Clonal propagation: a method of seed multiplication

What will a farmer who would like to plant a certain rice cultivar for the coming season do when he or she only has a limited amount of seeds? Clonal propagation can be resorted to.

Clonal propagation is a method of multiplying rice plants from a single grain, an aged seedling or a rice stubble. This method, developed by R. H. Richharia in India, has several advantages over the conventional seed-crop multiplication:

- applicable to any rice cultivar
- ensures genetic purity of multiplied material
- could be easily adopted by farmers
- except for labor, the system entails minimum costs to farmers.

PROCEDURE:

1. Germinate seeds in a pot or en isolated paddy. Initial plant materials or mother plants are best placed in pots for protection and easier maintenance.

2. Seeds germinate and grow and form tillers at approximately 12 days after planting (DAP). At 20 DAP, or when tillers possess new roots, tillers could be separated. Carefully detach these using a razor blade or a thumb's nail.

3. Plant the separated tillers and the mother plant immediately. If the procedure is done in the field, use wide-planting distances 0.20 x 0.20 m to encourage tillering.

4. The individual plants (clones) grow again and produce tillers. Rooted tillers could again be separated after 15 days. Replant the tillers after separation. Fifteen days after replanting, all the plants are uprooted and the tillers are again separated. In the case of short-duration varieties, the separation of tillers and replanting have to be done earlier (7-10 days).

Germinate seeds

At 70-80 days after sowing, maximum tillering occurs (or 3-4 primary tillers are formed) for all plants. Separation of tillers can be continued up to this point. The separated primary tillers thereafter serve as the new mother plants for subsequent splits. Further separation can be repeated until a sufficient number of seedlings are produced for field transplanting. During multiplication, pests should be controlled to prevent losses.

Multiplication

Note: The rate of multiplication is genotype-specific. In general, medium- and late- maturing cultivars tend to produce tillers longer due to a time lag between vegetative and reproductive stage. Hence, more tillers are produced. The number of initial plant material, therefore, has to be adjusted, i.e., more seeds should be supplied for early-maturing cultivars to compensate for lesser production of tillers.