True Potato Seed Research Articles

Performance of true potato seed families. 2. Comparison of transplants vs. seedling tubers

A potato crop can be grown from true potato seed (TPS) either by transplanting seedlings to the field (seedling transplants) or by planting tubers derived from seedlings (seedling tubers). The effect of the planting method on performance of TPS families was evaluated for three types of families, 4x×2x hybrid, open pollinated, and self pollinated. Families from seedling transplants and seedling tubers and their 4x parental clones were compared for tuber yield and specific gravity. Families from tubers had substantially higher yields and significantly more uniform specific gravity than families from transplants. Hybrid seedling tuber families had a higher mean yield than the parental clones and did not differ from them in specific gravity. Selection in the seedling generation could further improve both OP and hybrid families from transplants and from seedling tubers.

Performance of true potato seed families. 1. Effect of level of inbreeding

Successive generations of open pollinated (OP) true potato seed (TPS) families represent a low-cost planting material. This study was conducted to determine whether inbreeding occurred during two successive OP generations and, if so, whether it adversely affected the performance of transplant families from true seed. Potato seedling transplants from 4x×2x hybrid, OP1, OP2, S1 and S2 families were compared for plant vigour, flowering, pollen stainability, OP fruit set, tuber yield and specific gravity. Hybrids were consistently superior, while S2 families were inferior. The performance of OP1, OP2 and S1 families did not differ significantly for most traits. The accumulation of inbreeding in successive OP generations was limited by reduced OP seed production on selfed plants; thus, a synthetic TPS variety propagated by open pollination may be feasible.

Formation of first division restitution (FDR) 2n-megaspores through pseudohomotypic division in ds-1 (desynapsis) mutants of diploid potato: routine production of tetraploid progeny from 2xFDR × 2xFDR crosses

The level and mode of 2n megaspore formation was studied in full-sib diploid potato clones with either normal or desynaptic (ds-1ds-1) meiosis. Cytological analysis revealed that functional 2n megaspores produced by normal and desynaptic clones originate exclusively from 'second division restitution (SDR)' and 'first division restitution (FDR)', respectively. SDR 2n megaspores resulted from the omission of the second meiotic division following chromosome doubling after anaphase I, whereas FDR 2n megaspores resulted from a direct equational division of univalent chromosomes at anaphase I (pseudohomotypic division). Comparative data strongly indicated that the observed mechanisms of SDR and FDR 2n megaspore formation are extremes of a continuum that is being brought about by common genes for precocious chromosome division. Depending on the relative timing of cell cycle and chromosome division, this precocious chromosome division may impose postreductional (SDR) or prereductional (FDR) 'restitution' of the sporophytic chromosome number under normal synaptic and desynaptic conditions, respectively. The observed frequencies of 2n megaspores closely correlated with seed set, following pollination by tetraploid varieties and by desynaptic diploid clones with exclusive FDR 2n pollen formation. Up to 54.0 and 21.5 seeds/ fruit were obtained from normal synaptic (SDR) and desynaptic (FDR) progeny, respectively. The high frequency of segregants with either SDR or FDR 2n megaspore formation (78.0 and 45.2%, respectively) supports the hypothesis that sexual polyploidization is the driving force behind the origin and evolution of polyploid Solanum species. The present identification of diploid potato clones with consistent FDR 2n megaspore formation extends the opportunities for direct transfer of enhanced diploid germ plasm to tetraploids, and particularly advocates the feasibility of 2x(ds-1; FDR)×2x(ds-1; FDR) breeding schemes in cultivar development and the production of relatively vigorous and uniform true potato seed (TPS) varieties. Its potential value and limitations for breeding and the experimental induction of diplosporic apomixis are discussed.

True Potato Seed: Changing Potato Propagation from Vegetative to Sexual

“This thing called TPS [true potato seed] is a part of the future; how close that future is to us depends on whether people like us have what it takes.” R. Sawyer, 1984 The potato has traditionally been propagated vegetatively, but this may change someday. Today, many of the tubers produced from true potato seed (TPS), i.e., sexual seed, of selected potato progenies at the International Potato Center [Centro Internacional de la Papa (CIP)] could be sold in the markets of developing countries (Mendoza, 1984). Over the past decade of research at CIP, TPS technology has advanced significantly. More than 40 National Potato Programs are currently investigating the use of TPS. In eight countries, potatoes are being produced commercially from the first generation of tubers grown from TPS (Malagamba, 1988). CIP’s more widely tested TPS progenies are crosses between two tetraploid clones selected for progeny uniformity of tuber characteristics. Further improvements in TPS progeny uniformity could be obtained by using pollen selection techniques (Pallais et al., 1985a) and sorting for specific seed size characteristics. High levels of hybrid vigor and uniformity of tuber yields may be transmitted to the TPS progeny when produced with 2n pollen (first division restitution) of selected diploid clones crossed onto flowers of tetraploid mother plants (Peloquin, 1982; Peloquin et al., 1984). Ovules with unreduced gametes can also be formed in some potato diploids (Mendiburu and Peloquin, 1977). TPS may possibly be produced by crossing two diploid parents, which form 2n gametes, which would maximize heritability, heterozygosity, and, presumably, yield and uniformity. At present, the TPS technology has the possibility of being adopted in many tropical regions because high-quality seed tubers are difficult to produce in warm climates (Malagamba, 1988) because of the high inoculum pressure of the many tuber-borne pathogens

Detection, distribution and long-term persistence of potato spindle tuber viroid in true potato seed from heilongjiang, China

Return-polyacrylamide gel electrophoresis (R-PAGE) and tomato bioassay followed by R-PAGE were compared for the detection of potato spindle tuber viroid (PSTVd) from individual true potato seed (TPS). Both methods detected PSTVd from single TPS. TPS extract formulated as sap or nucleic acids in two different buffers did not affect the percentage of viroid detection on tomato plants. There was some evidence of viroid inhibitor in TPS extracts but not in nucleic acid extracts of TPS. Because R-PAGE is more rapid than the tomato bioassay followed by R-PAGE, the former was used to determine the extent of PSTVd in TPS of China’s Keshan Potato Research Institute breeding material. Over 1700 individual TPS were tested. Twenty-four of the 46 seedlots tested (inbred and outcrossed) contained PSTVd. The viroid was detected in 70% of lots from inbred lines compared to 38% of lots from outcrosses. TPS (20 lots) stored in paper bags at room temperature as far back as 1965 were also tested, and PSTVd was detected in TPS stored for 21 years.

Pollen fertility in relation to open pollinated true seed production in potatoes

The cost and difficulty of producing hybrid true potato seed (TPS) currently limits their use for commercial production. Twelve clones, selected in preliminary trials for low pollen stainability but high fruit and seed set, initially seemed promising for inexpensive production of mostly hybrid open-pollinated (OP) TPS. However, in subsequent tests, pollen stainability of these clones appeared to be highly variable and fruit and seed set were not as high. Bumblebees favored the most fertile clones, especially during periods when pollen stainability was the highest. Amounts of OP fruit and seed set correlated with maximum observed pollen stainability levels of the clones. Most of the OP seeds produced by these clones were probably the result of self-pollination; therefore, other methods must be used to obtain hybrid TPS.

The identification and evaluation of hybrid plants among open pollinated true seed families

An increase in the proportion ofhybrid vs. selfed plants improves the performance ofopen pollinated (OP) true potato seed (TPS) families. Strategies to increase the proportion ofhybrid seeds were investigated. A marker gene for yellow tuber flesh in a diploid clone, interplanted as the male parent, permitted identification of 4x × 2x hybrids among the OP progeny. Only 5% of the OP progeny were 4x × 2x hybrids. The proportion of 4x × 2x hybrid plants among the OP progeny was increased when the female parent had low male fertility and when only the largest 25% of the seeds were planted. The hybrid 4x × 2x plants were superior for all traits evaluated on the OP seedling transplant families. Traits included vigor, flowering, pollen stainability, OP fruit set, and tuber yield. Effects of the female parent were significant only for vigor and flowering, while seed size did not affect values for any trait consistently: With the limited outcrossing observed, the low seed set obtained when using parents with low male fertility and the work involved in selecting the largest seeds within individual fruits were not justifiable. However, research with OP true seed families asa low cost planting material should be continued, since high yielding OP families have been identified.

A SEED SELECTION SYSTEM FOR VIGOROUS TRUE POTATO SEEDS

In developing countries, the use of True Potato Seed (TPS) technology offers some potential economic and biological advantages compared to using seed tubers. One problem with using TPS technology is the lack of seedling vigor, poor germination and non-uniformity of seedlings derived from TPS. Open-pollinated true seeds were divided into three classes based on differences in embryo morphology. Highly significant differences were observed among these seed classes for 100-seed weights, percent germination, rate of germination, 10-seedling weights and percent seedlings with leaves unfurled, ten days after sowing. Seed classes were quantified in terms of 100-seed weight with Seed class 1 having the lowest weight and Seed class 3 the highest; A significantly high r value (0.99) was obtained between seed classes and 10-seedling weight. High r values (0.93) and (0.94) were also obtained between seed classes and percent germination and percent seedlings with unfurled leaves, respectively. Results indicate that it may be possible to use these differences on embryo morphology as a basis for selecting vigorous true potato seeds.

On-farm evaluation of true potato seed in the Philippines

Potato production using true potato seed (TPS) was evaluated with a cooperative group of farmers. The cooperative grew TPS or seed tubers (1 to 3 g) produced from TPS in beds in screenhouses to avoidPseudomonas solanacearum (BW). From 250 to 400 tubers/m2 were obtained. Tubers > 3 g were replanted by farmers at high elevation for further multiplication. Yields always exceeded the control (clonally produced cultivar). Seed tubers from TPS of 3 to 5 g produced up to 32 t/ha resulting in a multiplication rate of 145:1. Farmers are in various stages of adopting this technology. An early maturing progeny with resistance to BW is needed to permit a more rapid spread of this technology.

Potato Production from True Seed in Tropical Climates

Abstract Research on true potato seed (TPS) at the International Potato Center (CIP) started in 1977. Based on the advantages offered by growing potatoes from TPS in many potential potato-producing areas within the tropical region, research efforts have concentrated on developing genetic materials and techniques adapted to environmental conditions and cultural methods in those areas. The research has extended rapidly to a great number of cooperating institutions throughout the world and, at present, is being carried out in more than 40 countries within the tropics.

Needed Engineering Aids and Mechanization for True Potato Seed Seedling, Seedling Tuber Harvest, and Seedling Tuber Planting

Abstract Although extensive research is currently being conducted related to true potato seed (TPS) in the areas of breeding, production, and cultural practices (1, 3, 4, 5), there is little information generated on the engineering aspects of potato production from TPS. Potato production from TPS varies greatly from current methods in which potatoes are grown from tubers. Potatoes can be produced from TPS in three different ways: 1) seeding TPS in rows to produce potatoes similar to other crops produced by direct seeding; 2) planting TPS to raise transplants for planting in another field; and 3) using TPS for the production of seedling tubers to be used like “seed” tubers. Mechanization needs for each of these TPS uses are different. It might be necessary to modify the existing equipment or develop new equipment to meet specific needs of using TPS. Equipment needs for potato production from TPS in developing countries also will need special consideration. Engineering research conducted at the Georgia Coastal Plain Experiment Station, related to potato production from TPS has been reported in detail by Ghate et al. (2). Since that publication, we have concentrated our research efforts in the direction of the equipment needs for TPS use in developing countries.

Cultural Practices in Use of True Seeds of Potato and Screening of Tuber-forming Solanum Species Under Hot Climatic Conditions

Abstract Potato (Solanum tuberosum L.), the most important dicotyledonous food crop in the world, is grown mostly under temperate climatic conditions and is usually planted vegetatively with tubers (often called “seed” tubers) (12). Use of seed tubers for potato production has many advantages, including ease of planting, vigorous plant growth, uniform tubers, and high tuber yields (27). However, with increased interest in production of potatoes in warm regions, use of seed tubers often becomes costly and has disadvantages (1, 2, 23, 27, 30). Some of the disadvantages of seed tubers in warm or developing regions of the world are: there is a lack of seed tuber certification programs; imported seed tubers are expensive; seed tubers often are contaminated with plant pathogens and other pests; and available potato cultivars often are not adapted to warm regions (2, 18, 19). Consequently, during the past decade, research efforts on adopting true potato seed (TPS) instead of seed tubers for potato production were initiated in many areas of the world (5, 8, 16, 17, 20).

True potato seed research and development in Vietnam

Quality tuber planting material is unavailable in the Red River Delta (RRD). The use of True Potato Seed (TPS) was considered as an alternative planting material. During the 1985–86 and 1986–87 seasons, 21 and 40 kilos of open pollinated TPS, respectively, were collected in the southern highlands and distributed to over 40 cooperative groups of farmers in the RRD. Fifty-two hectares (1985-86) and 120 hectares (1986-87) of potatoes were produced from transplants in the two years of on-farm production. Approximately 50% of the farmers were successful in both years. Lack of experience and too wet or too dry growing conditions caused most of the failures. Yields from transplants ranged from 5 to 13 t/ha with 150 to 300 seedling tubers/m2. Seedling tubers can be stored for eight months with low storage losses and when replanted give substantially higher yields than those obtained from locally grown, degenerated seed tubers.

Effect of supplemental nitrogen on true potato seed weight

The effect on true potato seed (TPS) weight of supplemental nitrogen (N) applied during seed development was investigated using crosses DTO-33 × R128.6 (“A” produced in the field) and Atzimba × R128.6 (“B” produced in the field and in a screenhouse). Dry weights of tops and tubers of the mother plants were also measured in the screenhouse.

True potato seed in China: Past, present and future

China has gained recognition for its pioneer work on true potato seed (Song Bofu, 1984,Liand Shen, 1979). The history of true potato seed (TPS) in China dates back to 1959 when research was started. Now numerous countries around the world are developing TPS technology (Hoang, et al., 1986; CIP, 1984). These countries could gain much from the experience of China. This report attempts to summarize past experience, describes the present status with particular reference to farmers’ opinions, and outlines briefly the future of TPS.

Physical Relationships Between Berries and Seeds of Potato

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.

A method of producing seed tubers from true potato seed

First-generation seed tubers (seedling tubers) derived from true potato seed (TPS) were produced in nursery beds; the yields were up to 12 kg and total numbers up to 1242 tubers (>1 g) per m2 of bed. Direct sowing of TPS in beds followed by thinning gave yields similar to those from transplanted seedlings and reduced the total growing period. The optimum plant population was 100 plants per m2 spaced at 10 cm×10cm. The application of 3 cm of substrate (1∶1 shredded peat moss:sand) after seedling emergence was sufficient to maximize tuber number and to minimize tuber greening. Two or three applications of N-dimethylaminosuccinamic acid (B9) gave sturdier plants but did not increase the number of tubers >1 g. The seedling tubers when multiplied gave yields similar to those of low virus clonal seed tubers.

Engineering needs for potato production from true seed

Potatoes grown from true potato seed (TPS) are generally small and nonuniform in size and shape, compared to the ones produced conventionally from seed tubers. Potato production from TPS would be considerably less expensive than from seed tubers because of the negligible storage and handling costs of the TPS. Potato production from TPS would therefore have the greatest potential in the developing countries. In developed countries, this production method would have some potential in commercial production as well as in home gardening. Research related to the TPS potato production has been mostly directed toward investigating suitable cultural practices, screening breeding lines for higher yield and warm climate adaptability, weed control in the field, and other similar production areas. Research concerning mechanization of TPS potato production has been limited. Engineering input to the TPS potato production, handling and storage needs considerable attention to develop practical and economical practices. This paper highlights some research areas which the authors believe are worth investigating. Engineering research that is conducted at the Coastal Plain Experiment Station related to the TPS potato production has been outlined along with future plans.

Performances of true potato seed families derived from intermating tetraploid parental lines

Four different sets of true potato seed (TPS) families, representing a total of 262 hybrids derived from intermating tetraploid clones were evaluated in three different locations in Peru. Significant differences were observed among families in tuber yield, uniformity and transplant survival rate in the field. Several families produced an average tuber yield of more than 1.0 kg per plant, with a tuber uniformity of some families approaching that of standard varieties. Hybrid TPS families gave higher tuber yields and more uniform tubers than families from open-pollination. On the basis of an observed family-environment interaction for tuber yield, it is suggested that locally adapted cultivars or advanced selections should be used as parents to generate TPS progenies for specific areas.

True potato seeds as arable weeds

The proportion of the Scottish potato area planted to cultivars such as Maris Piper and Desiree, which can produce large numbers of berries, increased markedly during the 1970s. Such cultivars may add large quantities of true potato seed (TPS) to the soil and create serious weed problems. TPS can survive in the soil through a 7-year potato rotation, whilst tubers from seedlings add to the traditional groundkeeper problem. The implications of TPS as weeds of seed potato rotations are discussed in relation to data presented on seed production and survival and on tuber production by seedlings in the field under Scottish conditions. Seedlings may also present problems as ‘rogues’ in fields where TPS selected lines are grown.