Seed definitions

1. Pure seed The true seeds of the variety based on seed shape, size, coloration, usually the majority of seeds.  Other rice seeds appearing as off-types should be placed under rice varietal mixture.
2. Best seeds The pure seeds that are bold or fully filled having no or low amount of discoloration (<0.5% discolored seed surface).  Half-filled and empty will fall under partially filled or unfilled.

3. Spotted


4. Discolored

There are two types of discoloration on rice seeds,
1. Spotting caused by certain diseases (brown spot) or insects (rice bug feeding damage) and,
2. Discoloration on a portion or portions of rice seeds caused by Curvularia (black kernel) or sometimes by Alternaria padwickii
(stackburn disease) or by sheath rot on certain occasions. Other rice diseases do not produce consistent discoloration. We
consider any seed having more than 0.5% discolored or spotted seed surface as discolored. Discoloration can occur on fully or
partially filled or empty grains.

5. Partially filled

Seeds that are not fully filled due to immaturity at harvest or due to infection of seeds by certain diseases or insect damage.

6. Deformed seeds Seeds with non-normal shape due to mechanical pressure during grain formation or due to seed infection (sheath rot) or infestation white tip or stem nematode.
7. Germinated seeds Could be genetic in nature when there is no dormancy (vivipary) or when panicles come in contact with paddy water before harvest.

8. Smuttered seeds (Seed diseases)

Generally are due to infection like false smut (Ustilaginoidea virens) or kernel smut (Tilletia barclayana) [organ specific diseases].
9. Unfilled seeds Glumes without endosperms could be due to several factors for failure of some spikelets to fertilize and form endosperm, abortion of ovary due to early infectin (ex. brown spot, sheath rot, white tip nematode, black kernel, bakanae, etc.)

10. Species other than Oryza sativa

Seeds other than Oryza sativa

10a. Rice varietal mixtures

Mainly discriminated from true seed of the variety by difference in seed size, shape, seed coloration, pubescence of lemma and palea, and seed coat color.  Usually minor in numbers.

11. Weed seeds One of the seeds of the other species; vary in size from big (Rottboella & Ischaemum) to small (Scirpus juncoides) are reported as number of seeds in the working sample.
12. Other plant parts Usually are present in improperly processed seed lot having pieces of broken leaves, stem or panicle branches.
13. Inert matter Refers to soil, sand, etc. attached or with the seeds
14. Insect damage Seed infested by storage insects could be reported by counting the number of insect damage seeds.

For more information:

Visit the Rice Knowledge Bank website (, email; or call +63 2 580 5600.

Prepared by M Gummert with inputs from JF Rickman (2004); updated by M Gummert (2010)