PARS-70: An interspecific potato hybrid suitable for long storage and autumn-to-autumn seed multiplication

Summary Potato production in Pakistan has been largely based on imported cultivars. Efforts have been made to breed indigenous cultivars adapted to local seed multiplication and production practices. An indigenously bred hybrid(Solarium chacoense xSolatium acaule), named PARS-70 has been approved and released for cultivation in Pakistan. In yield trials, this hybrid was found superior to cultivars Diamant, Patroness, Ultimus, Cardinal and indigenous cultivars/selections Sialkot Sufaid and FB-9555-28. It produces white-yellow tubers, roundoval in shape with an average dry matter content of 21.8%. PARS-70 has the ability to store for up to 13 months in commercial storage (10–14 °C) and also can be stored in improvised unrefrigerated storage as a seed for next crop. Yields were reduced in crops grown from seed tubers stored under improvised unrefrigerated conditions. The long storage characteristic permits use of PARS-70 in autumn-to-autumn seed multiplication cycle without any loss of yield after several cycles of seed multiplication.     

Etablierung von Kartoffelsorten im Feld nach physiologischer Alterung der Pflanzknollen

Zusammenfassung Die physiologische Alterung der Pflanzknollen durch Lagerung bei überoptimalen Temperaturen (jahresunterschiedlich 16–29,5°C, 1988–90 vor dem Pflanzen abgekeimt, 1991 vorgekeimt wie Kontrolle) führte im Vergleich zur vorgekeimten Kontrolle im Mittel von 25 Sorten in allen Versuchsjahren zu einer Verminderung der Bestandesdichte und des Ertrages. Eine Gruppe von Sorten erwies sich in allen Jahren als relativ tolerant gegen die Alterung, eine andere als signifikant empfindlicher, dazwischen lag ein breites Mittelfeld mit zum Teil erheblichen Schwankungen in den Jahren. Die Reaktion der Sorten zeigte keine Beziehung zu ihrer Reifegruppe und ihrer Keimintensit?t, dagegen war die sortentypische Ertragsdepression nicht sehr eng, aber signifikant mit dem Schwund w?hrend der Lagerung korreliert.

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Summary Seed tubers were stored at above optimal temperatures. Mean temperatures varied during test years from 16 to 29.5°C (in 1988–1990 tubers desprouted before planting; in 1991 chitted tubers as in control; Table 1). This procedure of physiological ageing of seed tubers resulted in reduced plant density and lower yield compared to the chitted control in every year of the test period (average of 25 cultivars). The emergence was significantly delayed as compared to the control in all years (Table 2). Assessed for yield, the cultivars Désirée, Sanetta, Astilla and Andra showed a significantly higher degree of tolerance to warm storages (>80%, when compared to the control) than the cultivars Arkula, Dorisa, Karlena and Koretta (<25%; Table 3). Between these two extremes there was a large number of intermediate levels of tolerance, a result of fluctuating reactions of various cultivars to changing conditions in the years of the test period (Fig. 1). No correlation could be found between the cultivars' reactions and their maturity group or their sprouting behaviour. There was, however, for each cultivar a significant negative correlation between loss in weight through transpiration and respiration and plant density and yield (r=−0.55 and −0.54; Table 4). Plant density and yield were closely correlated (Table 4). The regressions between loss of plants and reductions in yields show that after seed tuber storage at higher temperatures a reduced yield must be expected even when plant density is not reduced (loss of plant 0%; Fig. 2). With complete stands, the use of physiologically aged seed tubers that were desprouted before planting (1988–1990) resulted in a reduction of yield of 17–20%; when old seeds were chitted as in control a loss in yield of 15% was calculated.

     

The effect of seed-and soilborne inoculum ofColletotrichum coccodes on the incidence of black dot on potatoes

Summary Soil in a potato field naturally infested with black dot (Colletotrichum coccodes) was fumigated with methyl bromide at 126 g m⁻² or left unfumigated. Potato seed tubers (cv. BP1) uninfected, lightly infected (1–25% surface affected), severely infected (26–100% surface affected) and severely infected withC. coccodes but dusted with prochloraz manganese chloride as Octave 2.5% DP at 750 g per 100 kg seed were planted in fumigated and unfumigated soil. When harvested, the incidence of black dot on the progeny of infected seed planted in unfumigated soil was twice that of progeny in fumigated soil, with progeny of uninfected seed having a 68.5 times higher disease incidence in unfumigated soil. Black dot on progeny tubers was reduced by pre-treatment of seed with prochloraz in fumigated soil only. With black dot infested fields, planting disease-free seed or treating seed with fungicides would not decrease disease on progeny tubers.     

Pre-sprouting as a Tool for Early Harvest in Organic Potato (Solanum tuberosum L.) Cultivation

Earlier harvest of potatoes (Solanum tuberosum L.) can be achieved by different pretreatments of the seed tubers. In factorial field trials in 2008–2010, two different pre-sprouting methods were evaluated: conventional pre-sprouting of tubers and pre-sprouting of tubers with stimulation of adventitious root formation (PR). The results were compared with those for untreated seed tubers stored at 4 °C until planting (control). One variety was included in three trials, and two varieties were included in one trial. The new PR method was intended to give faster development and tuber initiation than conventional pre-sprouting, which can be of value when the growing season is restricted or when early harvest is important. Plant emergence, leaf necrosis (as a measure of maturity) and incidence of late blight were assessed during the growing season. After harvest, tuber fresh weight, size and density were assessed. It was found that pre-sprouting treatments gave on average 7 days earlier emergence compared with the control. Necrosis began earlier in pre-sprouted treatments in all cases except for the late variety Sarpo Mira. In 2008 and 2009 potato late blight struck late, after onset of senescence, but in 2010 it struck earlier and the pre-sprouted treatments proved more susceptible than the control. Total tuber yield was 7–24% higher on average in all pre-sprouted treatments in the different field trials. Tests on time of harvest showed that the advantage for the pre-sprouting treatments was maintained during the season, but the difference with the control decreased with time. When the different pre-sprouted treatments were compared, the new PR method proved to be not better than conventional pre-sprouting.     

Influence de la durée de prégermination et de l'époque de plantation sur le rendement et la qualité technologique de la pomme de terre. 1. Effets sur le rendement en tubercules et amidon

Résumé Un essai de prégermination et de plantations différées a été effectué de 1973 à 1977 avec trois variétés de pommes de terre qui présentent une bonne aptitude pour la transformation technologique. La prégermination des plants pendant 6 et 12 semaines permet d'avancer la levée des cultures de 10–12 jours par rapport à l'utilisation de plants non prégermés. Un effet favorable de la prégermination sur le rendement a été particulièrement observé pour la variété tardive Maritta, avec 10–15% d'augmentation. L'effet a été moins marqué pour les variétés Bintje et Saturna. La prégermination a également permis d'augmenter la proportion de grands tubercules. La plantation à fin avril-début mai para?t être légèrement plus favorable au rendement que celle effectuée un mois plus t?t. Ni la prégermination, ni l'époque de plantation n'ont permis d'influencer la teneur en amidon des tubercules.

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Summary Field experiments with chitted seed planted on different dates were carried out from 1973 to 1977 (Fig. 1–3) with cvs. Bintje, Maritta and Saturna whose tubers could be used industrially. Two chitting treatments of 6 and 12 weeks duration were compared with unchitted seed stored at 4°C until planting time. The treated seed were planted on two dates with a one month interval (Table 1). The mean duration of emergence over 5 years of trials was 25–30 days for chitted seed that was planted early. Non-chitted seed stored at low temperature emerged after 37–39 days. The equivalent emergence periods for seed planted late, in early May, were 15–16 days and 25–27 days respectively (Fig. 4). Yield increases of 12–15% were obtained with chitted seed of the mid-late cv. Maritta but no significant differences in yield were found with Bintje and Saturna. Chitting also favoured an increase in the proportion of large tubers (Fig. 5). Yield was slightly higher in crops planted late than in those planted a month earlier (Fig. 5). Tuber starch content was affected neither by chitting nor by planting time (Fig. 6). In these studies, yield was more affected by growth conditions than by seed preparation.

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Zusammenfassung W?hrend den Jahren 1973–1977 (Abb. 1–3) wurde an der Station fédérale de recherches agronomiques de Changins/Nyon ein Vorkeim- und Pflanzzeitversuch mit den Kartoffelsorten Bintje, Maritta und Saturna, welche für die technologische Verarbeitung bestimmt waren, durchgeführt. Drei Lagerungsverfahren des Saatguts wurden geprüft, wobei 12 und 6 Wochen vorgekeimtes mit nicht vorgekeimtem, kühlgelagertem (4°C) Saatgut verglichen wurde. Das Saatgut der drei Verfahren wurde an zwei Terminen ausgepflanzt (Tab. 1). Im Durchschnitt der 5 Jahre ben?tigte bei der frühen Pflanzung anfangs April das vorgekeimte Saatgut 25–30 Tage zum Auflaufen, das kühlgelagerte, nicht vorgekeimte hingegen 37–39 Tage. Bei der sp?ten Pflanzung anfangs Mai waren es nur noch 15–16 und 25–27 Tage für gleich behandeltes Saatgut (Abb. 4). Die Vorkeimung erlaubte eine Ertragssteigerung von 12–15% bei der mittelsp?ten Sorte Maritta, hingegen waren die Ertragsunterschiede bei Bintje und Saturna nicht signifikant (Abb. 5). Der Anteil an grossen Knollen wurde durch die Vorkeimung ebenfalls gesteigert (Abb. 5). Die sp?te Pflanzung führte zu einer leichten Ertragserh?hung gegenüber der frühen. Der St?rkegehalt der Knollen wurde weder durch die Vorkeimung noch durch den Pflanztermin beeinflusst (Abb. 6). In diesem Versuch übte die Witterung einen gr?sseren Einfluss auf den Ertrag aus als die geprüften anbautechnischen Massnahmen.

     

The quality of seed tubers multiplied in the Golan Heights for the spring season in Israel

Summary Seed tubers grown in the northern mountain region — the Golan Heights — were as productive as imported seed tubers. In cvs. Blanka and Désirée, both the locally grown and the imported seed tubers were similar when yield components and tuber fresh weight are considered. In Up-to-Date, the locally grown seeds produced higher yields of marketable tubers (over 60 g/tuber) than those imported. Désirée seed tubers grown for two generations in the Golan Heights did not differ significantly in their productivity as compared with common Golan seeds and with imported ones. Seed tubers harvested from plots which were protected by means of white coarse nets and weekly sprays with insecticides, were virtually virus-free and were used for growing commercial seeds in the Golan. The use of this method for seed multiplication is suggested. Contribution from the Agricultural Research Organization. The Volcani Center, Bet Dagan, Israel. No 137-E, 1981 Series.     

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.     

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.     

Techniques for using sprouts for potato production in the tropics

A series of experiments were conducted in Vietnam to develop a system whereby detached sprouts from physiologically old green sprouted seed tubers could be used to grow potatoes. Three node segments from the mid or basal portion of the detached sprout produced the greatest percentage of shoots and roots. Growth was best in a medium of equal parts of sub-soil, pig manure and brick kiln ash. Sprout cuttings produced plantlets ready for transplanting in 14–20 days with mean daily temperatures of 22 to 24°C. When transplanted in mid-November, yields from sprout cuttings in field experiments were 10 to 18 t/ha which were 33% lower than from healthy seed tubers but more than the national average yield using degenerated seed tubers. Tubers produced by plants grown from sprout stored well and gave good yields when replanted the following year. Requests for reprints to International Potato Center, Box 933, Manila, Philippines.     

The effect of water stress on the yielding capacity of potato crops and subsequent performance of seed tubers

Summary The effect of water stress on yielding capacity of potatoes was studied in 3 years using four different levels of soil water potential (0.7, 1.9, 3.4 and 7.8 atm.) in experiments in specially adapted structures that excluded uncontrolled water supply. Seed tubers from these crops were planted in the following years to investigate effects of water stress on their subsequent performance. Limited soil moisture availability decreased yield and the number and size of tubers. The growing period was shortened by 1–4 weeks and dormancy period by 2–8 weeks. In the following year, seed produced under conditions of moisture stress gave plants with 20% fewer stems. 24–33% less yield, 18–22% fewer tubers and 19–22% fewer large tubers than plants from seed produced under abundant water supply. It is concluded that the yield potential of seed tubers can be improved by careful attention to the availability of soil moisture during their production.     

Sugar content and dry matter in potatoes stored under fluctuating temperatures in non-refrigerated stores in Greece

Summary Potatoes were stored in non-refrigerated stores in the Marmarini area (central Greece, altitude about 50 m) and in the Polymylos area (northern Greece, altitude about 900m). In Polymylos, the tubers (cvs Fina and Spunta) were harvested in October 1985 and stored until April 1986; the temperature in the store fluctuated between −1°C and 14°C (mostly between 3°C and 7°C). In Marmarini, the tubers (cvs Sebago and Spunta) were harvested in December 1985 and stored until April 1986; the temperature in the store fluctuated between 0°C and 18°C (mostly between 5°C and 10°C). Every 1–2 months tubers were analysed for dry matter (DM), total sugars (TS) and reducing sugars (RS). In Marmarini, a significant increase of TS and RS was found in both cultivars from December to January, followed thereafter by a significant decrease. In Polymylos, a continuous (from November to April) increase in TS and RS was observed in cv. Fina while in cv. Spunta the sugars increased only until January, followed thereafter until April by a significant decrease.     

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.     

Improving production and health of seed potato stocks in Italy

Summary When nodal explants from sprouts grown from virus-free tubers of ten cultivars were propagated on half-strength Murashige and Skoog medium, cvs Arsy, Nicola, Kennebec and Spunta grew best. Rooted plantlets, 5–8 cm tall, were transplanted from culture vessels into pots containing soil, vermiculite and sand. They were weaned by growing in a glasshouse for about three weeks. Over 90% of the plantlets survived and these were then planted in the field and protected against aphids by a double screen (a large tunnel covering four adjacent small tunnels) and chemical treatments. Prebasic seed tubers thus obtained were virus-free and production ranged from 49.9 t.ha⁻¹ (‘Monalisa’) to 27.1 t.ha⁻¹ (‘Majestic’). A survey showed that ‘elite’ (near virus-free) seed could be produced from prebasic seed by early planting and early haulm killing regardless of location, but late planting on the plains and normal planting dates on the mountains resulted in 1 to 5% virus infection levels acceptable only for certified seed.     

超干长期贮藏对不同类型水稻种子生活力和活力的影响

采用硅胶干燥的方法对籼稻、粳稻和杂交籼稻3种类型的种子进行超干处理,并经过9年室温密闭贮藏。通过发芽试验、过氧化物酶（POD）和超氧歧化酶（SOD）活性测定表明,粳稻秀水37的种子不适宜室温下长期贮藏,籼稻（浙733）和杂交籼稻（协优46、汕优63）种子在含水量分别降至2.7%和5.0%左右时生活力和活力最高,发芽率达到80%左右,其中杂交籼稻种子耐藏性更好,发芽率只下降了8%~9%;但在过高或过低的含水量条件下,种子的生活力和活力均明显下降。POD活性与种子生活力和活力呈正相关。     

Reduction of potato damage during grading by radiant heating

Summary The effect of using radiant heat to quickly warm potatoes and reduce damage in handling after cold storage was investigated. Two treatments were investigated: tubers dropped 350 mm with no radiant heat applied, and tubers dropped with radiant heat applied. Both treatments were compared with a control set of tubers which were taken directly out of store. The mean damage index per tuber was significantly reduced following radiant heat treatment although there were cultivar and size variations. The temperature profile under radiant heat was also measured which showed an increase in the outside flesh temperature of 8–12°C depending on tuber colour.     

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.     

The effect of controlled atmosphere storage at 4°C on crisp colour and on sprout growth,rotting and weight loss of potato tubers

Summary After three weeks curing at 10°C, potato tubers cv. Record were stored at 4°C under different controlled atmospheres (CA) for six months to study the effect on crisp fry colour, sprout growth and rotting. Combinations of low levels of CO₂ (0.7–1.8%) and low levels of O₂ (2.1–3.9%) gave a significantly lighter crisp colour, low sprout growth and fewer rotted tubers compared with 0.9% CO₂ and 21.0% O₂. Tubers stored in these conditions. showed a significantly higher weight loss and shrinkage after reconditioning. High CO₂: low O₂ combinations during storage completely inhibited sprout growth and caused the darkest crisp colour, but after reconditioning tubers gave the same level of sprouting and crisps as light as the other CA combinations. Furthermore these combinations, especially CO₂ at 10 or 15%, increased the onset of rotting. Also our results showed that at low concentrations of CO₂ (0.7–1.6%), and low O₂ (2–2.4%) there was an increase in tuber rotting.     

The effect of potato seed tuber age and soil temperature on the phenomenon of non-emergence

Summary In three experiments seed tubers of cvs Jaerla, Bintje and Alpha, stored at 12 °C in the dark, were planted in glasshouses on various dates at soil temperatures varying from 8 °C to 28 °C to study the phenomenon of ‘non-emergence’ with ageing seed tubers. In general the tubers were desprouted before planting. At all plantings cv. Alpha produced normal plants. The cvs Jaerla and Bintje, however, showed high proportions of the ‘little potato’ phenomenon when planted in cold soil, and high proportions of decayed tubers more frequently in warm soil. When using physiologically older seed at later planting dates, both the range of soil temperatures became wider and the proportions of seed tubers experiencing both ‘little potato’ and decay increased.     

High temperature storage of potato (Solanum tuberosum L.) for processing — a feasibility study

Tubers of three potato cultivars were stored at room temperature (20–39°C, 30–75% RH), under an insulated storage run on passive evaporative cooling (16–30°C, 70–90% RH) and a refrigerated storage (2–4°C, 90–95% RH) for 14 weeks and studied periodically for storage losses, reducing sugar content and dry matter percent of tubers, in order to explore the possibility of storing potatoes for processing at higher temperatures. Physiological losses in tubers remained less than 10% until 12 weeks of storage under evaporatively cooled storage. Reducing sugar contents increased by only 52.4–242.1% in tubers stored in evaporatively cooled storage as compared to 90.5–484.2% increase in tubers stored in refrigerated storage until 14 weeks. Potatoes stored in evaporatively cooled store were more suitable for processing into chips and french fries due to lower physiological losses and lower reducing sugar content of tubers.     

Osmotic priming of true potato seed: Effects of seed age

Summary The effects on germination and early seedling growth of presowing true potato seed in water or gibberellic acid (GA) at 1500 ppm and of priming in −1.0, −1.25 and −1.5 MPa solutions of KNO₃+K₃PO₄ were studied using 30, 18, 6 and 3/4 month-old seed. The influence of light during presowing on the effectiveness of treatments was also investigated. Overall, priming in the light at −1.0 MPa was the most, and GA the least successful treatment for enhancing emergence and subsequent seedling growth. Though GA increased final emergence from about 20 to 70% in the most recently harvested lot (3/4 mo), the rate and extent of final germination or emergence in this dormant seed was still much lower than that of the nondormant lots (6–30 mo), especially when the latter were primed. For all lots, dry weight per seedling was 40% lower in dormant than in nondormant seed, and 20% higher when seeds were primed at −1.0 MPa than when GA treated. In conclusion, the use of nondormant seed may be a requirement for both effective priming and sowing of potato crops via true seed.