Wild Strains - Wild Core Collection - Cultivation Manual Of Wild Rice Species

Cultivation Manual Of Wild Rice Species

Caution :
Care must be taken by growing wild Oryza taxa in pots and green/screenhouses to ensure that the plants do not spread by seed or rhizomes and thus become weeds at a research station or in farmer's fields. Wild relatives of rice are easy to be weedy grass especially near the wild growth place. However, rice will not become weeds if handled carefully.

Wild Oryza species have various characteristics which make growing them more difficult than cultivated rices. The common characteristics include strong seed dormancy, slow seedling growth, photoperiod sensitivity, and seed shattering from the panicle. Several species such as O. meyeriana, granulata, longiglumis, ridleyi, and minuta grow better under partial shade, while most others grow well under full sunlight.

  1. Break the dormancy of freshly harvested seeds by heat treatment (50C-54C for five days) and by dehulling and scratching the pericarp near the embryo with a sterilized needle or scalpel.

  2. Treat dehulled seeds with a fungicidal suspension (for example; 0.2% Benlate solution for 30min at room temperature), wash thoroughly; germinate on moist filter paper in petri dishes, and in a germinator, if possible.

  3. Plant germinated seed in a flat or tray containing moist, fine, clean (preferably sterilized) soil with a complete range of nutrients; grow young seedlings under partial shade until a week before transplanting.

  4. Transplant at 3-leaf stage (about 30 days from seeding): water plants carefully (plants are slow-growing); apply fertilizer in small doses; use large pots (30 cm diameter) to accommodate 3-4 plants and to prevent rhizomes from encroaching on another accession.

  5. Many strains are strongly-photoperiod-sensitive and may require short-day (10-hour) treatment to induce panicle initiation when grown under long day length. The best time to grow them is during a season with shortening day length.

  6. Protect plants against virus diseases, leafhoppers, aphids, other insects, birds, and rodents.

  7. Many wild rices are tall or straggling. Periodically, tie up the plants to a tall stake to keep plants from growing among one another and to facilitate panicle bagging.

  8. Bag newly emerged panicles to collect easily shattered seeds and to prevent outcrossing; use ventilated bags to facilitate anther dehiscence and to prevent mold formation on glumes.

  9. Cut back the plants at about 20 cm from their culm base after the first harvest to induce a ratoon crop, since one planting usually does not provide large quantities of seeds. Apply a small amount of fertilizer after ratooning.

  10. Keep seeds of different plants of one accession in separate paper bags as components of the accession? wild taxa are heterozygous and the collected samples are usually the bulked seeds of a population. For critical research and breeding, a pure stock is desired; however, for conservation purpose, the population should be maintained as a bulk.

  11. For O. meyeriana and O. granulata the following additional pointers are vital to the maintenance of these species:

    1. Break dormancy with heat treatment for 7 to 10 days at 50C.
    2. Transplant seedlings in pots with light soil and good internal drainage. These two species thrive best in mesophytic condition and should be kept under partial shade.
    3. Re-pot and separate the tillers after the first cycle. Sustained fertilization (complete fertilizer) will yield more viable seeds.
    4. Water lightly but do not allow the soil to dry out for more than two days.

  12. For the partially self-incompatible species, O. longistaminata, bagging two or three panicles of different plants together may help to produce seeds. If different accessions are crossed, record the accession numbers of the parents on the bag.

  13. For other wild taxa not readily propagated by seed, such as Porteresia coarctata, tissue culture may help in propagation and shipping.

Our Request: We would appreciate receiving data of your screening tests, results of your experiments and/or published papers involving the different accessions of wild species supplied to you. This would facilitate the updating of our files which would in turn benefit other users of the exotic germplasm.

Based on "Suggestions on growing wild taxa of Oryza", Rice Biotechnology Quarterly 8: 52-53 (1991), IRRI.