All about potatoes.pdf - Vegetableipmasia.org

4.
SEED PREPARATION AND PRODUCTION
Some people think that seed generation influences production characteristics.
However, a seed potato not originating from true potato seed will have the same
characteristics as its parent stock, as no hybridization takes place. In the production
process, however, plants can get infected by viruses, which are passed on to the
next generation in seed tubers, as well.
4.3 Criteria for healthy seed
The seed tubers produced by farmers usually originate either from plants they have
farmed themselves, from other farmers, or from seed producers. General criteria for
healthy seed are:
• Seed must originate from healthy parent stock; and be free from disease,
particularly bacterial wilt and viruses.
• Seed bearing plants should be more than 100 days old at the time of harvest.
• Tubers for seed should not be damaged by pests or improper harvest and postharvest
handling. Damaged tubers are more susceptible to diseases that influence
growth.
• Tuber size is not a criterion for healthy seed, however it is best to use seeds of
uniform size, weighing between 40-60 grams/tuber. Seeds of this size are large
enough to provide the nutrients potato plants need during the early stages of
growth, and not too large a volume of seeds will be required per hectare.
• Tuber skins appear fresh and not wrinkled.
• Uniform sprout size of around 1-2 cm. Uniform sprouts will
produce uniform growth, and make it easier to manage pests
and disease (see the chapter on managing leaf rot). Shorter
sprouts will mean plants take longer to emerge from the
ground and extend the plants’ critical period. Sprouts that are
too long will make transporting and planting more difficult as
they are prone to snap easily.
• Robust sprouts with bluish colored bases.
Seed from producers follow certificated standards. Seed potato certification is very
strict making it difficult for farmers to produce them. Certified seed standards are
given in Table 7.
Table 7: Standards for certified potato seed categories
Certified seed category (%)
A B C
Plants in the field
Purity 99.95 99.90 99.50
Bacterial wilt 0.0 0.1 0.5
Dry wilt 0.5 1.0 2.0
Virus 1.0 2.0 3.0
Weak/non-productive 2.0 3.0 4.0
Tubers
Bacterial rot 0.0 0.5 1.0
Dry rot 0.5 1.0 1.0
Black rot 0.5 1.0 1.0
Late blight 1.0 2.0 2.5
Nematodes 1.0 2.0 3.0
Tuber moth larvae 1.0 2.5 3.0
Mechanical damage 1.0 2.0 3.0
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ALL ABOUT POTATOES