Effect of cultivar maturity period on the growth and yield of potato plants grown from microtubers and conventional seed tubers

Potato plants of early cultivars grown from microtubers have been reported to have a much lower growth vigor and produce lower yields than microtubers of late cultivars. This study intended to clarify the field performance of plants grown from directly planted microtubers of cultivars with different maturity periods, with a special attention to early cultivars. The experiments were conducted at Hokkaido University, Japan, over four years. Microtubers and conventional seed tubers of the early cultivar Kitaakari, late cultivars Konafubuki and Norin 1, and very late breeding line IWA-1 were planted, and the plant growth and tuber yields were analyzed. The microtuber plants of Kitaakari had a lower initial increase in leaf area index than conventional seed tuber plants, but at the maximum shoot growth had the same leaf area index. This pattern was also observed in the other cultivars. Tuber initiation and tuber bulking occurred on average five days later in microtuber plants than in conventional seed tuber plants of cultivar Kitaakari. At maximum shoot growth, microtuber plants had on average 65% of tuber dry weight of conventional seed tuber plants, with small variation among cultivars. Irrespective of maturity period, microtuber plants showed a higher tuber increase after maximum shoot growth, achieving around 86% of tuber dry weight of conventional seed tuber plants at harvest. From the results of this study we conclude that microtuber plants of early and late cultivars have a similar yield potential relative to conventional seed tuber plants, and microtubers of both early and late cultivars might be used as an alternative seed tuber source for potato production, if necessary.     

Soil water stress and the growth and yield of potato plants grown from microtubers and conventional seed tubers

Tuber yields of potato plants grown from microtubers in fields are more variable than yields from conventional seed tubers (CT). One reason could be their higher susceptibility to water stress. This study clarified the effect of soil water stress from 1 month after emergence on the growth and yield of plants grown from conventional seed tubers and microtubers in fields. Microtubers (0.5–3 g) and conventional seed tubers (50 g) were grown in Hokkaido, Japan, over three field seasons. One month after emergence, poly-shelters were placed over the plots to prevent rainfall, and either irrigated (wet plot) or non-irrigated (dry plot) treatments were formed. At mid-flowering (about 50 days after emergence) leaf area index (LAI) in microtuber plants was decreased relatively more due to soil water stress than LAI in conventional seed tuber plants. However, at maximum shoot growth (about 80 days after emergence) both microtuber and conventional seed tuber plants had a similar relative decrease in LAI due to soil water stress. At mid-flowering and maximum shoot growth microtuber and conventional seed tuber plants had reduced stomatal conductance due to soil water stress, but the reduction in stomatal conductance was greater in conventional seed tuber plants than in microtuber plants. Microtuber and conventional seed tuber plants had similar root development at maximum shoot growth. Tuber production from mid-flowering until plant maturity was similarly affected by soil water stress in microtuber and conventional seed tuber plants. At harvest, plants affected by soil water stress had about 87% of the tuber dry weight of irrigated plants. We conclude, that the greater variation on tuber yield of microtuber plants cannot be attributed to soil water stress from 1 month after emergence.     

Effect of Potato Microtuber Size on the Growth and Yield Performance of Field Grown Plants

Abstract

To examine the effect of the size of the potato microtuber (MT) produced in vitro on the posterior field performance, we examined the growth and yield of the late maturity cultivar Norin 1 using four sizes of MT: 0.3–0.5 g, 0.5–1 g, 1–3 g and 3–5 g, and conventional seed tubers (CT) (approximately 50 g). The experiment was conducted at Hokkaido University, Sapporo Japan in 1998 and 1999. The tubers were planted in May of each year, in a randomized block design with three replications. Plants from MT lighter than 0.5 g showed a slower initial leaf and tuber growth than heavier MT, but around the full flowering stage there was no significant difference with the MT size in leaf or tuber growth. CT plants showed higher initial leaf and tuber growth compared with MT plants, especially in 1999. No differences in growing period, number of tubers, and tuber fresh and dry yield were observed with the MT size. However, in 1999, the growing period was longer and tuber fresh and dry yields at harvest were higher in CT plants. MT of all sizes used in the study can be used for direct field planting, but more studies are needed to increase the yield stability of MT plants.     

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.     

Assessment of Possibilities of Microtuber and in vitro Plantlet Seed Multiplication in Field Conditions. Part 1: PVY,PVM and PLRV Spreading

Currently in vitro plantlets and microtubers provide the basis for pre-base production of potato seeds, from which minitubers are produced under covers – they serve later as seed material to be planted in the field. The aim of the research was to determine the possibility for multiplication of material produced in vitro directly in field conditions. The research assessed PVY, PVM and PLRV infection of potato tubers derived from plants grown directly from in vitro plantlets, microtubers, minitubers and traditional seed potatoes planted in the field at different times. Moreover, testing in laboratory conditions, the susceptibility of these plants to virus infection was determined for the case of artificial inoculation of Myzus persicae and Aphis nasturtii. It was found that the infection of tubers derived from in vitro plantlets and microtubers was greater than that of seed potatoes and minitubers. Yet it seems that the reason for their higher infection level resulted not from the plant’s sensitivity or its greater attractiveness to aphids but from a largely unknown cause. Earlier planting of microtubers and in vitro plantlets in the field in case of the more resistant cultivar and certainly later in relation to the main time of planting had an impact on limiting the PVY and PVM infection of potato tubers. Hence multiplication of microtubers and in vitro plantlets in field conditions could be very economical using cultivars which are relatively resistant to viruses. However, adopting a later than usual planting period (end of June) and applying an additional protective cover (such as non-woven agricultural fabric) in the first period of a plant’s growth, promotes multiplication of microtubers and in vitro plantlets in field conditions for cultivars with low resistance levels.     

Field performance of potato microtubers as propagation material

Summary In five field trials with the cultivars Gloria (early), Bintje (mid-early) Désirée (mid-late) and Morene (late), crops grown from conventional 28–35 or 35–45 mm seed were compared with crops grown from microtubers, of various sizes and from various sources, that had been producedin vitro. The following means to quicken initial crop development from the micropropagated material were tested: large microtubers, plastic soil cover, and transplanting of plantlets grown from microtubers pre-planted in a glasshouse. Crops grown from microtubers weighing less than half a gram yielded much less than crops grown from conventional seed crops but their yields were increased by each treatment. With the later-maturing cultivars, which generally produce few tubers per plant, the yields within seed grades from plants grown from transplanted microtuber plants were comparable with those of conventional crops. Reasons are given, why direct planting of microtubers, with or without plastic foil, is not a practical option.     

Field performance of potato minitubers with different fresh weights and conventional seed tubers: Multiplication factors and progeny yield variation

Summary Multiplication factors and progeny yield variation in crops from minitubers of five weight classes (ranging from 0.13–0.25 g to 2.00–3.99 g) and conventional seed tubers were studied in field experiments in three years. Multiplication factors were calculated as the number and weight of progeny tubers produced per planted tuber or per unit planted tuber weight. They were lower for the lighter minitubers when calculated per tuber and higher when calculated per weight. Yield variation was described by coefficients of variation for the number and weight of progeny tubers produced. Variation over individual plants of a crop was higher in stands from the lighter minitubers. Variation over plots within a field was sometimes higher for the lighter minitubers, but variation over years was similar for all minituber classes. Variation over plots in progeny tuber weight was higher for minitubers than for conventional tubers.     

Potato microtuber production and performance: A review

Almost half a century has passed sincein vitro tubers (microtubers) were first described in potato, but their adoption as a seed propagule has been uneven globally. Consensus is lacking regarding optimal production practices for microtubers and their relative productivity in relation to other propagules for minituber production. There is significant uncertainty regarding the utility of microtubers for evaluation of agronomic characters. However, the application of microtubers in germplasm conservation is widely accepted. Microtubers are producedin vitro in a plethora of different growing systems with varying environment, media constituents, and storage intervals. Many of the interactions between growth parametersin vitro and subsequent productivity appear to be genotype-specific. Accordingly, microtubers come in different sizes, have different dormancy requirements, and differ widely in relative growth potential and productivity. Despite these differences, there is evidence for strong analogies in growth responses between fieldgrown tubers and microtubers. The use of microtuber technology in seed tuber production, breeding programs, germplasm conservation, and research appears to have enormous potential. This review discusses microtuber production, yield and performance,in vitro screening, and germplasm storage and exchange.     

Effect of gibberellic acid and multiple harvests on production and reproductive value of seed potatoes produced above ground on stem cuttings

Summary Potato plants of cvs Eersteling and Bintje were grown from stem cuttings and induced to form aerial tubers for use as seed. Spraying the plants with gibberellic acid in concentrations of 10, 25 and 50 mg/l to induce stolon formation in the leaf axils led to a decrease in the number of tubers formed per plant. Multiple harvesting of the largest tubers from plants treated with gibberellic acid or not, approximately doubled the number of tubers formed but halved their individual weight compared with only one harvest at plant senescence. After a storage period of about 1 year, with their vigour declining, the aerial tubers were planted in the field. Aerial seed tubers taken from multiple harvests during the previous year produced the same number of tubers as plants grown from above-ground tubers harvested at plant senescence only, but the tuber yields declined with earlier harvesting when small (5–13 mm) aerial tubers were used, compared to larger (14–19 mm) tubers.     

Microtuber and minituber production and field performance compared with normal tubers

Summary Microtuber and minitubers of cv. Monalisa were produced in the laboratory and compared with normal seed tubers in a field experiment. These tubers were planted at similar plant densities (13.6 sprouts per m²) with two distances between rows (60 and 90 cm). Final ground cover was almost complete only in the plots derived from normal tubers and decreased with the size of the mother tubers. Normal seed, mini- and microtubers yielded respectively 50.8, 31.7, and 17.0 t/ha (means of two spacings). At close and wide spacing between rows, microtubers yielded respectively 27.3 and 6.7 t/ha, and minitubers 38.9 to 24.4 t/ha. Row spacing did not influence the yields from normal seed tubers. Total number of tubers per m² was also affected and, as means of the two spacings, ranged from 107.8 with microtubers, 122.1 with minitubers, to 142.9 with normal tubers. Mother tuber type also affected the yield distribution in three tuber grades (<36, 36–55, and 55–80 mm) and micro and minitubers produced many small tubers. Multiplication rates and the possible use of different propagation sources are discussed.     

Manipulation of microtubers for direct field utilization in seed production

A two-year field study was conducted to determine the effects of jasmonic acid (JA), light (duringin vitro explant production andin vitro tuberization phases), and dormancy-breaking treatment on performance of microtubers in the production of seed tubers (pre-elite) in five potato cultivars. Microtubers were produced under short day (8-h) conditions and in darkness, from stock plantlets pre-treated with JA and untreated, and on tuberization media with or without JA. Microtuber performance was compared to invitro plantlets transplanted directly to the field. Yields of tubers from microtubers were 30% to 40% of those from plantlets. Microtubers of cultivars Amisk and Russet Burbank produced the highest yields of pre-elite tubers. Atlantic microtubers performed poorly in the field. JA pre-treatment of stock plantlets, prior toin vitro tuberization, enhanced seeds tuber production from microtubers in Russet Burbank and lowered in Shepody. JA presence in media duringin vitro tuberization significantly lowered production of tubers while exposure to 8-h light resulted in microtubers performing significantly better in the field than microtubers produced in the dark. Dormancy release was the key factor influencing microtuber performance. Unlike greenhouse studies, gibberellic acid (GA₃) was more effective than Rindite. A further refinement of the production and handling methods is required before microtubers can be recommended for field production of seed tubers.     

马铃薯微型薯田间繁殖的研究

以马铃薯晚熟品种“下寨６５”为试验材料,研究了离体诱导微型薯直播田间繁殖块茎繁殖脱毒田间１～５代种薯的质量和效率。结果表明,生育阶段比同品种网室繁殖脱毒小薯同代脱毒种薯略迟;生长势、株高、茎粗、主茎分枝数、单株叶面积、根系数、匍匐茎数和匍匐茎长度等生长发育指标,ＰＶＸ、ＰＶＹ、ＰＬＲＶ和ＰＶＡ等重要病毒害发病率及病情指数,干腐病和软腐病发病率,晚疫病发病率和叶面枯死率相同;未发现环腐病和黑经病。单薯重量平均４５．１ｇ,随田间种植代数增加而增大;单株结薯数、单位面积结薯数逐代减小,脱毒田间１～４代单株产量和单位面积产量逐代增加,繁殖效率与脱毒小薯相同,故离体诱导微型薯田间繁殖块茎繁殖脱毒种薯是经济有效且切实可行的。     

Effect of whole seed tuber size and pre-plant storage conditions on yield and tuber size distribution of Russet Burbank

Field experiments were conducted in 1995, 1996, and 1997 at Agriculture and Agri-Food Canada’s Harrington Research Farm to assess the effect of whole seed tuber size and pre-plant seed storage conditions on processing yield (> 51 mm dia.) of potato (Solanum tuberosum L. cv Russet Burbank). Following commercial storage, seed tubers were stored at 4.4 C then subjected to one of three pre-plant treatments: (1) planted directly from storage, (2) held at 10 C for 3 wk before planting, or (3) green-sprouted for 3 wk before planting. Five sizes of whole seed were used (28, 42, 56, 70, and 84 g) with a variable size cut seed treatment added for comparison. Plots were harvested 138,134, and 131 days after planting in 1995, 1996, and 1997, respectively. Cut seed produced a higher yield of tubers > 51 mm diameter in comparison to all whole tuber seed sizes, with the exception of the 28 and 56 g sizes. In terms of total yield, the 28and 42-g whole seed tubers yielded significantly less than all other seed sizes examined. Warming or greensprouting seed tubers prior to planting did not increase tuber yield. The larger whole seed tuber sizes tended to result in greater numbers of stems and tubers per plant. To maximize marketable yield of Russet Burbank planted from whole seed tubers, it is recommended that the seed be between 28 and 42 g in size. Accepted for publication 25 May 2004.     

马铃薯二年制脱毒种薯体系建设及其关键技术改良

马铃薯脱毒种薯生产和利用是马铃薯生产的重要环节,传统的脱毒种薯生产体系因繁殖周期长,病毒再侵染风险高,使种薯质量很难保证。本研究以品种脱毒和试管薯生产为基础,以微型薯生产和标准种薯生产为扩繁环节,建成了二年制种薯生产体系。该体系将种薯生产在田间多年繁殖改进为只需一年繁殖,从而降低了病毒再侵染机率,保证了脱毒种薯质量。     

Innovative propagation methods in seed tuber multiplication programmes

Summary The production of large volumes of vitroplantlets and greenhouse tubers for increasing the rate of multiplication at the start of seed programmes provides the opportunity of reducing the total number of field generations grown before the seed moves into commerce. This implementation is especially useful for countries where high quality potato seed tubers cannot be produced because there are no vector-free production areas. This review covers the following steps: a) laboratory production of microplantlets and microtubers; b) minituber production in the glasshouse; c) storage and dormancy of micro- and minitubers; d) field performance of micro- and minitubers compared with conventional seed tubers; e) incorporation of the mentioned propagules in seed production systems. Many optimized protocols are already available for propagating plantlets, inducing microtubers and obtaining minitubers in the glasshouse at all periods of the year. Advanced molecular approaches techniques (RFLP and RAPD) to detect genetic variation in the progeny of these propagules have been described. Investigations carried out in this field have shown genetic stability, with the propagules usually reproducing plants true-to-type and tubers without deviants. By contrast, variations were demonstrated in DNA extracted from old suspension cell culture. Field trials assessed a lower yield potential crops from in vitro propagules compared with conventional seed tubers., mainly due to slow early crop development and the failure of plants caused by early stress after emergence. This may cause problems when the growing season is short because of the necessity for planting late to avoid night frosts and the mandatory haulm killing dates, common in many seed producing areas. Strategies for improving the field performance of micro- and minitubers are discussed. The most promising crop husbandry techniques appear to be: a) using tubers of a suitable physiological age, properly presprouted and encapsulated; b) optimizing the time application of fertilizer and irrigation, and c) using floating films. Outside the classical seed tuber areas of Northern Europe where the length of the growing period for pre-basic seed is usually not more than 80 days, the growing season is long enough to obtain reasonable yields even from micro- and minitubers.     

Growth in Netted Gem potatoes as influenced by transplanting and by greensprouting

The basis of difference in field growth and yield in Netted Gem potato plants grown from greenhouse transplants, from seed which was greensprouted for two weeks prior to planting and from seed which was retained in storage until planting was studied by measuring changes in plant dry weight and leaf area throughout the season. Cut seed, approximately 70g in size, which were either two or four-cut from 142g or 283g mother tubers respectively, were used in the comparisons. Transplants were started in 7.6 cm peat pots in the greenhouse and were transplanted to the field when 10 cm high. The greensprouted seed was cut from mother tubers which had been sprouted under fluorescent light at 15–18°C for two weeks producing strong sprouts 5 mm long. Transplants, greensprouted seed and seed from mother tubers held in 3°C storage were all planted in the field May 30, 1974, coinciding with commercial plantings of Netted Gem in the province. Backup field experiments, comparing similarly treated greensprouted and storage seed and transplants, were conducted in 1974 and 1975 but were not subjected to growth analysis. All plantings were grown on a Riverbank sandy loam soil. The 1974 growing season in New Brunswick was excellent while that for 1975 was dry and required extensive irrigation. The use of transplants established a substantial advantage in terms of early emergence and yields were consistently and significantly greater than those of greensprouted-seed and unsprouted-seed plants. The transplant yield advantage was attributed to the fact that tuberization was advanced substantially compared with the latter two types. Higher relative growth rates were associated with later emergence so that the rate for plants growing from unsprouted seed was greater than that for plants growing from greensprouted plants which, in turn, was superior to that of transplants. This pattern was maintained through the season. Consequently, small advantages in time of emergence, such as that obtained with greensprouted-seed plants, were not accompanied by significant yield differences. Canopy size decreased as emergence was delayed and canopy size differences were determined largely by the amount of branching. As canopy size decreased and emergence was delayed, the net assimilation rate was found to increase.     

Comparative performance of three small seed tuber sizes and standard size seed tubers planted at similar stem densities

Summary Small seed tubers of 1–5 g, 5–10 g and 10–20 g were planted at the same sprout densities as standard size seed tubers of 40–60 g in order to give similar stem densities. Early ground cover by foliage, total yield, and yield of tubers >45 mm were consistently greater in plots planted with larger seed tubers. The effect of seed tuber size on yield and tuber number per stem varied between years but 1–5 g seed tubers always gave lower yields per stem than larger seed tubers. Reducing the spacing between rows from 90 cm to 60 cm and maintaining the same sprout density was more effective in increasing yields from small seed tubers than increasing sprout density from 20 to 40 sprouts per m² by reducing plant spacing within the row.     

株行距和施肥量对木薯产量及生长的影响

采用裂区试验设计方法,研究株行距和施肥量对华南5号木薯产量和生长的影响.结果表明:在本试验株行距和施肥量条件下,施肥量对木薯产量和生长的影响比株行距大.密植(0.6～0.8 m)有利于提高淀粉产量、鲜薯产量和鲜薯淀粉含量,以0.8m株行距最佳,而疏植(1.2～1.4m)有利于提高单株薯数、单株鲜薯重、单株鲜茎叶重、收获指数和茎径.施肥有利于提高淀粉产量、鲜薯产量、单株鲜薯重、单株鲜茎叶重、茎径、株高和单株薯数,但降低鲜薯淀粉含量和收获指数.丰产栽培技术要兼顾单位面积株数、单株鲜薯重和鲜薯淀粉含量.建议在土壤肥力差和少施肥时,用0.6 m株行距;土壤肥力中等且较高施肥时.采用0.8 m株行距;土壤肥力中上且优越水肥管理,采用1.0 m株行距.     

马铃薯种薯生产技术标准参数研究──Ⅰ．不同种植密度对种薯产量和块茎大小的影响

本研究以马铃薯极早熟品种“东农３０３”脱毒种薯为试验材料，将种薯分成（２０±５）ｇ和（３０±５）ｇ两组，分别按５个密度进行种植（行距均为７０ｃｍ，株距分别为１２．５、１５．０、１７．５、２０，０和２２．５ｃｍ）．试验结果表明，在哈尔滨的自然条件下，马铃薯块茎产量和单位面积块茎数目随着种植密度的增大而增加，单个块茎重量则随着密度的增加而减少．大种薯（３０±５）ｇ播种可以获得较高的块茎产量．在本试验中，种薯重量为（３０±５）ｇ、株１２．５和１５．０ｃｍ时，获得了较高的块茎产量和较多的块茎数．通过对植株地上部鲜重和叶面积指数变化的分析，表明高密度群体具有发育快、生长旺盛的特点。     

Seed Potato Performance after Storage in Light at Elevated Temperatures

In regions with short growth seasons, it is of great importance to use potato (Solanum tuberosum L.) seed tubers with a high growth vigour and a short growth cycle. Such qualities may be obtained by treatments advancing the physiological age of the seed tubers. In this study, we have exposed tubers from four cultivars to various combinations of temperature and light conditions (green-sprouting) for 3–7 months in controlled climate. Subsequent sprout quality, seed tuber health and performance were studied in laboratory, greenhouse and field trials. Satisfactory short, sturdy and leafy sprouts were produced even after 7 months storage at 15 °C under light exposure. An assay of black scurf (Rhizoctonia solani) on the tuber skin showed that light exposure significantly reduced the occurrence compared with dark-stored tubers, while the average effect of storage temperatures was insignificant. In general, green-sprouting advanced emergence and plant growth by 1–2 weeks, and showed early tuber initiation and growth, compared to untreated material. Yields, 107 days after planting in the field trial, did not deviate significantly from untreated tubers. However, plant development at harvest was in accordance with general responses to physiological ageing of potato seed tubers, i.e. still tall and immature plants from untreated tubers, and short and mature plants from aged tubers. Results demonstrated the possibility of successful long-term storage of potato seed tubers in light at elevated temperatures and a potential for earlier harvests and higher early yields from such treatments.