Tuber Appearance Research Articles

Elucidating the impact of environmental factors on the growth of Colletotrichum coccodes strains isolated from potato tubers in Great Britain

Black dot and silver scurf caused by Colletotrichum coccodes and Helminthosporium solani, respectively, are tuber blemish diseases affecting quality in the fresh and pre-pack potato industry. In the last 20 years, the importance of high-quality tuber appearance has increased considerably due to the growing demand for washed and pre-packed potatoes in the UK. Changing climate characterised by rising temperatures and wetter summers is a threat as this will favour the development of pathogens such as C. coccodes in the soil increasing the risk of food spoilage. Moreover, both diseases can develop not only in the field but also after harvest, with postharvest storage temperatures being a crucial factor in controlling fungal growth. Furthermore, anecdotal evidence showed differences on the aggressiveness of black dot depending on its origin (i.e. England and Scotland) on potato tubers. Silver scurf and black dot are difficult to differentiate as they present similar phenotypes characterised by silvery lesions making it challenging for managers to take the necessary corrective action during storage. Hence, the aim of this study was to give a general insight into the ecological conditions affecting the establishment of the causal agent of potato black dot in the field, and black dot and silver scurf during the supply chain. Therefore, invitro experiments were designed to study the growth rate and lag times simulating both scenarios respectively: on soil extract agar (SEA) media at different temperatures (4, 11, 15 °C) and matric potentials (control [unmodified] and − 1.4 MPa [modified]); and on natural potato dextrose agar (NPDA) for different temperatures (4, 11, 15 and 20 °C) at 99 % relative humidity (RH) for 25 days. When simulating the field environment, drier conditions (matric potential = −1.4 MPa) reduced fungal growth for both isolates by 0.1 cm day−1 at the temperature of 15 °C, suggesting temperature as the main limiting factor for the growth of C. coccodes in the soil. The causal agent of black dot exhibited a faster growth rate under retailer-like conditions (i.e., 15 °C) compared to H. solani. Understanding the environmental influence on both the pathogen and the crop is vital for proper disease management to help reduce food loss and waste.

‘BRS F50’ (Cecília): Cultivar de batata multiuso com resistência a doenças foliares

ABSTRACT ‘BRS F50’ (Cecilia) is a yellow skin potato cultivar for the fresh market, with good tuber appearance and versatile culinary use. The tuber has oval shape, shallow eyes, and light yellow flesh. It has a relatively high dry matter and medium-low glucose content, giving possibility even to use for processing into shoestring fries. The vegetative cycle and dormancy are medium. The maturity and tuber dormancy are medium. ‘BRS F50’ (Cecilia) shows a very low external and internal tuber disorder incidence, except growing cracks under varying soil humidity. It is moderately resistant to late and early blight, which make it also suitable for organic production. ‘BRS F50’ (Cecilia) was released by Embrapa in 2022, and is a product of its potato breeding program, developed by Embrapa Clima Temperado, in Pelotas-RS and Canoinhas-SC, and Embrapa Hortaliças, in Brasília-DF, Brazil.

Stability of potato clones resistant to potato virus Y under subtropical conditions

Abstract Brazilian potato production is based on cultivars originating from the USA and Europe; however, these cultivars were developed under different environmental conditions than those found in Brazil. The aim of this study was to evaluate the adaptability and stability of 18 potato clones (MLG), developed by the Universidade Federal de Lavras, and four cultivars in six environments in the state of Minas Gerais, Brazil. The following traits were evaluated: marketable tuber yield (MTY), specific gravity (SG), and tuber appearance (TA). Clones, environments, and the genotype × environment interaction had significant effects on all traits. The GGE-biplot explained 71.78, 98.13, and 62.86 % of the sum of squares from the G+G×E for MTY, SG, and TA, respectively. Three MLG clones had higher adaptability and stability, as well as better performance, than the cultivars, making them good candidates for release as cultivars.

Image‐based phenotyping and genetic analysis of potato skin set and color

AbstractImage‐based phenotyping offers new opportunities for fast, objective, and reliable measurement for breeding and genetics research. In the current study, image analysis was used to quantify potato (Solanum tuberosum L.) skin color and skin set, which are critical for the marketability of new varieties. A set of 15 red potato varieties and advanced breeding lines was evaluated over 2 yr at a single location, with two harvest times in the second year. After mechanical harvest and grading, seven to eight representative tubers per plot were photographed, and the photos were analyzed with ImageJ to measure skinning (as percentage surface area) and skin color using the hue, chroma, and lightness (HCL) representation. The plot‐based heritability was consistently high (> .77) across traits and environments; the genetic correlation between environments was also high, ranging from .81–.98. Significant increases in lightness and chroma, as well as a decrease in skinning, were observed at the late compared with early harvest, whereas the opposite trends for color were observed after 6 wk of storage. The three color traits were unexpectedly collinear in this study, with the first principal component explaining 86% of the variation. This result may reflect the physiology of red color in potato, but the highly selected nature of the 15 genotypes may also be a factor. Image‐based phenotyping offers new opportunities to advance genetic gain and understanding for tuber appearance traits that have been difficult to precisely measure in the past.

Effects of Polyhalite Fertilization on Skin Quality of Potato Tuber.

The protective peel of potato tuber consists of periderm tissue, the outmost cell layers of which contain corky cell walls and are termed “skin”. The skin protects the tuber from water loss and pathogen invasion, and its visual appearance is a highly important marketing factor. Physiological skin blemishes are of great concern, mainly russeting disorder and skinning injuries. We previously showed that application of calcium (Ca) reduces the rate and severity of skin russeting. Here, polyhalite fertilization was tested as an alternative source of Ca. The polyhalite mineral is a hydrated sulfate of potassium (K), Ca, and magnesium (Mg), and thus contains additional important nutrients that may contribute to skin quality. Furthermore, in view of the direct interaction of soil mineral elements with the tuber skin, we tested application of polyhalite at the end of the growth period, assuming that providing the mineral at the last stages of skin development may enhance its quality. Accordingly, polyhalite was applied at three time points: preplanting, in-season at around 3–4 weeks prior to haulm desiccation, and 2 days post-haulm desiccation. The experiments included several cultivars and locations. Data indicated that late application of polyhalite, after haulm desiccation, results in reduced concentrations of Ca and Mg and increased concentration of K in the tuber peel of fertilized plants compared to controls. Tuber appearance was improved, and the expression of FHT and CYP86A33, indicator genes for skin suberization, was significantly upregulated. Earlier applications of the polyhalite mineral did not alter mineral elements concentrations in the tuber peel compared to control plants. Overall, polyhalite fertilization positively affected tuber skin appearance and skin-related gene expression. However, the effect was moderate, and the mineral did not fully mitigate skin imperfections. The effect of polyhalite may be dependent on local conditions and cultivar type.

Effects of Field Selection Parameters and Specific Gravity on Culinary Evaluation Traits in a Potato Breeding Programme

Potato culinary evaluation is an integral component of a breeding programme to determine suitability of new cultivars to specific end-uses. In most breeding programmes, quality assessment is conducted after a few generations of field selection on tubers collected from the field or from storage conditions. In order to optimize selection procedures, we analysed the relationship between specific gravity of potato tubers and quality evaluation traits as well as the effects of field selection parameters in clones that are intended for fresh market and processing uses. A total number of 237 advanced breeding clones were analysed over three consecutive years in the potato breeding programme at Agriculture and Agri-Food Canada (AAFC). Principal component analysis (PCA) and linear mixed-effects model fit by maximum likelihood indicated that parameters used in field selection significantly contributed to specific gravity and culinary components. Specific gravity also contributed significantly to culinary traits related to acceptable quality of baked, boiled and French-fried products. However, such relationship was not observed for chip quality. Significant associations were found between field selection parameters, such as maturity, early vigour, top vigour, early harvest, tuber size and tuber appearance and culinary components related to French fry and chip quality, but not for quality of baked and boiled products. Broad-sense heritability estimates for various culinary evaluation traits ranged from 57 to 92%. The results suggest that specific gravity and culinary traits should be incorporated in early or intermediate generation selection parameters in order to optimize selection gains for specific end-uses.

Cracking and fracture properties of potato (Solanum tuberosum L.) tubers and their relation to dry matter, starch, and mineral distribution.

Potato disorders lead to a significant reduction in the yield and quality of marketable tubers. Thumbnail cracks are physiological tuber skin disorders that can significantly affect the tuber's appearance and, hence, the overall quality. The aim of this study was to characterize fracture properties of the tuber skin. Knowledge of the physiological reasons that influence the resistance of potato tubers to mechanical impacts and thus to cracking and fracturing is limited. Tuber dry matter (DM) and starch content were found to correlate with the rheological properties of tubers, which, in turn, could affect the resistance of the tubers to cracking and fracturing. Moreover, divalent cations, such as calcium (Ca) and magnesium (Mg), and their distribution in the tuber can affect the tuber's resistance to mechanical impacts via cell-wall stabilizing properties. Tubers with higher DM, starch, and Ca concentrations exhibited the highest resistance to mechanical impacts. The reason for the increased resistance of tubers with higher DM and starch concentrations to mechanical impacts is assumed to be related to a certain cell structure of these tubers, which is why considerable force is needed to damage the cell structures. The relation between higher Ca concentrations and an improved resistance of tubers to mechanical impacts is assumed to be connected with the role of Ca in linking cell-wall polymers and thus stabilizing the cell wall. © 2018 Society of Chemical Industry.

Combining ability of potato parents for tuber appearance and tuber yield component traits

Abstract The purpose of this study was to estimate the combining ability between two groups of potato parents in early generations of selection. Twelve potato families, derived from two groups of parents crossed in a 4x3 partial diallel design, were evaluated, in a randomized complete block design with three replications. Additive effects of genes were predominant for the traits tuber shape uniformity, tuber pointiness, tuber curvature, general tuber appearance, tuber size uniformity, tuber number, total tuber yield, and average tuber weight. With regard to general combining ability, for all tuber appearance traits, the foreign parents ‘Pukara’ and ‘Asterix’, and the national parent ‘Eliza’ contributed with complementary favorable alleles. For tuber yield component traits, the foreign parent ‘Rioja’ and the national parent ‘Eliza’ were outstanding. The specific combining ability indicated ‘Pukara’/‘Eliza’ as the most promising cross for the development of superior genotypes for the traits general tuber appearance and tuber number.

Genetic parameters associated with tuber yield and tuber appearance traits of potatoes in early generations of selection

The knowledge of genetic parameters of traits, in early generation selection, is important for breeding programs to define strategies and obtain success. The objective of this study was to estimate genetic parameters of yield components and tuber appearance traits in early selection generations of potatoes and their implications in the selection process. Twelve segregating potato families originated from crosses between two groups of parents of the Embrapa potato breeding program were evaluated. Group 1 was formed by foreign potato parents: Pukara, Asterix, Rioja, and Caesar; and group 2, by national parents: Eliza, C1730-07-94, and C1750-15-95. The experiment was conducted in autumn seasons of 2012 and 2013. A randomized complete block design with three replications was used. Considering all traits together, Pukara/Eliza, Asterix/Eliza, and Rioja/Eliza families had the highest means on a large number of tuber appearance and yield traits. The results of this study suggest that selection may be applied with mild to moderate intensity in the seedling generation for skin texture, tuber general appearance, tuber number, average tuber weight and total tuber yield, based on the moderate to high heritability estimated on the seedling generation. The highest selection gains were for skin texture, tuber general appearance, tuber number, average tuber weight and total tuber yield.

Expected response to early-generation selection for yield and tuber appearance traits in potatoes

The aim of this study was to evaluate the performance of potato clonal families, and to estimate genetic variance, heritability and the expected response to selection of tuber yield and appearance traits in early generations. Twelve potato families were obtained from crosses between two groups of randomly-selected genotypes, including Eliza, C1730-7-94, and C-1742-8-95 in group 1; and Shepody, Asterix, Caesar, and White Lady in group 2. The crosses were made in factorial design (3 genotypes x4 genotypes), and each family consisted of 75 genotypes. Experiments were conducted in the fall of 2010, with a seedling generation under greenhouse conditions, and in the fall of 2011, with a clonal generation under field condition. High heritability estimates suggest that mild to moderate selection can be applied in the seedling generation to eye depth, eyebrow prominence, tuber curvature, flattening and shape uniformity. The C1742-8-95/White Lady stood out as a superior cross, as did all other crosses with White Lady, regarding tuber appearance and yield traits.

Potato Vine Killing or Desiccation

Proper tuber maturity at harvest is an important factor in producing high-quality fresh-market potatoes. Tuber maturity is generally recognized as an important determinant of storage ability and cooking quality. Maturation can be artificially induced by killing the potato vines prior to harvest. This will benefit tuber appearance, limit tuber size, and improve tuber release from the vine. This revised 4-page fact sheet describes the importance of tuber maturation, potato vine killing timing and available methods, and how to determine when to vine kill and when to harvest after vine kill. Written by Lincoln Zotarelli, Steven Sargent, Peter Dittmar, and Mildred Makani, and published by the Horticultural Sciences Department, January 2016. HS925/HS181: Potato Vine Killing or Desiccation (ufl.edu)

Combining abilities for agronomic traits and marker-assisted selection for Potato virus X and Potato virus Y resistance.

Disease-resistant potato cultivars with good tuber appearance and desirable agronomic traits are essential for meeting the demands of producers and the market. Attaining these cultivars is the focus of potato breeding programs whose aim is to benefit the productive chain. The purpose of this study was to estimate combining abilities and evaluate potato clones based on tuber appearance, yield, and resistance to the PVY and PVX viruses. Crosses between four commercial cultivars of potato with good tuber appearance were performed, using eight clones with proven resistance to PVY and PVX from the breeding program of UFLA. The clones obtained were evaluated for agronomic traits, tuber appearance, and the presence of both Ryadg and Rx1 alleles, which confer extreme resistance to the PVY and PVX viruses, respectively. The independent culling level method was used to select genotypes of commercial interest, as well as to estimate the combining abilities of the parents. We identified clones carrying the Ryadg and Rx1 alleles with agronomic traits suitable for the fresh market and for processing. The BRS Ana cultivar and CMA-399 and CMA-385 clones showed positive effects on general combining ability (GCA) for tuber yield, while the Monalisa cultivar showed positive effects on GCA for general tuber appearance.

Tuber shape and eye depth variation in a diploid family of Andean potatoes.

BackgroundTuber appearance is highly variable in the Andean cultivated potato germplasm. The diploid backcross mapping population ‘DMDD’ derived from the recently sequenced genome ‘DM’ represents a sample of the allelic variation for tuber shape and eye depth present in the Andean landraces. Here we evaluate the utility of morphological descriptors for tuber shape for identification of genetic loci responsible for the shape and eye depth variation.ResultsSubjective morphological descriptors and objective tuber length and width measurements were used for assessment of variation in tuber shape and eye depth. Phenotypic data obtained from three trials and male–female based genetic maps were used for quantitative trait locus (QTL) identification. Seven morphological tuber shapes were identified within the population. A continuous distribution of phenotypes was found using the ratio of tuber length to tuber width and a QTL was identified in the paternal map on chromosome 10. Using toPt-437059, the marker at the peak of this QTL, the seven tuber shapes were classified into two groups: cylindrical and non-cylindrical. In the first group, shapes classified as ‘compressed’, ‘round’, ‘oblong’, and ‘long-oblong’ mainly carried a marker allele originating from the male parent. The tubers in this group had deeper eyes, for which a strong QTL was found at the same location on chromosome 10 of the paternal map. The non-cylindrical tubers classified as ‘obovoid’, ‘elliptic’, and ‘elongated’ were in the second group, mostly lacking the marker allele originating from the male parent. The main QTL for shape and eye depth were located in the same genomic region as the previously mapped dominant genes for round tuber shape and eye depth. A number of candidate genes underlying the significant QTL markers for tuber shape and eye depth were identified.ConclusionsUtilization of a molecular marker at the shape and eye depth QTL enabled the reclassification of the variation in general tuber shape to two main groups. Quantitative measurement of the length and width at different parts of the tuber is recommended to accompany the morphological descriptor classification to correctly capture the shape variation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-015-0213-0) contains supplementary material, which is available to authorized users.

Evaluation of selected Polish potato cultivars and breeding lines regarding their resistance against Phytophthora infestans and usefulness for organic farming

The presented studies concern an evaluation of 10 potato cultivars (5 starch and 5 table) and 9 selected potato breeding lines re-garding their resistance against Phytophthora infestans as well as other traits such as length of vegetation period, yield, tuber size, regularity of tuber shape, depth of eyes. The aim of these studies was to evaluate of the potential usefulness of tested potato cultivars/clones for organic farming. The obtained results indicate that none of the tested table cultivars should be recommended for organic farming, due to their low resistance to P. infestans. The examined starch cultivars show high resistance to P. infestans, but their cultivation in organic farming seems to be restricted due to other features’ for example very long vegetation period. On the cont-rary, the group of tested potato breeding lines seems to be very useful for organic farming since they are high yielding and display relatively short vegetation period and high resistance to P. infestans. Moreover, these clones produce tubers with an attractive tuber appearance that is indispensable for table potatoes. Przedstawione badania dotyczą oceny 10 odmian (5 jadalnych i 5 skrobiowych) oraz 9 klonów hodowlanych ziemniaka pod względem poziomu odporności na Phytophthora infestans oraz wybranych cech użytkowych (długość wegetacji, wysokość plonu, wielkość bulwy, regularność zarysu, głębokość oczek). Badania te miały na celu określenie ewentualnej przydatności badanych form do upraw ekologicznych. Wyniki badań wskazują, że żadna z badanych odmian jadalnych nie powinna być rekomendowana do upraw ekologicznych ze względu na bardzo niski poziom odporności na P. infestans. Badane odmiany skrobiowe posiadają wysoki poziom odporności na P. infestans, bardzo pożądany w uprawach ekologicznych. Jednakże ich wykorzystanie w tym celu może być ograniczone przez niedobory innych cech użytkowych (np. bardzo długą wegetację). Natomiast grupa badanych klonów hodowlanych charakteryzowała się bardzo wysokim poziomem odporności na P. infestans, skróconym okresem wegetacji, wysokim plonem oraz atrakcyjnym wyglądem bulw.

The Influence of Ethephon Application Timing and Rate on Plant Growth, Yield, Tuber Size Distribution and Skin Color of Red LaSoda Potatoes

Optimizing the response of growth regulators depends in part on finding the most appropriate application rate and timing. Preliminary trials indicate that ethephon (2-chloroethylphosphonic acid) may be useful for improving potato (Solanum tuberosum L.) tuber appearance and skin color of red-skinned cultivars, but relatively little is known about optimum application practices. Two separate trials were conducted at the University of Idaho Parma Research and Extension Center to evaluate the effect of ethephon foliar application timing and rate on plant growth, tuber yield, size distribution, and skin color of the cultivar Red LaSoda. Skin color was rated visually and by colorimeter at harvest and periodically throughout storage at 4 °C. In 2011, ethephon application timing did not influence plant height, total yield, tuber size or skin color but did affect some tuber size classes. In contrast, all of these parameters were significantly influenced by application timing in 2012. The optimum application timing to influence skin color was a relatively narrow window during initial flower development, to 10 days after initial flowering (coinciding with tuber initiation). Increasing rates of ethephon significantly reduced plant height, increased foliar injury symptoms, and reduced average tuber size, but did not influence total yield in Red LaSoda. Higher ethephon rates resulted in significantly darker tuber skin (lower L* values) and increased red color (increased chroma and reduce hue angle values) when compared to the non-treated control. Evaluation of samples held in storage showed that differences in skin color ratings at harvest were maintained throughout the storage period. It is concluded that two foliar applications of ethephon at a rate between 292 and 438 ml ha−1applied ten days apart, initiated at pre-bloom, will provide the optimum change in skin color and reduce average tuber size without reducing total yield.

Seleção de famílias para aparência dos tubérculos e tolerância a temperaturas elevadas em batata

A seleção de famílias é um método que possibilita maior eficiência nos programas de melhoramento, já que as famílias inferiores são descartadas e concentram-se os recursos nas famílias mais promissoras. O objetivo deste estudo foi avaliar a eficiência da seleção de famílias para os caracteres de aparência e de produção de tubérculos em condições de calor e temperatura amenas. Utilizaram-se neste estudo famílias geradas do cruzamento biparental entre clones tolerantes ao calor e cultivares de boa aparência dos tubérculos. Foram avaliados caracteres de aparência, produtividade e peso específico de tubérculos na geração seedling, primeira e segunda geração clonal. Para os caracteres de aparência dos tubérculos, algumas famílias se destacaram na geração seedling por apresentarem maior frequência de clones superiores. Na primeira e segunda geração clonal identificaram-se famílias tolerantes ao calor e responsivas para melhorias, nas condições de temperatura amena, em produtividade e peso específico dos tubérculos. Concluiu-se que a seleção de famílias para produtividade e peso específico dos tubérculos foi eficiente e que a seleção de famílias para o conjunto de caracteres de aparência dos tubérculos se mostrou menos eficiente.

Histological study on tuberisation of potato (Solanum tuberosum L.) promoted by inhibitors of gibberellin biosynthesis

The application of antigibberellins to potato plant cultures results in an accelerated tuber appearance, caused by stimulation of pith-,and cortex-cell growth, particularly in the radial direction. Their growth considerably precedes the initiation of parenchymatous cell divisions, which are the first steps of naturally occurrring tuberisation, regulated by a different mechanism than the quantitative proportion of endogenous gibberellins and cytokinins. Part of the cortex cells change the orientation of their divisions to a periclinal one. The xylem parenchyma cells also undergo hypertrophy.

Capacidade de combinação de genitores de batata para caracteres de aparência e rendimento de tubérculos

O objetivo deste trabalho foi estimar as capacidades de combinação de genitores de batata, em gerações iniciais de seleção. Os experimentos foram realizados em Pelotas e Canoinhas. Foram estudadas 12 famílias, derivadas de dois grupos de genitores, cruzados em esquema dialelo parcial (3 x 4) 'Eliza', 'C-1730-7-94' e 'C-1742-8-95'; 'Shepody', 'Asterix', 'White Lady' e 'Caesar'. As famílias foram avaliadas, na geração de plântula e na primeira geração de campo, para caracteres componentes de aparência e rendimento de tubérculos. Os dados foram submetidos às análises de variância e dialélica parcial. No conjunto de caracteres avaliados, verificou-se superioridade de efeitos significativos para a capacidade geral de combinação, em relação à capacidade específica de combinação, indicando predominância de efeitos aditivos dos genes, no controle dos caracteres. Em relação à capacidade geral de combinação, 'White Lady' é o genitor mais destacado positivamente, contribuindo com genes de ação aditiva para a melhoria, tanto dos caracteres que compõem a aparência dos tubérculos, quanto dos caracteres de rendimento. Quanto à capacidade específica de combinação, o cruzamento ('C1730-7-94' x 'White Lady') é o mais indicado para a geração de famílias superiores quanto a caracteres de aparência e a caracteres componentes do rendimento de tubérculos.

Owyhee Russet: A Variety with High Yields of U.S. No. 1 Tubers, Excellent Processing Quality, and Moderate Resistance to Fusarium Dry Rot (Fusarium solani var. coeruleum)

Owyhee Russet (AO96160-3) originated from a cross between A89384-10 and A89512-3 in 1996. Owyhee Russet was released in 2009 by Oregon State University, in cooperation with the USDA-ARS and the Agricultural Experiment Stations of Idaho and Washington and is a product of the Northwest Potato Variety (Tri-State) Development Program. Owyhee Russet has semi-erect medium sized vines with medium to late maturity. The tubers are long, with a tan skin, medium russeting, and attractive tuber appearance for fresh market. Owyhee Russet was evaluated in several locations across the Northwest for more than 15 years. Total yield of Owyhee Russet is similar to that of Russet Burbank and Ranger Russet but significantly higher than Russet Norkotah. U.S. No.1 tuber yield of Owyhee Russet is significantly higher than Russet Burbank and Russet Norkotah, resulting in substantially higher marketable yield. Owyhee Russet tubers have significantly higher specific gravity than Russet Burbank and Russet Norkotah. Fry color following tuber storage at 4°C and 9°C is significantly lighter for Owyhee Russet than the comparison varieties. Relative strengths include high yield with a very high proportion of U.S. No.1 tubers, good tuber appearance and excellent processing quality, resistance to cold sweetening, common scab and Fusarium dry rot. Weaknesses include susceptibility to foliar and tuber late blight and susceptibility to metribuzin herbicide injury. Allelic patterns of five SSR markers have shown that Owyhee Russet has a distinctive DNA genetic fingerprint from its russet type reference varieties which are Ranger Russet, Russet Burbank, and Russet Norkotah.

Genetic gains for heat tolerance in potato in three cycles of recurrent selection

Practically all potato cultivars grown in Brazil are native to Europe and not fully adapted to the tropical conditions. The purpose of this study was to estimate the genetic gains of three cycles of recurrent selection for heat tolerance in potato. The base population in this study consisted of five Brazilian and five heat-tolerant clones. In the winter of 2006 and rainy growing season of 2007 103 clones were evaluated (eight clones of the base population, 29 of the first cycle, 32 and 30 of the second and third recurrent selection cycle, respectively, and four control cultivars). The genetic gains for tuber traits in both growing seasons were 37.8 % (yield), 13.0 % (weight), 32.4 % (percent of large tubers), 0.8 % (tuber specific gravity) and 16.6 % (general tuber appearance). The percentage of physiological disorders (second-growth tubers and cracking) was also reduced by selection.