Genetic variance estimates in a heterogenous potato population propagated from true seed (TPS)

Genetic variances were estimated for 11 traits in a potato breeding population propagated from true seed (TPS). Means were high and no genetic variability was found for seed germination and transplant survival. Additive variance and heritability were high for TPS production which was positively correlated with tuber yield. No additive variance was found for uniformity of tuber size, but heritability estimates for other component traits of tuber uniformity and yield were relatively high. The results indicated that index selection should be effective for improvement of yield and tuber uniformity.     

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

Summary 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. Paper no. 3163 from the Department of Genetics, University of Madison.     

Estimation of genetic parameters for characters related to potato propagation by true seed (TPS) in an andigena population

Genetic variances were estimated for a population ofSolarium tuberosum L. subsp.andigena, selected for adaptation to north temperate climatic conditions. Estimates for 15 traits, including some unique to true seed (TPS) propagation, were obtained from trials conducted under short day conditions in Peru. Only non-additive variance was found for yield, but heritability estimates were relatively high for tuber number and tuber size. The results indicated that yield could be increased through selection utilizing additive variance for the component traits, especially tuber size. Estimates of genetic variability for tuber uniformity were low. TPS yield was positively correlated with most other traits except tuber number.     

马铃薯新型栽培种在实生种子选育中的应用研究

本文研究比较了马铃薯实生种子选育中,新型栽培种(Neo-tuberosum)利用的6类不同组合方式产生的杂种实生种子在群体生产力和一致性上表现的差异,结果表明:①不同组合方式形成的具有不同Neo-tubersum基因频率的实生种子,群体间生产力表现极显著的差异。这一差异主要表现在产量构成因素上,商品薯数量和小薯数量对构成群体产量均有极显著的作用;小薯数量的增加对提高群体的商品薯率有极显著的负作用,即块茎数量越多,块茎越小。后代商品薯率取决于S.tuberosum种质,而块茎数量主要由Neo-tuberosum决定,并找出其生产力表现的优先顺序。②S.tuberosum×Neo-tuberosum组合表现的一致性水平在株高、薯形、皮色和芽眼深浅等性状上与S.tuberosum自交群体相似,没有显著差异,是利用新型栽培种进行实生种子选育的最佳组合方式。     

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.     

马铃薯育种早代选择的初步研究

早代评价和选择的有效性取决于不同组合的遗传基础,本文就单株块茎数、单株产量和商品率在实生苗阶段的相关性进行了分析,说明对某些组合而言,实生苗阶段选择是有效的,而另一些组合则是无效的。为此,实生苗收获时必须保留块茎家系(保持整个组合的全部基因型)是非常重要的。通过分析单株块茎数与商品率的相关性,对于寻找重点组合是非常有意义的。因为这一相关系数达到显著的正相关,对实生种子育种和杂交育种都需要;特别有利于商品薯的实生种子直播或移栽。     

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.     

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.     

Repeatability of Progeny Mean, Combining Ability, Heterosis and Heterobeltiosis in Early Generations of a Potato Breeding Programme

Thirty-three populations of Andigena potatoes developed by 11 × 3 (line × tester) mating were studied from seedling to third clonal generations for number of tubers, average tuber weight, tuber yield, plant vigour, predominant tuber shape, predominant tuber size and uniformity in tuber shape, uniformity in tuber size and uniformity in tuber colour. Inter-generation correlation coefficients for progeny means, general combining ability, specific combining ability, heterosis and heterobeltiosis were computed for various characters. Magnitude of inter-generation correlation coefficients showed that various parameters for uniformity in tuber shape, uniformity in tuber size, uniformity in tuber colour, predominant tuber shape and predominant tuber size could be reliably estimated in early generations starting from the seedling generation. The parameters for tuber yield, average tuber weight and tuber number could only be reliably estimated from second clonal generation onward. Repeatability of progeny means showed that negative selection for tuber yield and average tuber weight could be initiated from first clonal generation and for tuber number from second clonal generation. Plant vigour was found to be a highly inconsistent character.     

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.     

Tuber yield of true potato seed families from different breeding schemes

Economical and environmental conditions in the south of Italy suggest that the direct utilization of TPS, as propagation material for potatoes, could be worth exploring. Thus, it is important to identify the most appropriate breeding scheme to enhance productivity and uniformity of the progeny. For this purpose 44 TPS families deriving from different breeding schemes and emphasizing different levels of heterozygosity were tested for yield at two locations in the U.S.A. and one in Italy. The results indicate the superiority of the 4x progeny from 4x X 2x crosses as a family group, and in the frequency of high yielding individual families in all locations. The 4x X 2x family group outyielded the OP progeny group by 45%, 79% and 114% at Hancock, Rhinelander (U.S.A.) and in Italy, respectively.     

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.     

马铃薯2n花粉植株后代与优良四倍体株系的遗传分析

本试验对5个TD后代和Serrana作母本与4个4x后代杂交得到的24个家系进行了评价,按设计Ⅱ方法对此群体的单株重、单株块茎数、商品率的配合力及遗传力进行了分析。HP.278.22×AVRDC单株重的特殊配合力最高为333.13,母本以Serrana,HP.278.22的一般配合力最高,分别为125.96,69.71,而父本以LT—7,AVRDC最高分别为62.88、10.88。单株重的遗传力为41.62％,而商品率、单株块茎数的遗传力均低,TD后代作亲本对特殊配合力影响较大表明2n花粉在传递杂合性方面的优势。6个最好家系中既有一般配合力作用大的,也有特殊配合力作用大的,或者两者兼而有之,并表明实生种子育种时,亲本的配合力测定是非常重要的。     

不同遗传背景马铃薯杂种群体生产力和一致性评价

本试验研究了具不同血缘和基因频率的马铃薯杂种群体的主要经济性状表现和一致性的差异,结果表明: 1.马铃薯杂种优势的表现是以亲本自身生产力高低为前题的,由自身生产力较低的亲本产生的杂种群体,即使具有较高的杂合性,与也很难表现较高的产量,只有对亲本加以选择和在改造的基础上利用,才能充分表现其杂种优势。 2.Neo-tuberosum参与杂交的组合,优于其它类型的杂种群体,是目前马铃薯新品种和实生种子选育的最优组合方式。 3.杂种群体薯形,皮色和芽眼深浅等经济性状的一致性表现于群体的杂合性程度相关不同,而与两亲本在这些性状上的差异有关。因此选择在性状上差异较小的亲本杂交,是获得整齐一致实生种子的关键。     

Performance of haploid x wild species, 2x hybrids (involving five newly evaluated species) in 4x × 2x families

The 4x × 2x breeding scheme in potato allows introgression of germ-plasm from the 2x wild species into the cultivated tetraploid. Eighteen 4x × 2x, forty-five 4x × 4x, seven 4x-selfs, and five open pollinated (OP) families were transplanted in a randomized complete block design with two replications and 18 plants per family per replication. The 2x parents of the 4x × 2x families were seven haploid x wild species hybrids. These hybrids involve five 2x, wild species,Solanum bukasovii, S. gourlayi, S. muhidissectum, S. vermi, andS. verrucosum, which had not previously been evaluated in the 4x × 2x breeding scheme. Data were recorded for family yield, maturity, tuber uniformity, tuber number, and general tuber appearance. The 4x × 2x families as a group performed as well as or better than the 4x × 4x, 4x-self, and 4x-OP groups for all traits except maturity. Within family maturity distributions for 4x × 2x families indicate the possibility to select early maturing clones from high yielding families. Eleven of the fifteen families in the top 25% of the 4x × 2x and 4x × 4x families for yield were 4x × 2x families. Three of the four 2x parents evaluated for parental performance gave highly significant responses for increased yield. 4x × 2x families with Chiquita as a parent were the poorest yielding while several of the 4x x 4x families of which it was a parent were among the highest yielding: This indicates that the benefits of maximum heterozygosity may be overridden if the percentage of unadapted germplasm is too high.     

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.     

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.     

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.     

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.