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.     

Effects of inoculum source and irrigation on black dot disease of potatoes (Colletotrichum coccodes (Wallr.) Hughes) and its development during storage

Summary In 1985 and 1986 plots were planted with seed tubers affected with black dot and with healthy seed inoculated or not with cultures ofColletotrichum coccodes at planting. Half the plots were irrigated from shoot emergence to the end of July. Seed tubers rotted more often when they were diseased than when they were not and rotting was increased by irrigation; by contrast, up to 18 weeks after planting irrigation decreased infection of stem-bases, roots and tubers. Tuber infection, first recorded in July, increased throughout the season and most rapidly from September, when the irrigation applied earlier increased disease. Soil-applied inoculum gave most disease in both years and tubers from healthy seed gave least in 1986 but as much as from diseased seed in 1985. Incidence and severity of black dot increased more during storage at 15°C than at 5°C and only on unwashed tubers.     

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.     

Survey of the distribution and perceived losses caused by paspalum leaf blight in Northern Victoria

A survey of the distribution of paspalum leaf blight caused by Ascochyta paspali in the Northern Irrigation region of Victoria indicated that the disease had increased from 14 infected properties in 1982 to 203 infected properties in 1986. Estimates by farmers and extension officers indicated that the mean pasture area infected with disease was 52% and 43% respectively in 1984–1985 and 63% and 45% respectively in 1985–1986. The majority of farmers and extension officers perceived mean yield losses in infected pasture that ranged between 11% and 40% in 1984–1985 and 11% and 30% in 1985–1986. Extension officers and farmers estimated that the area of infected pasture has increased between 1984–1985 and 1985–1986. The problems of assessing real losses caused by A. paspali are discussed.     

Exceptional Potato Clones Selected by Filipino Farmers from True Potato Seed: Status after 30 Years

In a remote mountainous region of the Philippines, farmers selected their own clones from hybrid True Potato Seed (TPS) populations and have maintained them for 30 years without public support. In 1985, the International Potato Center (CIP) initiated on-farm TPS research in the Mount Kanlaon area to help farmers control or reduce the rates of bacterial wilt caused by Ralstonia solanacearum. Seedlings were either grown in nursery beds or as transplants in the field. At harvest, farmers not only harvested their crop for either food or for sale but also selected their preferred clones. A survey conducted in 2016 showed that farmers are still growing potato clones selected from TPS and that these clones had spread to numerous areas within and around Mount Kanlaon. Farmers kept these clones because it was profitable because they required minimum inputs and their resistance to various pests and diseases and adverse weather conditions. ELISA tests showed that these clones have excellent virus resistance which partially explains why these clones have been growing for 30 years without a formal seed production program or any government support. Parents used to develop the TPS hybrids included those with virus and R. solanacearum resistance.     

Calcium and potassium fertilization of potatoes grown in North Florida. II. Effect on the bacterial soft rot potential in the tubers

In studies on a sandy soil in Florida over a 3-yr period (1984–86), applications of Ca (CaSO₄) inconsistently affected the bacterial soft rot potential of potato tubers (Solanum tuberosum). The potential was estimated from the severity of the disease (percent surface area decayed) in tubers that had been immersed in an aqueous cell suspension ofErwinia carotovora subsp.carotovora and then incubated 4 days in a mist chamber at 24 C. With freshly harvested tubers (tested within 5 days after harvest), disease severity averaged 49, 11, and 4% over all treatments in 1984, 1985, and 1986, respectively, which was roughly proportional to rainfall on the crop,e.g., 37, 18, and 15 cm, respectively. Disease severity decreased, did not change, and increased with increased Ca rate (0, 450, and 900 kg.ha^-1) in 1984, 1985, and 1986, respectively. In each season, severity was affected by interactions involving the Ca treatments. Most interactions involved cultivar. The efficacy of Ca applications to potatoes grown in low Ca soils for enhancement of tuber resistance to bacterial soft rot may be limited by factors associated with environment or cultivar that are not completely understood.     

The Use of True Potato Seed as Pro-poor Technology: The Efforts of an International Agricultural Research Institute to Innovating Potato Production

The International Potato Center (CIP) and collaborating institutions implemented an intensive research programme over a period of 25–30 years on the use of botanical seed of potato as an alternative way of growing a potato crop. The use of botanical or ‘true’ potato seed (TPS) had many advantages over the use of seed tubers. Potentially, the use of TPS was especially attractive for small-scale farmers in developing countries. The difference of using TPS as compared to using seed tubers meant in many respects the development of a new crop–commodity chain, requiring research on breeding, seed production, agronomy and marketing aspects. This research made it possible to produce potatoes from TPS at commercial scale: it removed a number of important constraints in the uniformity and earliness of the TPS varieties and in seed physiology. Experimentation and adoption by farmers in a wide range of countries showed that the technological advantages of using TPS were only translating in economical benefits as compared to tuber seed when the last one was costly or not available. Since the economic performance of seed tubers is likely to continue to fluctuate, TPS remains an interesting alternative. Study of the use of TPS in various countries could contribute to better understanding of factors that promote or inhibit crop technology innovation. The article gives an overview of the various areas of TPS research in CIP and presents information on the application of TPS technology in several developing countries.     

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.     

Current status of the TPS technology in the world

Summary The availability of improved True Potato Seed (TPS) varieties for short and long photoperiod conditions has recently increased the interest in the TPS technology. A summarized overview is presented of the TPS technology for potato tuber production, TPS breeding and production. TPS competes successfully with clonal cultivars in Egypt and India. In other developing countries higher yields and better adaptation are needed to make the TPS technology economically attractive; the case of TPS in Indonesia is used to illustrate this. In industrialised countries, well-performing seed tuber programmes, productivity and legislative restrictions are difficult to beat by TPS. However, the use of TPS can be economically attractive where disease pressure is high. It is concluded that TPS has a place within potato systems where agroecological conditions for seed tuber systems and steady supply of good quality tubers from a formal seed programme are most constrained. Further genetic improvement will increase the areas where TPS provides better and cheaper planting material.     

Effects of plant density on the yield and yield components of true potato seed (TPS) hybrids in early and main crop potato production systems

This study was conducted to evaluate true potato seed (TPS) technology for use in ware or seed potato production in two contrasting environments in Turkey during 2002 and 2003. The field experiments were carried out in the Hatay and Nevsehir provinces in Turkey, which represent a Mediterranean early crop potato production area and a temperate main crop potato production area, respectively. The plug seedlings of six TPS hybrids were transplanted to the fields at four densities (15, 20, 25 or 30 plants m⁻²). The seed tubers of the medium early cultivar Marfona were also planted in the experimental plots to compare the performance of the TPS hybrids with traditional seed tubers. Transplanting of the seedlings was significantly delayed in Hatay due to unsuitable weather conditions in both years. The seedlings needed an adaptation period of 2–4 weeks after transplanting depending on the location and the growing conditions. The adaptation period was longer in Hatay due to high air temperatures after transplanting. Although the yield performance of the TPS hybrids differed depending on the location and year, the TPS hybrids produced noticeably higher total tuber yields in Nevsehir location (ranging from 43.1 to 62.5 t ha⁻¹ in 2002 and from 39.5 to 50.6 t ha⁻¹ in 2003) than in Hatay (ranging from 15.3 to 19.6 t ha⁻¹ in 2002 and from 15.1 to 19.1 t ha⁻¹ in 2003). The percentage of marketable tubers (>28 mm) was also considerably higher in Nevsehir. The optimal plant density varied between 25 and 30 plants m⁻² with regard to the total yield, while the optimal density with regard to the marketable yield was 20 or 25 plants m⁻² depending on hybrids in Nevsehir. However, none of the tested plant densities caused competition between plants in Hatay, where the environmental conditions during the growing period considerably restricted the growth of individual TPS seedlings.It was concluded that transplanting of TPS seedlings can be considered a feasible alternative for ware or seed potato production in temperate environments like Nevsehir that have growing periods of at least 4 months. However, there are several obstacles, such as difficulties with the timing of transplanting, long adaptation period that threaten the practicability of TPS technology in Mediterranean-type environments. Further agronomical studies focused on reducing inter- and intra-plant competition are needed for both environments in order to improve the acceptability of TPS technology to farmers.     

Comparative performance of different-sized seed tubers derived from true potato seed

The growth and yield of plants from different-sized seed tubers derived from true potato seed were evaluated on a per stem, per plant, and per unit area basis using either single or multiple-sprout tubers. In single-sprout tubers, haulm dry weight per stem 47 days after planting was greater in the 40–60 g tubers when compared with that in the 5–10 g or the 10–20 g tubers. This resulted in greater tuber weight per stem in the 40–60 g tubers throughout the growing season. The number of tubers per stem was not affected by seed tuber size. In multiple-sprout seed tubers of increasing size, total tuber number and total tuber weight, as well as weight of those tubers larger than 45 mm, increased on a per plant basis but decreased on a per stem basis. At different rates of planting, 1–5 g seed tubers produced smaller tubers than 5–10 g or 10–20 g seed tubers. Increased rate of planting resulted in non-significant yield increases per unit area in plots planted with 1–5 g seed tubers. The yield increases were significant when 5–10 g and 10–20 g seed tubers were planted at higher rates. The number of main stems per unit of seed tuber weight was five times greater in 1–5 g tubers compared with that in 40–60 g tubers. This resulted in low seed weights per hectare when small tubers were planted and in a high ratio of harvested to planted tuber weight.     

A heat-sum model to determine yield and onset of internal heat necrosis for atlantic potato

The influence of temperature on tuber yield and development of internal heat necrosis (IHN) in Atlantic (Solanum tuberosum L.) was examined in field trials in two locations over three years (seven plantings). Under simulated commercial production, yield and development of IHN varied significantly between Virginia (VA) and New Jersey (NJ) in 1986, 1987, and 1988. Marketable yield ranged from 49.8 mt.ha^?1 for the early planting in 1986 in New Jersey (NJ86E) to 17.9 for VA87. Tubers developing IHN to a level which potato chip processors would rate unacceptable (off-grade) varied with year and location. Significant correlations were found between the number of days to off-grade and the mean maximum temperature for 0–30 (r = ?.83), 30–60 (r = ?.86) and 60–90 DAP (r = ?.81) as well as the mean minimum temperature for the same periods (r = ?.91,, ?.80 and ?.91, respectively). The relationship between yield or IHN and temperature was examined using heat-sum models with a penalty for maximum daily temperature > 25C but with or without a penalty for minimum temperature > 21C. The multiple coefficients of determination for yield were similar using either variables generated from the heat-sum model with maximum and minimum temperature penalties or from the model with maximum temperature penalty only (R² = 0.83 and R² = 0.82). The prediction of the time from first symptom of necrosis to off-grade (interval) was improved by including variables generated by the heat-sum model that included both the minimum and maximum temperature penalty (R² = 0.50 vs. R² = 0.27), respectively. High minimum temperatures as reflected in the days to maximum heat-sum were found to significantly affect tuber yield and the expression and development of IHN.     

Production and use of seedling tubers from true potato seed (TPS) for potato cultivation in Italy

Summary The effect of varying plant population on the production of tubers from potato seedlings was investigated during 1992 and 1993 using three different plant densities: 35, 70, 100 plants/m². Increasing the plant population significantly increased the number of tubers produced, but no significant difference was found between the plant densities of 70 and 100 plants/m². The seedling tubers produced in nursery beds were tested in the field for ware potato production using different sized tubers. The best performances were obtained using tubers 30–40 mm. Significant differences were evident among the 7 true potato seed (TPS) families used, but data grouped by type of cross did not indicate any significant difference between 4X×4X and 4X×2X crossing groups.     

Canopy photosynthesis,stomatal conductance and yield ofSolanum tuberosum grown in a warm climate

Selected potato (Solanum tuberosum L.) genotypes were grown in the field from May to September during 1984 and 1985, to study their growth and gas exchange responses in a warm climate. The parameters measured were leaf area index (LAI), canopy photosynthesis on ground area basis (CPn-Ga), stomatal conductance, dry matter partitioning and yield. The LAI ranged from 1.40 for Dakchip to 6.60 for Pungo during August 1984. The LAI also differed significantly among the potato genotypes for the three samplings during 1985. Atlantic, Chipbelle and DTO-33 showed no decline in their LAI up to 73 days after planting (DAP), indicating a better heat-stress tolerance response than the other genotypes. During both years, CPn-Ga differed significantly among the genotypes and Pungo had higher CPn-Ga than all the other genotypes. Mean CPn-Ga rates were 1.72 and 4.34 g CO₂ m^?2hr^?1 during 1984 and 1985, respectively. Mean adaxial and abaxial stomatal conductances were 0.86 and 1.46 cm sec^?1, during 1984, and stomatal conductances were similar for both years. Stomatal conductance did not appear to limit gas exchange in potato leaves. Dry matter partitioning to tubers ranged from 8.9% for Pungo to 55.5% for Atlantic 67 DAP during 1984. At final harvest, July 19, 1985, dry matter partitioning to tubers varied from 47.5% for Pungo to 69.9% for Chipbelle. The tuber yield ranged from 9.6 to 27.8 MT/ha. This study indicated that Atlantic and La Chipper have potential for growing in a warm climate.     

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.     

Improving the field performance of micro-and minitubers

Summary In many seed potato producing areas, micro- and minitubers are too small for direct planting as seed tubers in the field. Such use of these propagules can, however, be feasible if the crop's growth and development can be advanced. Increasing light interception, harvest index and yield of useable progeny tubers has been proved possible with plastic mulch and pre-planting of small tubers in a greenhouse. High amounts of nitrogen (up to 180 kg ha⁻¹) or deep planting (up to 9 cm) were less effective. Using older or pre-sprouted micro- or minitubers may be beneficial, because this might increase the number of sprouts per mother tuber (and thus stems per plant) or advance the growth of sprouts or stems. However, this would require even more careful management, due to the weakness of these sprouts and stems. Micro- and minitubers should be as large as feasible when used for direct planting in the field.     

Furrow vs hill planting of sprinkler-irrigated russet burbank potatoes on coarse-textured soils

Surface water runoff from the hill, where potatoes are planted, to the furrow may exacerbate potato drought sensitivity. Planting into furrows and constructing midrow ridges may improve water use efficiency and relieve water stress on potato by directing water toward, not away from, the plants. A 3-year field study was conducted to compare yields and tuber size distributions of furrow- and hill-planted potato (Solanum tuberosum L., ‘Russet Burbank’) on coarse-textured, well-drained soils under sprinkler irrigation. A split-plot experimental design with main plots of row orientation (N-S vs E-W) and subplots of planting method (hill and furrow) combined with two planting depths was used at two central North Dakota sites. Except for planting method and limiting the post-emergence cultivation in the furrow treatments, all cultural practices (fertilizer, irrigation, etc.) were identical and corresponded with conventional practices for hill planted potato. Row orientation did not affect yield for any tuber size category. Averaged over 3 years, furrow-planted potato produced 24% larger tubers (188 vs 151 g), 31% smaller yield for tubers <113 g (4.99 vs 7.21 Mg ha^?1), 28% smaller yield for tubers 113 to 170 g (8.14 vs 11.3 Mg ha^?1), 8% larger yields for tubers 170 to 283 g (18.0 vs 16.6 Mg ha^?1), 103% larger yields for tubers 283 to 454 g (10.9 vs 5.36 Mg ha^?1), 341% larger yields for tubers >454 g (2.65 vs 0.60 Mg ha^?1), and 10% larger total yields (46.2 vs 41.9 Mg ha^?1) compared with hill-planted potato. There were no differences in tuber specific gravity. Preliminary soil water measurements indicated an inter-row water-harvesting effect for furrow planting compared with hill planting. The furrow-planting method may offer significant potential for ameliorating the drought sensitivity of potato.     

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.     

Impact of early-season water deficits on Russet Burbank plant development,tuber yield and quality

Russet Burbank potatoes grown on Owyhee silt loam were subjected to early-season moisture stress by delaying initiation of furrow irrigation up to seven weeks after planting. A range of water stress treatments from 4 to 7 weeks after planting resulted in reduced plant size, tuber number and total tuber weight per plant 8 1/2 weeks after planting. Early-season water stress resulting from delayed irrigation onset was associated with improved tuber quality at harvest. Plants water stressed before tuber initiation had fewer tubers with dark stem-end fry colors, reduced percentage of US No. 2 potatoes, and increased percentage and size of US No. 1 potatoes. Increasing duration of soil water potential below -60 kPa early in the season was associated with declining total yield in 1985 but not in 1986. To obtain optimum yield and processing quality, the first irrigation should be no sooner than full plant emergence.     

Response of Potato Genotypes to Bacterial Wilt Caused by Ralstonia Solanacearum (Smith)(Yabuuchi et al.) In the Tropical Highlands

Potato varietal resistance to bacterial wilt disease caused by Ralstonia solanacearum Yabuuchi et al., (Microbiology and Immunology 39:897–904, 1995) is the best management of the disease. Because the causal pathogen exhibits strong host-pathogen-environment interaction, screening the potential parents for resistance under the target growing environmental conditions is the first important step for effective resistance breeding. The objective of this study was to determine the response to bacterial wilt of selected potato genotypes currently grown by farmers in Kenya and candidate clones from the International Potato Center to identify parents that can be used in the local breeding program to develop resistant cultivars. A study was carried out at Kabete, Kenya for three consecutive seasons between November 2011 and February 2013. Thirty six potato genotypes were planted on an inoculated field at the Kenya Agricultural Research Institute (KARI), Kabete using alpha lattice experimental design with three replications. Data collected were days from planting to onset of wilting (DTOW), bacterial wilt incidence (BWI), total tuber weight (ton ha^?1) (TTW), total tuber numbers/hectare (TTN), proportion of ware sized tubers (PWTTW), proportion of symptomatic tubers based on weight (PSTTW), proportion of symptomatic tubers based on tuber numbers (PSTTN) and latent infection (LI) of the tubers. Almost, all the potato genotypes evaluated in this study were susceptible to bacerial wilt. Ranking of genotypes based on resistance differed among the three seasons. On average, the three most resistant genotypes were Kenya Karibu, Kenya Sifa and Ingabire. The study identified eight potato genotypes (Meru, Ingabire, Kenya Karibu, Sherekea, Kihoro, Tigoni, Bishop Gitonga and Cangi) to be used as promising parents for subsequent crosses. The chosen genotypes are prolific in pollen production and popularly grown by Kenyan farmers.