Hybrid Carrot Research Articles

Insect visitation to flowering hybrid carrot seed crops

Although there is some literature published on insect visitation to open pollinated carrot seed crops in several regions around the world, there is none in Australasia and none on insect visitation to hybrid carrot seed crops worldwide. With a growing hybrid carrot seed crop industry in southern Australia and New Zealand, a survey of insect visitation to carrot seed crops is timely as the first step in elucidating which insects may be pollinators. Surveys of insect visitation were thus undertaken over two consecutive seasons in the south of Tasmania in order to identify potential pollinators in carrot seed crops. Sticky traps, water traps and observations were conducted within five carrot crops at three geographically independent sites to determine the variety and quantity of insects present in carrot crops. Nearly 42,000 insects were counted from observations, sticky traps and water traps. More than 100 morphological groupings were discerned. Small insects (<5 mm), most of which were thrips, made up 78% of the catch on sticky traps. Among the insects observed visiting umbels, nectar scarabs (Phyllotocus spp.) were the most abundant taxa but honey bees (Apis mellifera), muscoid flies and ladybirds were more often observed but at lower numbers. Nectar scarabs, soldier beetles and muscoid flies warrant further investigation of their role as pollinators of carrot flowers.

Apis mellifera and Megachile rotundata: a comparison of behaviour and seed yield in a hybrid carrot seed crop

The movement of managed alfalfa leafcutting bees (Megachile rotundata (F.)) in and around carrot flowers is compared with that of the honey bee (Apis mellifera L.) in a field trial to assess their relative efficacy as pollinators of hybrid carrot seed crops. Seed set is measured on carrot flowers inside cages with and without alfalfa leafcutting bees and compared with seed set in open field conditions in the presence of honey bees. Non-caged alfalfa leafcutting bees spend a similar amount of time on umbels and visit a similar number of umblets per umble as honey bees. Seed yield (number and weight of seeds) for flowers pollinated by caged alfalfa leafcutting bees is similar to that of flowers pollinated mainly by honey bees. However, it is not known how effective alfalfa leafcutting bees are compared with honey bees when not confined in cages (i.e. open pollination) under a range of commercial field conditions, particularly in the absence of plant species preferred by alfalfa leafcutting bees.

Behaviour of some F1 Hybrid of Carrot (Daucus carota L.) in the Area South and South East of the Country

Although the open-pollinated carrot cultivars are hybrid populations, caused by protandry phenomenon, there is an increased variability of the morphological features, of 30-50% (Mazurkiewicz, 1973). For the F1 hybrids which have homozygote inbred lines as genitors, we have the heterosis phenomenon. This is materialized through: root uniformity as form and size, fast growing, increased efficiency in using fertilizers (Kastlersi and co., 1982), production quality, (Gauchene, 1989), increased volume of the goods production (Axelson, 1976). Over the years 2007 and 2008, six carrot hybrids created at RDIVFG Vidra were studied in the south and south-east of the country, grown in a comparative trial for evaluation and selection of the best one, in order to be registered (homologated).

Divergência genética entre acessos de cenoura pertencentes a grupos varietais distintos utilizando caracteres morfológicos

A utilização de híbridos de cenoura tem aumentado consideravelmente na última década no Brasil. Estudos de determinação de divergência genética entre genótipos têm sido ferramentas de grande importância em programas de melhoramento, auxiliando na identificação de genitores com potencial heterótico. No entanto, pouco ainda se sabe sobre a capacidade combinatória de acessos de cenoura adaptados às regiões tropicais. Os objetivos do presente trabalho foram: (1) estimar parâmetros genéticos, (2) estimar a importância relativa de quatro caracteres morfológicos na discriminação de grupos varietais de cenoura e (3) obter indicação, a partir deste conjunto de dados morfológicos, de combinações promissoras para cruzamentos, visando utilização prática da heterose. Dois experimentos foram conduzidos em campo, nas primaveras de 2000 e 2001, no delineamento em blocos ao acaso com duas repetições. Foram avaliadas quinze plantas competitivas em cada parcela para os caracteres comprimento de folha, tamanho da raiz, diâmetro de raiz e massa fresca de raiz. Os dados foram submetidos às análises de variância, de dissimilaridade e da importância relativa dos caracteres. Todos os caracteres apresentaram valores de herdabilidade e da relação entre os coeficientes de variação genética e ambiental de medianos a altos. Os caracteres comprimento e diâmetro de raiz foram os que mais contribuíram para a diferenciação dos genótipos. O grupo mais divergente foi 'Imperator'. Desta forma, cruzamentos deste grupo com os demais acessos tendem a proporcionar maior efeito da heterose. Os acessos pertencentes ao grupo 'Brasília', podem ser cruzados com a maioria dos acessos (exceto para aqueles derivados dos grupos varietais 'Chantenay' e 'Danvers'), com probabilidade de geração de populações superiores em relação à heterose.

Tunnel production enhances quality in organic carrot seed production

In Denmark, organic vegetable seed production is possible for some of the late-maturing species when the maturing is performed in lightweight tunnels which are also relevant for the isolation of small-scale production. The tunnel system offers several advantages, e.g., it is possible to control water supply and thereby introduce drought at proven optimum times, restrict geneflow through insect- and pollen-proof netting, raise the temperature to prolong the growing season and hence the crop duration, and reduce pest attack by preventing pest entrance to the tunnel. In an experiment, tunnel production of open-pollinated carrot varieties increased the yield and germination percentages when compared with normal field conditions. Yield was in the range of 100–250 g and 2–17 g seeds m−2 respectively, and germination percentage was 84–95 and 43–55, respectively. However, hybrid carrot seed production showed lower yields than did their open-pollinated counterparts. Yields ranging from 60–123 g seeds m−2 can be obtained, but the production needs to be carefully planned and monitored. Different growing systems in tunnels have been studied in both open-pollinated and hybrid carrot (Daucus carota L.) for their seed production.

GENETIC ANALYSIS OF PRODUCTIVITY AND MORPHOLOGICAL TRAITS OF EDIBLE CARROT (DAUCUS SATIVUS RÖHL.)

Evaluation of carrot hybrids according to the different properties revealed significant differences among them. According to the ratio of the total and specific ability, it is possible to state that carrot total and marketable yields are more controlled by genes with additive effects, but genes with dominant effects also have influence. It was established that in the investigated carrot groups of CMS lines the inheritance of root-crop diameter, length and average weight are more influenced by non-additive genes; and in the group of the selected testers additive genes had bigger influence. It was showed that not only carrot genotype, but also environmental conditions influence traits of productivity and morphology.

Componentes genéticos e fenotípicos para caracteres de importância agronômica em população de cenoura sob seleção recorrente

O objetivo deste trabalho foi estimar os componentes genéticos e fenotípicos para caracteres em populações de cenoura, no intento de orientar estratégias de seleção. Os experimentos foram conduzidos em Lapão (BA) e Embrapa Hortaliças Brasília (DF) no verão de 2004. Foram avaliadas nove populações híbridas de cenoura, utilizando-se delineamento em blocos ao acaso com quatro repetições de cada tratamento de 2 m². Aos 90 dias após o plantio, 15 plantas competitivas por parcela foram colhidas e avaliadas individualmente para os caracteres rendimento de raiz, comprimento de raiz, comprimento do ombro verde, tipo de ponta, tipo de ombro, diâmetro da raiz, diâmetro do xilema da raiz, relação diâmetro do xilema/diâmetro da raiz, e cor a* (cor de cor determinado por colorimetria, variando de verde a vermelho) para o xilema e floema. Os dados foram submetidos à análise de variância e foram estimadas a herdabilidade no sentido amplo na média das parcelas pelo quadrado médio e a correlação entre os caracteres. De acordo com as estimativas de herdabilidade, para os caracteres diâmetro de xilema (0,92 e 0,87), cor a* do xilema (0,96 e 0,95) e relação entre diâmetro de xilema e diâmetro de raiz (0,87 e 0,91), pode-se aplicar forte pressão de seleção nos dois locais de avaliação. O maior rendimento de raiz foi associado a maiores diâmetros de raiz e de xilema, bem como por maiores valores da relação entre diâmetro de xilema e de raiz. Raízes mais grossas são associadas a menor a* (quantidade de β-caroteno), principalmente em relação à parte da raiz que é constituída pelo xilema. Pelos valores de correlação, há indicação de que a seleção para maior teor de carotenóides não pode ser efetuada sem considerar os caracteres de diâmetro de raiz, que são importantes componentes do rendimento.

MANIFESTATION INTENSITY OF HETEROSIS PHENOMENON FOR SOME OCHEMICAL CONTENTS IN SOME F1 CARROT HYBRIDS (DAUCUS CAROTA L.)

Superiority of the carrot hybrids by comparison with the varieties is revealed by the uniformity and quality of the roots, their productive potential as well a high rate of biochemical compounds accumulation (Sycheva, 1986; Barbara Michalik end al., 1988 Gauchene,1989). During the 2004-2006 period, 10 F1 carrot hybrid combinations were studied in order to establish of the intensity of behaviour of heterosis phenomenon (e.g. suppositional one, real one and competitive one) in some biochemical traits (total carotenes content and soluble dry matter) in order to identify the most valuable perspective hybrids. So, it was performed by comparison of the hybrid value with the average of parental lines and with the best parent as well as with the best grown variety Nantes for each heterosis type, namely suppositional one (Hi), real one (Hr), and competitive one (Hc) which were computed in per cent (%).

Developing and Successfully Implementing a Strategy for Breeding Frost-hardy Carrots

Freezing stress resistance is composed of several components namely tolerance, avoidance and acclimation ability. These three components of freezing stress are heritable traits. We have demonstrated that progress in the improvement of freezing stress resistance can be made by individually selecting for various components of this resistance and then recombining them to get the desired plan. Freeze-thaw injury in carrots is manifested as damage to the foliage, cracks on the roots (especially on the crown), and crown root rot. We found that foliage damage following freeze-thaw stress was related to the tolerance of the foliage to ice formation. The formation of cracks in the crown and root tissue was related to formation of ice itself. The carrot breeding lines we tested varied considerably for the crown position in relation to soil surface. The carrot crowns and roots below the soil surface will be better in avoiding ice in the tissue, thus avoiding cracks. The freeze-thaw injury observed on the foliage in the field was highly correlated to the freeze-thaw tolerance of leaf tissue (measured as ion leakage from the leaf tissue) determined by controlled freeze-thaw test in the laboratory. Based on this work we developed a breeding strategy to improve frost hardiness in carrots by combining the characteristics that avoid ice in the crown and root tissues (e.g., crown position underground) with the characteristics that reduce foliage and root injury by ice (freezing tolerance of foliage). By using this strategy we were able to successfully obtain the desired plant. Two hardy carrot hybrids (Eskimo, Artico) were released by Vilmorin and their hardy characteristics have been confirmed under field conditions.

Changes in the Carotene Content of Nantes Type Carrots during Storage

Changes in carotene content occurring during winter storage in Nantes type carrot hybrids grown on soils of different quality (sand and loam) have been investigated. The carotene content of the samples grown in a rainy year (1999) was lower than that of the samples grown in a dry year (2000). Lower carotene content was found in carrots produced on sandy soil (Szatymaz) than on loam soil (Tordas). The increase in carotene content (2-11 mg1100 g) measured at the end of winter storage was related to the season's character.

Changes in the Dry Matter and Sugar Content of Nantes Type Carrots during Storage

Changes in the dry matter and sugar content occurring during the winter storage of Nantes type carrot hybrids grown on soils of different quality were studied in 199912000 and 200012001. The dry matter content of the varieties tested depended on the production site and on the weather conditions prevailing in the growing season. The increase in the dry matter content during winter storage reached 6 to 7 per cent in the crop grown in a dry year and 1.5 to 2 per cent in a rainy year. The sugar content was lower in the rainy year (1999) and on brown sand (Szatymaz) than in the rather dry year (2000) and on chernozem soil with residual forest (Tordas), respectively. The increase in sugar content (1 to 5 per cent) measured at the end of storage was related to the season's weather conditions.

Production and analysis of plants that are somatic hybrids of barley (Hordeum vulgare L.) and carrot (Daucus carota L.)

In order to obtain plants that were somatic hybrids of barley (Hordeum vulgare L.) and carrot (Daucus carota L.), we fused protoplasts that had been isolated from 6-month-old suspension cultures of carrot cells with protoplasts isolated from barley mesophyll by electrofusion. After culture for 1 month at 25°C , the cells were cultured for 5 weeks at 4°C , and were then returned to 25°C for culture on a shoot-inducing medium. Three plants (nos. 1, 2 and 3) were regenerated from the cells. The morphology of the regenerated plants closely resembled that of the parental carrot plants. A cytological analysis of callus cultures induced from these plants indicated that most of the cells had about 24 chromosomes, fewer than the sum of the numbers of parent chromosomes which was 32. Southern hybridization analysis with fragments of the rgp1 gene used as probe showed that the regenerated plants contained both barley and carrot genomic DNA. Chloroplast (ct) and mitochondrial (mt) DNAs were also analyzed with several probes. The ctDNA of the regenerated plants yielded hybridization bands specific for both barley and carrot when one fragment of rice ctDNA was used as probe. Furthermore, the regenerated plants yielded a barley specific band and a novel band with another fragment of rice ct DNA as a probe. One of the regenerated plants (no. 1) yielded a novel pattern of hybridized bands of mt DNA (with an atp6 probe) that was not detected with either of the parents. These results indicated that the regenerated plants were somatic hybrids of barley and carrot and that recombination of both the chloroplast genomes and the mitochondrial genomes might have occurred.

Wisconsin Wild: Another Petaloid Male-sterile Cytoplasm for Carrot

Cytoplasmic diversity is a desirable attribute in the production of F1 hybrids. Even though most breeders agree with this concept, the vast majority of carrot (Daucus carota L.) hybrids produced in the United States are in one cytoplasm, i.e., the Cornell cytoplasm. To expand the diversity of cytoplasm for cultivated carrot, the U.S. Dept. of Agriculture announces the release of the Wisconsin Wild cytoplasm.

The influence of a fly attractant on hybrid carrot pollination

The influence of a fly attractant on hybrid carrot pollination

Genetic variability of carrot seed proteins analyzed by one- and two-dimensional electrophoresis with immobilized pH gradients.

The genetic variability of eight carrot populations representing commercially important morphological types was analyzed for seed protein polymorphism by one- and two-dimensional electrophoresis using immobilized pH gradients (IPG) in order to assess the potential of both techniques in carrot hybrid breeding as well as genetic quality testing of carrot trade seeds. The digitized silver-stained one- and two-dimensional gels of the urea/detergent-soluble seed proteins were subjected to computer analysis to estimate both the inter- and intrapopulation genetic variability. The results indicated that isoelectric focusing (IEF-IPG) of seed proteins is a powerful tool for quick screening of the genetic variability present between and within carrot populations, while two-dimensional polyacrylamide gel electrophoresis (IPG-DALT) can be employed to establish detailed genetic relationships of carrot populations selected by initial IEF-IPG screening in order to use genetic distant and homogeneous populations for successful carrot hybrid breeding. However, the applicability of IEF-IPG in genetic quality testing of carrot seeds seems to be restricted to hybrid purity testing. IPG-DALT is a far more powerful tool to profile unambiguously all carrot varieties commercially used in order to test the genetic quality of trade seeds, because this technique exhibits protein spots or spot combinations exclusively found in each of the eight varieties investigated.

Host Range of Rhizomonas suberifaciens, the Causal Agent of Corky Root of Lettuce

(...) R.s. induced corky root symptoms on endive, common sowthistle, and prickly lettuce of the Compositae but not on safflower and sunflower. The pathogen was reisolated from each of the susceptible hosts, and the reisolated strains were similar to the original strain in affinity to polyclonal antibodies and pathogenicity on lettuce. Inoculation of species of the Chenopodiaceae, Cruciferae, Cucurbitaceae, Gramineae, Leguminosae, Solanaceae, and Umbelifferae with R.s. did not result in visible symptoms, except for a hybrid carrot cultivar that reacted with root proliferation and orange-brown discoloration of feeder roots

A rapid method for purification of organelles for DNA isolation: self-generated percoll gradients

Self-generated Percoll gradients have been used for rapid purification of crude chloroplasts and mitochondria, obtained by common differential centrifugation techniques. Such purified organelles were used for isolating DNA from safflower (Carthamus tinctorius L.), carrot (Daucus carota L.), various Solanaceae, and numerous somatic hybrids. The method is simple, has the advantage of not requiring DNase, and is particularly well suited when only limited amounts of aseptically grown shoots are available. As judged by restriction enzyme analyses and chloroplast DNA cloning experiments, the DNAs are of sufficient purity for many molecular biological applications without CsCl gradient purification.

Carrot Response to Sludge Application and Bed Type

Abstract A 2-year carrot (Daucus carota L.) nutrition experiment involving 3 sludge treatments, 3 bed types, and 3 advanced hybrid carrot selections was conducted on a silt loam in Arlington, Wis., to determine the influence of these variables on growth and elemental concentration levels in edible, mature carrot roots. Sludge treatments included a 90 MT/ha/year application of municipal or industrial sludge plus a control with no sludge application. When significant differences occurred, highest yields and elemental concentration levels in edible roots occurred with hybrids grown in municipal sludge-amended soils. Root Cd levels in 1982 were the only exception, being greatest in plants grown on industrial sludge-amended soils. Lowest yields and highest heavy metal concentrations in the edible root were found in carrots grown on overcover beds (15-cm raised bed of unamended topsoil over prepared level or flat bed) as compared to those grown on 15-cm raised beds or level beds. Hybrid carrot selection (B6373 × B6345) × B6274 (B) accumulated less heavy metals in its edible root tissue than did B4367 × B6274 (A) or (B34602 × B3316) × F524 (C).

Comparison of plant-to-plant variability from F1-hybrid and open-pollinated carrot cultivars

In recent studies of variability in carrot (Umlauf, 1978; Dowker &amp; Gray, 1985) it was concluded that increasing the genetic uniformity of the seed populations did not bring about a detectable reduction in the variability in embryo sizes, the spread of emergence or seedling weight. In these experiments, however, only broad comparisons were possible since the seed sources used were not obtained from crops grown under identical cultural conditions or harvested at the same stage of maturity, both of which affect variability in the subsequent crop (Gray &amp; Steckel, 1983). The purpose of the present experiment was to examine the influence on variability of the greater genetic uniformity of an F1-hybrid compared with an open-pollinated cultivar, when both were sown under identical conditions.

The Effects of Sludge, Bed, and Genotype on Carrot and Cucumber Flavor

Abstract Sensory analysis was performed on 3 advanced hybrid carrot (Daucus carota L.) selections, and the genetically nonbitter cucumber hybrid ‘County Fair’ (Cucumis sativus L.). The crops were grown in field plots of silt loam amended with 90 MT/ha of industrial or municipal sludge and a control with no sludge application. The 3 bed types used were a ground level bed, a 15-cm raised bed, and a 15-cm raised bed of unamended topsoil over prepared ground bed (overcover bed). Carrots produced in industrial sludge-amended soil and raised bed had the harshest, least desirable flavor. Cucumbers grown in raised and overcover beds produced the most bitter fruit.