Raceme Length Research Articles

Morphology, anatomy and karyology of endangered Turkish endemic Physoptychis haussknechtii Bornm. (Brassicaceae) from Central Anatolia

Abstract In this study, the morphology, anatomy, pollen morphology, leaf and seed micromorphology and karyology of the Turkish endangered endemic Physoptychis haussknechtii were investigated in detail for the first time. The species was studied in terms of detailed morphology. Basal leaves are narrowly spatulate and cauline leaves are linear to oblanceolate; both leaves are covered with flattened stalked five-armed trichomes. Raceme length was found to be up to 6 cm and 9 cm in the flowering and fruiting stages, respectively. Sepals are linear-oblong, rarely elliptic with obtuse to subacute apex. Petals are spatulate with emarginate apex. Some morphological characteristics such as dimensions of cauline leaves and ovary and length of pistil were measured for the first time. In an anatomical study, root, stem, basal leaf and cauline leaf were examined. The anatomical results showed that the plants have secondary growth in roots, primary growth in stems, amphistomatic and equifacial basal and cauline leaves with anisocytic stomata. Pollen grains are radial symmetrical, isopolar and tricolpate. The ratio of polar axis to equatorial diameter is 1.16, and pollen shape is subprolate. Exine sculpturing is reticulate under light microscope and scanning electron microscope. Seeds are obovatesuborbicular, compressed and pale brown. The chromosome number of P. haussknechtii was defined to be 2n=16. The karyotype formula of P. haussknechtii consists of five metacentric chromosome pairs and three submetacentric chromosome pairs.

Study on correlation among different character pairs and path coefficient analysis in yellow sarson (Brassica Rapa. Var. Yellow Sarson)

Correlation and path coefficient analysis carried out using forty four genotypes of yellow sarson (Brassica rapa. Var. yellow sarson) were evaluated for thirteen quantitative and qualitative characters. Seed yield per plant revealed significant and positive correlation with biological yield, while positive but non-significant correlation with silique length, harvest-index, seeds per-siliqua, day to maturity, 1000-seed weight, while non-significant negative correlation with plant height and primary branches per plant, significant and negative correlation coefficient of oil content was observed with silique on main raceme. Oil content showed negative and non-significant association with plant height length, length of main raceme and primary branches per plant, while seeds per silique and days to 50 percent flowering showed significant and positive correlation with oil content. Harvest-index showed significant and negative correlation coefficient with plant height. 1000 seed weight exhibited significant positive correlation with silique length and seed per silique. Biological per plant (g) exhibited significant and positive correlation with plant height and seed per silique non-significant and positive correlation with silique length, days to 50 percent flowering and plant height. Siliqua length exhibited significant and positive correlation with plant height, siliquae on main raceme significant and positive association with length of main raceme exhibited significant and positive association with plant. Height primary branches per plant exhibited highly non-significant and positive association with length of main raceme, plant height exhibited non-significant and positive association with day to maturity and day to 50 percent flowering and days to maturity exhibited highly non-significant and positive association with day to 50 percent flowering. The path coefficient analysis of biological yield showed maximum direct effect, while silique length and oil content exerted negative direct effect on seed yield and days to 50 percent flowering exerted negative indirect effect on seed yield.

Heritability and combining ability of vegetative growth and phenological development of diallel crosses of rapeseed

To estimate combining ability and heritability of F2 populations of 4 x 4 full diallel crosses and parents, an experiment was carried out at The University of Agriculture, during 2012-2013. Four parental lines and F2 populations of six direct and six reciprocal crosses were planted in the experiment using RCB design. Data were recorded on phenological and vegetative growth traits: Days to flowering, plant height, main stem length, main raceme length, primary branches, and days to maturity. Analysis of variance revealed significant variation among genotypes for all the parameters studied. The results of combining ability analysis showed that general combining ability (GCA) was highly significant for primary branches plant-1, significant for plant height and days to physiological maturity and non-significant for the remaining traits. Specific combining ability (SCA) and reciprocal effects (RE) were significant for plant height, days to flowering, main raceme length and days to physiological maturity. Genotype AUP-401 was best general combiner for main raceme length, primary branches plant-1 and days to physiological maturity. Among the crosses, AUP-404 x AUP-402 was best specific combiner for plant height, days to flowering and main stem length. Broad sense heritability was high (>70%) for plant height, main stem length and primary branches. Moderate heritability was observed for main raceme length, days to 50% flowering and days to physiological maturity. The variance components of SCA were greater than respective GCA components of all the characters signifying the presence of non- additive genetic effects in transfer of these traits and selection in the later generations should be practiced for improvement of these traits.

Genetic variability studies for yield and yield components in kodo millet (Paspalum scrobiculatum L.)

The experimental material comprised of one hundred and three germplasm accessions of kodo millet (Paspalum scrobiculatum L.) were evaluated to assess the genetic variability, heritability and genetic advance for fifteen yield component traits. Analysis of variance revealed that there were significant differences among the accessions for all the traits studied. The coefficient of variation at phenotypic (PCV) and genotypic (GCV) levels were high for Zn content, grain yield per plant, Fe content, number of productive tillers and thumb length. Broad sense heritability ranged from 54.18 per cent for length of the longest raceme to 97.30 per cent for days to 50 per cent flowering. High heritability coupled with high genetic advance as per cent of mean was observed for plant height, number of basal tillers, number of productive tillers, flag leaf width, inflorescence length, thumb length, Zn content, Fe content and grain yield per plant which indicates that these traits are under the influence of additive gene effects and selection may be effective for these characters.

Multivariate Based Variability within Diverse Indian Mustard (<i>Brassica juncea</i> L.) Genotypes

Indian mustard (Brassica juncea L.) germplasm consisting 167 accessions including one check cultivar was evaluated for qualitative and quantitative traits. The present study was conducted to investigate genetic diversity and correlation among studied genotypes of B. juncea L. based on agro-morphological at NARC, Islamabad, Pakistan. To investigate the genetic diversity based on morphological characters, data was recorded on 20 quantitative and 12 qualitative traits. The calculated data was analyzed through two complementary methods, i.e. PCA (Principal Component Analysis) and cluster analysis. Among all the studied cultivars, significant diversity was recorded for different agro-morphological characters. Among all the parameters, maximum variance was recorded for pod shattering (427.2) followed by plant height (345.6), days to 100% flowering (336.2) and main raceme length (210.0). Among all the characters, the greatest and highly significant association (0.99) was found between days to maturity 50% and days to maturity 100% followed by correlation (0.86) among days to flowering 50% and days to flowering 100%, correlation value (0.71) was calculated among leaf length and leaf width. Using cluster analysis all the genotypes were divided into five major groups. It was observed that 7 out of 20 principal components with an Eigen value of ≥1.0 calculated for 73.92% of the total diversity observed between 167 accessions of Indian mustard (B. juncea L.). The contribution of first three PCs in the total PCs was 23.25, 12.87 and 11.24, respectively. Among all the investigated accessions two genotypes 26,813 and 26,817 showed great potential for seeds/silique, 1000-seed weight and seed yield/plant, respectively, so these genotypes are recommended for future breeding programs for achieving promising results.

Genetic analysis of seed yield and yield attributes in Indian mustard (Brassica juncea (L.) Czern and Coss.)

An experiment was conducted during winter seasons of 2005-06 and 2006-07 to study the nature and magnitude of gene effects involved in the genetic control of seed yield and yield attributing traits in Indian mustard [Brassica juncea (L.) Czern and Coss.] through generation mean analysis. Two crosses namely; RH 0115 x EC 126745 and RH 0120 x EC 126745 were grown in a randomized block design under normal and late sown conditions. In six parameter model additive gene effects were significant for days to maturity, number of primary and secondary branches per plant, number of seeds per siliqua and oil content. Both additive and non-additive gene effects were found to be significant for main raceme length, number of siliquae on main raceme, seed yield per plant and 1000-seed weight. Thus on the basis of above study it is advocated that the breeding methods which exploit both the components of genetic variation may be useful for further genetic amelioration. For the improvement of seed yield and its component characters; reciprocal recurrent selection or diallel selective mating would be helpful.

Genetic Variability and Characters Associations in Rapeseed (Brassica napus L.)

Thirty eight rapeseed genotypes were evaluated to estimate the genetic variability and association among the genotypes, following 8 quantitative characters. A considerable amount of genetic variability were found ranges from 1000 seed weight (11.09g) to harvest index (44.00%) and phenotypic variability for plant height (13.36m) to harvest index (44.14%). High heritability was found for all characters except 1000 seed weight (67.04g). Minimum genetic advance was observed for 1000 seed weight (0.63g) and maximum for plant height (29.72m). The lowest genetic advance in percent of mean was found in 1000 seed weight (18.70g) and highest in harvest index (90.35%). Plant height, raceme length and 1000 seed weight have significant positive association with yield with harvest index. Plant height, raceme length, 1000 seed weight and harvest index have imposed direct positive effect on yield per plant (g). As Plant height, raceme length, 1000 seed weight and harvest index are mainly driven by the additive genes so that selection criteria based on this characters should be effective.Bangladesh J. Pl. Breed. Genet., 29(2): 11-16, 2016

English

Nowadays, the society is seeking renewable energy sources that will replace in a sustainable way, fossil fuels. A source of energy that has stood out with great energetic potential showing itself to be promising in the world is biodiesel. Among several alternatives, the crop, Crambe (Crambe abyssinica Hochst) stands out as an oilseed species plant that belongs to the Brassicaceae family. This culture as a source of feedstock for biodiesel production was studied for its high yield of oil production, with about 38% of its grains. In order to get more information on the development of the crop in west of Paraná, it is necessary to develop studies on the response of this crop to fertilization. This study aimed to evaluate the crambe response to doses of potassium (K) grown in Oxisol in west of Paraná. The experimental design was of randomized blocks and the treatments consisted of doses of K (0, 40, 80, 120 and 160 kg ha-1 of K2O), with four replicates. For the assessments, a week preceding the harvest, five plants were collected per plot to measure the morphological features and yield components: plant height, average number of racemes per plant, average length of racemes per plant, number of fruits per plant, and fruit number per raceme and productivity. The results indicate that the soil Oxisol of Toledo has good availability of K. Because of this, significant increments in K2O doses on morphological characteristics and yield components have not been verified. The K2O doses did not promote increments on crambe production components. Key words: Biodiesel, development, Crambe abyssinica Hochst, feedstock.

Mapping a major QTL responsible for dwarf architecture in Brassica napus using a single-nucleotide polymorphism marker approach

BackgroundKey genes related to plant type traits have played very important roles in the “green revolution” by increasing lodging resistance and elevating the harvest indices of crop cultivars. Although there have been numerous achievements in the development of dwarfism and plant type in Brassica napus breeding, exploring new materials conferring oilseed rape with efficient plant types that provide higher yields is still of significance in breeding, as well as in elucidating the mechanisms underlying plant development. Here, we report a new dwarf architecture with down-curved leaf mutant (Bndwf/dcl1) isolated from an ethyl methanesulphonate (EMS)-mutagenized B. napus line, together with its inheritance and gene mapping, and pleiotropic effects of the mapped locus on plant-type traits.ResultsWe constructed a high-density single-nucleotide polymorphism (SNP) map using a backcross population derived from the Bndwf/dcl1 mutant and the canola cultivar ‘zhongshuang11’ (‘ZS11’) and mapped the dwarf architecture with the down-curved leaf dominant locus, BnDWF/DCL1, in a 6.58-cM interval between SNP marker bins M46180 and M49962 on the linkage group (LG) C05 of B. napus. Further mapping with other materials derived from Bndwf/dcl1 narrowed the interval harbouring BnDWF/DCL1 to 175 kb in length and this interval contained 16 annotated genes. Quantitative trait locus (QTL) mappings with the backcross population for plant type traits, including plant height, branching height, main raceme length and average branching interval, indicated that the mapped QTLs for plant type traits were located at the same position as the BnDWF/DCL1 locus.ConclusionsThis study suggests that the BnDWF/DCL1 locus is a major pleiotropic locus/QTL in B. napus, which may reduce plant height, alter plant type traits and change leaf shape, and thus may lead to compact plant architecture. Accordingly, this locus may have substantial breeding potential for increasing planting density.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0865-6) contains supplementary material, which is available to authorized users.

Phenotypic characteristics for discrimination between advanced genotypes of Brachiaria ruziziensis.

The aim of this study was to use multivariate methods and Pearson and partial correlations to disregard phenotypic characteristics that contribute little to differentiation between Brachiaria ruziziensis genotypes. Eighty-one genotypes of B. ruziziensis were assessed in completely randomized blocks with three replications. Ten phenotypic characteristics were assessed: plant height, leaf length, leaf width, sheath length, length of the flower stem, length of the inflorescence axis, number of racemes per inflorescence, length of the basal raceme, number of spikelets per basal raceme, and width of the rachis. The best traits for differentiation between genotypes were determined by assessing relative contribution to diversity, canonical variables, as well as Pearson and partial correlations. Four canonical variables were found to account for 57% of the overall variation, while plant height, sheath length, and number of racemes per inflorescence were considered traits that could potentially be disregarded in future assessments.

Genotype x environment interactions and stability analysis for seed yield and yield attributing characters in castor (Ricinus communis L.)

The forty six genotypes including 36 hybrids, 9 parents and GCH-7 as commercial check were evaluated for stability in three environments (sowing dates and spacing) at RRS, AAU, Anand. The partitioning of G x E interaction indicated that substantial portion of G x E interaction was linear for seed yield per plant, number of secondary spikes per plant, number of tertiary spikes per plant, total number of capsules per plant, total length of primary raceme and oil content. Both linear and nonlinear components were equally important for these characters. The study of the stability parameters revealed that parent ANDCP-06-07 as well as hybrids ANDCP-08-01 x JP-65, ANDCP-06-07 x ACP-1-06-07, ANDCP-06-07 x DPC-9, VP-1 x DPC-9 and DPC-9 x ANDCP-06-07-1 had average stability and wider adaptability for seed yield per plant; whereas, parents ACP-1-06-07, SKP-84, ANDCP-06-07-1 and hybrid ACP-1-06-07 x JP-65 had above average stability (bi 1) and specifically adapted to favorable environment. None of the parents or hybrids was found consistently stable for all the characters in any environment. Key words Castor, genotype x environment interaction, seed yield per plant, stability

Genetic diversity revealed by Morphological Descriptors Among Yellow Sarson Germplasm Under Timely and Late Sown Conditions

Thirty-one local germplasm lines of Brassica rapa var. yellow sarson, collected from eastern parts of Uttar Pradesh (India) were evaluated along with two commercial varieties as checks in two environmental conditions (timely sown E1 and late sown E2 conditions). Data collected on 14 morphological characters was subjected to D2 statistics. The 31 germplasm lines were classified into 8 and 12 clusters under E1 and E2, respectively. In E1, cluster I had a maximum of 15 genotypes while cluster III, VII and VIII had only one genotype each, in E2, cluster III had maximum of 15 genotypes whereas cluster IV, V, VII, VIII, X, XI, and XII had only one genotype each. Likewise, the inter-cluster average D2value was maximum (26.81) between cluster III and VIII and minimum between cluster V and I (2.80). Intra-cluster average D2 values ranged from 0.00 to 4.63. In late sown condition, the inter-cluster distance was maximum between IV and II (51.93) and minimum in cluster VI and IX (4.965). Intra-cluster average D2 value ranged from 0.0 to 4.594. The genotypes which occupied distant clusters can be used in hybridization programme as parents to recover more heterotic hybrids. Secondary branchesplant−1, glucosinolatecontent, seed yield, seeds siliqua−1, primary branches plant−1 and siliqua length contributed maximum towards total divergence in timely sown condition whereas secondary branches plant−1, seed yield, primary branches plant−1, glucosinolate content, and main raceme length were the major contributors in late sown conditions.

CORRELATION AND PATH COEFFICIENT ANALYSIS OF FOURTEEN DIFFERENT GENOTYPES OF LABLAB BEAN (Lablab purpureus L.)

Fourteen genotypes of Lablab bean were studied for sixteen yield and yield contributing characters. The experiment was conducted at Field Laboratory of Department of Genetics and Plant Breeding, Bangladesh Agricultural University, Mymensingh. Seed yield per plant showed positive and significant correlation with days to maturity, number of raceme per plant, raceme length, pod length, green pod yield per plant, green test weight and shelling percentage and significant negative correlation with days to maturity, number of seeds per pod and protein content at both phenotypic and genotypic levels. Path analysis revealed that green pod length exhibited high positive direct effect on number of raceme per plant, raceme length, green pod width, dry test weight and shelling percentage. The direct negative effects on seed yield were observed by days to maturity, number of flower buds per raceme, green pod yield per plant, green test weight and protein content and revealed the importance of these traits for simultaneous selection of plant for yield improvement.

Genetic variability and traits association in castor bean (Ricinus communis L.)

Genetic diversity of 12 castor bean accessions collected from different geographical regions of Iran was assessed in a randomized complete block design with three replications under filed condition. The data were recorded for 32 agro-morphological traits. Significant differences were observed among accessions for main stem length, main stem moist weight, main stem dry weight, 10-seeds weight on primary raceme, seed number on primary raceme, leaf area dry weight, female flower length, male flower length, secondary and tertiary raceme weight and oil percentage. A strongly positive correlation was observed between total seed weight on primary raceme as yield with seed number on primary raceme, female flower length, primary raceme length and main stem diameter. Path coefficient analysis indicated high direct effect of seed number on primary raceme (0.82) on seed yield. In addition, direct effect of primary raceme length on seed yield was negative (-0.13). Primary raceme length had the greatest indirect effect via seed number on seed yield (0.35).

Mapping of Quantitative Trait Loci Associated with Terminal Raceme Length in Soybean

ABSTRACTSoybean [Glycine max (L.) Merr.] develops inflorescence meristems on each node, including the shoot apex. The flower clusters of the soybean raceme have a highly branched inflorescence structure, and their racemes are classified as terminal, primary, secondary, and so on. Raceme phenotype is an important trait associated with the number of floral buds and pods, and is dependent on the genotype. The breeding line 1532–1 was characterized by remarkably long racemes at the shoot apex of the main stem. To identify quantitative trait loci (QTLs) conditioning the terminal raceme length (TRL), a recombinant inbred line (RIL) population was developed from a cross between 1532–1 and an ordinary cultivar, Toyoharuka. The RILs were divided into two groups according to their alleles for a maturity locus, E1. The early‐maturing RIL group with the e1 genotype was used for QTL analysis of TRL, while the late‐maturing RIL group with the E1 genotype could not mature normally and lodged severely. Analysis of the early‐maturing group resulted in the identification of a stable QTL, qTRL18–1, where the 1532–1 allele had a positive effect on TRL. Another QTL, qTRL11–1, was detected only in the RILs with the 1532–1 alleles at the qTRL18–1 locus, indicating an interaction between qTRL18–1 and qTRL11–1. The qTRL18–1 locus was located in the proximal region of the Dt2 locus. No stable QTLs for flowering time or maturing time were detected in the proximal region of qTRL18–1 or qTRL11–1. Our results provide a new strategy to increase pod number on the main stem by marker‐assisted selection (MAS) for qTRL18–1 and qTRL11–1.

Combining ability analysis for seed yield and yield components in castor (Ricinus communis L.)

The genetic analysis was done through a line x tester design involving 70 castor (Ricinus communis L.) hybrids generated by crossing 5 pistillate lines with 14 pollen parents. The combining ability analysis for yield and its components revealed that both additive and non-additive genetic variance were significantly influenced by environment. The preponderance of additive gene action was observed for the control of daysto 50 % flowering and days to 50 % maturity of main raceme as well as number of nodes up to main raceme. Non-additive gene effect was predominant for the characters, plant height and oil content. The parents SKP-8, 103745, 1379, SKP-93, TMV-5, Aruna, SH-72 and SK2-8A were good general combinersfor imparting earliness, former three as well as VP-1 were good general combiner forshort plantstature. The parents SH-72, SK 2-BA, SKP-82,JH-128, SH-41 and 48-1 were good general combiners for oil content. The estimates of gca effects suggested that parents SKP-93, SKP-82, 48-1, Aruna, SPS-35-9B,JI-77 and JH-128 were good general combinersforseed yield and several yield components viz., 100 seed weight, effective branches/plant, number of capsulesin main raceme and length of main raceme. The good specific cross combinations for yield viz., SKP-8 x TMV-5, VP-l x SKI-41 and SKP 25 x 1379 were also identified as superior hybrids for earliness, high oil content and short plant stature, respectively and may be exploited for commercial cultivation. The hybrids SKP-8 x TMV-5, SKP-25 x JH- 128 and SKP-82 x 48-1 with significant positive sca effect for seed yield could be exploited for development of hybrids and new inbred as well as pistilate lines in castor. The potence ratio of genetic variance suggested preponderance of non-additive gene effect for inheritance of the seed yield/plant, number of capsules in main raceme and number of effective branches.

Response of Castor Bean Plants to Different Row Spacings and Planting Seasons

The cultivation of the castor bean plant is prominent and important because of its potential for producing vegetable oils with special properties. However, research on cultivating castor bean plants is scarce, especially in areas with altitudes of 300 m or below. Moreover, the currently available cultivars have not been widely tested in Brazil. Thus, the aim of this study was to evaluate the response of the castor bean cultivar BRS Nordestina to different spacings at low altitudes during two cropping seasons. The study was conducted in the municipality of Itaocara, in the northwest Fluminense region, Brazil, which has an altitude of 60 m. The treatments consisted of five row spacings (1.5, 2.0, 2.5, 3.0 and 3.5 m) with 1 m between plants. The plants were cultivated in the 2007/2008 spring/summer season or in the 2008 autumn/winter season. A randomised block design with four replicates was used. The following parameters were assessed: plant height, height of insertion of primary raceme, number of racemes per plant, raceme length, number of fruits per raceme and grain yield. The spacing of 2.5 m between rows had the highest yield of castor beans during the two cropping seasons. The average yield of the cultivar BRS Nordestina indicates its potential for cultivation in northern Rio de Janeiro, below an altitude of 300 m. The yield was higher during the summer cropping season. The less-dense arrangement of the plant population contributed to the cultivation of plants with more racemes in both growing seasons.

Diversity Analysis in Indian Mustard (Brassica juncea L. Czern & Coss)

The present investigation was conducted with forty-six Indian mustard genotypes involving B. juncea x B. juncea and related species i.e. B. juncea x B. carinata, B. juncea x B. napus and somaclone background. These were evaluated to identify the genetically diverse genotypes for exploitation in a breeding programme aimed at improving yield potential of Indian mustard. Amongst seven clusters formed (Mahalanobis D2, 1936), each of the cluster I and IV had the largest genotypes (nine) and cluster II with smallest (two genotypes). Maximum divergence was observed between cluster V and VI followed by cluster V and VII and cluster II and VI. The genotypes RAURD-166, RAURD-205, RAURD-241, RAURD-32, JD-6, RAURD-168, RAURD-78, RAURD-195, RAURD-246, RAURD-172, RAURD-25 and RAURD-34 were observed as more divergent. Cluster V recorded minimum for plant height with early flowering and maturity, cluster VI, had more for primary branches per plant, secondary branches per plant, number of siliqua per plant, number of seeds per siliqua, biological yield per plant and seed yield per plant. The cluster VII had high mean for length of main raceme, siliqua on main raceme and seed yield per plant and cluster II, had high mean value for siliqua density. The clusters VI, VII, V and II were observed as more divergent clusters with high seed yield. The probability of getting better segregants and promising recombinants is expected to be more, from selecting genotypes of these clusters.

Genetic Variability for Panicle Characters in Indigenous and Exotic Barnyard Millet(Echinochloa frumentacea(Roxb.) Link) Germplasm Over Environment

Total 65 barnyard millet indigenous and exotic accessions were evaluated for genetic variability for eight panicle traits viz., earhead length, earhead width, lower raceme length, number of racemes, single earhead weight, grain weight per earhead, thousand grain weight and grain yield per plant at four different environments. A wide range of variability both at genotypic and phenotypic level was observed for all the characters studied. The difference between PCV and GCV was low for all the traits studied, which indicated little influence of environment over phenotype of the traits. High heritability coupled with high genetic advance observed in the present study for the traits viz., earhead width, grain weight per earhead, single earhead weight, grain yield per plant and earhead length at four locations indicates that these traits are under the influence of additive gene action. Selection based on these characters would be effective for future barnyard millet crop improvement programme.

Effect of indigenous aphids on the development of invasive common ragweed,Ambrosia artemisiifolia(L.) in Hungary

The common ragweed, Ambrosia artemisiifolia (L.), is a widespread invasive weed species in Europe. In order to estimate the hampering effect of native arthropods on the invasive ragweed, the effect of three indigenous aphid species on plant development and pollen production was studied. Common ragweed plants grown in a greenhouse were artificially infested with five apterous individuals of either Aphis fabae Scopoli, Brachycaudus helichrysi (Kaltenbach) or Myzus persicae (Sulzer) at the 4-leaf stage. Feeding by all three aphid species over a five-week period significantly reduced plant height, the number of male inflorescences, the length of racemes, pollen emission and plant dry weight. Brachycaudus helichrysi produced the largest colonies, followed by A. fabae and M. persicae. In a field experiment, the growth rate of A. fabae on caged ragweed plants was similar to that in the greenhouse, but the final numbers of B. helichrysi and M. persicae after 30 days was ten and seven times lower, respectively tha...