Pure seeds:
The true seeds of the variety based on seed shape, size, and coloration; usually the majority of seeds. Other rice seeds appearing as off-types should be placed under rice varietal mixture.
Best seeds:
The pure seeds that are bold or fully filled, having no or low amount of discoloration (<0.5% discolored seed surface). Halffilled and empty will fall under partially filled or unfilled.
Spotted and discolored
There are two types of discoloration on rice seeds. One is spotting caused by certain diseases (brown spot) or insects (rice bug feeding damage). The other is discoloration on a portion or portions of the grains 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.
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.
Deformed seeds
Seeds with abnormal shape due to mechanical pressure during grain formation or due to seed infection (sheath rot) or infestation with white tip or stem nematode.
Germinated seeds
Germination could be genetic in nature when there is no dormancy (vivipary) or when panicles come in contact with paddy water before harvest.
Smutted seeds (seed diseases)
These are generally those infected with false smut (Ustilaginoidea virens) or kernel smut (Tilletia barclayana) [organ-specific diseases].
Unfilled seeds
Glumes without endosperms could be due to several factors: failure of some spikelets to fertilize and form endosperm or ovary abortion due to early infection (e.g., brown spot, sheath rot, white tip nematode, black kernel, bakanae, etc.).
Other species
Seeds other than Oryza sativa.
Rice varietal mixtures
Mainly discriminated from true seed of the variety by difference in seed size, shape, seed coloration, awn, pubescence of lemma and palea, and seed coat color. Usually low in number.
Weed seeds
Seeds of other species, varying in size from large (Rottboella and Ischaemum spp.) to small (Scirpus juncoides), these are reported as number of seeds in the working sample.
Other plant parts
Usually are present in improperly processed seed lots having pieces of broken leaves, stem, or panicle branches.
Inert matter
Seeds that are not fully filled due to immaturity at harvest or due to infection of seeds by certain diseases or insect damage.
Insect damage
Seed lot infested by storage insects could be reported by counting the number of insect-damage seeds.
