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

Summary 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. Paper no. 3162 from the Department of Genetics, University of Madison.     

Tuber yields of families from open pollinated and hybrid true potato seed

This work was undertaken to compare the tuber yields, vegetative vigor and uniformity of seedling transplants obtained from different breeding methods. Twenty hybrid families from different groups of crosses involving 4x clones and 2x Phureja-haploid Tuberosum hybrids; 4x × 4x, 4x × 2x (FDR), 4x × (4x × 2x), and (4x × 2x) × (4x × 2x) and eleven open pollinated families from 4x clones, and 4x hybrids from 4x × 2x crosses were compared in a replicated yield trial. Families from 4x × 2x (FDR) crosses were the highest yielding among the hybrid groups having approximately twice the yield of the open pollinated 4x clones. They also were the best group in relation to plant vigor and uniformity. Based on these results, it appears that a good breeding scheme for high-yielding and uniform progeny from true potato seeds is the 4x × 2x hybridization method where the male parent is capable of producing 2n pollen via a first division restitution mechanism.     

An assessment of true potato seed families ofSolanum phureja

Summary Experiments were carried out withSolanum phureja germplasm which had been selected for tuberization response under W. European growing conditions. Selected clones and seedling (true potato seed; TPS) families ofS. phureja were raised in the field and tubers assessed for yield, tuber number, skin colour, size, shape and cooking characteristics. Some families had low within-family variances for cooked flesh hardness and some appeared as uniform for tuber size and shape as the selectedS. phureja clones. Skin colours of the tubers within TPS families were often assorted. The commercial potential ofS. phureja as a possible TPS-derived crop is discussed, as its self-incompatibility makes possible the cheap production of true potato seed.     

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.     

Planting materials for warm tropic potato production: growth and yield of transplanted seedlings or rooted cuttings and tuber materials in the field

Expansion of potato production in lowland tropical regions has been constrained by the lack of planting materials, given that adapted genotypes and suitable field management practices now exist.

The respective performance of transplanted materials (i.e., true potato seed (TPS) seedlings or rooted stem cuttings) produced in situ in the warm tropics were compared with that of genetically identical seedling tubers (tubers produced from seedlings) or seed tubers. Seed and seedling tubers had been previously produced under optimal cool conditions. Transplanted materials achieved lower maximum leaf area index than did tuber materials (1.3–2.2 vs. 2.7) but relative growth rates of cuttings and seedlings were greater. This was in part due to the greater net assimilation rate of cuttings and to greater leaf:stem ratio for both compared with plants originating from tubers. Stolon and tuber formation were greater in seed tubers than in cuttings and in seedlings versus seedling tubers. On average, seedlings produced 14 tubers per plant, apical cuttings 12, seedling tubers 8, and stem cuttings 6.

Tuber yields within a genotype were statistically similar for crops from seed tubers or cuttings and for crops from seedling tubers or seedlings. However, the proportion of marketable (i.e., > 3.5 cm diameter) tubers was approximately 12% less in the crops from seed tuber and seedlings compared with those from cuttings and seedling tubers, respectively. Within a genotype, the crop duration in the field was similar whatever the type of planting material. Maximum yields, at 23 t/ha in warm sites, were still below those of temperate potato crops, but could be achieved equally well with transplanted in situ-produced materials or imported cool-climate seed tubers.     

Field production of potatoes from true seed and its use in a breeding programme

Summary Potato crops, grown from true potato seed (TPS) sown directly into fields, required a long growing season and the yield, tuber size and quality were inferior to tuber-propagated crops. Some plants produced excellent yields of high-quality tubers and some lines had earliness, high yield capacity, uniform tuber type and high solids. Field sowing of TPS has good potential, both as a breeding tool and for potato production in long-season, underdeveloped countries where healthy seed tubers are not readily available. Correlation analyses showed positive relationships between seedling vigour, mature plant size, and number and yield of tubers but these growth parameters were not significantly related to tuber size and they had a strong negative relationship to density (specific gravity). Mention of a trade name of a company is for specific information only and does not constitute a guarantee or warranty of a product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.     

The identification and evaluation of hybrid plants among open pollinated tkue 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.     

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.     

General combining ability of Neo-Tuberosum for potato production from true seed

Neo-Tuberosum clones from the Cornell breeding population were evaluated as female parents in combination with Tuberosum for production from true seed. Field trials of hybrid seedling families were carried out in 1982 and 1983. Families were also grown in a hot greenhouse to measure combining abilities for tolerance to heat stress. General combining ability was highly significant for yield, vine and tuber characteristics, and heat tolerance. Several clones were identified which produced outstanding seedling families for yield, uniformity, and tuber appearance. Some individual crosses were equal to cultivars in yields, uniformity, and tuber appearance. Hybrids of Neo-Tuberosum and Tuberosum appear to be an excellent choice for potato production from true seed.     

Sequential Path Analysis of Yield Components in Potato

In order to determine proper selection criteria for tuber yield in potato clones obtained from true potato seed (TPS) and to evaluate relationships between tuber yield and its components, an investigation was conducted using the five check cultivars Agria, Marfona, Draga, Agata, and Arinda, and 120 potato clones obtained from TPS. The study was conducted in an augmented randomized complete block design with three replications. Yield and its components were recorded. Correlation coefficient analysis showed that tuber yield had significant positive associations with number of tubers per plant, average weight per tuber (tuber size), plant height, diameter of main stem, and number of main and secondary stems per plant, whereas its correlation with tuber dry-matter concentration was significantly negative. Number of tubers per plant, tuber size, and plant height had significant standardized partial regression coefficients with very small tolerance and large variance inflation factor (VIF) values. These were considered as the first-order variables in sequential path analysis.     

Progeny mean, heterosis and heterobeltiosis inSolanum tuberosum x tuberosum andS. tuberosum x andigena families under a short day sub-tropic environment

Summary Solanum tuberosum x tuberosum (TxT) families were compared withS. tuberosum x andigena (TxA) families as progeny mean, heterosis and heterobeltiosis for ten important agronomic characters by evaluating 72 cross combinations (36 of TxT and 36 of TxA, from 18 common female parents), for three successive seedling and clonal generations under short day sub-tropic conditions. TxA families had more vigorous progenies, higher tuber yield, higher number of tubers, larger tubers and better general impression than TxT families. The TxA families were inferior to the TxT families for characters such as tuber colour and uniformity of tuber colour, but their progeny means were within the acceptable range. High progeny means of TxA families were associated with high heterosis and high heterobeltiosis in these families, although there were a few exceptions. High mean performance for tuber yield and tuber number were associated with high variance of these traits in TxA families. It is concluded that, unlike under long day environments, andigena adapted to short days can be used advantageously for exploiting heterosis in the potato breeding programmes of short day subtropic environments.     

Potato production from true potato seed (TPS) in Egypt: Effect of the growing season on seedling development,recovery from transplanting and yield

Summary Ware potatoes were produced from true potato seed by transplanting seedlings to the field in different growing periods to evaluate environmental constraints of this production method in the Nile delta. In the autumn season, with high temperatures and long-day conditions during seedling culture in the nursery and transplant establishment in the field, seedling development was fast, and transplants resumed growth within 5 days of transplanting in the field. Tuber yields ranged between 120 and 160 dt ha⁻¹. In the spring season, with low temperatures and short-day conditions during the initial growing phase, seedling development in the nursery was slow and biomass partitioning between above ground organs (stems, leaves) and tubers was shifted towards the tubers. This partitioning was further enhanced by transplanting the seedlings in the field. Seedlings recovered only slowly from transplanting or died. It is concluded that potato production via transplants is poor in the spring season when premature tuberization of seedlings in the nursery leads to slow field establishment and low tuber yield.     

Use of seedling tubers from TPS in southern Italy

The TPS seedling tuber technique can be successfully adopted in developing as well as in developed countries as a standard agronomic system for potato production. Experimental work has been started in order to select the best parental lines and to evaluate the appropriate breeding schemes for the use of this technique in southern Italy. During 1989 48 true potato seed (TPS) families with different genetic backgrounds were tested for seedling tuber production and they produced a good yield. The seedling tuber families were tested for tuber production during 1990 by subdividing them in two size classes: 25mm-35mm and 35mm-45mm. The highest yield was attained by 4X x 2X families and the analysis of variance indicated significant differences with regard to tuber size and TPS families for both total and marketable tuber yield. This technique has significant potential for providing tubers for both the fall and winter crop in Italy.     

Comparative field performance of potatoes from seedlings and tubers

A field trial was conducted at Freeville, NY to compare yields from hybrid families ofSolanum tuberosum L. with yields from their corresponding full sib, first clonal generation tubers. Unselected tubers were saved after harvesting transplanted seedlings of four Neo-Tuberosum × Tuberosum hybrids in 1982. The following year these tubers were planted for comparison with seedlings of the same hybrids in a split plot design. Total yields and yields of tubers ≥ 38 mm in diameter were respectively 34% and 38% higher from tuber propagated plants than from seedlings. The biggest difference was in tubers ≥ 63 mm diameter, where plants from tubers gave yields more than double those from seedlings. Seedlings had twice as many large axillary branches per stem as plants from tubers. Uniformity of tuber size and shape, and overall appearance ratings of tubers were better with seedling propagation; however, these comparisons are biased by the tendency of seedlings to produce smaller tubers, which inherently receive higher ratings.     

Carbon Disulphide (CS<Subscript>2</Subscript>) Promotes Sprouting and Affects the Metabolism of Harvested Minitubers Grown from True Potato Seed

Chemical agents may be used to overcome dormancy in potato tubers so as to permit early planting. In this paper, the effect of carbon disulphide on sprouting and related metabolic processes in potato tubers grown from true potato seed (TPS) was investigated. Carbon disulphide was applied to potato tubers derived from TPS, at a rate of 20 ml m^?3 container volume for 72 h. It accelerated tuber sprouting and increased tuber weight loss. It also caused an increase in the respiration rate, as well as ethylene emission from the tubers during the first 6 days after treatment. The respiration rate of carbon disulphide-treated tubers remained at a higher level than that of untreated controls for 35 days after treatment. In addition, carbon disulphide increased the concentrations of the soluble sugars sucrose and fructose, but not glucose, in the tuber tissues (buds, parenchyma). These findings suggest that carbon disulphide releases potato minitubers from dormancy and that dormancy breakage is associated with changes in tuber metabolism prior to the visible sprouting.     

Comparison of seasonal development of tuber specific gravity among seven potato clones

Specific gravity of potato tubers provides an estimate of starch content of which uniformly high levels are important for product quality. The objectives of this study were to document the relationship between the level of specific gravity and the variability among tubers and to model the seasonal development o f specific gravity for seven potato clones. Individual determinations were made on twenty tubers from each plot using the weight-in-air, weight-in-water method on each of eight harvest dates spanning the tuber growth period. For each plot, the mean and standard deviation of specific gravity were calculated and used to define the correlation between specific gravity level and tuber-to-tuber variability and to construct a predictive model of the seasonal specific gravity developmental pattern. As the season progressed, tuber-to-tuber variability of specific gravity increased for some clones but not for others. A positive correlation existed between tuber specific gravity mean and its standard deviation for four of the seven clones in 1991 and five in 1992. Correlation coefficients were generally low, suggesting only a weak association between specific gravity and its standard deviation. Tuber specific gravity developed in a similar seasonal pattern for the seven clones. It generally started low, reached a maximum approximately seven to eleven weeks after tuberset, at which time some clones showed a tendency to decline through the remainder of the season. Quadratic regression equations provided an adequate model to describe specific gravity development for all seven clones over the tuber growth period. Statistical contrasts were used to test for differences in equation parameters, including line coincidence, line slope, and intercept. The model showed that initial specific gravity level at tuber set, the rate of early season increase, as well as the length of time from tuber set to specific gravity maximum, varied by clone and determined the level of specific gravity at season’s end.     

马铃薯高淀粉育种初世代比重相关性分析和测选方法的研究

本文通过1982～1987年的连续试验,总计获得了4组600多对相关数据,论证了马铃薯高淀粉育种实生苗和无性世代比重间的相关性,从而说明了在实生苗世代进行高淀粉材料筛选的可靠性;并认为在实生苗世代测定和筛选高淀粉材料的株系系统测定法,是可行而有效的方法。     

Evaluation of potato clones for severity of Verticillium wilt, yield and specific gravity in Maine

In 1994 and 1995, the effect of Verticillium wilt, caused byVerticillium dahliae andV. albo-atrum, on tuber yields, number and weight of U.S. No. 1 and B size tubers, and specific gravity was studied in northern Maine, an area with a short growing season. Seven clones (four resistant and three susceptible) were evaluated in a split-plot design with three replications. Clones were the whole-plot factor, and seed pieces in sub-plots were either uninoculated or inoculated with 50 ml of 4 × 10⁴ cfu/mlVerticillium spp. at planting. Individual plants were scored for Verticillium wilt symptoms before harvest on a 1= <3% wilt to 10= >97% wilt. Differences among clones for wilting and specific gravity were significant. The inoculation treatment had no effect on any of the tuber traits measured. However, there were significant clone x inoculation interactions for most tuber traits. Reductions in yield, weight and number of U.S. No. 1 potatoes, and specific gravity were greater in the Verticillium wilt susceptible clones than in the resistant clones. These results suggest that breeding clones with resistance toVerticillium spp. will reduce yield losses, while maintaining tuber size and specific gravity under disease pressure.     

实生苗世代测定和筛选马铃薯高淀粉材料方法探讨

本文介绍了一种在实生苗世代准确测定和筛选高淀粉材料的有效方法——株系系统测定筛选法.此法通过对实生苗单株块茎淀粉含量的系统测定和统计,得到单株块茎淀粉含量的平均数、变异幅度和上下限,最后以所得数据的综合分析结果作为依据,准确筛选高淀粉材料.连续几年的试验结果证明这种方法可行、有效.     

Yield-enhancing and tuber-downsizing effects of transplantation cultivation method of case-held tuber seedlings in the sweet potato cultivar Beniharuka

We developed transplantation cultivation method of case-held tuber seedlings (CTS), which was derived from direct planting method of seed tubers, and applied this method to the sweet potato cultivar Beniharuka. A plastic case made of polypropylene was designed for cultivation of CTS. Seed tubers of cultivar Beniharuka in the range of 30–80 g were cut in half. The half-cut tubers were placed inside the plastic cases, and the cases were filled with a commercial soil mix. The case-held tubers were incubated under natural sunlight in a glass house. After 3–4 wk, the CTS were transplanted into a field. Mother tuber (seed tuber) enlargement was suppressed by the plastic confinement of the cases, and daughter tubers were formed above the case as vine-root-originated tubers. In the field experiments in 2012 and 2013, daughter tuber yields were increased 19% and 21% by case-held tuber seedling transplanting (CTST) over conventional vine-planting (VP), the number of daughter tubers per plant in CTST were 36 and 68% higher than in VP, and the mother tuber yields were limited to 2.1 and 4.3% of the total fresh yield of mother and daughter tubers, respectively in 2012 and 2013. Application of CTST method to cultivar Beniharuka enhanced tuber yield, increased the number of daughter tubers per plant, downsized daughter tubers compared to VP, and mother tuber enlargement was suppressed by case-holding. The CTST method is expected to produce more and smaller good in shape tubers of cultivar Beniharuka compared to VP.