Genetic Analysis of Growth in Tomato: Segregating Generations

Genetical control of certain aspects of plant development hasbeen studied in the segregating generations derived from a diallelcross involving three varieties of L. esculentum and one ofL. pimpinellifolium. In the first experiment, dry-weight relativegrowth-rate was found to be inherited additively with a largedominance component which, however, was probably overestimatedin the F₁ by the inclusion of only one type of reciprocal cross.Gene association in the parents was suggested by the distributionof the points in the diallel regression graph. In a second experiment,the increase in leaf number with time was followed in parental,F₁, F₂, F₃, and backcross generations. Genetical analysis forvarious parameters of rates of production of leaves showed thecontrol to be additive with various degrees of dominance, andsimilar results were found for analysis of results on time-to-floweringand fruit yields. There was, throughout the experiments, agreementbetween the results for each generation. It is believed thatcombined genetical and physiological studies of growth in cropplants will be of value in the selection of parents for breedingimproved varieties.     

Local Differentiation Among Populations of Arabis stelleri var. japonica in a Sand Dune Habitat

Local variation in ecological and genetic traits was analysedin the perennial herb Arabis stelleri var. japonica in a sanddune area in western Japan. Plants of this species are establishedin three contiguous habitats (subpopulations): sand dune, forestand an ecotonal zone between both habitats. Morphological, ecologicaland genetic traits of A. stelleri var. japonica plants wereanalysed to discover the extent of microdifferentiation amongthese subpopulations. All plants in nine quadrats were markedand followed during 2 years. The ecotonal zone presented thehighest number of mature individuals per quadrat. Plants mayproduce the same number of shoots per plant but rosette sizewas larger in plants from sand dune and forest subpopulationsthan the ecotone. Plants in the sand dune showed the highestnumber of large capsules per plant. Mortality of seedlings andmature plants was slightly higher in the ecotone than in theother two subpopulations. Sand dune plants had the highest variationamong quadrats in almost all traits measured. In the electrophoreticanalyses, 21 loci were detected on twelve enzyme systems. Fifteenloci were monomorphic and six loci had 1·2 alleles perloci. Genetic distances and genetic identity Nei's values werevery similar among subpopulations (means I = 0·994, D= 0·006). The total genetic diversity (H_T) was 0·340and the within-population component (H_s) was 0·333 indicatinglow genetic differentiation among subpopulations. Gene flowvaried between genes but most of the values were high (meanNm = 188·3). Subpopulations of A. stelleri showed differentiationin morphological and ecological traits and low genetic differentiationin the loci studied. This may be related with the plastic responseof plants to different microenvironments and a significant geneflow between habitats.Copyright 1994, 1999 Academic Press Arabis stelleri var. japonica, Brassicaceae, gene flow, genetic diversity, local differentiation, mortality, plant population, reproduction     

Partitioning of 14C Labelled Assimilates in Arctium tomentosum

Plants of the biennial Arctium tomentosum were grown from seedto seed-set in an open field under three different treatments:control plants receiving full light intensity, plants with aleaf area reduced by 45 per cent, and shaded plants receivingonly 20 per cent of natural illumination. At various stagesof development the youngest fully expanded leaf of one plantin each treatment was exposed to ¹⁴CO₂ for half an hour. Subsequentdistribution of labelled assimilates in various plant partswas determined after eight hours. In the first year, the mostdominant sink was the tap root irrespective of variation inassimilate supply. During the production of new vegetative growthin the second season, a larger amount of radioactive photosynthatewas recovered from above ground parts, especially during formationof lateral branches. Seed filling consumed 80–90 per centof labelled carbon exported from the exposed leaf. In the secondyear, the most pronounced difference between treatments wasin the degree of apical dominance, being highest in shaded plantsand lowest in the plants with cut leaves. Results from ¹⁴C experimentsagreed fairly well with a ‘partitioning coefficient’derived from a growth analysis of plants grown independentlyunder the same experimental conditions. Reasons for discrepanciesbetween the ¹⁴C results and the partitioning coefficient arediscussed. Arctium tomentosum, burdock, variation in assimilate supply, assimilate distribution, ¹⁴CO₂, labelling, growth analysis     

Different Expression Patterns of the Promoters of the NgrolB and NgrolC Genes during the Development of Tobacco Genetic Tumors

Hybrids (F1) between Nicotiana glauca and N. langsdorffii areprone to develop tumorous tissues on normaltype F1 tissues,namely, genetic tumors. To investigate the patterns of expressionof Ngrol genes during the development of genetic tumors, weperformed an analysis of transgenic genetic tumors that harboredthe promoters of the NgrolB and NgrolC genes fused to a reportergene for rß-glucuronidase (GUS) using a tumorization-redifferentiationsystem derived from F1 plants in vitro. Histochemical analysis of the expression of NgrolB-GUS in normal-typeF1 transgenic plants revealed GUS activity in meristematic zones,while in NgrolC-GUS transformed plants the activity was detectedmainly in the vascular systems of various organs. Tumorous tissues,which arose spontaneously as a consequence of aging or wereinduced by cutting, showed high levels of GUS expression underthe control of promoters of both the NgrolB and the NgrolC gene.Time course analysis during tumorization that followed cuttingof leaves of normal-type F1 plants showed clearly that NgrolB-GUSwas expressed in all dividing cells in the cut region after3 days. By contrast, the expression of NgrolC-GUS was detectedin organized tissues, such as procambium in teratomatous tumors,7–10 days after cutting treatment. During redifferentiationfrom genetic tumors to normal-type plants, the expression ofGUS under control of both Ngrol promoters decreased and expressionresembled that in normal-type tissues. These results suggestthe possibility that the Ngrol genes might be involved in formationof genetic tumors and, moreover, that the expression of NgrolBmight be linked to mitosis and while that of NgrolC might berelated to differentiation of tissues, such as the vascularsystem, in F1 plants. (Received January 19, 1996; Accepted March 24, 1996)     

Effect of Number of Photoperiodic Cycles on Flowering and Fruiting in Early and Late Varieties of Okra (Abelmoschus esculentus (L.) Moench.)

Early and late varieties of the short day plant, Abelmoschusesculentus (L.) Moench. (= Hibiscus esculentus L.), were subjectedto various numbers of short days (SD; 10 h natural daylight)before transfer to 16 h long days. Short day treatments werestarted at the time of cotyledon release following seed germination,and their effects on the induction and development of flowersand fruits were recorded. While early okra required 6 SD cyclesfor the induction of flowering in all plants, late okra required14. However, both varieties needed more than 20 SD cycles forflower opening; flower buds produced by plants given fewer SDcycles abscinded with little or no development. In both varieties,the number of flower buds produced on each plant increased asthe number of short day cycles was increased from 5 to 20; flowerbuds were initiated at more axillary bud sites on the main stem.Three fruits were formed on each plant of both varieties subjectedto more than 30 SD cycles but, while the last formed fruit abscindedwithout development, the other two developed and became filledwith seeds. However, the greatest yield in fruit dry weightwas from plants kept under SD throughout and also in late okraplants given 55 SD. In general, the total number of seeds perplant increased as a larger number of SD cycles were imposed.     

Constitution of Mitochondrial and Chloroplast Genomes in Male Sterile Tobacco Obtained by Protoplast Fusion of Nicotiana tabacum and N. debneyi

Chloroplast DNA (cpDNA) and mitochondrial DNA (mtDNA) of malesterile tobacco plants obtained by fusion of Nicotiana tabacumprotoplasts and X-irradiated N. debneyi protoplasts were analyzed.Digestion of cpDNA isolated from ten male sterile lines withfour restriction endonucleases (EcoRI, XhoI, SmaI and HindIII)indicated that these lines possessed either one or the otherparental chloroplast genome. Neither mixture of two types ofcpDNA nor unique restriction fragments were detected in anyof the cases examined. The genetic constitution of chloroplastgenomes identified by restriction analysis of cpDNA showed goodagreement with that based on isoelectric focusing of the largesubunit of the Fraction I protein. The mtDNA from five fusion-derivedmale sterile plants showed banding patterns quite differentfrom each other and from the parental plants. Each plant exhibitednew restriction fragments not found in the parental species.These findings indicate that recombinational events in the mitochondrialgenomes take place rather frequently in the mixed cytoplasmsafter protoplast fusion, whereas the mixed chloroplasts becomesegregated to homogeneity. (Received June 19, 1987; Accepted October 5, 1987)     

An Analysis of Seed Development in Pisum sativum II. The Effect of the r-Locus on the Growth and Development of the Seed

The r-locus is one of the few genetic loci known to affect thestorage product composition and the morphology of pea (Pisumsativum) seeds. Lines which are near-isogenic except for ther-locus have been developed to study the effects of this locuson seed development. The plant phenotypes of these lines werevery similar except for those characteristics previously attributedto the r-locus. The seed development of the two lines followedsimilar patterns until the endosperm was absorbed by the embryo.The fresh weight of the rr line then increased more rapidlydue to the overall effect of a higher rate of water uptake anda lower rate of dry weight increase of the rr embryos comparedwith embryos homozygous for the R-allele. The effect of the r-locus on the relationship between embryofresh weight and dry weight suggests that the alleles may beaffecting the osmotic regulation of the developing embryo. Pisum sativum, pea, seed development, r-locus, genetic variation, growth analysis     

Rates of Dry-matter Production in Some Tropical Forest-tree Seedlings

An analysis of growth in full daylight of four tropical forest-treeseedlings and Helianthus was made with the view of ascertainingwhether woody plants in the tropics have a lower net assimilationrate than herbaceous plants as has been demonstrated in otherenvironments. Significant differences in net assimilation ratewere found between Helianthus and three of the woody speciestested: Chlorophora excelsa, Musanga cecropioides, and Terminaliaivorensis; the fourth woody plant, Ceiba pentandra, had an unusuallyhigh net assimilation rate which, in one experiment, did notdiffer significantly from the value found for Helianthus. The data are discussed in relation to the general problems ofcomparative growth-rates of herbaceous and woody plants andof factors contributing to differences in forest productivitybetween climates.     

Changes in plant response to NaCl during development of rice (Oryza sativa L.) varieties differing in salinity resistance

The effects of NaCl stress on growth and development of rice{Oryza sativa L.) were studied and compared in varieties ofvarious origins. During the vegetative stage, tall indica landraces(Nona Bokra, Buhra Rata, Panwell, and Pokkali) appeared to beresistant throughout while in japonica varieties (I Kong Pao(IKP) and Tainung 67) and elite breeding lines (IR 4630, IR2153 and IR 31785), resistance fluctuated. Panwell, which wasthe only indica variety evaluated during the reproductive stage,also expressed salt resistance during booting, heading and grainmaturation while varieties with the greatest variability insalt stress response during the vegetative phase (IR 4630, IR31785 and IKP) also showed the greatest variability during reproductivedevelopment. Thus, varietal levels of resistance to salinityat different growth stages are not necessarily interdependentcharacteristics. Variability in salt resistance of differentgenotypes during the vegetative and reproductive phases of developmentwas not correlated to their mean level of relative resistance. There was an ontogenic evolution of salt resistance and theyoung seedling stage appeared to be the most sensitive to NaCIduring vegetative growth. Nevertheless, short- and middle termeffects of stress have to be distinguished for each genotypesince some varieties showed better growth during the secondweek of stress than during the first, whilst others showed anopposite trend. Moreover, even at specific stages of development,plant responses to NaCI were quite variable according to thecriterion used to quantify salinity resistance. The identificationof genotypes resistant to NaCI at specific developmental stagesis essential to improve the understanding of the effects ofsalt stress upon phenology and to elaborate further breedingprogrammes. Key words: Rice, Oryza sativa L., salt resistance, NaCl, phenology     

Morphological Description of Transgenic Soybean Chimeras Created by the Delivery, Integration and Expression of Foreign DNA Using Electric Discharge Particle Acceleration

Transgenic soybean (Glycine max L.) plants derived from electricdischarge particle acceleration experiments exhibited varyingdegrees of chimerism which was followed by the expression ofthe introduced ß-glucuronidase (gus) gene. Degreesof chimerism in transgenic plants were established by determiningexpression of the gus gene observed as blue spots, streaks orsectors in stem and leaf tissues in in vitro grown plantletsand greenhouse plants. Clonal plants were also obtained. Presenceof the gene was confirmed by Southern blot analysis. These studiespermitted the reconstruction of a partial picture for the developmentof the soybean plant. Glycine max L. cv. Williams 82, soybean, transformation, ß-glucuronidase, chimeric plant phenotypes, development     

Pith Autolysis in Herbaceous, Dicotyledonous Plants: Experimental Manipulation of Pith Autolysis in Several Cultivated Species

Pith autolysis, a condition in which dicotyledonous herbaceousplants have a hollow stem, results from the autolysis of a plant'sstorage pith. Our central hypothesis concerning the aetiologyof pith autolysis states that the carbon from the pith is transportedto the growth regions of the plant and used at times when theplant cannot meet its carbon needs by photosynthesis alone.According to this hypothesis, accelerated growth should increasepith autolysis. We here provide supporting evidence for thecentral hypothesis. More pith autolysis was found in fastergrowing tomato varieties than in dwarf varieties. More pithautolysis was found in both beans and tomatoes treated withGA₃ than in controls. More pith autolysis was found in leggybean plants grown in low light than in normal plants grown undernormal light conditions. Pith autolysis decreased in both beansand tomatoes when mechanically perturbed or sprayed with paclobutrazol,both treatments that reduced growth. The stems of buckwheatplants that were flowering showed greater pith autolysis andtherefore were more hollow than plants which were not floweringor which had the incipient flowers pinched off. This indicatedthat carbon from the storage pith may also be used in the formationof reproductive structures which require extra carbon. Alsoin support of the central hypothesis is the prevention of pithautolysis by the addition of extra carbon to the plant, in theform of an increased CO₂ concentration of the surrounding air.Copyright1995, 1999 Academic Press Bean, tomato, buckwheat, pith autolysis, CO₂, GA, thigmomorphogenesis, packobutrazol     

The Use of Canonical Correlation Analysis in the Investigation of Relationships Between Plant Growth and Environmental Factors

The relationship between environmental factors and growth inImpatiens parviflora was analysed by the method of canonicalcorrelation analysis. The method was able to identify the majorrelationships which had been detected by conventional methodsof analysis. The method was also able to detect relationshipsnot identified by conventional methods. The canonical correlationanalysis also clearly showed that relationships between growthand environment detected at a plant dry weight of 100 mg couldalso be detected at 300 mg despite masking due to ontogeneticdrift and confusion by different patterns of adaptation. Itis concluded that the method of canonical correlation analysisis most useful for the analysis of considerable bodies of datarelating plant growth to environmental factors. Marked effectsof spectral composition on growth and development of both leavesand stems were demonstrated. Different spectral compositioneffects on hypocotyl and internode elongation exist. Impatiens parviflora, growth analysis, canonical correlation analysis, spectral composition, stemelongation     

Competition and Allometry in Kochia scoparia

Comparisons between crowded and uncrowded Kochia scoparia individualsdemonstrate pronounced effects of competition on plant allometryas well as on the distributions of different aspects of size.Non-destructive measurements of height and stem diameter and,for a subset of the populations, the number and length of leavesand branches, were taken at three times, and the plants wereharvested after the third measurement. The sequential measurementsafforded the opportunity to obtain information of the effectsof competition on allometric growth trajectories of individuals,as well as on static inter-individual allometric relationships. The distributions of most size measures appeared to be normalfor the uncrowded population. Crowded populations developeda negatively-skewed height distribution and a high-inequalitymass distribution, whereas the diameter distributions remainednormal. Plants grown without neighbours showed simple allometricrelationships between height, diameter and weight. For isolatedplants, the 'static' allometric relationship between plantsof different sizes and the allometric growth trajectory of individualswere similar. Crowded populations showed complex allometry;the static inter-individual relationships between height, diameterand weight were curvilinear (on log-log scale). There were largedifferences in the allometric growth slopes of uncrowded vs.crowded plants. Allometric relationships between stem diameterand plant mass, and between total length of leaves and totallength of branches, did not seem to be altered by competition. The data suggest that height was the most important aspect ofsize influencing future growth of individuals in the crowdedpopulation. Only plants above a certain height were able tocontinue to grow from the second to third measurement in thecrowded population. This supports the hypothesis that asymmetriccompetition for light is the cause of the allometric changesand of the increase in size variability due to competition.Copyright1994, 1999 Academic Press Allometric growth, allometry, competition, growth, Kochia     

Pithiness and Growth of Radish Tubers as Affected by Irradiance and Plant Density

Pithiness in radish tubers (Raphanus sativus L.) is a syndromewhere xylem parenchyma cells die and are filled with air. Featuresassociated with rapid tuber growth such as large cells, greatdistances between strands of vascular tissue and rupture ofxylem vessels have been suggested to induce pithiness. The objectiveof this study was to analyse the extent to which pithiness inradish was related to tuber growth. Growth rates were variedby altering irradiance and plant density. In addition, the relationshipbetween pithiness and tuber growth (length, diameter, freshmass) was investigated in batches of plants grown under identicalconditions. The growth rates of shoot and tuber strongly increased withincreasing inter-plant distance and irradiance. Our resultssuggest a ‘true’ effect of assimilate supply ondry matter partitioning, as not only the ratio between shootand root dry mass, but also the slope of this relationship decreasedwith increasing irradiance and inter-plant distance. Withina treatment the ratio between tuber growth and shoot growthremained constant with plant age. Increase in length of thetuber did not appear to be an important factor in inducing pithiness.Within a batch of plants, a positive correlation between tuberdiameter and pithiness was observed only for tubers smallerthan 14 mm. An increase in both irradiance and inter-plant distanceincreased tuber size (diameter, mass) and pithiness, but theeffects on pithiness could not be ascribed only to differenttuber sizes. Pithiness strongly increased with plant age andit was concluded that pithiness occurred, to a great extent,according to genetic programming. The data showed that for treatmentswhich affect tuber growth, conclusions about their effects onpithiness depend on whether comparisons were made at the sametuber size or the same time, explaining apparent contradictionsin the literature. Raphanus sativus L.; radish; pithiness; genetic programming; cell death; light; plant density; growth rate; dry matter partitioning; shoot; tuber     

Relative Nitrogen Limitation at Steady-state Nutrition as a Determinant of Plasticity in Five Grassland Plant Species

Partitioning of biomass between roots and different shoot partshas often been used to explain the response of plants to variationsin resource availability. There are still many uncertaintiesin the importance of this trait for plant performance, and clearguidelines on how partitioning should be quantified in relationto growth rate and resource supply are of fundamental importancefor such an understanding. This paper reports an attempt toshow how plant nitrogen status relates to root:shoot partitioningand other plastic responses, in a manner that can be used forquantitative predictions. The reactions to nitrogen limitationof five grassland plant species, with different ecological demands,were compared. The species used were the forbs Polygala vulgarisand Crepis praemorsa, and the grasses Danthonia decumbens, Agrostiscapillaris and Dactylis glomerata. The experiment was conductedin a climate chamber where the plants were grown hydroponically(1) under non-limiting nutrient conditions and (2) at a steady-statenitrogen limitation, which enabled the plants to express halfof their growth potential. The relative growth rate (RGR) ofthe species was strongly related to plant nitrogen concentration(PNC) and leaf area ratio (LAR), whereas the effects on netassimilation rate (NAR) were very small. Despite large differencesin maximum relative growth rate, the species showed remarkablesimilarities in dry matter partitioning between root and shoot.It is concluded that root:shoot partitioning can be treatedas a direct function of the relative resource limitation ofthe plant. The difficulty of attaining well-defined levels ofresource limitation in soil, other solid substrates and manyhydroponic systems may be the most important reason for thedivergent results in earlier studies. Better knowledge of soil-rootinteractions, and plant responses to the whole span of resource-supplylevels, is required for a thorough understanding of how nutrientslimit growth. Copyright 1999 Annals of Botany Company Growth rate, plant strategies, plasticity, partitioning, biomass, nitrogen, nutrient limitation, grassland.     

A comparison between methods used to control nutrient supply

Experimental methods to supply nutrients to culture solutionsin order quantitatively to control plant nutrition are compared.In experiments with tomato and birch plants, for which the dataare available in databases (Ingestad et al., 1994a, b), thenutrients were supplied at constant relative addition rates(R_A over sufficiently long periods of time to achieve acclimatedplants and reliable measurements of plant responses. The plantswere maintained under steady-state conditions, i.e. the internalnutrient concentrations (c₁) remained constant, as a resultof a numerical equality between the relative uptake rate (R_U)and the relative growth rate (R_G). These results are comparedto experiments with pea plants (Macduff et al., 1993). In oneseries (a), R_A was applied, but without strict control of internalsteady-state, and in the other series (b), the external concentration(c_e) was maintained constant. With limiting nitrogen, in bothseries, there was a substantial deviation from equality betweenR_U and R_G. In (a), c_I changed during the experimental periodand the purpose of the R_A approach was lost. In (b), a constantc_e had little effect on nitrogen uptake and plant growth. Atthe three highest concentrations, steady-states were obtainedat non-limiting uptake rates. At the lowest concentration, theuptake rate of nitrogen was about the same, but there was adecrease of R_a, which apparently was not caused by reduced uptake.Clear-cut relationships can not therefore be established betweentreatment variables and plant responses and the conclusionsreached by Macduff et al. (1993) have little support in theirexperimental results. This indicates an urgent need to updateboth theories and experimental methods together: in particular,it is important to identify the system under investigation andto distinguish between control of the medium and control ofthe plant. Key words: Experimental control, external nutrient concentration, non-limiting and limiting nutrient supply, relative addition rate, relative uptake rate, relative growth rate, steady-state     

Parthenocarpic Fruit Growth Reduces Yield Fluctuation and Blossom-end Rot in Sweet Pepper

The aim of this work was to investigate whether parthenocarpicfruit growth could avoid flushing, i.e. an irregular yield pattern,in sweet pepper. Plants were grown in a greenhouse compartmentfrom April until August. Half of the plants were grown withouta fruit set treatment (control), whereas parthenocarpic fruitswere allowed to develop on the other plants by preventing self-pollinationand applying auxin to the stigma. For node positions 3 to 17,fruit set per node varied between 21 and 55% for control plants[coefficient of variation (CV) = 11%], whereas auxin-treatedplants showed much less variation in fruit set (41–57%;CV = 5%) and average fruit set was higher. In agreement withfruit set, fruit yield was also much more regular in the auxin-treatedplants. Fruit fresh yield varied between 0.2 and 1.0 kg m^-2forcontrol plants (CV = 20%), and between 0.4 and 0.8 kg m^-2forauxin-treated plants (CV = 9%). Results showed that developingseeds in sweet pepper fruits are the main cause of the abortionof new flowers, and irregular fruit set and yield. Parthenocarpicfruit growth resulted in flatter, 30% smaller fruits, becauseof a reduction in fruit growth rate; the duration of fruit growthwas 1 week longer than for fruits from control plants. Parthenocarpicfruits were hardly affected by blossom-end rot (BER) with only1% of fruits being affected compared to 31% in the control.Total dry mass production was the same for treated and controlplants; however, in auxin-treated plants, 50% of the total drymass was allocated to the fruits, compared to 58% in controlplants. Copyright 2001 Annals of Botany Company Abortion, auxin, BER, blossom-end rot, Capsicum annuum L., flushing, fruit set, irregular yield pattern, parthenocarpy, sweet pepper     

Plant Influence on Water Flow Through Artificial Membranes

This paper describes a simple, reproducible method of monitoringwater uptake by plants operating in an ad libitum system. Thesystem consists of a thin microporous membrane interfaced witha water reservoir on one side and potted plant on the other.The plant establishes control over the membrane through itsroots, which modify the permeability of the microporous waterbarrier in accordance with autonomic cycles in growth activity.It was shown that the pattern of water flow is modified in themanner expected by changes in environment that affect wholeplant physiology. Impatiens, Ficus indica, Coleus blumei, water flow, artificial membranes, periodicity, surfactant, root exudate     

Studies on Variability in White Clover: Growth Habits and Cyanogenic Glucosides

Growth habits and cyanogenesis were studied in a field experimentwith white clover (Trifolium repens L.) cv. Huia. Eighty controlplants propagated by seeds, and 80 clones of an in vivo selectedvariant were examined in mid-late August and late September.The temperature effect on cyanogenic glucoside levels was alsoexamined on in vitro grown plantlets of the variant in growthchambers. Results showed that the upright growth habit dominated in controlplants. The population of the variant plants was mainly composedof prostrate clones and a transition from prostrate to uprightgrowth habit occurred. Considerable variation was observed withregard to all measured morphological characters in both controland variant plants. Great variation was also noted in cyanogenicglucoside content in the leaf laminae of the control plants.Low cyanogenic plants, on the other hand, dominated in the variant.The number of low and high cyanogenic plants increased in thecontrol by the end of the growth season, after the first frosts.A one-way shift of cyanogenic (slight increase) was recordedin the variant. Similar levels of cyanogenic glucoside and linamarasewere determined in the in vitro and field-grown plants. Cyanogenicglucoside content slightly decreased with the age of the invitro plantlets, but variation in temperature did not causeany changes in their level. The response to the environmentalchanges, regarding cyanogenesis, appear to be genetically determined. Trifolium repens, in vitro, somaclonal variation, cyanogenic glucosides     

不同寄主植物上灰飞虱种群生命表的比较

为比较不同寄主植物上灰飞虱种群发展趋势,通过室内实验,组建了灰飞虱Laodelphax striatellus Fallèn在武育粳3号、盐稻8号、徐稻3号、Ⅱ优084、Ⅱ优42、扬麦12、稗草和千金子这8种寄主植物上的实验种群生命表;通过田间调查,比较了粳稻武运粳7号和籼稻Ⅱ优084上灰飞虱自然种群发生动态。不同寄主植物上灰飞虱实验种群生命表的比较结果表明,灰飞虱的若虫发育历期在稗草上最短,其次为扬麦12和粳稻上,而在杂交籼稻Ⅱ优084、Ⅱ优42和杂草千金子上的发育历期长达近30 d;灰飞虱在稗草上的种群趋势指数亦最高,为45.57,其次为粳稻品种盐稻8号（39.36）、徐稻3号（34.54）和武育粳3号(31.70)上,其中盐稻8号与稗草上无显著差异;杂交稻Ⅱ优084和Ⅱ优42上灰飞虱的种群趋势指数显著低于粳稻上的;而灰飞虱在千金子上的种群趋势指数最低,仅为11.04。大田调查则表明,一定时期粳稻武运粳7号上灰飞虱种群个体数量显著高于籼稻Ⅱ优084上。研究表明灰飞虱的适宜寄主植物依次为稗草、粳稻品种和小麦。