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