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Storage specifications Storage management

• Most accessions of wild rices require different cultural management practices for seed increase compared to those of the cultivated rices.
• Several species such as O. meyeriana, O. granulata, O. ridleyi, and O. longiglumis grow better under partial shade, while others grow well under full sunlight.
• Grown the plants in 30 cm wide-mouthed pots without holes, so they can be placed in different levels of shade in the screen house.
• Wild species are also known to have stronger dormancy than the cultivated species.

Planting season

• Most of them are strongly photoperiod-sensitive so that the best time to grow them is during a season with short daylength to induce panicle initiation.

Wild species are also known to have stronger dormancy than the cultivated species.

• Plant the germinated seeds 1-2 cm apart, in a seed box containing moist, fine, clean (preferably sterilized) soil mixed well with appropriate amount of ammonium sulfate.
• Apply a granular insecticide (e.g. Furadan) 3-4 days after planting to protect the seedlings from ants and other insects.
• Water the seedlings carefully with a fine spray, and grown them under partial shade until a week before transplanting.

Transplanting

• Transplant the seedlings 30 days after sowing to water-tight pots with good quality soil mixed with about 5 g of complete fertilizer.
• Maintain the water level to at least 1 cm depth.
• A granular insecticide (e.g. Carbofuran) should be applied 7 and 14 days after transplant to protect the plants against hoppers and defoliators.
• For species of the O. meyeriana complex, the seedlings should be transplanted into pots with light soil and good internal drainage to prevent water logging as they thrive best in mesophytic conditions.
• For the highly stoloniferous species, such as O. schlechteri and some related genera like Luziola, Leersia, and Hygroryza, a modified flat bed should be constructed and used for growing and maintaining a single accession.
• The pots should be laid-out at least 100 cm apart to provide sufficient ventilation between plants and enough space for plant management.
• All species of the genus Oryza grow well under full sunlight except members of the O. meyeriana complex and O. ridleyi complexes which are best maintained in partial shade.

Different varieties of rice being grown inside an IRRI green house (photo: IRRI)

Crop management

• Top dressing is recommended at 30 and 45 days after transplant with 5 g ammonium sulfate per pot.
• For O. meyeriana complex, 2 g of ammonium sulfate should be applied weekly during three weeks, 30 days after transplant.

• Plants should be watered daily.

• Plant health should be monitored regularly.
• Appropriate control measures should be applied to specific pest and diseases once symptoms appear.
• Maintaining the cleanliness of plants also helps preventing the spread of diseases.

Thinning

• When purelines are to be developed, only 1 plant per pot should be maintained and spaced widely, preferably alternating species of different complexes.
• If a bulk population of seeds is required, 2-3 seedlings per pot should be transplanted and all the plants should be maintained.

Harvesting

Panicle bagging

• At the late vegetative stage, (about 60 days after transplant) the tillers should be tied loosely with, for example, an abaca twine to a bamboo stake (5 cm x 2 m) to prevent plants from encroaching from one pot to another, at the late reproductive stage, to facilitate panicle bagging.
• Panicle bagging is necessary for handling wild rices to minimize outcrossing, to prevent seed loss due to shattering, and to prevent mixtures at harvesting.
• Panicles should be bagged a week after full panicle emergence using nylon net bags which provides ample ventilation to facilitate anther dehiscence and prevent mold formation on glumes.
• For species with shorter panicles, glassine bags are a good substitute.
• The net bag should be pinned to the bamboo pole.
• Prior to bagging, labels should be prepared using shipping tags written with plot number and date of bagging with indelible ink.
• The labels must be attached inside the net bags.

Rice being grown inside an IRRI screen house. Notice the bagged panicles (photo: IRRI)

Panicle harvesting

• The panicles should be harvested 30 days after bagging or when most of the seeds have shattered.
• If sufficient seeds are obtained, the plants should be discarded and disposed through burning.
• However, for species with low seed set like O. rufipogon and O. longistaminata, the plants should be ratooned by cutting about 20-25 cm from the culms base, a little amount of ammonium sulfate should be applied and plants should be maintained until the next flowering to maximize seed production.
• After harvesting, the panicles should be dried and kept inside the drying room for two weeks, before carefully hand-threshing and cleaning the seeds.