ than virus-infectedpods, and there was no difference in ‘X’. A lupin abscission test was developed and the effects of proximaland distal application of -naphthyl acetic acid (NAA) are presented,and discussed with respect to results of other abscission tests. ‘A’ accelerated abscission when applied proximally,and delayed or prevented it when applied distally. ‘B’strongly accelerated abscission when applied in either way.A possible mechanism explaining the abscission-inducing effectof developing pods on later flowers is discussed in terms ofthe substances ‘A’ and ‘B’. The partlyprevented abscission observed on virus-infected plants was foundto agree well with the proposed mechanism.     

Characterization of RNA-dependent RNA Polymerases in Healthy and Tobacco Mosaic Virus-infected Tomato Plants

Healthy tomato plants were shown to contain high levels of RNA-dependentRNA polymerase activity, mainly in a ‘soluble’ form,but also partly in a ‘ bound’ form. The ‘bound’enzyme was solublized by EDTA treatment. Both forms of enzymewere partially purified and characterized. The ion and pH optimaof the two forms were identical at all stages of purification.Both enzymes exhibited uridylyl transferase activity, whichmade up 35 per cent of total incorporation. Infection with tobacco mosaic virus (TMV) increased activityof ‘soluble’ enzyme by twofold, and of solubilized‘bound’ enzyme by less than twofold. Uridylyl transferaseactivity was also increased by infection. General propertiesof the enzymes were unaltered by infection with one exception:in the presence of TMV RNA as added template, the ‘soluble’enzyme from infected plants incorporated ³H-UTP into productswith the electrophoretic properties and RNase sensitivitiesexpected for replicative form and replicative intermediate ofTMV. ‘Soluble’ enzyme from healthy plants, and solublized‘ bound’ enzyme from either healthy or infectedplants did not synthesize these products. The ‘soluble’ and solubilized ‘bound’enzymes behaved differently on ion-exchange chromatography.Under the conditions used, ‘soluble’ enzyme didnot bind to the column, whereas solublized ‘bound’enzyme did. No differences in chromatographic behaviour werefound between enzymes from healthy or infected plants. Withboth ‘soluble’ and solublized ‘bound’enzymes, the uridylyl transferase activity co-chromatographedwith the polymerase activity. Tomato, Lycopersicon esculentum, RNA-dependent RNA polymerase, tobacco mosaic virus, tobacco mosaic virus replicase     

Effects of Inorganic Phosphate on the Utilization of Sucrose by Suspension-cultured Catharanthus roseus Cells

The metabolic fate of [U-¹⁴C]sucrose in suspension culturesof Catharanthus roseus cells was monitored for 96 h after thecells were transferred to fresh complete (‘+Pi’)or to phosphate-deficient Murashige and Skoog (‘–Pi’)medium. Sucrose was hydrolysed extracellularly to glucose andfructose. The rate of uptake of sugars by the cells was 1.5–3times higher in ‘+Pi’ culture than in ‘–Pi’culture. Little difference in the rate of incorporation of radioactivityinto the ethanol-soluble fraction was found between the ‘+Pi’and ‘– Pi’ cultures during the initial 24h of culture, but after 48 h the rate in ‘ +Pi’cultures was higher than that in ‘–Pi’ cultures.Incorporation of radioactivity into ethanol-insoluble macromoleculeswas always significantly higher in the cells in ‘+Pi’cultures than in those in ‘–Pi’ cultures.The results suggest that Pi strongly affects the utilizationof sugars by cultured plant cells through the stimulation oftransport of sugars as well as through the activation of metabolism. Catharanthus roseus, Madagascar periwinkle, suspension culture, inorganic phosphate, sucrose, transport, metabolism     

Plant Morphology: The Historic Concepts of Wilhelm Troll, Walter Zimmermann and Agnes Arber

Recent molecular systematic and developmental genetic findingshave drawn attention to plant morphology as a discipline dealingwith the phenotypic appearance of plant forms. However, sincedifferent terms and conceptual frameworks have evolved overa period of more than 200 years, it is reasonable to surveythe history of plant morphology; this is the first of two paperswith this aim. The present paper deals with the historic conceptsof Troll, Zimmermann and Arber, which are based on Goethe'smorphology. Included are contrasting views of ‘unity anddiversity’, ‘position and process’, and ‘morphologyand phylogeny’, which, in part, are basic views of currentplant morphology, phylogenetic systematics and developmentalgenetics. Wilhelm Troll established the ‘type concept’and the ‘principle of variable proportions’. Hehas provided the most comprehensive overview of the positionalrelations of plant forms. Agnes Arber started from the universaldynamics of life and attempted to describe all structures asprocesses. She paid attention to ‘repetitive branching’,‘differential growth’, and ‘parallelism’.As a result she has recently been rediscovered by developmentalbotanists. Walter Zimmermann rejected any metaphysical influenceon plant form and instead called for objective procedures. Hewas mainly interested in phylogenetic ‘character transformation’and the ‘reconstruction of genealogical lines’.Guided by the example of flower-like inflorescences, a futurepaper will deal with functional and developmental constraintsinfluencing plant forms. Recent morphological concepts (‘trialectical’,‘continuum’/‘fuzzy’, ‘processmorphology’) will be discussed and related to currentmorphological and developmental genetic research. Copyright2001 Annals of Botany Company Plant form, plant morphology, natural philosophy, homology, phylogeny, Goethe, Troll, Arber, Zimmermann, typology, character transformation, differential growth, complementarity     

Molecular ecotoxicology of plants. Ecological Studies Vol. 170. * Sandermann H. ed. 2004. * Berlin: Springer. $89{middle dot}95 (hard cover). 241 pp.

Googling the term‘molecular ecotoxicology’ results in less than 1000hits compared to more than 8·5 million for ‘moleculargenetics’. Hence, we are dealing with a rather new orless well-defined and less propagated field of science. Springer'sbook Molecular ecotoxicology of plants edited by H. Sandermannmay therefore fill a gap and it is unique in focusing on plants.A first introductory chapter sets the stage and tries to definethe term for a broad     

The Growth and Carbon Economy of Selection Lines of Lolium perenne cv. S23 with Differing Rates of Dark Respiration: 2. Grown as Young Plants from Seed

Young plants of two selection lines of Lolium perenne cv. S23with ‘fast’ and ‘slow’ rates of ‘maturetissue’ respiration were individually grown from seed,together with plants of S23, their common parent, in 9.2 cmpots in a controlled environment at 20/15 °C day/night temperatures. No significant differences were found between the genotypesin leaf extension and tiller production during this early stageof their growth. They did differ however, by an average of 26%,in the rate of dark respiration of fully expanded leaf laminae.The use of a simple model demonstrated that such a differencein respiration could alone account for the different rates ofdry matter production shown by the selection lines when grownas young crops from seed. Possible penalties of ‘slow’respiration are also considered. Lolium perenne L., ryegrass, respiration, maintenance respiration, stimulated swards, leaf growth, tiller production, carbon economy     

Concentration-dependent changes of perceived odor quality

In order to assess the dependence of perceived odor qualityon odorant concentration, we studied 21 subjects. For eightsubjects all possible pairs from a pool of six odorants at threedecimal dilutions were presented, and subjects were requestedto state whether members of the pair were qualitatively ‘similar’or ‘different’ It was found that while pairs withthe same odorant at identical concentrations were judged ‘similar’in >90% of the cases by all subjects, scores went down to10% ‘similar’ judgements in some cases when thesame odorant was presented at a 100-fold concentration difference.Large time-invariable differences were found among subjectsand among odorants. For the additional 13 subjects, all possiblepairs from a pool of four odorants at three decimal dilutionswere presented. Subjects were instructed to state whether membersof the pair were qualitatively ‘same’ or ‘different’,and were also requested to rank the degree of difference ona visual analogue scale. Results for this group were, in general,similar to the results of the former group of subjects and goodagreement between the two tasks was found. The results suggestthat variations in olfactory stimulus magnitude may be perceivedas quality differences, as previously shown for vision and audition.     

The Effect of High Temperature at Different Stages of Ripening on Grain Set, Grain Weight and Grain Dimensions in the Semi-dwarf Wheat 'Banks'

Grain number in the wheat cultivar Banks was reduced by up to11 % with a rise in temperature from 21/16 °C to 30/25 °Cover a 10-d period immediately following first anthesis in general,the upper ‘d’ and ‘c’ florets were moreaffected by high temperature than the basal ‘a’and ‘b’ florets within a spikelet and florets fromthe upper spikelets were more sensitive than those lower onthe ear Grain weight and grain length at maturity were most affectedby a 10 d period of high temperature commencing 7–10 dafter anthesis However, if dry-matter accumulation between thestart of a treatment and grain maturity was used as a base forcomparison, the response was more uniform throughout development,with a peak in sensitivity 25 d after anthesis Although grainposition within an ear did not have a large effect on the responseto temperature, grains from the basal spikelets were more sensitivethan those from the apex, and the upper floret grains of a spikeletwere more sensitive to high temperature than those at the base There is a need to obtain, for a range of cultivars, more comprehensivedata on the effect of the timing and degree of temperature stressfollowing anthesis, for use in interpreting the response torising temperatures late in the development of the crop in thefield Triticum aestivum L, wheat, temperature, grain development     

Factors Determining Petal Colour of Baccara Roses II: THE EFFECT OF PIGMENT CONCENTRATION

‘Blueing’ in young and senescing petals was comparedin the red rose cv. Baccara. The ‘blueing’ of senescingflowers is accompanied by a bathochromic shift in the lightreflectance curve, a rise in the pH value and a decrease inthe malic acid concentration of the petal tissue. These factorsindicate that a complex with a co-pigment is produced. Similarchanges were not found in the ‘blueing’ of youngflowers, where a decrease was found in pigment concentrationper unit weight as well as per unit area of petal. A similar‘blueing’ was achieved by diluting a solution ofcrystalline cyanin. The phenomenon of ‘blueing’by dilution is discussed in the light of Bougeur's law.