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André Snyder, Matthew J. Morra, Jodi Johnson-Maynard and Donald C. Thill

in carrot production. We are specifically targeting the potential use of Brassicaceae seed meals in organic agricultural systems. Carrot ( Daucus carota L. subsp. sativus ) was chosen as the test crop because of its potentially greater tolerance to

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G. Bélair and L.E. Parent

The influence of various crop rotations on population densities of Meloidogyne hapla, the northern root-knot nematode, and subsequent carrot yields was studied in organic soil under field conditions. Seven 3-year sequences with barley (Hordeum vulgare L.), carrot (Daucus carota L.), onion (Allium cepa L.), or weedy fallow, all with carrot as the third-year crop, were replicated six times in a completely randomized block design. Carrot monoculture, two seasons of weedy fallow, or carrot followed by onion resulted in high M. hapla population densities and severe root damage on carrot the third year. Barley followed by onion or onion followed by barley harbored low M. hapla population densities and provided the highest yields, with 56.8 and 47.2 t marketable carrots/ha, respectively, compared to 2.2 t·ha–1 in the carrot monoculture. A single crop of barley reduced nematode population densities and provided 88% and 73% marketable carrot roots in the subsequent years. High M. hapla population densities and the high proportion of culls recorded in plots in weed fallow emphasize the importance of an effective weed management program for successfully using crop rotation against root-knot nematode in muck-grown carrot.

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Jolene Wright, Ann Reilley, Jean Labriola, Stephanie Kut and Thomas Orton

An experiment was conducted to determine the types, extent, and heritability of new phenotypic variants recovered from carrot cell cultures initiated from mature tap-root explants of the male-fertile carrot (Daucus carota L.) `Slendero'. Embryogenic callus was transferred to plant-growth-regulator-free medium 66 days after culture initiation, and regenerated plantlets were harvested and eventually planted in a field. The tap roots of mature regenerated plants were vernalized at 5C for 9 weeks and replanted. Of 31 flowering regenerants, 25 exhibited some form of petaloid male sterility; the remaining six regenerants were male fertile. All plants from the same original explant were either all sterile or all fertile. Three generations of sterile regenerant × petaloid cytoplasmic male sterility (CMS) maintainer (M) progeny tests showed that the new CMS behaved in a similar manner to that previously reported. Comparison of mitochondrial DNA restriction patterns of sterile and fertile regenerants with those of `Slendero', petaloid CMS, petaloid M, and brown anther CMS lines resulted in the following conclusions: 1) the sterile regenerants exhibited patterns identical to the known petaloid CMS and 2) the fertile regenerants were different from the original `Slendero' and the sterile regenerants and nearly identical to a known petaloid CMS M line. The high frequency of CMS among regenerants from `Slendero' carrot cell cultures may provide an efficient method to develop sterile M tandem lines and corresponding new hybrid varieties.

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Claire H. Luby and Irwin L. Goldman

freedom to operate for breeding and create diverse carrot populations based on market class and root color. These composite populations are meant to represent some of the diversity present in commercially available carrot germplasm that is available to use

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Djamila Rekika, Katrine A. Stewart, Guy Boivin and Sylvie Jenni

The carrot weevil, Listronotus oregonensis (Le conte), is the most significant pest of carrot ( Daucus carota L.) crops in Quebec, where more than 40% of the crop may be damaged if the weevil is left uncontrolled ( Zhao et al., 1991 ). Carrots

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María S. Alessandro and Claudio R. Galmarini

In almost all crop species we know as biennials, early flowering or annual plants are usually found. These crops include carrot, beet [ Beta vulgaris L. var. crassa (Alef) J.Helm], sugar beet ( Beta vulgaris L. var. saccharifera Alef

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Melissa Bonham, Gerald M. Ghidiu, Erin Hitchner and Elwood L. Rossell

The carrot weevil is the most economically important insect pest of carrot in the northeastern United States ( Simonet and Davenport, 1981 ). In New Jersey, adults overwinter in and near hedgerows and fields where carrots were grown the previous

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Lynn Brandenberger, William McGlynn, Lynda Wells, Bruce Bostian and Mark Payton

Carrot is a cool-season vegetable belonging to the Apiaceae . It probably originated in the Middle East, with the first carrots grown for consumption in Afghanistan ( Peirce, 1987 ). Carrots are a substantial source of dietary fiber and vitamin A

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Milton E. McGiffen Jr. and Edmund J. Ogbuchiekwe

Farms for donation of land and materials, and Susana Aparicio for manuscript preparation. Research was funded by a grant from the California Fresh Carrot Advisory Board. The cost of publishing this paper was defrayed in part by the payment of page

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Edmund J. Ogbuchiekwe, Milton E. McGiffen Jr., Joe Nunez and Steven A. Fennimore

Alisal St., Salinas, CA 93905. Our research was funded by grants from the California Fresh Carrot Advisory Board and the USDA. Susana Aparicio, John Masiunas, and Thomas Lanini reviewed an earlier draft of this manuscript.