Regeneration guidelines for rice

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This information was extracted from: Reano R, Sackville Hamilton R, Romero G. 2008. Regeneration guidelines: rice. In: Dulloo ME, Thormann I, Jorge MA, Hanson J. (editors). Crop specific regeneration guidelines [CD-ROM]. CGIAR System-wide Genetic Resource Programme, Rome, Italy. 11 pp.

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


Rice is the most important cereal crop, and the staple food of more than half the world’s population.

Domesticated rice comprises two species of food crops in the Poaceae (‘true grass’) family, Oryza sativa L. and Oryza glaberrima Steud. Oryza sativa (Asian rice) originated between the Himalayas and Indochina. It has two eco geographic races: indica and japonica (including temperate and tropical japonica, formerly known as javanica in some literature). Oryza glaberrima (African rice) originated in West Africa.

Rice is cultivated as a monocarpic annual plant, although in tropical areas some varieties can be grown as a perennial, producing a ratoon crop. Rice can reach a height of 1–1.8m with long, slender leaves 50–100cm long and 2–2.5cm broad. The small wind-pollinated flowers are produced in a panicle 20–50cm long. The rice grain (caryopsis) is 5–12mm long and 2–3mm thick. The life cycle of the rice plant is from 3 to 6 months (90 to 180 days), depending on the variety and the environment in which it is grown.

Cultivated rice is predominantly self-pollinating, with a low percentage of natural cross-pollination. The cross-pollination rate is typically less than 1%, but can be higher, for example between adjacent panicles that are in physical contact. Varieties with a greater proportion of the stigma protruding outside the glumes have a higher outcrossing rate (Reaño and Pham 1998).
These guidelines apply only to regeneration of genebank accessions with the intention to maintain their genetic integrity. They do not apply where the objective is to create or maintain pure-line genetic stocks or to conserve transgenic lines.

Choice of environment and planting season

For details on wild rice click here.

Climatic conditions

Rice has a tropical to warm-temperate distribution and is widely grown in every continent except Antarctica.

Planting season

Regenerating rice accessions at IRRI, Philippines. Note diversity in maturity and plant architecture (photo: Renato Reaño/IRRI)

Preparation for regeneration

When to regenerate


Preparing furrows in a raised seedbed using an improvised wooden implement (photo: Roel C. Rabara/PhilRice)

Field selection and preparation

Method of regeneration

Planting layout, density and distance (see photo below)

Rice accessions growing in the field (photo: Roel C. Rabara/PhilRice)

Schema for numbering field plots. (photo: Renato Reaño/IRRI)

Sowing method

After sowing, seeds are covered with soil (photo: Roel C. Rabara/PhilRice)

Bundled seedlings are distributed in
the field following the planting plan and
manually transplanted (photo: Roel C. Rabara/PhilRice)

Seedbed management

Isolation (method)

The following procedures are recommended for isolating plants:

Label of the accession attached to the bunch of seedlings (photo: Roel C. Rabara/PhilRice)


Crop management

Weed management

Irrigation and flooding


Common pests and diseases

Contact plant health experts to identify pests and diseases and appropriate control measures. Some of the major pest and diseases of rice are as follows:






Pest and disease control



Special care


Post-harvest management

Seed cleaning

Seed drying

Seed testing

Seed packaging

Monitoring accession identity

Documentation of information during regeneration

System for tracking materials/inventory system during regeneration

The following information should be collected during regeneration:

References and further reading

Borromeo TH, Sanchez PL, Vaughan DA. 1994. Wild rices of the Philippines. Philippine Rice Research Institute, Maligaya, Nueva Ecija, Philippines.

Chang TT, Vaughan DA.1989. Conservation and potentials of rice genetic resources. In: Bajaj YFS, editor. Biotechnology in agriculture and forestry. Berlin: Springer Verlag.

Hanson J. 1985. Practical Manuals for Genebanks: Procedures for handling seeds in genebanks. IBPGR, Rome, Italy. HTML version available from: Date accessed: 10 June 2010.

Lu BR.1999. Taxonomy of the genus Oryza (Poaceae): Historical perspective and current status. IRRN 24.3. IRRI, Los Baños, Laguna.

Manual of operations and procedures of the International Rice Genebank. 2000. Genetic Resources Center, IRRI. Available here.

Naredo MEB, Juliano AB, Lu BR, de Guzman FC, Jackson MT. 1998. Responses to seed dormancy breaking treatments in rice species (Oryza L). Seed Science and Technology, 26:675-689.

Rao NK, Jackson MT. 1996a. Seed longevity of rice cultivars and strategies for their conservation in genebanks. Annals of Botany 77:251-260.

Rao NK, Jackson MT. 1996b. Seed production environment and storage longevity of japonica rices (Oryza sativa L.). Seed Science Research 6:17-21.

Rao NK, Jackson MT. 1996c. Effect of sowing date and harvest time on longevity of rice seeds. Seed Science Research 7:13-20.

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).

Reaño R, Pham JL. 1998. Does cross-pollination between accessions occur during seed regeneration at the International Rice Genebank. International Rice Research Notes 23(3):5-6.

Reed BM, Engelmann F, Dulloo ME, Engels JMM. 2004. Technical guidelines for the management of field and in vitro germplasm collections. Handbook for Genebanks No. 7. IPGRI, Rome, Italy. Available here.

Sackville-Hamilton NRS, Chorlton KH. 1997. Regeneration of accessions in seed collections: a decision guide. Handbook for Genebanks No. 5. IPGRI, Rome, Italy. Available here.

Tateoka T. 1962a. Taxonomic studies of Oryza I. O. latifolia complex. Bot. Mag. Tokyo 75:418-427.

Tateoka T. 1962b. Taxonomic studies of Oryza II. Several species complexes. Bot. Mag. Tokyo 75:455-461.

Tateoka T. 1963. Taxonomic studies of Oryza III. Key to the species and their enumeration. Bot. Mag. Tokyo 76:166-173.

van Soest LJM. 1990. Plant Genetic Resources: Safe for the future in genebanks. Impact of Science on Society 158:107-120.

Vaughan DA. 1989. The genus Oryza L. Current status of taxonomy. IRRI Research Paper Series 138, Manila, Philippines.

Vaughan DA, Sitch LA. 1991. Gene flow from the jungle to farmers. Bioscience Vol. 41(1):22-28.

Vaughan DA. 1992. The wild relatives of rice: A genetic resources handbook. IRRI, Los Baños, Philippines.

Vaughan DA, Chang TT. 1992. In situ conservation of rice genetic resources. Economic Botany 46(4):368-383.

Vaughan DA, Morishima H, Kadowaki K. 2003. Diversity in the Oryza genus. Current Opinion 6:139-146.

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The Genebanks

The 11 CGIAR genebanks currently conserve 730,000 of cereals and grain legumes, forage crops, tree species, root and tuber crops, bananas and crop wild relatives.