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- Author or Editor: Jose Santos-Rojas x
Abstract
Berry weight was correlated with the total weight of true potato seed (TPS) per berry and with the number of TPS per berry. 100-TPS weight was weakly correlated with berry weight and with TPS weight per berry. A negative correlation was found between 100-TPS weight and the number of TPS/berry. The degree of negative association between 100-TPS weight and TPS number per berry increased substantially as berry weight decreased in four of the five progenies investigated. Mean 100-TPS weights from large and from small berries were not significantly different for all progenies. Since seed weight is considered the measure of TPS sowing value, it is suggested that culling small berries is not an appropriate method to improve the quality of a given TPS lot.
Sexual potato (Solanum tuberosum L.) seeds require many months of afterripening in dry storage to completely lose dormancy and germinate readily at >25C. We examined the relationship between storage temperature and seed dormancy, as assessed by the percentage of germination after 4 days. Two F1 hybrid lots of `Desiree' × 7XY.1 were used; one seed lot was produced by carefully removing half of the developing tubers from the mother plant during seed development, and the control remained undisturbed. Seeds were stored with 3.4% moisture (dry-weight basis) at 10, 20, 30, 40, and 50C and were tested eight times during 29 months for daily germination at 27/40C (21/3 h) for the first 8 days, followed by 6 days at 17C. After 29 months of storage, final germination was <97% only when control seeds were stored at 50C, in which germination was 72%. Germination after 4 days increased curvilinearly with increasing storage temperature, and both seed lots similarly lost dormancy (germination >90%) after 10 months at 40C. Optimum germination levels were maintained after 29 months at 40C. Seeds stored at 50C never completely lost dormancy, and after 7 months of storage, germination at 4 days gradually decreased to zero. Dormancy was eventually lost after 29 months in most seeds stored at <40C, and differences between seed lots suggest that removing tubers from the mother plant increased dormancy. We conclude that dry potato seeds can be safely afterripened at temperatures up to 40C; lower temperatures slow the rate of dormancy loss, and higher ones are detrimental to seed quality.