Regeneration of radish genetic resources

Contributors to this page: CAAS, China (Qiu Yang, Li Xixiang); Bioversity International, Italy (Imke Thormann, Ehsan Dulloo); CGN, Netherlands (Noortje Bas); IPK, Germany (Andreas Börner, Ulrike Lohwasser); AVRDC, Taiwan (Andreas Ebert); USDA, USA (Larry Robertson); NBPGR, India (Chitra Pandey); SASA, UK (George Campbell); University of Warwick, UK (Charlotte Allender).

Before reading the regeneration details for this crop, read the introduction that gives general guidelines to follow by clicking here.

Introduction

Radish (Raphanus sativus L.) is a cross-pollinated, cool-season and annual or biennial vegetable crop. Some cultivars, especially those developed for spring production and of tropical origin have an annual habit. In the first development year biennials develop a fleshy root.and require vernalization to bolt and flower in the second year. Radishes have numerous varieties, varying in size, color and duration of required cultivation time. The period of cold treatment needed to bolt and flower is different among varieties. Temperatures above 32 °C may not only have a negative effect on seed set as the stigma dries out and the pollen may not germinate but also on seed size and percentage of seed germination as the development of the embryo and endosperm will be negatively affected.

Choice of environment and planting season 

Climatic conditions 

• If possible, choose an environment corresponding to the original collection site conditions.
• For vegetative growth
  • Radish is a cool-weather, short-season vegetable crop. Grows best in cool and moist weather (15-22 °C for leaf, 13-18 °C for root).
• For reproductive growth
  • Radish flowers initiate (bolt) after vernalization. It is important to expose plants to cool outside temperatures below 15°C for at least 20 days (usually 30~60 days in CAAS).
  • Another option is the storage of germinating seeds or radish seedlings with two leaves in a cool room at 2-5°C for 14 to 40 days. In some specific case, the time should be up to 50~60 days.
  • Temperature at flowering and seed set is optimal at 25± 3 °C.

Preparation for regeneration

When to regenerate

• When seed stocks drop to 1,500 seeds the accession should be scheduled for regeneration. Distribution can continue until seed stock drops to less than 1000 seeds.
• When germination is reduced to 80% or to 85% of initial germination (FAO/IPGRI 1994 and ISTA 2008).
• Newly introduced, collected or received materials might require regeneration to meet international standards if seed amount and quality are insufficient.

Pre-treatments

• Treat seed with fungicides and insecticides or sterilize the seeds using 1% solution of sodium hypochlorite for 10 minutes or hot water at 50°C for 20 minutes, if required.
• Wild types are not pre-treated as they are not sown directly into the field.
• Use local recommendations as a guide to types and rates of chemical application.

Field selection and preparation

• Choose a field in which the previous crop did not belong to the Brassicaceae family.
• Fields selected for regeneration should be at an isolation distance of more than 1000 m away from other Brassicaceae crops.
• If the materials are planted in an insect proof net house or mesh cage and isolated safely each other, the isolation distance is not required.
• Light soils are preferable e.g. sandy loam, silt loam, or soils with high organic matter, with good drainage and deep soils with a pH of 6.0-7.0.
• Greenhouse or cold-frames are needed in some places for cultivation to protect the plants from frost.
• Mesh cages or sulfite paper bags are needed if more than one variety is regenerated and the physical isolation is not possible.
• Some examples:
  • SASA: favours the use of polythene tunnels for maintaining isolation, containing pollinators and maximizing plant development in a controlled environment.
  • USDA: All regenerations are performed using 12 x 12 x 6 foot mesh covered cages with honeybee five frame nuclear hives introduced at flowering.
  • WARGRU: regeneration is carried out in insect-proof cages in an unheated glasshouse. Plants are grown in pots using a standard commercial compost.

Method of regeneration

Methods used

Radish is regenerated using two methods, seed to seed or root to seed.

• Seed-to-seed. Sow seeds into a cold-frame for at least 20 days at temperatures below 15°C for natural vernalization. Alternatively, store the germinating radish seeds in a cool room at 2-5°C for 14 to 40 days. Then, the plants are carefully transplanted to the field at least 30 cm apart.
  • CGN: seed-to-seed: sow seed in trays in March, transplant the seedlings in small pots and leave them in a cold frame for at least 20 days before planting out in isolation plots.
• Root-to-seed. Sow seeds in autumn and pull up the mature fleshy radish roots in winter. Select the healthiest and most typical of the variety in size, shape and colour for seed saving. Store roots in the cold room or bury them underground after defoliation of top parts. In February expose to 9±1°C for at least three weeks. Replant them at a temperature of 25±3°C, at least 30cm apart. 

Planting layout, density and distance

• For heterogeneous accessions, such as landraces, plant a total of 300 seeds (at least 100 plants are needed) in rows 2-5m long. Adjust the number of rows according to the length of rows and the distance between plants or rows.
• For pure lines that are genetically fixed, such as advanced breeding material, plant a total of 100 seeds (at least 30 plants).
• Leave at least 45 cm between rows to allow adequate space for inter-row cultivation.
• Space plants 30-45 cm apart, sow from 1cm deep recommended for small radishes to 4 cm deep for large radishes, with up to three seeds per hole.
• In the greenhouse or cold-frame, sow three seeds per seedling pot or sow in trays. Transplant the radish seedling at 45 × 30 cm apart.
• When the area is subject to heavy rainfall and strong winds, the plants need be protected.
• Use net cages to protect each accession. Alternatively, leave 1000 m isolation distance between plots where physical barriers are available and 2000 m if in an open landscape.
• Plants grown in rows benefit from support when top-heavy with seed.
• Example IPK:
  • Cultivated radish: two rows of 2 m are directly sown in the field in spring (small radish) or autumn (radish) using 3-4 g of seeds. 25-30 plants are selected in spring or autumn based on morphological characteristics such as root colour, form, taste, consistency and leave form. The selected plants are transferred into pots and placed into a cold house (4-5 °C) during winter to keep them free from frost. In the following spring they are transferred into small greenhouses and seeds are harvested in late summer to early autumn.
  • Wild radish types: 50 seeds are sowed onto a tray in Jan-Feb. The small plantlets are thinned into small pots and then transferred into the greenhouse. 2 rows of a total of 20 plants of the bigger types and 30 of the small types are planted in the greenhouse in early April.

Artificial pollination 

• Radish is cross-pollinated with a self-incompatibility system.
• It is pollinated from the same plant during the bud stage to overcome self-incompatibility, when using paper bags
• Spray 3-4% NaCl solution to the stigma before the dew dries every morning during the flowering stage to help overcome self-incompatibility.
• Use bees, bumble bees or flies with mesh cage.
• Some examples from genebanks regarding type of pollinators and timing of introduction to cages:
  • AVRDC: Introduces honey bees in each net cage at the onset of flowering
  • CGN: Introduces bumble bees or blow flies when about half of the plants is flowering.
  • IPK: uses solitary bees for pollination in greenhouses.
  • NGB-NBPGR: Introduces honey bees at the onset of flowering
  • SASA: uses polytunnels with bumble bees introduced when about 75% of the plants are flowering.
  • USDA: introduces common honey bee five frame nuclear hives at flowering.
  • WARGRU: blowflies used as pollinators, introduced when first flowers open and further flies are added as required until flowering has ceased.
• Manual pollination by a bamboo pole of one end wrapped with absorbent cotton for each accession in different mesh enclosures under a big house of machine-woven net fabric with meshes

Labelling 

• Label or tag each row. Use weather-resistant labels and ink.
• If using polythene tunnels, each tunnel must be clearly numbered. As with outside labels, graphite pencil is preferable to ink as ink bleaching can occur in a short time when exposed to sunlight.

Crop management

Irrigation

• Keep soil moist for uninterrupted growth and best quality.
• Peak demand during rapid growth and development stage.
• SASA: reduces to almost no irrigation at pre-harvest yellow pod stage

Fertilization

• Keep the soil mineral and nutrient content steady for normal plant growth and flower production.
• Apply a fertilizer balanced for nitrogen, phosphorus and potassium, based on location conditions, practices, soil test results and fertilizer availability, if necessary.
• Example CAAS:
  • Apply 2000-3000 kg of farmyard manure, 15 kg of diammonium phosphate, 10 kg of urea per 667 m2 and incorporate it before last ploughing.
  • A second application of 10-15 kg of urea per 667 m2 two weeks after planting encourages quick growth.
  • Apply 20-30 kg of Compound Fertilizer, 20N-20P-20K at early flowering stage.

Common pests and diseases

Contact plant health experts to identify the symptoms of the likely pests and diseases and the appropriate control measures.
The following are common pests and diseases for radish:

Viruses

• Turnip mosaic virus (TuMv)
• Cucumber mosaic virus (CMV)
• Cauliflower mosaic virus (CaMV )
• Radish enation mosaic virus (REMV)

Bacteria

• Black Rot (Xanthomonas campestris pv. campestris)
• Bacterial leaf spot, Peppery leaf spot (Pseudomonas syringae pv. maculicola)

Fungi

• Alternaria leaf spot (Alternaria brassicae, A. brassicicola, and A.raphani)
• Black leg (Leptosphaeria maculans, anamorph Phoma lingam)
• Black root (Aphanomyces raphani)
• Cercospora leaf spot (Cercospora cruciferarum and C. atrogrisea)
• Fusarium yellows or Fusarium wilt of radish (Fusarium oxysporum f. sp. raphani)
• Downy mildew (Peronospora parasitica)
• Clubroot (Plasmodiophora brassicae)
• Rhizoctonia scurf (Rhizoctonia solani)
• Sclerotinia (Sclerotinia sclerotiorum)
• White Rust (Albugo candida)

Insects

• Cabbage maggot (Delia radicum)
• Cabbage seedpod weevil (Ceutorhynchus obstrictus)
• Cabbage aphid (Brevicoryne brassicae)
• Turnip aphid (Lipaphis erysimi)
• Green peach aphid (Myzus persicae)
• Diamondback moth (Plutella xylostella)
• Cabbage Looper (Trichoplusia ni)

Others

• Nematodes (Meloidogyne spp., Heterodera spp., Ditylenchus dipsaci)

Pest and disease control

Preventive

• Seed treatment
• Field crop rotation
• Herbicide spray before sowing
• Sterilizing soil
• Deep ploughing
• Barrier system
• Prevent from slugs through pellets
• Remove and destroy all previous crop debris.

Non-preventive

• Identify weeds, pests, pathogens in time by inspection. Invite pathologists and virologists to the radish field during the growing season.
• Loose soil during early stages of crop growth.
• Get rid of off-types within the accession; eliminate unhealthy and dead leaves and roots during the growing season.
• Spray with appropriate fungicides, herbicide and insecticide.

Harvesting

• Before harvest, prepare mesh or paper harvest bags labeled with the genebank code number and plot identification number.
  • Example for treatment before harvest: Pre-harvest, SASA will gently lift, detach from the soil and replace each swollen root by hand to prevent further soil-based moisture entering the plant. The stems are supported by strings stretched between posts. In this condition, the plants can be left until all pods ripen and dry evenly.
• Harvest when most or all siliques are dry. Examples for harvest procedures
  • AVRDC/NBG-NBPGR/USDA: Harvest is done when all siliques are dry and the inflorescence is cut and stored in nylon mesh bag.
  • CGN: Harvest is done when a large number of dry siliques are observed. The top with unripe siliques is cut off; the inflorescence is cut from the plant and placed in a linen sac.
  • IPK: Cultivated radish is harvested when the whole plant is dry. The whole plant is cut and put into a linen sac. Siliques of wild plants are harvested in paper bags, rarely in linen sac, when all pods are dry, including those that have already been scattered and lie on the ground. If necessary harvest is carried out in several moments.
  • SASA: plants are harvested when all pods are dry. Plant stems are cut below seed-pod level and packed in a large polypropylene self-supporting harvest bag. Most seed collects in the bottom of the bag and the remainder is machine-threshed and winnowed directly off the stem.
  • WARGRU: pods from each individual plant are harvested into separate paper bags, labeled with the accession and plant number. Aim to collect seed from a minimum of 40 individually labeled plants. 
• Record the numbers of plants harvested
• Check that the information on the bag label and plot tag are the same. Place the seed harvested from a plot and the plot tag into the labeled harvest bag.
• The radish pods need to be dried further under sunshine, in a glasshouse or a drying cabinet for a few days after harvesting.
• Examples for drying:
  • AVRDC: nylon mesh bags are placed under shade for drying before threshing.
  • CGN: Linnen sacs are placed in a drying cabinet where the seeds are dried by forced heated air at about 25 °C for a few days. The sacs are then stored in room at 13°C and 30% RH until the seeds are cleaned in winter. 
  • IPK: The harvested radish is placed in a drying room at 22±2°C and 20±3% RH until they are dry enough for threshing and cleaning.
  • NGB-NBPGR: Harvested siliquaes are placed under shade or in a drying room until the material is dry enough for threshing and cleaning.
  • USDA: nylon mesh bags are placed in a forced air drying room for drying before threshing.
  • WARGRU: paper bags are placed in a drying room (15% RH, 15°C) until the material is dry enough to thresh.

Post-harvest management 

• After the radish siliques have been dried in the sun or in a drying cabinet, they need to be broken to release the seed by beating or threshing.
• Check the labels of the seed inside and outside of the seed bag or the seed envelope to ensure the identity.
• Threshing can be done by stomping on, beating or driving over the pods. USDA uses for example a rubber roller belt thresher to break the siliques and release the seeds.
• Wild radish siliques are difficult to thresh. When siliques cannot be removed, the seeds are conserved in the siliques and the siliques are broken into single pieces.
• After threshing remove all debris, separate empty seeds and other light material with sieves, a seed cleaner or by blowing or hand cleaning.
• Manually separate and discard any visually shriveled, discolored, infected, damaged, empty or germinated seeds.
• Place the seeds of the same accession into one paper bag labeled on the inside and outside.
  • WARGRU: seed from each individual plant is weighed and recombined in proportion in a single paper bag.
• If seed quantity is below threshold and/or obtained from too few plants, reschedule the accession for a further regeneration from the original seed.
• Dry the seeds to 3–7% moisture content for medium-term and long-term conservation using a dehumidified drying room. Depending on seed size, drying takes a minimum of 2-4 weeks.
• The seed samples should be kept in a paper, mesh or cotton bag on mesh racks during the drying period.
• All seed samples are dried to equilibrium in a controlled environment of 5-20 °C and 10-25 % RH.
• Examples of drying conditions used in genebanks:
  • AVRDC: 15% RH and 20 ºC for at least 4 weeks
  • CAAS: 13-30% RH and 15-25 ºC
  • CGN: 15% RH and 15ºC for at least 6 weeks
  • IPK: 10% RH and 18 ºC, 2-3 weeks.
  • NGB-NBPGR: 15%RH and 15ºC for up to four weeks. Seeds received with high moisture content are pre-dried in a warm dry place before transferring into walk-in seed drying rooms or seed drying cabinets
  • SASA: 15%RH and 15ºC for up to four weeks.
  • USDA: 20% RH and 5oC; drying for 2 months
• Prepare several sets of the seed samples for preservation in active, base and safety duplicate collections. Send a sample of each accession to a seed health laboratory for quarantine requirements.
• Determine 1000 seed weight, and take sample for viability testing of the seeds and record the results according to standard germination methods (ISTA, 2008). If viability is above threshold level, proceed to storage, if viability is lower, reschedule the accession for a further regeneration from the original seeds.
• Pack seeds in airtight containers for conservation and distribution.
• Store seeds in the genebank at 4°C and 30% RH in active storage or at -18 to -20°C in long-term storage.
• In some genebanks all seeds are stored at temperatures below 0°C: USDA stores active and base collections at -20°C in sealed aluminum foil packets; SASA stores all radish seeds at -22°C.

Monitoring accession identity

Comparisons with previous passport or morphological data

• Verify accession identity using leaf, flower, pod and seed traits during the planting and post harvest.

Documentation of information during regeneration

The following information should be collected during regeneration:

• Regeneration site
• Name of collaborator
• Plot reference
• Accession number
• Source of seed
• Preparation of planting materials (pre-treatments)
• Sowing date
• Field layout used
• Environmental conditions ((latitude, longitude, altitude, precipitation, soil type, others)
• Field management details (watering, fertilizer, weeding, abnormalities recorded, others)
• Germination in the field or greenhouse
• Agronomic evaluation; agro-morphological traits recorded
• Number of plants established
• Days from sowing to flowering
• Breeding system
• Pollination control method used
• Harvest date
• Number of plants harvested
• Quantity of seeds harvested
• Viability of seeds harvested (germination rate)

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References and further reading

Ara N, Ali MO, Ali MM, Basher MK. 1999. Effects of spacing and fertilizer levels on yield and quality of radish seed. Bangladesh journal of scientific and industrial research. 4(2): 73-178.

Breese EL. 1989. Regeneration and multiplication of germplasm resources in seed genebanks: The scientific background. Html version available from: http://www2.bioversityinternational.org/publications/Web_version/209/. Date accessed: 9 June 2010.

Engels JMM, Visser L, editors. 2003. A guide to effective management of germplasm collections. IPGRI Handbooks for Genebanks No. 6. IPGRI, Rome, Italy. Available here. 

FAO/IPGRI. 1994. Genebank standards. Food and Agriculture Organization of the United Nations, Rome and International Plant Genetic Resources Institute, Rome. Available in English, Spanish, French and Arabic .

FAO/IPGRI. 2001. Multi-Crop Passport Descriptors. FAO and IPGRI, Rome, Italy. Available in English, French and Spanish.

George RAT. 2009. Vegetable seed production. 3rd edition. CABI, UK.

IBPGR. 1990. Descriptors for Brassica and Raphanus. International Board for Plant Genetic Resources, Rome, Italy. Published in association with the Commission of the European Communities. ISBN 92-9043-184-9. Available here (1.5 MB).

ISTA. 2008. International Rules for Seed Testing. Edition 2008. International Seed Testing Association, Bassersdorf, Switzerland.

Kalb T, Sukprakarn S, Juntakool S and Huang Rk. 2006. Saving Seeds of Radish:Saving your own vegetable seeds—a guide for farmers. Publication No. 06-668. The World Vegetable Center; Taiwan

Lovato A, Montanari M, Miggiano A. 1994. Nitrogen fertilization of seed radish (Raphanus sativus L.): effects on yield and N-content in seed, plant and soil. International Symposium on Agrotechnics and Storage of Vegetable and Ornamental Seeds. ISHS Acta Horticulturae 362. ISSN: 0567-7572, Bari, Italy.

Navazio J. Principles and practices of organic radish seed production in the Pacific Northwest. Organic Seed Alliance. Supporting the ethical development and stewardship of seed PO Box 772, Port Townsend, WA 98368.

Peterson C. 1999. Radishes: Easy to sprout, hard to grow right. [online]. The New York Times, May 2, 1999. Available from: http://www.nytimes.com/1999/05/02/style/cuttings-radishes-easy-to-sprout-hard-to-grow-right.html. Date accessed: 9 June 2010.

Radish [online]. Available from http://www.seedtamilnadu.com/nradish.htm. Date accessed: 9 June 2010.

Tzay Fa Sheen. 1981. Vernalization and flower development in seed vernalization type of radish. Studies on seed production and vernalization of Cruciferous crops in the tropics. Journal of agricultural research of China 30(4):38-47

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Distribution of radish genetic resources

Contributors to this page: CAAS, China (Qiu Yang, Li Xixiang); Bioversity International, Italy (Imke Thormann, Ehsan Dulloo); CGN, Netherlands (Noortje Bas); IPK, Germany (Andreas Börner, Ulrike Lohwasser); AVRDC, Taiwan (Andreas Ebert); USDA, USA (Larry Robertson); NBPGR, India (Chitra Pandey); SASA, UK (George Campbell); University of Warwick, UK (Charlotte Allender).

Policies and regulations for distribution

Common policies on distribution and access to plant materials

• Germplasm should be distributed free of charge in response to official letter requests or e-mail.
• Requests by phone should not be accepted.
• A Standard Material Transfer Agreement (SMTA) should be signed before shipment.

Policy exceptions

• None

National laws and regulations

It is essential to follow the terms and conditions in the host country agreements.

• Phytosanitary certificate, specific to the requirements of the importing country.
• Letter of donation (with no commercial value).
• Certificate of origin.
• GMO-free certificate, if issued.
• Import Permit, when required.

International laws and regulations

• Any seed shipment should be accompanied with the SMTA or make reference to the SMTA.

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User related issues for distribution

Shipment time to users

• Up to 3-5 weeks from requesting germplasm to dispatching the seeds.

Customer assurance

• Curators should fulfill all reasonable seed requests if the accessions are available for distribution (sufficient seed stock; good viability).
• Curators should prepare the catalogs with descriptions of the seed accessions to guide the users.
• The samples sent to the user should match the request.
• Minimum passport and characterization data are usually sent with the seed samples.

Feedback from users

• Send a Germplasm Utilization Feedback form with every supply describing the most relevant information required to be received from users such as:
  • Comments on the appropriateness of the material supplied and the conditions in which the material was received.
  • Voluntary feedback of characterization and evaluation/use data.
  • Performance of the accessions under different environmental conditions and the special traits observed.
  • Voluntary feedback of further study and use information.

Quantity of material recommended to be distributed

• Use sampling of small quantities to assure a good representation of the accession and to avoid rapid depletion of seed stocks, thus, reducing the regeneration frequency of active collections.
• An appropriate quantity for distribution is 50 seeds per accession.Some genebanks however distribute larger samples such as CAAS (100 seeds) or CGN (300 seeds) 

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Procedures for distribution

Check availability

• Check availability of seeds in stock using the inventory database and verify the request.
• Distribute the requested seeds only if the seed stock does not drop below the minimum number of seeds required for safe storage.
• Inform the requester if accession have low amount of seeds in stock and possibly suggest alternative available accessions.

Preparing samples for distribution

• Register the request.
• Prepare a list of the accessions available.
• Generate two sets of labels and attach one to the seed envelopes.
• Check inventory files and note the location of containers in the genebank.
• Remove containers from genebank and apply the required acclimatization procedures.
• Assure accuracy in identification.
• Extract samples from the original containers.
• Place the other label with the seeds inside the envelope before sealing.
• Update the seed inventory of the genebank (the genebank database should always be kept updated. In some genebank databases the inventory is updated automatically when the request is imported to the database.
• Check the requirements for material transfer agreements. If the material cannot be distributed under the SMTA, use a tailored MTA for the selected accessions. The USDA uses a SMTA only for accessions requiring this as part of a Germplams Acquisition Agreement (GAA).
• Verify if import permit and phytosanitary certificate are necessary. Example: If request comes from outside the European Union, CGN needs to check if phytosanitary certificate and import permit are necessary. If so import permit is requested from requester and phytosanitary certificate from the national plant disease service.

Preparing the information list to accompany the plant materials

• List of accessions and passport data (e.g. accession number, accession identification, crop name, taxon name, country of origin, biological status, collecting location, source).
• Standard Material Transfer Agreement (SMTA) or reference to it; or GAA.
• Cover letter.
• If necessary, phytosanitary certificate and import permit

Dispatching the plant materials

• Pack the seed envelopes, cover letter, SMTA or GAA and the seed list in a plastic bag and then in a strong envelope or a cardboard box.
• The SMTA/GAA and the list along with copies of all documents should be put inside the box. The phytosanitary certificate and import permit should be attached outside the box.
• Include a reply form that the requester should complete and return to genebank to acknowledge that seeds have been received in good conditions.
• Make sure that the complete and correct address of the requester is on the label.
• Record the shipment details in the distribution data file.

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Recording information of the distribution

The following information must be recorded for each consignment:

• Reference number
• Crop name
• Consignee’s name and designation
• Name and address of organization
• User information (type of organization requesting material)
• Date of request
• Date of supply
• Number and quantity of samples provided
• Phytosanitary certificate
• Import/Export permit number
• Reference number of SMTA
• Intended germplasm use.

System for tracking materials/inventory system for distribution

• Seed distribution should be one of the modules of the genebank documentation system

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References and further reading

International Treaty on Plant Genetic Resources for Food and Agriculture (ITPGRFA). [online]. Available from: http://www.planttreaty.org/ Date accessed: 8 June 2010.

Rao NK, Hanson J, Dulloo ME, Ghosh K, Nowel D, Larinde M. 2006. Manual of seed handling in genebanks. Handbooks for Genebanks No. 8. Bioversity International, Rome, Italy. Available in English (1.5 MB),  Spanish (1.4 MB) and French (1.9 MB).

Standard Material Transfer Agreement SMTA. [online]. Available from http://www.planttreaty.org/smta_en.htm Date accessed: 8 June 2010.  

Characterization of radish genetic resources

Contributors to this page: CAAS, China (Qiu Yang, Li Xixiang); Bioversity International, Italy (Imke Thormann, Ehsan Dulloo); CGN, Netherlands (Noortje Bas); IPK, Germany (Andreas Börner, Ulrike Lohwasser); AVRDC, Taiwan (Andreas Ebert); USDA, USA (Larry Robertson); NBPGR, India (Chitra Pandey); SASA, UK (George Campbell); University of Warwick, UK (Charlotte Allender).

Cultural practices

Environment

• Choose a field in which the previous crop was not a crop belonging to the Brassicaceae family.
• Light soils are preferable e.g. sandy loam, silt loam, or soils with high organic matter with good drainage and deep soils with a pH of 6.0-7.0 and uniform fertility.
• Surrounding climate (temperature, light, etc.) should meet the requirement of radish plant growth and development.

Season

For vegetative growth 

• Radish is a cool-weather, short-season vegetable crop. It grows best in cool and moist weather (15-22°C for leaf, 13-18°C for root).
• It is grown during spring and autumn in temperate zone and during the cooler parts of the year in the tropics.

For reproductive growth

• Radish flowers (bolt) initiate after vernalization. It is important to expose plants to cool outside temperatures below 15°C for at least 20 days.
• Another option is to store the germinating seeds or radish seedlings with two leaves in a cool room at 2-5°C for 14 to 40 days. A few accessions need 2-5℃ for more than 60 days.
• Temperature at flowering and seed set is optimal at 25± 3 °C. Radish may be sown at the end of winter (January) in a non-heated greenhouse and planted in the field in spring (mid-March In North China).

Plot size

• Row to row distance 30-60 cm – 90 cm are used in AVRDC, 3-45 cm between plants depending on the radish type and the vegetative or reproductive growth.
• Plant border rows around the plot.

Replications

• No replications are needed.

Standard check cultivars

• Use standard varieties for all characterizations.

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Descriptors for characterization

Morphological descriptors for characterization

•  See list for radish descriptors developed by IBPGR, (now Bioversity International, 1990), CAAS descriptors, or UPOV (such as the ‘UPOV Guidelines for the Conduct of Tests for Distinctness, Uniformity and Stability’ for Black Radish (TG/63/6), Fodder Radish (TG/178/3) and Radish (TG/64/6), used by SASA).

Pictures for characterization

Sufficient detail should be captured in images to taxonomically identify the plant and demonstrate the traits that show variation.

• Take images for character(s) which may be difficult to describe verbally or to score.
• Images of whole plant, racemes (if applicable), flowers, siliques.
• Store pictures in a database file linked to other characterization data.

Molecular markers for characterization

• SSR, EST-SSR, AFLP, RAPD (more efficient techniques).

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Recording information during characterization

The following information should be recorded for each trial:

• Observation location
• Culture season and condition
• Sowing and planting date.
• Bolting date
• Fleshy root harvest date
• Bolting date
• Data collector (full name).
• Date of data collection (this may be done several times, record the date of each time for specific character in remarks)
• All data of morphological or molecular characterization for each accession

System for characterization data

• All basic information, morphological data and pictures should be stored in one of the modules of the genebank documentation system.

References and further reading

Beattie JH. 1882. Production of radishes. [online]. Washington, D.C.. UNT Digital Library. Available from: http://digital.library.unt.edu/ark:/67531/metadc1562/m1/1/. Date accessed June 8, 2010.

Cornell University. 2006. Growing guide: Radishes. [online] Cornell University. Available from http://www.gardening.cornell.edu/homegardening/scene341b.html. Date accessed June 8, 2010.

Dainello FJ. 2003. Radish. Texas Cooperative Extension, Horticulture Crop Guides Series. Available from http://aggie-horticulture.tamu.edu/extension/vegetable/cropguides/radish.html. Date accessed June 8, 2010.

IBPGR. 1990. Descriptors for Brassica and Raphanus. International Board for Plant Genetic Resources, Rome, Italy. Published in association with the Commission of the European Communities. Available here (1.5 MB).

Li XX, Shen D, Wang HP, Song JP et al. 2008. Descriptors and Data Standard for Radish (Raphanus sativus L.). Beijing: Chinese Agricultural Press.

Radish. [online] New world Encyclopedia. Available from http://www.newworldencyclopedia.org/entry/Radish. Date accessed June 8, 2010.

Shippers RR. 2004. Raphanus sativus L. [online] Record from Protabase. Grubben GJH, Denton OA, editors. PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. Available from: http://database.prota.org/search.htm. Date accessed: 22 January 2010. 

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Health diagnosis of radish genetic resources

Contributors to this page: CAAS, China (Qiu Yang, Li Xixiang); Bioversity International, Italy (Imke Thormann, Ehsan Dulloo); CGN, Netherlands (Noortje Bas); IPK, Germany (Andreas Börner, Ulrike Lohwasser); AVRDC, Taiwan (Andreas Ebert); USDA, USA (Larry Robertson); NBPGR, India (Chitra Pandey); SASA, UK (George Campbell); University of Warwick, UK (Charlotte Allender).

List of pests and diseases of quarantine importance

The list below mentions some of the diseases that are considered important worldwide, but many of them may or may not have relevance in specific countries. Diseases of limited relevance (e.g. only important in very few countries) are not listed.

Bacteria

• Black Rot (Xanthomonas campestris pv. campestris)
• Bacterial leaf spot, Peppery leaf spot (Pseudomonas syringae pv.maculicola)

Fungi

• Alternaria leaf spot (Alternaria brassicae, A. brassicicola, and A. raphani)
• Black leg (Leptosphaeria maculans (anamorph Phoma lingam))
• Fusarium yellows or Fusarium wilt of radish (Fusarium oxysporum f. sp. raphani)
• Downy mildew (Peronospora parasitica)
• Clubroot (Plasmodiophora brassicae)
• Rhizoctonia scurf (Rhizoctonia solani)
• Sclerotinia (Sclerotinia sclerotiorum)
• White Rust (Albugo candida)
• Black root (Aphanomyces raphani)

Testing procedures 

Recommended methods to detect the presence of each disease:

• Seed borne fungi (Blotter test).
• Bacteria (Indicator plant method)

Testing intervals/seasons

• Testing before material goes into the genebank or to the field is important to reduce transfer of diseases or pests.

Recording information during health diagnosis

The following information should be recorded for each health diagnosis step:

• Accession number (ID number).
• Lot number (ID number).
• Date of test.
• Number of replicates.
• Number of seeds sampled and tested per replicate.
• Pre-treatments (pre treatments used for the test).
• Test method.
• Duration of test
• Diseases identified.
• Incidence of each disease (%)

References and further reading

ISTA. 2005. International Rules for Seed Testing. Edition 2005. International Seed Testing Association, Bassersdorf, Switzerland.

Recommended Codes for Pest Organisms in Vegetable Crops. 2009. [online]. Available from: http://www.worldseed.org/cms/medias/file/TradeIssues/PhytosanitaryMatters/PathogenCoding/RecommendedCodesForPestOrganisms/
Path_Codes_2009_NL.pdf. Date accessed: 7 June 2010. 

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