Effect on berry production of varied day length during the life of two triumph potato strains

Summary

With an intermediate strain of Triumph potatoes (Triumph 22), the continual use of long photoperiods until pollination time resulted in the most berries.

When long photoperiods were used during relatively short intervals in the life of the plants, they appeared to be most useful when the flowers were making their final development.

Long photoperiods very early in the life of the plant were very useful for berry production, but were not indispensable and unless the long photoperiods were continued for 60 or 70 days they brought about the production of relatively few’ berries.

Berry production occurred with an 18-hour photoperiod, but production was only one-third as great as with a 24-hour photoperiod.

No berries were developed by the very early strain (Triumph 12) with an 18-hour photoperiod and with this strain berries were produced with only four of the 24-hour photoperiod treatments.

Our evidence indicates that induction of flowering in Triumph potatoes by using long photoperiods for short intervals of time is not feasible and except under very favorable conditions of high light intensity it is not possible.