Search Results
Freshly harvested, true potato (Solarium tuberosum L.) seeds (TPS) will germinate at 15 ± 5C, but because of dormancy they must be stored for ≈18 months before they will germinate at >25C. Effects of seed moisture content (SMC) and temperature in storage on germination and seedling emergence were periodically tested during 18 months for seeds harvested from three positions on the mother plant. Seeds were stored with 37.,5%, and 7% SMC (on a dry weight basis) at 5 and 45C; sublets were removed monthly (1 to 7 months) from 45C and stored at 5C. Seed dormancy and viability were best preserved in storage at low SMC and low temperature, Seeds stored at 45C and 3 % SMC progressively lost dormancy and, after 4 months of storage, germination was up to 88% after 4 days at 127C. This rate of germination decreased with further storage. Up to 100% emergence occurred in 9 days in seeds stored for 18 months at 45C and 3% SMC. Seeds stored at 45C and 5% SMC lost dormancy in 2 months and <50% emergence occurred after 18 months. Seeds stored at 45C and 7% SMC deteriorated and became nonviable within 6 months of storage. The position of seed development did not significantly affect seed size or weight. However, seeds produced from the bottom third of the plant (lot A) were the most vigorous after dormancy was released with sufficient storage. This suggests that efforts should be made to produce TPS in the primary branches of the mother plant.
The importance of sowing vigorous seed is particularly well recognized by commercial growers of small-seeded sexually propagated crops. The possibility of producing clean potato seed tubers with true potato seed (TPS) has existed in many developing countries since the seventies. In China, about 15,000 ha of potatoes are grown with seed tubers originally derived from TPS. The possibility to establish a fast field-stand and to produce a commercial crop of potatoes within 90 days after transplanting TPS seedlings has only been recently realized. This paper outlines the methodology used and the results obtained during 10 years of study focusing on the most critical factors involved in the production and preservation of high-quality TPS. Seed dormancy accounts for the most important difference between the undomesticated TPS and other related crops such as the tomato.
True potato seed of Atzimba × 104.12LB (intermediate dormancy) was dried to seed moisture contents ranging from 3.85 to 12.5% (dry wt basis) and was stored for 2 years at 30, 15 and 5°C. Seed was tested for various germination and seedling vigor criteria at 4 month intervals. Seed dormancy and viability were better preserved at seed moisture levels below 7% and as temperature decreased. High moisture (>9%) was lethal to seed stored at 30°C. TPS should be stored at <5% seed moisture content. Under this condition seed dormancy in the genotype studied was lost after about 12 months at 30°C.
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.
Sexual seeds of potato (Solanum tuberosum L.) usually emerge poorly under high-temperature conditions (> 25 C). A seedling vigor study was conducted during the warm season (1988-89) in Lima, Peru, and the results of two representative tests. are reported. Two presowing treatments and a rinsed control were compared for seedlingstand establishment in a screenhouse with old (>18 months) and new (> 6 months) sexual seeds of three potato crosses. The treatments consisted of soaking the seed in solutions of KN03 + K3P04 at – 1.0 MPa (priming) and gibberellic acid at 1500 ppm (GA1500). Seedling vigor was lower at 34C (February test) than at 29C (November test). In both tests, overall seedling performance was highest in seed of the cross Atlantic × LT-7. Old seed was more vigorous than new seed, particularly when the crosses Atzimba × R128.6 (B2) and Serrana × LT-7 (Cl) were tested at 34C. Priming increased percentage of early (10 days) emergence over the other treatments at 34C and increased seedling dry weight in both tests. GA1500 increased percentage of final (17 days) emergence in crosses B2 and Cl, as compared to rinsing, except at 29C, where there were no significant differences in old seed. For sowing true potato seed at high temperature, a) the genotype is a crucial factor, b) sufficient seed storage (> 18 months) may be essential, and c) seed priming is more effective than the standard GA1500 treatment.